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DESCRIPTION
The WM8776 is a high performance, stereo audio codec with five channel input selector. The WM8776 is ideal for surround sound processing applications for home hi-fi, DVD-RW and other audio visual equipment. A stereo 24-bit multi-bit sigma delta ADC is used with a five stereo channel input mixer. Each ADC channel has programmable gain control with automatic level control. Digital audio output word lengths from 16-32 bits and sampling rates from 32kHz to 96kHz are supported. A stereo 24-bit multi-bit sigma delta DAC is used with digital audio input word lengths from 16-32 bits and sampling rates from 32kHz to 192kHz. The DAC has an input mixer allowing an external analogue signal to be mixed with the DAC signal. There are also Headphone and line outputs, with volume controls for the headphones. The WM8776 supports fully independent sample rates for the ADC and DAC. The audio data interface supports I2S, left justified, right justified and DSP formats. The device is controlled in software via a 2 or 3 wire serial interface, selected by the MODE pin, which provides access to all features including channel selection, volume controls, mutes, and de-emphasis facilities. The device is available in a 48-pin TQFP package.
WM8776
24-bit, 192kHz Stereo Codec with 5 Channel I/P Multiplexer
FEATURES
* Audio Performance - 108dB SNR (`A' weighted @ 48kHz) DAC - 102dB SNR (`A' weighted @ 48kHz) ADC DAC Sampling Frequency: 32kHz - 192kHz ADC Sampling Frequency: 32kHz - 96kHz Five stereo ADC inputs with analogue gain adjust from +24dB to -21dB in 0.5dB steps Programmable Limiter or Automatic Level Control (ALC) Stereo DAC with independent analogue and digital volume controls Stereo Headphone and Line Output 3-Wire SPI Compatible or 2-Wire Software Serial Control Interface Master or Slave Clocking Mode Programmable Audio Data Interface Modes - I2S, Left, Right Justified or DSP - 16/20/24/32 bit Word Lengths Analogue Bypass Path Feature Selectable AUX input to the volume controls 2.7V to 5.5V Analogue, 2.7V to 3.6V Digital supply Operation
* * * * * * * * *
* * *
APPLICATIONS
* * Surround Sound AV Processors and Hi-Fi systems DVD-RW
DACREFN DACREFP VMIDDAC
BLOCK DIAGRAM
ADCREFGND ADCMCLK ADCREFP VMIDADC AGND AVDD
ADCBCLK DOUT ADCLRC DACMCLK DACBCLK DACLRC DIN
AINOPL AINVGL VOUTL AIN1L AIN1R AIN2L AIN2R AIN3L AIN3R AIN4L AIN4R AIN5L AIN5R VOUTR INPUT MIXER AUDIO INTERFACE STEREO ADC VMID
ALC
ZFLAGL ZFLAGR
HPVDD STEREO DAC
LOW PASS FILTERS
AND DIGITAL FILTERS
HPOUTL HPOUTR HPGND
z
AINVGR AINOPR
CONTROL INTERFACE
W WM8776
AUXL AUXR
DVDD
MODE
DGND
CE
CL
WOLFSON MICROELECTRONICS plc w :: www.wolfsonmicro.com
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Product Preview, June 2004, Rev 1.91 Copyright 2004 Wolfson Microelectronics plc
WM8776 TABLE OF CONTENTS
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DESCRIPTION .......................................................................................................1 FEATURES.............................................................................................................1 APPLICATIONS .....................................................................................................1 BLOCK DIAGRAM .................................................................................................1 TABLE OF CONTENTS .........................................................................................2 PIN CONFIGURATION...........................................................................................3 ORDERING INFORMATION ..................................................................................3 PIN DESCRIPTION ................................................................................................4 ABSOLUTE MAXIMUM RATINGS.........................................................................5 ELECTRICAL CHARACTERISTICS ......................................................................6
TERMINOLOGY ............................................................................................................ 7
MASTER CLOCK TIMING......................................................................................8
DIGITAL AUDIO INTERFACE - MASTER MODE ......................................................... 9 DIGITAL AUDIO INTERFACE - SLAVE MODE .......................................................... 10 3-WIRE MPU INTERFACE TIMING ............................................................................ 11 CONTROL INTERFACE TIMING - 2-WIRE MODE .................................................... 12
DEVICE DESCRIPTION.......................................................................................13
INTRODUCTION ......................................................................................................... 13 AUDIO DATA SAMPLING RATES............................................................................... 14 ZERO DETECT ........................................................................................................... 15 POWERDOWN MODES ............................................................................................. 15 POWER-ON-RESET ................................................................................................... 16 DIGITAL AUDIO INTERFACE ..................................................................................... 17 CONTROL INTERFACE OPERATION ........................................................................ 21 CONTROL INTERFACE REGISTERS ........................................................................ 23 LIMITER / AUTOMATIC LEVEL CONTROL (ALC) ...................................................... 32 REGISTER MAP ......................................................................................................... 39
DIGITAL FILTER CHARACTERISTICS ...............................................................47
DAC FILTER RESPONSES......................................................................................... 47 ADC FILTER RESPONSES......................................................................................... 48 ADC HIGH PASS FILTER ........................................................................................... 49 DIGITAL DE-EMPHASIS CHARACTERISTICS........................................................... 50
APPLICATIONS INFORMATION .........................................................................51
EXTERNAL CIRCUIT CONFIGURATION ................................................................... 51
RECOMMENDED EXTERNAL COMPONENTS ..................................................52 PACKAGE DIMENSIONS ....................................................................................54
ADDRESS: .................................................................................................................. 55
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WM8776
PIN CONFIGURATION
ORDERING INFORMATION
DEVICE WM8776EFT/V WM8776EFT/RV TEMPERATURE RANGE -25 to +85 C -25 to +85 C -25 to +85oC -25 to +85oC
o o
PACKAGE 48-pin TQFP 48-pin TQFP (tape and reel) 48-pin TQFP (lead free) 48-pin TQFP (lead free, tape and reel)
MOISTURE SENSITIVITY LEVEL MSL2 MSL2 MSL2 MSL2
PEAK SOLDERING TEMPERATURE 240C 240C 260C 260C
WM8776SEFT/V WM8776SEFT/RV Note: Reel quantity = 2,200
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WM8776 PIN DESCRIPTION
PIN 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 NAME AIN2L AIN1R AIN1L DACBCLK DACMCLK DIN DACLRC ZFLAGR ZFLAGL ADCBCLK ADCMCLK DOUT ADCLRC DGND DVDD MODE CE DI CL HPOUTL HPGND HPVDD HPOUTR NC NC VOUTL VOUTR VMIDDAC DACREFN DACREFP AUXR AUXL VMIDADC ADCREFGND ADCREFP AVDD AGND AINVGR AINOPR AINVGL AINOPL AIN5R AIN5L AIN4R AIN4L AIN3R AIN3L AIN2R TYPE Analogue Input Analogue Input Analogue Input Digital input/output Digital input Digital Input Digital input/output Open Drain output Open Drain output Digital input/output Digital input Digital output Digital input/output Supply Supply Digital input Digital input Digital input Digital input Analogue Output Supply Supply Analogue Output Not bonded Not bonded Analogue output Analogue output Analogue output Analogue input Analogue input Analogue input Analogue input Analogue Output Supply Analogue Output Supply Supply Analogue Input Analogue Output Analogue Input Analogue Output Analogue Input Analogue Input Analogue Input Analogue Input Analogue Input Analogue Input Analogue Input DAC channel left output DAC channel right output DAC midrail decoupling pin ; 10uF external decoupling DAC negative reference input DAC positive reference input DAC mixer right channel input DAC mixer left channel input DESCRIPTION Channel 2 left input multiplexor virtual ground Channel 1 right input multiplexor virtual ground Channel 1 left input multiplexor virtual ground DAC audio interface bit clock
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Master DAC clock; 256, 384, 512 or 768fs (fs = word clock frequency) DAC data input DAC left/right word clock DAC Right Zero Flag output (external pull-up resistor required) DAC Left Zero Flag output (external pull-up resistor required) ADC audio interface bit clock ADC audio interface master clock ADC data output ADC left/right word clock Digital negative supply Digital positive supply Control interface mode select (5V tolerant) Serial interface Latch signal (5V tolerant) Serial interface data (5V tolerant) Serial interface clock (5V tolerant) Headphone left channel output Headphone negative supply Headphone positive supply Headphone right channel output
ADC midrail divider decoupling pin; 10uF external decoupling ADC negative supply and substrate connection ADC positive reference decoupling pin; 10uF external decoupling Analogue positive supply Analogue negative supply and subVstrate connection Right channel multiplexor virtual ground Right channel multiplexor output Left channel multiplexor virtual ground Left channel multiplexor output Channel 5 right input multiplexor virtual ground Channel 5 left input multiplexor virtual ground Channel 4 right input multiplexor virtual ground Channel 4 left input multiplexor virtual ground Channel 3 right input multiplexor virtual ground Channel 3 left input multiplexor virtual ground Channel 2 right input multiplexor virtual ground
Note : Digital input pins have Schmitt trigger input buffers and pins 16, 17, 18 and 19 are 5V tolerant.
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WM8776
ABSOLUTE MAXIMUM RATINGS
Absolute Maximum Ratings are stress ratings only. Permanent damage to the device may be caused by continuously operating at or beyond these limits. Device functional operating limits and guaranteed performance specifications are given under Electrical Characteristics at the test conditions specified. ESD Sensitive Device. This device is manufactured on a CMOS process. It is therefore generically susceptible to damage from excessive static voltages. Proper ESD precautions must be taken during handling and storage of this device. Wolfson tests its package types according to IPC/JEDEC J-STD-020B for Moisture Sensitivity to determine acceptable storage conditions prior to surface mount assembly. These levels are: MSL1 = unlimited floor life at <30C / 85% Relative Humidity. Not normally stored in moisture barrier bag. MSL2 = out of bag storage for 1 year at <30C / 60% Relative Humidity. Supplied in moisture barrier bag. MSL3 = out of bag storage for 168 hours at <30C / 60% Relative Humidity. Supplied in moisture barrier bag. CONDITION Digital supply voltage Analogue supply voltage Voltage range digital inputs (DI, CL, CE and MODE) Voltage range digital inputs (MCLK, DIN, ADCLRC, DACLRC, ADCBCLK and DACBCLK) Voltage range analogue inputs Master Clock Frequency Operating temperature range, TA Storage temperature Notes: 1. Analogue and digital grounds must always be within 0.3V of each other. -25C -65C MIN -0.3V -0.3V DGND -0.3V DGND -0.3V AGND -0.3V MAX +3.63V +7V +7V DVDD + 0.3V AVDD +0.3V 37MHz +85C +150C
RECOMMENDED OPERATING CONDITIONS
PARAMETER Digital supply range Analogue supply range Ground SYMBOL DVDD AVDD, HPVDD, DACREFP AGND, DGND, DACREFN, ADCREFGND -0.3 TEST CONDITIONS MIN 2.7 2.7 0 TYP MAX 3.6 5.5 UNIT V V V
Difference DGND to AGND Note: digital supply DVDD must never be more than 0.3V greater than AVDD.
0
+0.3
V
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WM8776 ELECTRICAL CHARACTERISTICS
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Test Conditions AVDD = 5V, DVDD = 3.3V, AGND = 0V, DGND = 0V, TA = +25oC, fs = 48kHz, MCLK = 256fs unless otherwise stated. PARAMETER Digital Logic Levels (TTL Levels) Input LOW level Input HIGH level Output LOW Output HIGH Analogue Reference Levels Reference voltage Potential divider resistance 0dBFs Full scale output voltage SNR (Note 1,2) SNR (Note 1,2) Dynamic Range (Note 2) Total Harmonic Distortion (THD) DAC channel separation Power Supply Rejection Ratio PSRR 1kHz 100mVpp 20Hz to 20kHz 100mVpp Headphone Buffer Maximum Output voltage Max Output Power (Note 4) SNR (Note 1,2) Headphone analogue Volume Gain Step Size Headphone analogue Volume Gain Range Headphone analogue Volume Mute Attenuation Total Harmonic Distortion +Noise THD+N 1kHz Input 1kHz Input, 0dB gain 1kHz, RL = 32 @ Po = 10mW rms 1kHz, RL = 32 @ Po = 20mW rms Power Supply Rejection Ratio ADC Performance Input Signal Level (0dB) SNR (Note 1,2) SNR (Note 1,2) A-weighted, 0dB gain @ fs = 48kHz A-weighted, 0dB gain @ fs = 96kHz 64 x OSR A-weighted, -60dB full scale input 1kHz, 0dBFs 1.0 x AVDD/5 102 100 Vrms dB dB PSRR 20Hz to 20kHz, without supply decoupling Po RL = 32 RL = 16 A-weighted 85 0.5 -73 100 -80 0.01 -77 0.014 -40 -60 0.1 -40 1.0 0.9 25 50 92 1 1.5 +6 Vrms mW mW dB dB dB dB dB % dB % dB DNR A-weighted, @ fs = 48kHz A-weighted @ fs = 96kHz A-weighted, -60dB full scale input 1kHz, 0dBFs VVMID RVMID AVDD/2 50k 1.0 x AVDD/5 108 108 108 -97 100 50 45 -90 V Vrms dB dB dB dB dB dB dB VIL VIH VOL VOH IOL=1mA IOH=1mA 0.9 x DVDD 2.0 0.1 x DVDD 0.8 V V V V SYMBOL TEST CONDITIONS MIN TYP MAX UNIT
DAC Performance (Load = 10k , 50pF)
Dynamic Range (note 2) Total Harmonic Distortion (THD)
102 -90 -80
dB DB
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WM8776
Test Conditions AVDD = 5V, DVDD = 3.3V, AGND = 0V, DGND = 0V, TA = +25oC, fs = 48kHz, MCLK = 256fs unless otherwise stated. 1kHz, -3dBFs ADC Channel Separation Programmable Gain Step Size Programmable Gain Range (Analogue) Programmable Gain Range (Digital) Mute Attenuation (Note 6) Power Supply Rejection Ratio PSRR 1kHz Input 1kHz Input 1kHz Input, 0dB gain 1kHz 100mVpp 20Hz to 20kHz 100mVpp 0dB Full scale output voltage SNR (Note 1) THD Power Supply Rejection Ratio PSRR 1kHz, 0dB 1kHz, -3dB 1kHz 100mVpp 20Hz to 20kHz 100mVpp Mute Attenuation Supply Current Analogue supply current Digital supply current AVDD = 5V DVDD = 3.3V 48 8 mA mA 1kHz, 0dB 90 1kHz Input 0.25 -21 -103 76 50 45 -95 90 0.5 0.75 +24 -21.5 -85 dB dB dB dB dB dB dB dB
Analogue input (AIN) to Analogue output (VOUT) (Load=10k , 50pF, gain = 0dB) Bypass Mode 1.0 x AVDD/5 100 -90 -95 50 45 100 Vrms dB dB dB dB dB dB
Notes: 1. 2. Ratio of output level with 1kHz full scale input, to the output level with all zeros into the digital input, measured `A' weighted. All performance measurements done with 20kHz low pass filter, and where noted an A-weight filter. Failure to use such a filter will result in higher THD+N and lower SNR and Dynamic Range readings than are found in the Electrical Characteristics. The low pass filter removes out of band noise; although it is not audible it may affect dynamic specification values. VMID decoupled with 10uF and 0.1uF capacitors (smaller values may result in reduced performance). Harmonic distortion on the headphone output decreases with output power. All performance measurement done using certain timings conditions (Please refer to section `Digital Audio Interface'). A better MUTE Attenuation can be achieved if the ADC gain is set to minimum.
3. 4. 5. 6.
TERMINOLOGY
1. 2. Signal-to-noise ratio (dB) - SNR is a measure of the difference in level between the full scale output and the output with no signal applied. (No Auto-zero or Automute function is employed in achieving these results). Dynamic range (dB) - DNR is a measure of the difference between the highest and lowest portions of a signal. Normally a THD+N measurement at 60dB below full scale. The measured signal is then corrected by adding the 60dB to it. (e.g. THD+N @ -60dB= -32dB, DR= 92dB). THD+N (dB) - THD+N is a ratio, of the rms values, of (Noise + Distortion)/Signal. Stop band attenuation (dB) - Is the degree to which the frequency spectrum is attenuated (outside audio band). Channel Separation (dB) - Also known as Cross-Talk. This is a measure of the amount one channel is isolated from the other. Normally measured by sending a full scale signal down one channel and measuring the other. Pass-Band Ripple - Any variation of the frequency response in the pass-band region.
3. 4. 5. 6.
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WM8776
MASTER CLOCK TIMING
tMCLKL MCLK tMCLKH tMCLKY
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Figure 1 Master Clock Timing Requirements Test Conditions o AVDD = 5V, DVDD = 3.3V, AGND = 0V, AGND, DGND = 0V, TA = +25 C, fs = 48kHz, ADC/DACMCLK = 256fs unless otherwise stated. PARAMETER System Clock Timing Information
ADC/DACMCLK System clock pulse width high ADC/DACMCLK System clock pulse width low ADC/DACMCLK System clock cycle time ADC/DACMCLK Duty cycle
SYMBOL tMCLKH tMCLKL tMCLKY
TEST CONDITIONS
MIN 11 11 28 40:60
TYP
MAX
UNIT ns ns ns
60:40
Table 1 Master Clock Timing Requirements
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WM8776
DIGITAL AUDIO INTERFACE - MASTER MODE
DACBCLK ADCBCLK ADCLRC WM8776 CODEC DACLRC DOUT DIN DVD Controller
Figure 2 Audio Interface - Master Mode
ADCBCLK/ DACBCLK (Output) ADCLRC/ DACLRC (Outputs) tDL
tDDA DOUT
DIN tDST tDHT
Figure 3 Digital Audio Data Timing - Master Mode Test Conditions AVDD = 5V, DVDD = 3.3V, AGND, DGND = 0V, TA = +25oC, Master Mode, fs = 48kHz, ADC/DACMCLK = 256fs unless otherwise stated. PARAMETER ADC/DACLRC propagation delay from ADC/DACBCLK falling edge DOUT propagation delay from ADCBCLK falling edge DIN setup time to DACBCLK rising edge DIN hold time from DACBCLK rising edge SYMBOL tDL TEST CONDITIONS MIN 0 TYP MAX 10 UNIT ns
Audio Data Input Timing Information
tDDA tDST tDHT
0 10 10
10
ns ns ns
Table 2 Digital Audio Data Timing - Master Mode
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WM8776
DIGITAL AUDIO INTERFACE - SLAVE MODE
DACBCLK ADCBCLK WM8776 ADCLRC CODEC DACLRC DOUT DIN DVD Controller
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Figure 4 Audio Interface - Slave Mode
tBCH ADCBCLK/ DACBCLK tBCL
tBCY
DACLRC/ ADCLRC tDS DIN tDD DOUT tDH tLRH tLRSU
Figure 5 Digital Audio Data Timing - Slave Mode Test Conditions AVDD = 5V, DVDD = 3.3V, AGND = 0V, DGND = 0V, TA = +25oC, Slave Mode, fs = 48kHz, ADC/DACMCLK = 256fs unless otherwise stated. PARAMETER ADC/DACBCLK cycle time ADC/DACBCLK pulse width high ADC/DACBCLK pulse width low DACLRC/ADCLRC set-up time to ADC/DACBCLK rising edge DACLRC/ADCLRC hold time from ADC/DACBCLK rising edge DIN set-up time to DACBCLK rising edge DIN hold time from DACBCLK rising edge DOUT propagation delay from ADCBCLK falling edge SYMBOL tBCY tBCH tBCL tLRSU TEST CONDITIONS MIN 50 20 20 10 TYP MAX UNIT ns ns ns ns
Audio Data Input Timing Information
tLRH
10
ns
tDS tDH tDD
10 10 0 10
ns ns ns
Table 3 Digital Audio Data Timing - Slave Mode Note: ADCLRC and DACLRC should be synchronous with MCLK, although the WM8776 interface is tolerant of phase variations or jitter on these signals.
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WM8776
3-WIRE MPU INTERFACE TIMING
tCSL CE tSCY tSCH CL tSCL tSCS tCSS tCSH
DI tDSU tDHO
LSB
Figure 6 SPI compatible (3-wire) Control Interface Input Timing (MODE=1) Test Conditions AVDD = 5V, DVDD = 3.3V, AGND, DGND = 0V, TA = +25oC, fs = 48kHz, MCLK = 256fs unless otherwise stated PARAMETER CL rising edge to CE rising edge CL pulse cycle time CL pulse width low CL pulse width high DI to CL set-up time CL to DI hold time CE pulse width low CE pulse width high CE rising to CL rising SYMBOL tSCS tSCY tSCL tSCH tDSU tDHO tCSL tCSH tCSS MIN 60 80 30 30 20 20 20 20 20 TYP MAX UNIT ns ns ns ns ns ns ns ns ns
Table 4 3-wire SPI compatible Control Interface Input Timing Information
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WM8776
CONTROL INTERFACE TIMING - 2-WIRE MODE
t3 t5 t3
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DI
t6 t2 t4 t8
CL
t1 t9 t7
Figure 7 Control Interface Timing - 2-Wire Serial Control Mode (MODE=0) Test Conditions AVDD = 5V, DVDD = 3.3V, AGND, DGND = 0V, TA = +25oC, fs = 48kHz, MCLK = 256fs unless otherwise stated PARAMETER Program Register Input Information CL Frequency CL Low Pulse-Width CL High Pulse-Width Hold Time (Start Condition) Setup Time (Start Condition) Data Setup Time DI, CL Rise Time DI, CL Fall Time Setup Time (Stop Condition) Data Hold Time Pulse width of spikes that will be suppressed Table 5 2-wire Control Interface Timing Information. t1 t2 t3 t4 t5 t6 t7 t8 t9 tps 0 600 900 5 0 600 1.3 600 600 100 300 300 400 kHz ns us ns ns ns ns ns ns ns ns SYMBOL MIN TYP MAX UNIT
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WM8776
DEVICE DESCRIPTION
INTRODUCTION
WM8776 is a complete 2-channel DAC, 2-channel ADC audio codec, with flexible input multiplexor including digital interpolation and decimation filters, multi-bit sigma delta stereo ADC, and switched capacitor multi-bit sigma delta DACs with analogue volume controls on each channel and output smoothing filters. It is available in a single package and controlled by either a 3-wire or 2-wire software interface. The 3-wire interface is compatible with the SPI standard. An analogue bypass path option is available, to allow stereo analogue signals from any of the 5 stereo inputs to be sent to the stereo outputs via the main volume controls. This allows a purely analogue input to analogue output high quality signal path to be implemented if required. The DAC and ADC have separate left/right clocks, bit clocks, master clocks and data I/Os. The Audio Interface may be configured to operate in either master or slave mode. In Slave mode ADCLRC, DACLRC, ADCBCLK and DACBCLK are all inputs. In Master mode ADCLRC, DACLRC, ADCBCLK and DACBCLK are outputs. The input multiplexor to the ADC is configured to allow large signal levels to be input to the ADC, using external resistors to reduce the amplitude of larger signals to within the normal operating range of the ADC. The ADC has an analogue input PGA and a digital gain control, accessed by one register write. The input PGA allows input signals to be gained up to +24dB and attenuated down to -21dB in 0.5dB steps. The digital gain control allows attenuation from -21.5dB to -103dB in 0.5dB steps. This allows the user maximum flexibility in the use of the ADC. The DAC has its own digital volume control, which is adjustable between 0dB and -127.5dB in 0.5dB steps. There is also an analogue volume control on the headphone outputs, which is adjustable between +6dB and -73dB in 1dB steps. The analogue and digital volume controls may be operated independently. In addition a zero cross detect circuit is provided for both analogue and digital volume controls. When analogue volume zero-cross detection is enabled the attenuation values are only updated when the input signal to the gain stage is close to the analogue ground level. The digital volume control detects a transition through the zero point before updating the volume. This minimises audible clicks and `zipper' noise as the gain values change. The DAC output incorporates an input selector and mixer allowing a signal to be either switched into the signal path in place of the DAC signal or mixed with the DAC signal before the volume control. Use of external resistors allows larger input levels to be accepted by the device, giving maximum user flexibility. Internal functionality is controlled by CE, CL, DI and MODE input pins. These are 5V tolerant with TTL input thresholds, allowing the WM8776 to used with DVDD = 3.3V and be controlled by a controller with 5V output. The MODE pin determines which of the two control interface modes is selected. Operation using system clock of 128fs, 192fs, 256fs, 384fs, 512fs or 768fs is provided. In Slave mode selection between clock rates is automatically controlled. In master mode the master clock to sample rate ratio is set by control bits ADCRATE and DACRATE. ADC and DAC may run at different rates and have their own bit clocks and master clocks. The audio data interface supports right, left and I2S interface formats along with a highly flexible DSP serial port interface.
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WM8776
AUDIO DATA SAMPLING RATES
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In a typical digital audio system there is only one central clock source producing a reference clock to which all audio data processing is synchronised. This clock is often referred to as the audio system's Master Clock. The WM8776 uses separate master clocks for the ADC and DAC. The external master system clocks can be applied directly through the ADCMCLK and DACMCLK input pins with no software configuration necessary. In a system where there are a number of possible sources for the reference clock it is recommended that the clock source with the lowest jitter be used to optimise the performance of the ADC and DAC. The master clock for WM8776 supports DAC and ADC audio sampling rates from 256fs to 768fs, where fs is the audio sampling frequency (DACLRC or ADCLRC) typically 32kHz, 44.1kHz, 48kHz or 96kHz (the DAC also supports operation at 128fs and 192fs and 192kHz sample rate). The master clock is used to operate the digital filters and the noise shaping circuits. In Slave mode the WM8776 has a master detection circuit that automatically determines the relationship between the master clock frequency and the sampling rate (to within +/- 32 system clocks). If there is a greater than 32 clocks error the interface is disabled and maintains the output level at the last sample. The master clock should be synchronised with ADCLRC/DACLRC for optical performance, although the WM8776 is tolerant of phase variations or jitter on this clock. Table 6 shows the typical master clock frequency inputs for the WM8776. The signal processing for the WM8776 typically operates at an oversampling rate of 128fs for both ADC and DAC. The exception to this for the DAC is for operation with a 128/192fs system clock, e.g. for 192kHz operation where the oversampling rate is 64fs. For ADC operation at 96kHz it is recommended that the user set the ADCOSR bit. This changes the ADC signal processing oversample rate to 64fs. SAMPLING RATE (DACLRC/ ADCLRC) 32kHz 44.1kHz 48kHz 96kHz 192kHz System Clock Frequency (MHz) 128fs 192fs 256fs 384fs 512fs 768fs
DAC ONLY 4.096 5.6448 6.144 12.288 24.576 6.144 8.467 9.216 18.432 36.864 8.192 11.2896 12.288 24.576 12.288 16.9340 18.432 36.864 16.384 22.5792 24.576 24.576 33.8688 36.864
Unavailable Unavailable
Unavailable Unavailable Unavailable Unavailable
Table 6 System Clock Frequencies Versus Sampling Rate In Master mode DACBCLK, ADCBCLK, DACLRC and ADCLRC are generated by the WM8776. The frequencies of ADCLRC and DACLRC are set by setting the required ratio of DACMCLK to DACLRC and ADCMCLK to ADCLRC using the DACRATE and ADCRATE control bits (Table 7). ADCRATE[2:0]/ DACRATE[2:0] 000 001 010 011 100 101 ADCMCLK/DACMCLK: ADCLRC/DACLRC RATIO 128fs (DAC Only) 192fs (DAC Only) 256fs 384fs 512fs 768fs
Table 7 Master Mode MCLK:ADCLRC/DACLRC Ratio Select
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WM8776
Table 8 shows the settings for ADCRATE and DACRATE for common sample rates and ADCMCLK/DACMCLK frequencies. SAMPLING RATE (DACLRC/ ADCLRC) System Clock Frequency (MHz) 128fs
DACRATE =000
192fs
DACRATE =001
256fs
ADCRATE/ DACRATE =010
384fs
ADCRATE/ DACRATE =011
512fs
ADCRATE/ DACRATE =100
768fs
ADCRATE/ DACRATE =101
32kHz 44.1kHz 48kHz 96kHz 192kHz
4.096 5.6448 6.144 12.288 24.576
6.144 8.467 9.216 18.432 36.864
8.192 11.2896 12.288 24.576
12.288 16.9340 18.432 36.864
16.384 22.5792 24.576
24.576 33.8688 36.864
Unavailable Unavailable
Unavailable Unavailable Unavailable Unavailable
Table 8 Master Mode ADC/DACLRC Frequency Selection ADCBCLK and DACBCLK are also generated by the WM8776. The frequency of ADCBCLK and DACBCLK depends on the mode of operation. In 128/192fs modes (DACRATE=000 or 001) BCLK = MCLK/2. In 256/384/512fs modes (ADCRATE/DACRATE=010 or 011 or 100) BCLK = MCLK/4. However if DSP mode is selected as the audio interface mode then BCLK=MCLK. Note that DSP mode cannot be used in 128fs mode for word lengths greater than 16 bits or in 192fs mode for word lengths greater than 24 bits.
ZERO DETECT
The WM8776 has a zero detect circuit for each DAC channel, which detects when 1024 consecutive zero samples have been input. The two zero flag outputs (ZFLAGL and ZFLAGR) may be programmed to output the zero detect signals (see Table 9) that may then be used to control external muting circuits. A `1' on ZFLAGL or ZFLAGR indicates a zero detect. The zero detect may also be used to automatically enable the PGA mute by setting IZD. The zero flag output may be disabled by setting DZFM to 00. The zero flag signal for each DAC channel will only be enabled if it is enabled as an input to the output summing stage. DZFM[1:0] 00 01 10 11 ZFLAGL Zero flag disabled Left channel zero Both channel zero Either channels zero ZFLAGR Zero flag disabled Right channel zero Both channel zero Either channel zero
Table 9 Zero Flag Output Select
POWERDOWN MODES
The WM8776 has powerdown control bits allowing specific parts of the WM8776 to be powered off when not being used. The 5-channel input source selector and input buffer may be powered down using control bit AINPD. When AINPD is set all inputs to the source selector (AIN1l/R to AIN5L/R) are switched to a buffered VMIDADC. Control bit ADCPD powers off the ADC and also the ADC input PGAs. The stereo DAC has a separate powerdown control bit, DACPD allowing the DAC and analogue output mixer to be powered off when not in use. This also switches the analogue outputs VOUTL/R to VMIDDAC to maintain a dc level on the output. Setting AINPD, ADCPD and DACPD will powerdown everything except the references VMIDADC, ADCREF and VMIDDAC. These may be powered down by setting PDWN. Setting PDWN will override all other powerdown control bits. It is recommended that AINPD, HPPD, ADCPD and DACPD are set before setting PDWN. The default is for all blocks to be enabled other than HPPD.
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WM8776
POWER-ON-RESET
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The WM8776 has an internal power-on-reset circuit. The reset phase is entered at power-up of supplies. The DAC and ADC DSP circuitry is also reset when their respective master clocks are stopped. Register values are maintained unless either a power-on-reset occurs or a software reset is written. A software reset will also cause a reset of the DAC and ADC DSP. Figure 8 shows the power-on-reset logic, and Figure 9 shows the reset release characteristics.
Figure 8 Circuit Diagram for Power-on-Reset
Figure 9 Timing Diagram for Power on Sequence
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Product Preview
WM8776
DIGITAL AUDIO INTERFACE
MASTER AND SLAVE MODES
The audio interface operates in either Slave or Master mode, selectable using the MS control bit. In both Master and Slave modes DIN is always an input to the WM8776 and DOUT is always an output. The default is Slave mode. In Slave mode (MS=0) ADCLRC, DACLRC, ADCBCLK and DACBCLK are inputs to the WM8776 (Figure 10). DIN and DACLRC are sampled by the WM8776 on the rising edge of DACBCLK, ADCLRC is sampled on the rising edge of ADCBCLK. ADC data is output on DOUT and changes on the falling edge of ADCBCLK. By setting control bit BCLKINV the polarity of ADCBCLK and DACBCLK may be reversed so that DIN and DACLRC are sampled on the falling edge of DACBCLK, ADCLRC is sampled on the falling edge of ADCBCLK and DOUT changes on the rising edge of ADCBCLK.
DACBCLK ADCBCLK WM8776 ADCLRC CODEC DACLRC DOUT DIN DVD Controller
Figure 10 Slave Mode In Master mode (MS=1) ADCLRC, DACLRC, ADCBCLK and DACBCLK are outputs from the WM8776 (Figure 11). ADCLRC, DACLRC, ADCBCLK and DACBCLK are generated by the WM8776. DIN is sampled by the WM8776 on the rising edge of DACBCLK so the controller must output DAC data that changes on the falling edge of DACBCLK. ADC data is output on DOUT and changes on the falling edge of ADCBCLK. By setting control bit BCLKINV, the polarity of ADCBCLK and DACBCLK may be reversed so that DIN is sampled on the falling edge of DACBCLK and DOUT changes on the rising edge of ADCBCLK.
DACBCLK ADCBCLK ADCLRC WM8776 CODEC DACLRC DOUT DIN DVD Controller
Figure 11 Master Mode
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WM8776
AUDIO INTERFACE FORMATS
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Audio data is applied to the internal DAC filters or output from the ADC filters, via the Digital Audio Interface. 5 popular interface formats are supported: * * * * * Left Justified mode Right Justified mode I2S mode DSP Early mode DSP Late mode
All 5 formats send the MSB first and support word lengths of 16, 20, 24 and 32 bits, with the exception of 32 bit right justified mode, which is not supported. In left justified, right justified and I2S modes, the digital audio interface receives DAC data on the DIN input and outputs ADC data on DOUT. Audio Data for each stereo channel is time multiplexed with ADCLRC/DACLRC indicating whether the left or right channel is present. ADCLRC/DACLRC is also used as a timing reference to indicate the beginning or end of the data words. In left justified, right justified and I2S modes; the minimum number of BCLKs per DACLRC/ADCLRC period is 2 times the selected word length. ADCLRC/DACLRC must be high for a minimum of word length BCLKs and low for a minimum of word length BCLKs. Any mark to space ratio on ADCLRC/DACLRC is acceptable provided the above requirements are met. In DSP early or DSP late mode, DACLRC is used as a frame sync signal to identify the MSB of the first word. The minimum number of DACBCLKs per DACLRC period is 2 times the selected word length. Any mark to space ratio is acceptable on DACLRC provided the rising edge is correctly positioned. The ADC data may also be output in DSP early or late modes, with ADCLRC used as a frame sync to identify the MSB of the first word. The minimum number of ADCBCLKs per ADCLRC period is 2 times the selected word length.
LEFT JUSTIFIED MODE
In left justified mode, the MSB of DIN is sampled by the WM8776 on the first rising edge of DACBCLK following a DACLRC transition. The MSB of the ADC data is output on DOUT and changes on the same falling edge of ADCBCLK as ADCLRC and may be sampled on the rising edge of ADCBCLK. ADCLRC and DACLRC are high during the left samples and low during the right samples (Figure 12).
1/fs
LEFT CHANNEL DACLRC/ ADCLRC DACBCLK/ ADCBCLK
RIGHT CHANNEL
DIN/ DOUT
1
2
3
n-2 n-1
n
1
2
3
n-2 n-1
n
MSB
LSB
MSB
LSB
Figure 12 Left Justified Mode Timing Diagram
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Product Preview
WM8776
RIGHT JUSTIFIED MODE
In right justified mode, the LSB of DIN is sampled by the WM8776 on the rising edge of DACBCLK preceding a DACLRC transition. The LSB of the ADC data is output on DOUT and changes on the falling edge of ADCBCLK preceding a ADCLRC transition and may be sampled on the rising edge of ADCBCLK. ADCLRC and DACLRC are high during the left samples and low during the right samples (Figure 13).
1/fs
LEFT CHANNEL DACLRC/ ADCLRC DACBCLK/ ADCBCLK
RIGHT CHANNEL
DIN/ DOUT
1
2
3
n-2 n-1
n
1
2
3
n-2 n-1
n
MSB
LSB
MSB
LSB
Figure 13 Right Justified Mode Timing Diagram
2
I S MODE
In I2S mode, the MSB of DIN is sampled by the WM8776 on the second rising edge of DACBCLK following a DACLRC transition. The MSB of the ADC data is output on DOUT and changes on the first falling edge of ADCBCLK following an ADCLRC transition and may be sampled on the rising edge of ADCBCLK. ADCLRC and DACLRC are low during the left samples and high during the right samples.
1/fs
LEFT CHANNEL DACLRC/ ADCLRC DACBCLK/ ADCBCLK
1 BCLK 1 BCLK 3 n-2 n-1 n 1 2 3
RIGHT CHANNEL
DIN/ DOUT
1
2
n-2 n-1
n
MSB
LSB
MSB
LSB
Figure 14 I S Mode Timing Diagram
2
DSP EARLY MODE
In DSP early mode, the MSB of DAC left data is sampled by the WM8776 on the second rising edge on DACBCLK following a DACLRC rising edge. DAC right data follows DAC channel left data (Figure 15).
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1 BCLK 1/fs
Product Preview
1 BCLK
DACLRC
DACBCLK
LEFT CHANNEL
RIGHT CHANNEL
NO VALID DATA
DIN
1
2
n-1
n
1
2
n-1
n
MSB
Word Length (WL)
LSB
Figure 15 DSP Early Mode Timing Diagram - DAC Data Input The MSB of the left channel ADC data is output on DOUT and changes on the first falling edge of ADCBCLK following a low to high ADCLRC transition and may be sampled on the rising edge of ADCBCLK. The right channel ADC data is contiguous with the left channel data (Figure 16)
1 BCLK 1/fs 1 BCLK
ADCLRC
ADCBCLK
LEFT CHANNEL
RIGHT CHANNEL
NO VALID DATA
DOUT
1
2
n-1
n
1
2
n-1
n
MSB
Word Length (WL)
LSB
Figure 16 DSP Early Mode Timing Diagram - ADC Data Output
DSP LATE MODE
In DSP late mode, the MSB of DAC left data is sampled by the WM8776 on the first DACBCLK rising edge following a DACLRC rising edge. DAC right follow DAC left data (Figure 17).
1/fs
DACLRC
DACBCLK
LEFT CHANNEL
RIGHT CHANNEL
NO VALID DATA
DIN
1
2
n-1
n
1
2
n-1
n
1
MSB
Word Length (WL)
LSB
Figure 17 DSP Late Mode Timing Diagram - DAC Data Input
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Product Preview
WM8776
The MSB of the left channel ADC data is output on DOUT and changes on the same falling edge of ADCBCLK as the low to high ADCLRC transition and may be sampled on the rising edge of ADCBCLK. The right channel ADC data is contiguous with the left channel data (Figure 18).
1/fs
ADCLRC
ADCBCLK
LEFT CHANNEL
RIGHT CHANNEL
NO VALID DATA
DOUT
1
2
n-1
n
1
2
n-1
n
1
MSB
Word Length (WL)
LSB
Figure 18 DSP Late Mode Timing Diagram - ADC Data Output In both early and late DSP modes, the left channel is always sent first, followed immediately by the right channel. No DACBCLK edges are allowed between the data words.
CONTROL INTERFACE OPERATION
The WM8776 is controlled by writing to registers through a serial control interface. A control word consists of 16 bits. The first 7 bits (B15 to B9) are address bits that select which control register is accessed. The remaining 9 bits (B8 to B0) are data bits, corresponding to the 9 bits in each control register. The control interface can operate as either a 3-wire or 2-wire MPU interface. The MODE pin selects the interface format, as shown in Table 10. . MODE 0 1 Control Mode 2 wire interface 3 wire interface
Table 10 Control Interface Selection via MODE Pin The control interface is 5V tolerant, meaning that the control interface input signals CE, CL and DI as well as MODE may have an input high level of 5V while DVDD is 3V. Input thresholds are determined by DVDD.
3-WIRE (SPI COMPATIBLE) SERIAL CONTROL MODE
In 3-wire mode, every rising edge of CL clocks in one data bit from the DI pin. A rising edge on CE latches in a complete control word consisting of the last 16 bits. The 3-wire interface protocol is shown in Figure 19.
latch CE
CL
DI
B15
B14
B13
B12
B11
B10
B9
B8
B7
B6
B5
B4
B3
B2
B1
B0
control register address
control register data bits
Figure 19 3-wire SPI Compatible Interface
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B[15:9] are Control Address Bits B[8:0] are Control Data Bits CE is edge sensitive - the data is latched on the rising edge of CE.
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2-WIRE SERIAL CONTROL MODE
The WM8776 supports software control via a 2-wire serial bus. Many devices can be controlled by the same bus, and each device has a unique 7-bit address (this is not the same as the 7-bit address of each register in the WM8776). The WM8776 operates as a slave device only. The controller indicates the start of data transfer with a high to low transition on DI while CL remains high. This indicates that a device address and data will follow. All devices on the 2-wire bus respond to the start condition and shift in the next eight bits on DI (7-bit address + Read/Write bit, MSB first). If the device address received matches the address of the WM8776 and the R/W bit is `0', indicating a write, then the WM8776 responds by pulling DI low on the next clock pulse (ACK). If the address is not recognised or the R/W bit is `1', the WM8776 returns to the idle condition and wait for a new start condition and valid address. Once the WM8776 has acknowledged a correct address, the controller sends the first byte of control data (B15 to B8, i.e. the WM8776 register address plus the first bit of register data). The WM8776 then acknowledges the first data byte by pulling DI low for one clock pulse. The controller then sends the second byte of control data (B7 to B0, i.e. the remaining 8 bits of register data), and the WM8776 acknowledges again by pulling DI low. The transfer of data is complete when there is a low to high transition on DI while CL is high. After receiving a complete address and data sequence the WM8776 returns to the idle state and waits for another start condition. If a start or stop condition is detected out of sequence at any point during data transfer (i.e. DI changes while CL is high), the device jumps to the idle condition.
Figure 20 2-wire Serial Interface B[15:9] are Control Address Bits B[8:0] are Control Data Bits The WM8776 has two possible device addresses, which can be selected using the CE pin. CE STATE Low High DEVICE ADDRESS 0011010 (0 x 34h) 0011011 (0 x 36h)
Table 11 2-Wire MPU Interface Address Selection
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WM8776
CONTROL INTERFACE REGISTERS
DIGITAL AUDIO INTERFACE CONTROL REGISTER
Interface format is selected via the FMT[1:0] register bits: REGISTER ADDRESS R10 (0Ah) 0001010 DAC Interface Control R11 (0Bh) 0001011 ADC Interface Control BIT 1:0 LABEL DACFMT [1:0] ADCFMT [1:0] DEFAULT 10 DESCRIPTION Interface format Select 00 : right justified mode 01: left justified mode 10: I2S mode 11: DSP (early or late) mode
1:0
10
In left justified, right justified or I2S modes, the LRP register bit controls the polarity of ADCLRC/DACLRC. If this bit is set high, the expected polarity of ADCLRC/DACLRC will be the opposite of that shown Figure 12, Figure 13, etc. Note that if this feature is used as a means of swapping the left and right channels, a 1 sample phase difference will be introduced. In DSP modes, the LRP register bit is used to select between early and late modes. REGISTER ADDRESS R10 (0Ah) 0001010 DAC Interface Control BIT 2 LABEL DACLRP DEFAULT 0 DESCRIPTION In left/right/ I2S modes: ADCLRC/DACLRC Polarity (normal) 0 : normal ADCLRC/DACLRC polarity 1: inverted ADCLRC/DACLRC polarity In DSP mode: 0 : Early DSP mode 1: Late DSP mode
R11 (0Bh) 0001011 ADC Interface Control
2
ADCLRP
0
By default, ADCLRC, DACLRC and DIN are sampled on the rising edge of ADCBCLK and DACBCLK and should ideally change on the falling edge. Data sources that change ADCLRC/DACLRC and DIN on the rising edge of ADCBCLK/DACBCLK can be supported by setting the BCP register bit. Setting BCP to 1 inverts the polarity of BCLK to the inverse of that shown in Figure 12, Figure 13, etc.
REGISTER ADDRESS R10 (0Ah) 0001010 DAC Interface Control R11 (0Bh) 0001011 ADC Interface Control
BIT 3
LABEL DACBCP
DEFAULT 0
DESCRIPTION BCLK Polarity (DSP modes) 0 : normal BCLK polarity 1: inverted BCLK polarity
3
ADCBCP
0
The WL[1:0] bits are used to control the input word length. REGISTER ADDRESS R10 (0Ah) 0001010 DAC Interface Control R11 (0Bh) 0001011 ADC Interface Control BIT 5:4 LABEL DACWL [1:0] ADCWL [1:0] DEFAULT 10 DESCRIPTION Word Length 00 : 16 bit data 01: 20 bit data 10: 24 bit data 11: 32 bit data
5:4
10
Note: If 32-bit mode is selected in right justified mode, the WM8776 defaults to 24 bits. In all modes, the data is signed 2's complement. The digital filters always input 24-bit data. If the DAC is programmed to receive 16 or 20 bit data, the WM8776 pads the unused LSBs with zeros. If the DAC is programmed into 32 bit mode, the 8 LSBs are ignored.
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WM8776
2
Product Preview Note: In 24 bit I S mode, any width of 24 bits or less is supported provided that ADCLRC/DACLRC is high for a minimum of 24 BCLKs and low for a minimum of 24 BCLKs. A number of options are available to control how data from the Digital Audio Interface is applied to the DAC.
MASTER MODES
Control bit ADCMS selects between audio interface Master and Slave Modes for ADC. In ADC Master mode ADCLRC and ADCBCLK are outputs and are generated by the WM8776. In Slave mode ADCLRC and ADCBCLK are inputs to WM8776. REGISTER ADDRESS R12 (0Ch) 0001100 Interface Control BIT 9 LABEL ADCMS DEFAULT 0 DESCRIPTION Audio Interface Master/Slave Mode select for ADC: 0 : Slave Mode 1: Master Mode
Control bit DACMS selects between audio interface Master and Slave Modes for the DAC. In DAC Master mode DACLRC and DACBCLK are outputs and are generated by the WM8776. In Slave mode DACLRC and DACBCLK are inputs to WM8776. REGISTER ADDRESS R12 (0Ch) 0001100 Interface Control BIT 8 LABEL DACMS DEFAULT 0 DESCRIPTION Audio Interface Master/Slave Mode select for DAC: 0 : Slave Mode 1: Master Mode
MASTER MODE ADCLRC/DACLRC FREQUENCY SELECT
In ADC Master mode the WM8776 generates ADCLRC and ADCBCLK, in DAC master mode the WM8776 generates DACLRC and DACBCLK. These clocks are derived from the master clock (ADCMCLK or DACMCLK). The ratios of ADCMCLK to ADCLRC and DACMCLK to DACLRC are set by ADCRATE and DACRATE respectively. REGISTER ADDRESS R12 (0Ch) 0001100 ADCLRC and DACLRC frequency select BIT 2:0 LABEL ADCRATE[2:0] DEFAULT 010 DESCRIPTION Master Mode MCLK:ADCLRC ratio select: 010: 256fs 011: 384fs 100: 512fs 101: 768fs Master Mode MCLK:DACLRC ratio select: 000: 128fs 001: 192fs 010: 256fs 011: 384fs 100: 512fs 101: 768fs
6:4
DACRATE[2:0]
010
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WM8776
ADC OVERSAMPLING RATE SELECT
For ADC operation at 96kHz it is recommended that the user set the ADCOSR bit. This changes the ADC signal processing oversample rate to 64fs. REGISTER ADDRESS R12 (0Ch) 0001100 ADC Oversampling Rate BIT LABEL 3 ADCOSR 0 ADC oversampling rate select 0: 128x oversampling 1: 64x oversampling DEFAULT DESCRIPTION
MUTE MODES
Setting MUTE for the DAC will apply a `soft' mute to the input of the digital filters of the channel muted. REGISTER ADDRESS R8 (08h) 0001000 DAC Mute BIT 0 LABEL DMUTE DEFAULT 0 DESCRIPTION DAC Soft Mute select 0 : Normal Operation 1: Soft mute enabled
1.5 1 0.5 0 -0.5 -1 -1.5 -2 -2.5 0 0.001 0.002 0.003 Time(s) 0.004 0.005 0.006
Figure 21 Application and Release of Soft Mute Figure 21 shows the application and release of DMUTE whilst a full amplitude sinusoid is being played at 48kHz sampling rate. When DMUTE (lower trace) is asserted, the output (upper trace) begins to decay exponentially from the DC level of the last input sample. The output will decay towards VMID with a time constant of approximately 64 input samples. If DMUTE is applied to both channels for 1024 or more input samples the DAC will be muted if IZD is set. When DMUTE is de-asserted, the output will restart immediately from the current input sample. Note that all other means of muting the DAC: setting the PL[3:0] bits to 0, setting the PDWN bit or setting attenuation to 0 will cause much more abrupt muting of the output.
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WM8776
ADC MUTE
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Each ADC channel also has an individual mute control bit, which mutes the input to the ADC PGA. By setting the LRBOTH bit (reg22, bit 8) both channels can be muted simultaneously. REGISTER ADDRESS R21 (15h) 0010101 ADC Mute Left R21 (15h) 0001111 ADC Mute Right BIT 7 LABEL MUTELA DEFAULT 0 DESCRIPTION ADC Mute select 0 : Normal Operation 1: mute ADC left ADC Mute select 0 : Normal Operation 1: mute ADC right
6
MUTERA
0
DE-EMPHASIS MODE
The De-emphasis filter for the DAC is enabled under the control of DEEMP. REGISTER ADDRESS R9 (09h) 0001001 DAC De-emphasis Control BIT 0 LABEL DEEMPH DEFAULT 0 DESCRIPTION De-emphasis mode select: 0 : Normal Mode 1: De-emphasis Mode
Refer to Figure 34, Figure 35, Figure 36, Figure 37, Figure 38 and Figure 39 for details of the De-Emphasis modes at different sample rates.
POWERDOWN MODE AND ADC/DAC DISABLE
Setting the PDWN register bit immediately powers down the WM8776, including the references, overriding all other powerdown control bits. All trace of the previous input samples is removed, but all control register settings are preserved. When PDWN is cleared, the digital filters will be re-initialised. It is recommended that the 5-channel input mux and buffer, ADC and DAC are powered down before setting PDWN. REGISTER ADDRESS R13 (0Dh) 0001101 Powerdown Control BIT 0 LABEL PDWN DEFAULT 0 DESCRIPTION Power Down Mode Select: 0 : Normal Mode 1: Power Down Mode
The ADC, DAC and HEADPHONE PGA'S may also be powered down by setting the ADCD and DACD disable bits. Setting ADCD will disable the ADC and select a low power mode. The ADC digital filters will be reset and will reinitialise when ADCD is reset. The DAC has a separate disable DACD. Setting DACD will disable the DAC, mixer and output PGAs. Resetting DACD will reinitialise the digital filters. REGISTER ADDRESS R13 (0Dh) 0001101 Powerdown Control BIT 1 LABEL ADCPD DEFAULT 0 DESCRIPTION ADC Powerdown: 0 : Normal Mode 1: Power Down Mode DAC Powerdown: 0 : Normal Mode 1: Power Down Mode Headphone output/PGA Power down : 0 : HP out enabled 1 : HP out disabled
2
DACPD
0
3
HPPD
1
The analogue audio inputs and outputs can also be individually powered down by setting the relevant bits in the powerdown register.
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WM8776
REGISTER ADDRESS R13 (0Dh) 0001101 Powerdown Control BIT 6 LABEL AINPD DEFAULT 0 DESCRIPTION Analogue input PGA disable: 0 : Normal Mode 1: Power Down Mode
DIGITAL ATTENUATOR CONTROL MODE
Setting the ATC register bit causes the left channel attenuation settings to be applied to both left and right channel DACs from the next audio input sample. No update to the attenuation registers is required for ATC to take effect. REGISTER ADDRESS R7 (07h) 0000111 DAC Channel Control BIT 1 LABEL ATC DEFAULT 0 DESCRIPTION Attenuator Control Mode: 0 : Right channel use Right attenuation 1: Right Channel use Left Attenuation
INFINITE ZERO DETECT ENABLE
Setting the IZD register bit will enable the internal infinite zero detect function: REGISTER ADDRESS R7 (07h) 0000111 DAC Channel Control BIT 2 LABEL IZD DEFAULT 0 DESCRIPTION Infinite zero Mute Enable 0 : disable infinite zero mute 1: enable infinite zero Mute
With IZD enabled, applying 1024 consecutive zero input samples to the DAC will cause both DAC outputs to be muted. Mute will be removed as soon as any channel receives a non-zero input.
DAC OUTPUT CONTROL
The DAC output control word determines how the left and right inputs to the audio Interface are applied to the left and right DACs: REGISTER ADDRESS R7 (07h) 0000111 DAC Control BIT 7:4 LABEL PL[3:0] DEFAULT 1001 PL[3:0] 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111 DESCRIPTION Left Output Mute Left Right (L+R)/2 Mute Left Right (L+R)/2 Mute Left Right (L+R)/2 Mute Left Right (L+R)/2 Right Output Mute Mute Mute Mute Left Left Left Left Right Right Right Right (L+R)/2 (L+R)/2 (L+R)/2 (L+R)/2
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ANALOGUE OUTPUT VOLUME CONTROLS
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There are analogue volume controls for the headphone outputs which may be adjusted independently using separate volume control registers. REGISTER ADDRESS R0 (00h) 0000000 Analogue Attenuation Headphone Output Left BIT 6:0 7 LABEL HPLA[6:0] HPLZCEN DEFAULT 1111001 (0dB) 0 DESCRIPTION Attenuation data for Headphone Left channel in 1dB steps. See Table 13 Headphone left zero cross detect enable 0: zero cross disabled 1: zero cross enabled Controls simultaneous update of Headphone Attenuation Latches 0: Store HPLA in intermediate latch (no change to output) 1: Store HPLA and update attenuation on both channels. Attenuation data for Headphone Right channel in 1dB steps. See Table 13 Headphone right zero cross detect enable 0: zero cross disabled 1: zero cross enabled Controls simultaneous update of Headphone Attenuation Latches 0: Store HPRA in intermediate latch (no change to output) 1: Store HPRA and update attenuation on both channels. Attenuation data for both Headphone channels in 1dB steps. See Table 13 Master zero cross detect enable 0: zero cross disabled 1: zero cross enabled Controls simultaneous update of Attenuation Latches 0: Store gain in intermediate latch (no change to output) 1: Store gain and update attenuation on all channels. Headphone output/PGA Power Down 0 : HP out enabled 1 : HP out disabled
8
UPDATE
Not latched
R1 (01h) 0000001 Analogue Attenuation Headphone Output Right
6:0 7
HPLA[6:0] HPRZCEN
1111001 (0dB) 0
8
UPDATE
Not latched
R2 (02h) 0000010 Headphone Master Analogue Attenuation (both channels)
6:0 7
HPMASTA [6:0] MZCEN
1111001 (0dB) 0
8
UPDATEA
Not latched
R13 (0Dh) 0001101 Power Down
3
HPPD
1
Table 12 Headphone Attenuation Register Map Each analogue headphone output channel has a PGA which can be used to attenuate the output from that channel. The PGA's can be powered up or down using the HPPD bit. Attenuation is 0dB by default but can be set between +6dB and -73dB in 1dB steps using the two Attenuation control words. The attenuation registers are double latched allowing them to be updated in pairs. Setting the UPDATE bit on an attenuation write to one channel, for example HPOUTL, will cause the pre-latched value in HPOUTR to be applied to the PGA. A master attenuation register is also included, allowing both volume levels to be set to the same value in a single write. Note: The UPDATE bit is not latched. If UPDATE=0, the Attenuation value will be written to the pre-latch but not applied to the PGA. If UPDATE=1, pre-latched values will be applied from the next input sample. Writing to HPMASTA[6:0] overwrites any values previously sent to HPLA[6:0] and HPRA[6:0].
HEADPHONE OUTPUT PGA ATTENUATION
The analogue output PGAs are controlled by the HPLA and HPRA registers. Register bits MASTA can be used to control attenuation of both channels. Table 13 shows how the attenuation levels are selected from the 7-bit words.
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Product Preview
WM8776
HPLA/ HPRA[6:0] 00(hex) : 2F(hex) 30(hex) : 79 (hex) : 7D(hex) 7E(hex) 7F(hex) ATTENUATION LEVEL -dB (mute) : -dB (mute) -73dB : 0dB (default) : +4dB +5dB +6dB
Table 13 Headphone Volume Control Attenuation Levels In addition a zero cross detect circuit is provided for the output PGA volume under the control of bit 7 (ZCEN) in the each attenuation register. When ZCEN is set the attenuation values are only updated when the input signal to the gain stage is close to the analogue ground level. This minimises audible clicks and `zipper' noise as the gain values change. A timeout clock is also provided which will generate an update after a minimum of 131072 master clocks (= ~10.5ms with a master clock of 12.288MHz). The timeout clock may be disabled by setting TOD.
REGISTER ADDRESS R7 (07h) 0000111 Timeout Clock Disable
BIT 3
LABEL TOD
DEFAULT 0
DESCRIPTION DAC and ADC Analogue Zero cross detect timeout disable 0 : Timeout enabled 1: Timeout disabled
DAC DIGITAL VOLUME CONTROL
The DAC volume may also be adjusted in the digital domain using independent digital attenuation control registers
REGISTER ADDRESS R3 (03h) 0000011 Digital Attenuation DACL R4 (04h) 0000100 Digital Attenuation DACR R5 (05h) 0000101 Master Digital Attenuation (both channels)
BIT 7:0 8
LABEL LDA[7:0] UPDATED
DEFAULT 11111111 (0dB) Not latched
DESCRIPTION Digital Attenuation data for Left channel DACL in 0.5dB steps. See Table 14 Controls simultaneous update of Attenuation Latches 0: Store LDA in intermediate latch (no change to output) 1: Store LDA and update attenuation on both channels Digital Attenuation data for Right channel DACR in 0.5dB steps. See Table 14 Controls simultaneous update of Attenuation Latches 0: Store RDA in intermediate latch (no change to output) 1: Store RDA and update attenuation on both channels. Digital Attenuation data for DAC channels in 0.5dB steps. See Table 14 Controls simultaneous update of Attenuation Latches 0: Store gain in intermediate latch (no change to output) 1: Store gain and update attenuation on channels.
7:0 8
RDA[6:0] UPDATED
11111111 (0dB) Not latched
7:0 8
MASTDA[7:0] UPDATED
11111111 (0dB) Not latched
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L/RDA[7:0] 00(hex) 01(hex) : : : FE(hex) FF(hex) ATTENUATION LEVEL - dB (mute) -127dB : : : -0.5dB 0dB
Product Preview
Table 14 Digital Volume Control Attenuation Levels The digital volume control also incorporates a zero cross detect circuit which detects a transition through the zero point before updating the digital volume control with the new volume. This is enabled by control bit DZCEN. REGISTER ADDRESS R7 (07h) 0000111 DAC Control BIT 0 LABEL DZCEN DEFAULT 0 DESCRIPTION DAC Digital Volume Zero Cross Enable: 0: Zero cross detect disabled 1: Zero cross detect enabled
DAC OUTPUT PHASE
The DAC Phase control word determines whether the output of the DAC is non-inverted or inverted REGISTER ADDRESS R6 (06h) 0000110 DAC Phase BIT 1:0 LABEL PH[1:0] DEFAULT 00 Bit 0 1 DESCRIPTION DAC DACL DACR Phase 1 = invert 1 = invert
ADC GAIN CONTROL
The ADC has an analogue input PGA and digital gain control for each stereo channel. Both the analogue and digital gains are adjusted by the same register, LAG for the left and RAG for the right. The analogue PGA has a range of +24dB to -21dB in 0.5dB steps. The digital gain control allows further attenuation (after the ADC) from -21.5dB to -103dB in 0.5dB steps. Table 15 shows how the register maps the analogue and digital gains. LAG/RAG[7:0] ATTENUATION LEVEL (AT OUTPUT) - dB (mute) -103dB : -21.5dB -21dB : 0dB : +23.5dB +24dB ANALOGUE PGA DIGITAL ATTENUATION Digital mute -82dB : -0.5dB 0dB : 0dB : 0dB 0dB
00(hex) 01(hex) : A4(hex) A5(hex) : CF(hex) : FE(hex) FF(hex)
-21dB -21dB : -21dB -21dB : 0dB : +23.5dB +24dB
Table 15 Analogue and Digital Gain Mapping for ADC In addition, a zero cross detect circuit is provided for the input PGA, controlled by bit 8 in each attenuation register. This minimises audible clicks and `zipper' noise by updating the gain when the signal crosses the zero level.
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WM8776
In addition a zero cross detect circuit is provided for the output PGA volume under the control of bit 7 (ZCEN) in the each attenuation register. When ZCEN is set the attenuation values are only updated when the input signal to the gain stage is close to the analogue ground level. This minimises audible clicks and `zipper' noise as the gain values change. A timeout clock is also provided which will generate an update after a minimum of 131072 master clocks (= ~10.5ms with a master clock of 12.288MHz). The timeout clock may be disabled by setting TOD. Left and right inputs may also be independently muted. The LRBOTH control bit allows the user to write the same attenuation value to both left and right volume control registers, saving on software writes. The ADC volume and mute also applies to the bypass signal path.
REGISTER ADDRESS R14 (0Eh) 0001110 Attenuation ADCL
BIT 7:0
LABEL LAG[7:0]
DEFAULT 11001111 (0dB) 0
DESCRIPTION Attenuation data for Left channel ADC gain in 0.5dB steps. See Table 15. Left channel ADC zero cross enable: 0: Zero cross disabled 1: Zero cross enabled Attenuation data for right channel ADC gain in 0.5dB steps. See Table 15. Right channel ADC zero cross enable: 0: Zero cross disabled 1: Zero cross enabled Right channel input PGA controlled by left channel register 0 : Right channel uses RAG. 1 : Right channel uses LAG. Mute for left channel ADC 0: Mute Off 1: Mute on Mute for right channel ADC 0: Mute Off 1: Mute on
8
ZCLA
R15 (0Fh) 0001111 Attenuation ADCR
7:0
RAG[7:0]
11001111 (0dB) 0
8
ZCRA
R21 (15h) 0010101 ADC Input Mux R21 (15h) 0010101 ADC Input Mux
8
LRBOTH
0
7
MUTELA
0
6
MUTERA
0
ADC HIGHPASS FILTER DISABLE
The ADC digital filters contain a digital high pass filter. This defaults to enabled and can be disabled using software control bit ADCHPD. REGISTER ADDRESS R11 (0Bh) 0001011 ADC Control BIT 8 LABEL ADCHPD DEFAULT 0 DESCRIPTION ADC High pass filter disable: 0: High pass filter enabled 1: High pass filter disabled
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WM8776
LIMITER / AUTOMATIC LEVEL CONTROL (ALC)
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The WM8776 has an automatic pga gain control circuit, which can function as a peak limiter or as an automatic level control (ALC). In peak limiter mode, a digital peak detector detects when the input signal goes above a predefined level and will ramp the pga gain down to prevent the signal becoming too large for the input range of the ADC. When the signal returns to a level below the threshold, the pga gain is slowly returned to its starting level. The peak limiter cannot increase the pga gain above its static level.
input signal
PGA gain
signal after PGA
Limiter threshold
attack time
Figure 22 Limiter Operation
decay time
In ALC mode, the circuit aims to keep a constant recording volume irrespective of the input signal level. This is achieved by continuously adjusting the PGA gain so that the signal level at the ADC input remains constant. A digital peak detector monitors the ADC output and changes the PGA gain if necessary.
input signal
PGA gain
signal after ALC
ALC target level
hold time
Figure 23 ALC Operation
decay time
attack time
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WM8776
The gain control circuit is enabled by setting the LCEN control bit. The user can select between Limiter mode and three different ALC modes using the LCSEL control bits. REGISTER ADDRESS R17 (11h) 0010001 ALC Control 2 R16 (10h) 0010000 ALC Control 1 BIT 8 LABEL LCEN DEFAULT 0 DESCRIPTION Enable the PGA gain control circuit. 0 = Disabled 1 = Enabled LC function select 00 = Limiter 01 = ALC Right channel only 10 = ALC Left channel only 11 = ALC Stereo
8:7
LCSEL
00
The limiter function only operates in stereo, which means that the peak detector takes the maximum of left and right channel peak values, and any new gain setting is applied to both left and right PGAs, so that the stereo image is preserved. However, the ALC function can also be enabled on one channel only. In this case, only one PGA is controlled by the ALC mechanism, while the other channel runs independently with its PGA gain set through the control register. When enabled, the threshold for the limiter or target level for the ALC is programmed using the LCT control bits. This allows the threshold/target level to be programmed between -1dB and -16dB in 1dB steps. REGISTER ADDRESS R16 (10h) 0010000 ALC Control 1 BIT 3:0 LABEL LCT[3:0] DEFAULT 1011 (-5dB) DESCRIPTION Limiter Threshold/ALC target level in 1dB steps. 0000: -16dB FS 0001: -15dB FS ... 1101: -3dB FS 1110: -2dB FS 1111: -1dB FS
ATTACK AND DECAY TIMES
The limiter and ALC have different attack and decay times which determine their operation. However, the attack and decay times are defined slightly differently for the limiter and for the ALC. DCY and ATK control the decay and attack times, respectively. Decay time (Gain Ramp-Up). When in ALC mode, this is defined as the time that it takes for the PGA gain to ramp up across 90% of its range (e.g. from -21dB up to +20 dB). When in limiter mode, it is defined as the time it takes for the gain to ramp up by 6dB. The decay time can be programmed in power-of-two (2n) steps. For the ALC this gives times from 33.6ms, 67.2ms, 134.4ms etc. to 34.41s. For the limiter this gives times from 1.2ms, 2.4ms etc., up to 1.2288s. Attack time (Gain Ramp-Down) When in ALC mode, this is defined as the time that it takes for the PGA gain to ramp down across 90% of its range (e.g. from +20dB down to -21dB gain). When in limiter mode, it is defined as the time it takes for the gain to ramp down by 6dB. The attack time can be programmed in power-of-two (2n) steps, from 8.4ms, 16.8ms, 33.6ms etc. to 8.6s for the ALC and from 250us, 500us, etc. up to 256ms. The time it takes for the recording level to return to its target value or static gain value therefore depends on both the attack/decay time and on the gain adjustment required. If the gain adjustment is small, it will be shorter than the attack/decay time.
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WM8776
REGISTER ADDRESS R18 (12h) 0010010 ALC Control 3 BIT 3:0 LABEL ATK[3:0] DEFAULT 0010 DESCRIPTION
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LC attack (gain ramp-down) time ALC mode 0000: 8.4ms 0001: 16.8ms 0010: 33.6ms... (time doubles with every step) 1010 or higher: 8.6s Limiter Mode 0000: 250us 0001: 500us... 0010: 1ms (time doubles with every step) 1010 or higher: 256ms
7:4
DCY [3:0]
0011
LC decay (gain ramp-up) time ALC mode 0000: 33.5ms 0001: 67.2ms 0010: 134.4ms ....(time doubles for every step) 1010 or higher: 34.3ms Limiter mode 0000: 1.2ms 0001: 2.4ms 0010: 4.8ms ....(time doubles for every step) 1010 or higher: 1.2288s
TRANSIENT WINDOW (LIMITER ONLY)
To prevent the limiter responding to to short duration high ampitude signals (such as handclaps in a live performance), the limiter has a programmable transient window preventing it responding to signals above the threshold until their duration exceeds the window period. The Transient window is set in register TRANWIN. REGISTER ADDRESS R20 (14h) 0010100 Limiter Control BIT 6:4 LABEL TRANWIN [2:0] DEFAULT 010 DESCRIPTION Length of Transient Window 000: 0us (disabled) 001: 62.5us 010: 125us ..... 111: 4ms
ZERO CROSS
The PGA has a zero cross detector to prevent gain changes introducing noise to the signal. In ALC mode the register bit ALCZC allows this to be turned off if desired. REGISTER ADDRESS R17 (11h) 0010001 ALC Control 2 BIT 7 LABEL ALCZC DEFAULT 0 (disabled) DESCRIPTION PGA zero cross enable 0 : disabled 1: enabled
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WM8776
MAXIMUM GAIN (ALC ONLY) AND MAXIMUM ATTENUATION
To prevent low level signals being amplified too much by the ALC, the MAXGAIN register sets the upper limit for the gain. This prevents low level noise being over-amplified. The MAXGAIN register has no effect on the limiter operation. The MAXATTEN register has different operation for the limiter and for the ALC. For the limiter it defines the maximum attenuation below the static (user programmed) gain. For the ALC, it defines the lower limit for the gain. REGISTER ADDRESS R16 (10h) 0010000 ALC Control 1 BIT 6:4 LABEL MAXGAIN DEFAULT 111 (+24dB) DESCRIPTION Set maximum gain for the PGA (ALC only) 111 : +24dB 110 : +20dB .....(-4dB steps) 010 : +4dB 001 : 0dB 000 : 0dB Maximum attenuation of PGA Limiter (attenuation below static) 0011 or lower: -3dB 0100: -4dB .... (-1dB steps) 1100 or higher: -12dB ALC (lower PGA gain limit) 1010 or lower: -1dB 1011 : -5dB ..... (-4dB steps) 1110 : -17dB 1111 : -21dB
R20 (14h) 0010100 Limiter Control
3:0
MAXATTEN
0110
HOLD TIME (ALC ONLY)
The ALC also has a hold time, which is the time delay between the peak level detected being below target and the PGA gain beginning to ramp up. It can be programmed in power-of-two (2n) steps, e.g. 2.67ms, 5.33ms, 10.67ms etc. up to 43.7ms. Alternatively, the hold time can also be set to zero. The hold time only applies to gain ramp-up, there is no delay before ramping the gain down when the signal level is above target. REGISTER ADDRESS R17 (11h) 0010001 ALC Control 2 BIT 3:0 LABEL HLD[3:0] DEFAULT 0000 DESCRIPTION ALC hold time before gain is increased. 0000: 0ms 0001: 2.67ms 0010: 5.33ms ... (time doubles with every step) 1111: 43.691s
OVERLOAD DETECTOR (ALC ONLY)
To prevent clipping when a large signal occurs just after a period of quiet, the ALC circuit includes an overload detector. If the ADC input signal exceeds 87.5% of full scale (-1.16dB), the PGA gain is ramped down at the maximum attack rate (as when ATK = 0000), until the signal level falls below 87.5% of full scale. This function is automatically enabled whenever the ALC is enabled. (Note: If ATK = 0000, then the overload detector makes no difference to the operation of the ALC. It is designed to prevent clipping when long attack times are used).
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WM8776
NOISE GATE (ALC ONLY)
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When the signal is very quiet and consists mainly of noise, the ALC function may cause "noise pumping", i.e. loud hissing noise during silence periods. The WM8776 has a noise gate function that prevents noise pumping by comparing the signal level at the AINL1/2/3/4/5 and/or AINR1/2/3/4/5 pins against a noise gate threshold, NGTH. The noise gate cuts in when: * * Signal level at ADC [dB] < NGTH [dB] + PGA gain [dB] + Mic Boost gain [dB]
This is equivalent to: Signal level at input pin [dB] < NGTH [dB]
When the noise gate is triggered, the PGA gain is held constant (preventing it from ramping up as it would normally when the signal is quiet). The table below summarises the noise gate control register. The NGTH control bits set the noise gate threshold with respect to the ADC full-scale range. The threshold is adjusted in 6dB steps. Levels at the extremes of the range may cause inappropriate operation, so care should be taken with set-up of the function. Note that the noise gate only works in conjunction with the ALC function, and always operates on the same channel(s) as the ALC (left, right, both, or none). REGISTER ADDRESS R19 (13h) 0010011 Noise Gate Control BIT 0 LABEL NGAT DEFAULT 0 DESCRIPTION Noise gate function enable 1 = enable 0 = disable Noise gate threshold (with respect to ADC output level) 000: -78dBFS 001: -72dBfs ... 6 dB steps 110: -42dBFS 111: -36dBFS
4:2
NGTH[2:0]
000
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WM8776
ADC INPUT MIXER AND POWERDOWN CONTROL
REGISTER ADDRESS R21 (15h) 0010101 ADC Input Mux R13 (0Dh) 0001101 Powerdown Control BIT 4:0 LABEL AMX[4:0] DEFAULT 00001 DESCRIPTION ADC left channel input mixer control bits (see Table 16)
6
AINPD
0
Input mux and buffer powerdown 0: Input mux and buffer enabled 1: Input mux and buffer powered down
Register bits AMX[4:0] control the left and right channel inputs into the stereo ADC. The default is AIN1. One bit of AMX is allocated to each stereo input pair to allow the signals to be mixed before being digitised by the ADC. For example, if AMX[4:0] is 00101, the input signal to the ADC will be (AIN1L+AIN3L) on the left channel and (AIN1R+AIN3R) on the right channel. However if the analogue input buffer is powered down, by setting AINPD, then all 5-channel mixer inputs are switched to buffered VMIDADC. AMX[4:0] 00001 00010 00100 01000 10000 LEFT ADC INPUT AIN1L AIN2L AIN3L AIN4L AIN5L RIGHT ADC INPUT AIN1R AIN2R AIN3R AIN4R AIN5R
Table 16 ADC Input Mixer
AIN1L/R AIN2L/R AIN3L/R AIN4L/R AIN5L/R
AMX[0]
AMX[1]
AMX[2]
AMX[3]
AMX[4]
Figure 24 ADC Input Mixer
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WM8776
OUTPUT SELECT AND ENABLE CONTROL
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Register bits MX controls the output selection. The output select block consists of a summing stage and an input select switch for each input allowing each signal to be output individually or summed with other signals and output on the analogue output. The default for the output is DAC playback only. VOUT may be selected to output DAC playback, AUX, analogue bypass or a sum of these using the output select controls MX[2:0]. For example, to select sum of DAC and AUX, set MX[2:0] to 011. The output mixer is powered down with DACD. REGISTER ADDRESS R22 (16h) 0010110 Output Mux BIT 2:0 LABEL MX[2:0] DEFAULT 001 (DAC playback) DESCRIPTION VOUT Output select (see Figure 25)
Figure 25 MX[2:0] Output Select
SOFTWARE REGISTER RESET
Writing any value to register 0010111 will cause a register reset, resetting all register bits to their default values.
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WM8776
REGISTER MAP
The complete register map is shown below. The detailed description can be found in the relevant text of the device description. The WM8776 can be configured using the Control Interface. All unused bits should be set to `0'.
REGISTER B
B
B
B
B
B
B 9 0 1
B8
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT (HEX)
15 14 13 12 11 10 R0 (00h) R1 (01h) R2 (02h) R3 (03h) R4 (04h) R5 (05h) R6 (06h) R7 (07h) R8 (08h) R9 (09h) R10 (0Ah) R11 (0Bh) R12 (0Ch) R13 (ODh) R14 (0Eh) R15 (0Fh) R16 (10h) R17 (11h) R18 (12h) R19 (13h) R20 (14h) R21 (15h) R22 (16h) R23 (17h) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1
UPDATE HPLZCEN UPDATE HPRZCEN
HPLA[6:0] HPRA[6:0] HPMASTA[6:0] LDA[7:0] RDA[7:0] MASTDA
079 079 079 0FF 0FF 0FF
0 UPDATEA HPMZCEN 1 UPDATED 0 UPDATED 1 UPDATED 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 0 0 0 0 ADCHPD ADCMS 0 ZCLA ZCRA LCSEL[1:0] LCEN FDECAY 0 0 LRBOTH 0 0 0 MUTELA 0 ALCZC 0 DCY[3:0] 0 0 TRANWIN[2:0] MUTERA 0 0 MAXGAIN[2:0] 0 0 0 0 0 0 DACMS 0 AINPD 0 0 0 ADCMCLK 0 0 PL[3:0] 0 0 0 0 0
0
0 TOD 0 0 DACBCP ADCBCP ADCOSR
0 IZD 0
PHASE[1:0] ATC 0 DZCEN DMUTE DEEMPH
000 090 000 000 022 022 022 008 0CF 0CF
DZFM [1:0] DACLRP ADCLRP
DACWL[1:0] ADCWL[1:0]
DACFMT[1:0] ADCFMT[1:0] ADCRATE[2:0]
DACRATE[2:0] 0 0
HPPD
DACPD
ADCPD
PDWN
LAG[7:0] RAG[7:0] LCT[3:0] HLD[3:0] ATK[3:0] NGTH[2:0] 0 MAXATTEN[3:0] AMX[4:0] MX[2:0] NGAT
07B 000 032 000 0A6 001 001 not reset
SOFTWARE RESET
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WM8776
REGISTER ADDRESS R0 (00h) 0000000 Headphone Analogue Attenuation Headphone Left BIT 6:0 LABEL HPLA[6:0] DEFAULT 1111001 (0dB) 0 DESCRIPTION
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Attenuation data for HEADPHONE left channel in 1dB steps.
7
HPLZCEN
Left HEADPHONE zero cross detect enable 0: zero cross disabled 1: zero cross enabled Controls simultaneous update of all Attenuation Latches 0: Store HPLA in intermediate latch (no change to output) 1: Store HPLA and update attenuation on all channels. Attenuation data for Headphone right channel in 1dB steps.
8
UPDATE
Not latched
R1 (01h) 0000001 Headphone Analogue Attenuation Headphone Right
6:0
HPRA[6:0]
1111001 (0dB) 0
7
HPRZCEN
Right Headphone zero cross detect enable 0: zero cross disabled 1: zero cross enabled Controls simultaneous update of all Attenuation Latches 0: Store HPRA in intermediate latch (no change to output) 1: Store HPRA and update attenuation on all channels. Attenuation data for all ANALOGUE gains (L and R channels) in 1dB steps.
8
UPDATE
Not latched
R2 (02h) 0000010 Headphone Master Analogue Attenuation (All Channels)
6:0
HPMASTA[6:0]
1111001 (0dB) 0
7
MZCEN
Master zero cross detect enable 0: zero cross disabled 1: zero cross enabled Controls simultaneous update of all Attenuation Latches 0: Store gains in intermediate latch (no change to output) 1: Store gains and update attenuation on all channels. Digital Attenuation data for Left channel DACL in 0.5dB steps.
8
UPDATE
Not latched
R3 (03h) 0000011 Digital Attenuation DACL
7:0
LDA1[7:0]
11111111 (0dB) Not latched
8
UPDATE
Controls simultaneous update of all Attenuation Latches 0: Store LDA1 in intermediate latch (no change to output) 1: Store LDA1 and update attenuation on all channels Digital Attenuation data for Right channel DACR in 0.5dB steps.
R4 (04h) 0000100 Digital Attenuation DACR
7:0
RDA1[6:0]
11111111 (0dB) Not latched
8
UPDATE
Controls simultaneous update of all Attenuation Latches 0: Store RDA1 in intermediate latch (no change to output) 1: Store RDA1 and update attenuation on all channels. Digital Attenuation data for all DAC channels in 0.5dB steps.
R5 (05h) 0000101 Master Digital Attenuation (All Channels
7:0
MASTDA[7:0]
11111111 (0dB) Not latched
8
UPDATE
Controls simultaneous update of all Attenuation Latches 0: Store gain in intermediate latch (no change to output) 1: Store gain and update attenuation on all channels.
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Product Preview REGISTER ADDRESS R6 (06h) 0000110 Phase Swaps R7 (07h) 0000111 DAC Control BIT 1:0 LABEL PHASE DEFAULT 00 DESCRIPTION
WM8776
Controls phase of DAC outputs (LEFT, RIGHT channel) 0: Sets non inverted output phase 1: inverts phase of DAC output DAC Digital Volume Zero Cross Enable: 0: Zero Cross detect disabled 1: Zero Cross detect enabled Attenuator Control 0: All DACs use attenuations as programmed. 1: Right DAC uses left DAC attenuations Infinite zero detection circuit control and automute control 0: Infinite zero detect automute disabled 1: Infinite zero detect automute enabled DAC and ADC Analogue Zero cross detect timeout disable 0 : Timeout enabled 1: Timeout disabled DAC Output Control PL[3:0] 0000 0001 0010 0011 0100 0101 0110 0111 Left Output Mute Left Right (L+R)/2 Mute Left Right (L+R)/2 Right Output Mute Mute Mute Mute Left Left Left Left PL[3:0] 1000 1001 1010 1011 1100 1101 1110 1111 Left Output Mute Left Right (L+R)/2 Mute Left Right (L+R)/2 Right Output Right Right Right Right (L+R)/2 (L+R)/2 (L+R)/2 (L+R)/2
0
DZCEN
0
1
ATC
0
2
IZD
0
3 7:4
TOD PL[3:0]
0 1001
R8 (08h) 0001000 DAC Mute R9 (09h) 0001001 DAC Control
0
DMUTE
0
DAC channel soft mute enables: 0: mute disabled 1: mute enabled De-emphasis mode select: 0 : Normal Mode 1: De-emphasis Mode DZFM 00 01 10 11 ZFLAG1 disabled left channels zero both channels zero either channel zero ZFLAG2 disabled right channels zero both channels zero either channel zero
0
DEEMPH
0
2:1
DZFM
00
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WM8776
REGISTER ADDRESS R10 (0Ah) 0001010 DAC Interface Control BIT 1:0 LABEL DACFMT[1:0] DEFAULT 10 DESCRIPTION DAC Interface format select 00: right justified mode 01: left justified mode 10: I2S mode 11: DSP mode DACLRC Polarity or DSP Early/Late mode select Left Justified / Right Justified / I 2S 0: Standard DACLRC Polarity 1: Inverted DACLRC Polarity 3 DACBCP 0 DSP Mode 0: Early Mode 1: Late Mode
Product Preview
2
DACLRP
0
DAC BITCLK Polarity 0: Normal - DIN and DACLRC sampled on rising edge of DACBCLK. 1: Inverted - DIN and DACLRC sampled on falling edge of DACBCLK. DAC Input Word Length 00: 16-bit Mode 01: 20-bit Mode 10: 24-bit Mode 11: 32-bit Mode (not supported in right justified mode) ADC Interface format select 00: right justified mode 01: left justified mode 10: I2S mode 11: DSP mode ADCLRC Polarity or DSP Early/Late mode select Left Justified / Right Justified / I 2S 0: Standard ADCLRC Polarity 1: Inverted ADCLRC Polarity DSP Mode 0: Early Mode 1: Late Mode
5:4
DACWL[1:0]
10
R11 (0Bh) 0001011 ADC Interface Control
1:0
ADCFMT[1:0]
10
2
ADCLRP
0
3
ADCBCP
0
ADC BITCLK Polarity 0: Normal - ADCLRC sampled on rising edge of ADCBCLK; DOUT changes on falling edge of ADCBCLK. 1: Inverted - ADCLRC sampled on falling edge of ADCBCLK; DOUT changes on rising edge of ADCBCLK. ADC Input Word Length 00: 16-bit Mode 01: 20-bit Mode 10: 24-bit Mode 11: 32-bit Mode (not supported in right justified mode) ADCMCLK Polarity: 0: non-inverted 1: inverted ADC Highpass Filter Disable: 0: Highpass Filter enabled 1: Highpass Filter disabled
5:4
ADCWL[1:0]
10
6
ADCMCLK
0
8
ADCHPD
0
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Product Preview REGISTER ADDRESS R12 (0Ch) 0001100 Master Mode Control BIT 2:0 LABEL ADCRATE[2:0] DEFAULT 010 DESCRIPTION Master Mode ADCMCLK:ADCLRC ratio select: 010: 256fs 011: 384fs 100: 512fs ADC oversample rate select 0: 128x oversampling 1: 64x oversapmling Master Mode DACMCLK:DACLRC ratio select: 000: 128fs 001: 192fs 010: 256fs 011: 384fs 100: 512fs
WM8776
3
ADCOSR
0
6:4
DACRATE[2:0]
010
7
DACMS
0
DAC Maser/Slave interface mode select 0: Slave Mode - DACLRC and DACBCLK are inputs 1: Master Mode -DACLRC and DACBCLK are outputs ADC Maser/Slave interface mode select 0: Slave Mode - ADCLRC and ADCBCLK are inputs 1: Master Mode - ADCLRC and ADCBCLK are outputs Chip Powerdown Control (works in tandem with ADCD and DACD): 0: All circuits running, outputs are active 1: All circuits in power save mode, outputs muted ADC powerdown: 0: ADC enabled 1: ADC disabled DAC powerdown 0: DAC enabled 1: DAC disabled Headphone Output/PGA's powerdown 0: Headphone out enabled 1: Headphone out disabled AINPD powerdown 0: ANALOGUE INPUT enabled 1: ANALOGUE INPUT disabled Attenuation data for Left channel ADC gain in 0.5dB steps. 00000000 : digital mute 00000001 : -103dB ........... 11001111 : 0dB ............ 11111110 : +23.5dB 11111111 : +24dB Left ADC zero cross enable: 0: Zero cross disabled 1: Zero cross enabled
8
ADCMS
0
R13 (0Dh) 0001101 PWR Down Control
0
PDWN
0
1
ADCPD
0
2
DACPD
0
3
HPPD
1
6
AINPD
0
R14 (0Eh) 0001110 Attenuation ADCL
7:0
LAG[7:0]
11001111 (0dB)
8
ZCLA
0
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WM8776
REGISTER ADDRESS R15 (0Fh) 0001111 Attenuation ADCR BIT 7:0 LABEL RAG[7:0] DEFAULT 11001111 (0dB) DESCRIPTION
Product Preview
Attenuation data for right channel ADC gain in 0.5dB steps. 00000000 : digital mute 00000001 : -103dB ........... 11001111 : 0dB ............ 11111110 : +23.5dB 11111111 : +24dB Right ADC zero cross enable: 0: Zero cross disabled 1: Zero cross enabled Limiter threshold/ALC target level in 1dB steps 0000: -16dB FS 0001: -15dB FS ... 1101: -3dB FS 1110: -2dB FS 1111: -1dB FS Set Maximum Gain of PGA 111 : +24dB 110 : +20dB ....(-4dB steps) 010 : +4dB 001 : 0dB 000 : 0dB ALC/Limiter function select 00 = Limiter 01 = ALC Right channel only 10 = ALC Left channel only 11 = ALC Stereo (PGA registers unused) ALC hold time before gain is increased. 0000: OFF 0001: 2.67ms 0010: 5.33ms ... (time doubles with every step) 1111: 43.691s ALC uses zero cross detection circuit. Enable Gain control circuit. 0 = Disable 1 = Enable
8
ZCRA
0
R16 (10h) 0010000 ALC Control 1
3:0
LCT[3:0]
1011 (-5dB)
6:4
MAXGAIN[2:0]
111 (+24dB)
8:7
LCSEL[1:0]
00 (Limiter)
R17 (11h) 0010001 ALC Control 2
3:0
HLD[3:0]
0000 (OFF)
7 8
ALCZC LCEN
0 (zero cross off) 0
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Product Preview REGISTER ADDRESS R18 (12h) 0011000 ALC Control 3 BIT 3:0 LABEL ATK[3:0] DEFAULT 0010 (33ms/1ms) DESCRIPTION ALC/Limiter attack (gain ramp-down) time ALC mode 0000: 8.4ms 0001: 16.8ms 0010: 33.6ms... (time doubles with every step) 1010 or higher: 8.6s ALC mode 0000: 33.5ms 0001: 67.2ms 0010: 134.4ms ....(time doubles for every step) 1010 or higher: 34.3ms Noise gate enable (ALC only) 0 : disabled 1 : enabled Noise gate threshold 000: -78dBFS 001: -72dBfs ... 6 dB steps 110: -42dBFS 111: -36dBFS Maximum attenuation of PGA Limiter (attenuation below static) 0011 or lower: -3dB 0100: -4dB .... (-1dB steps) 1100 or higher: -12dB 010 Length of Transient Window 000: 0us (disabled) 001: 62.5us 010: 125us ..... 111: 4ms ADC left channel input mixer control bit AMX[4:0] 00001 00010 00100 01000 10000 6 MUTERA 0 ADC LEFT IN AIN1L AIN2L AIN3L AIN4L AIN5L ADC RIGHT IN AIN1R AIN2L AIN3R AIN4R AIN5R
WM8776
Limiter Mode 0000: 250us 0001: 500us... 0010: 1ms (time doubles with every step) 1010 or higher: 256ms Limiter mode 0000: 1.2ms 0001: 2.4ms 0010: 4.8ms ....(time doubles for every step) 1010 or higher: 1.2288s
7:4
DCY[3:0]
0011 (268ms/ 9.6ms)
ALC/Limiter decay (gain ramp up) time
R19 (13h) 0010011 Noise Gate Control
0
NGAT
0
4:2
NGTH
000
R20 (14h) 0010100 Limiter Control
3:0
MAXATTEN [3:0]
0110
ALC (lower PGA gain limit) 1010 or lower: -1dB 1011 : -5dB ..... (-4dB steps) 1110 : -17dB 1111 : -21dB
6:4
TRANWIN [2:0]
R21 (15h) 0010101 ADC Mux Control
4:0
AMX[4:0]
00001
Mute for right channel ADC 0: Mute off 1: Mute on Mute for left channel ADC 0: Mute off 1: Mute on
7
MUTELA
0
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WM8776
REGISTER ADDRESS BIT 8 LABEL LRBOTH DEFAULT 0 DESCRIPTION
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Right channel input PGA controlled by left channel register 0 : Right channel uses RAG and MUTERA. 1 : Right channel uses LAG and MUTELA. VOUT Output select (Analogue ByPass Enable / Disable) 001: DAC 010: AUX 100: BYPASS Writing to this register will apply a reset to the device registers.
R22 (16h) 0010110 Output Mux R23 (17h) 0010111 Software Reset
2:0
MX[2:0]
001
[8:0]
RESET
Not reset
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Product Preview
WM8776
DIGITAL FILTER CHARACTERISTICS
PARAMETER ADC Filter Passband Passband ripple Stopband Stopband Attenuation Group Delay DAC Filter Passband Passband ripple Stopband Stopband Attenuation Group Delay Table 17 Digital Filter Characteristics f > 0.546fs 0.546fs -60 19 dB fs 0.05 dB -3dB 0.4892 fs 0.05 dB 0.454fs f > 0.5465fs 0.5465fs -65 22 dB fs 0.01 dB -6dB 0 0.5fs 0.01 dB 0.4535fs TEST CONDITIONS MIN TYP MAX UNIT
DAC FILTER RESPONSES
10
0 -20 Response (dB) -40 -60 -80 -100 -120 0 0.5 1 1.5 2 2.5 3 Frequency (Fs)
Response (dB)
0 -10 -20 -30 -40 -50 -60 -70 -80 0.4 0.45 0.5 Frequency (Fs) 0.55 0.6
Figure 26 DAC Digital Filter Frequency Response - 44.1, 48 and 96kHz
Figure 27 DAC Digital Filter Transition Band - 44.1, 48 and 96kHz
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WM8776
0.2 0.15 0.1 Response (dB)
Response (dB)
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0
-20
0.05 0 -0.05 -0.1
-40
-60
-0.15 -0.2 0 0.1 0.2 Frequency (Fs)
0 0.2 0.4 0.6 Frequency (Fs) 0.8 1
0.3
0.4
0.5
-80
Figure 28 DAC Digital Filter Ripple - 44.1, 48 and 96kHz
Figure 29 DAC Digital Filter Frequency Response - 192kHz
0.2
0
-0.2
Response (dB)
-0.4
-0.6
-0.8
-1 0 0.05 0.1 0.15 0.2 0.25 0.3 Frequency (Fs) 0.35 0.4 0.45 0.5
Figure 30 DAC Digital filter Ripple - 192kHz
ADC FILTER RESPONSES
0.02
0
0.015 0.01
-20
Response (dB)
Response (dB)
0.005 0 -0.005 -0.01 -0.015 -0.02
-40
-60
-80
0
0.5
1
1.5 Frequency (Fs)
2
2.5
3
0
0.05
0.1
0.15
0.2 0.25 0.3 Frequency (Fs)
0.35
0.4
0.45
0.5
Figure 31 ADC Digital Filter Frequency Response
Figure 32 ADC Digital Filter Ripple
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Product Preview
WM8776
ADC HIGH PASS FILTER
The WM8776 has a selectable digital highpass filter to remove DC offsets. The filter response is characterised by the following polynomial.
H(z) =
1 - z-1 1 - 0.9995z-1
0
Response (dB)
-5
-10
-15
0
0.0005
0.001 Frequency (Fs)
0.0015
0.002
Figure 33 ADC Highpass Filter Response
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WM8776
DIGITAL DE-EMPHASIS CHARACTERISTICS
0 1 0.5 -2 0
Response (dB)
Response (dB)
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-4
-0.5 -1 -1.5 -2
-6
-8 -2.5 -10 0 2 4 6 8 10 Frequency (kHz) 12 14 16 -3 0 2 4 6 8 10 Frequency (kHz) 12 14 16
Figure 34 De-Emphasis Frequency Response (32kHz)
0
Figure 35 De-Emphasis Error (32KHz)
0.4 0.3
-2 0.2
Response (dB)
-4
Response (dB)
0.1 0 -0.1 -0.2
-6
-8 -0.3 -10 0 5 10 Frequency (kHz) 15 20 -0.4 0 5 10 Frequency (kHz) 15 20
Figure 36 De-Emphasis Frequency Response (44.1KHz)
0
Figure 37 De-Emphasis Error (44.1KHz)
1 0.8
-2
0.6 0.4
Response (dB)
-4
Response (dB)
0.2 0 -0.2 -0.4
-6
-8
-0.6 -0.8
-10 0 5 10 15 Frequency (kHz) 20
-1 0 5 10 15 Frequency (kHz) 20
Figure 38 De-Emphasis Frequency Response (48kHz)
Figure 39 De-Emphasis Error (48kHz)
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WM8776
APPLICATIONS INFORMATION
EXTERNAL CIRCUIT CONFIGURATION
In order to allow the use of 2V rms and larger inputs to the ADC and AUX inputs, a structure is used that uses external resistors to drop these larger voltages. This also increases the robustness of the circuit to external abuse such as ESD pulses. Figure 40 shows the ADC input multiplexor circuit with external components allowing 2Vrms inputs to be applied.
5K
AINOPL
10uF 10K
AINVGL AIN1L
10uF
10K
AIN2L
10uF 10K
AIN3L
10uF 10K
AIN4L
10uF 10K
AIN5L
SOURCE SELECTOR INPUTS
5K
AINOPR
10uF 10K
AINVGR AIN1R
10uF
10K
AIN2R
10uF 10K
AIN3R
10uF 10K
AIN4R
10uF 10K
AIN5R
Figure 40 ADC Input Multiplexor Configuration
10K
MX[0]
DACL/R 10uF
10K
MX[1]
AUX input
AUXL/R BYPASSL/R
10K
MX[2]
10K
Figure 41 5.1 Channel Input Multiplexor Configuration
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WM8776 RECOMMENDED EXTERNAL COMPONENTS
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Figure 42 External Component Diagram
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Product Preview
WM8776
It is recommended that a low pass filter be applied to the output from the DAC for hi-fi applications. Typically a second order filter is suitable and provides sufficient attenuation of high frequency components (the unique low order, high bit count multi-bit sigma delta DAC structure used in WM8776 produces much less high frequency output noise). This filter is typically also used to provide the 2x gain needed to provide the standard 2Vrms output level from most consumer equipment. Figure 43 shows a suitable post DAC filter circuit, with 2x gain. Alternative inverting filter architectures might also be used with as good results.
4.7k 4.7k
+VS
_
51 10uF
+
1.8k
7.5K
+
1.0nF 10k 680pF -VS
Figure 43 Recommended Post DAC Filter Circuit To ensure that system `pop' noise is kept to a minimum when power is applied or removed, a transistor clamp circuit arrangement may be added to the output connectors of the system. A recommended clamp circuit configuration is shown below.
When the +VS power supply is applied, PNP transistor Q10 of the trigger circuit is held on until capacitor C49 is fully charged. With transistor Q10 held `on', NPN transistors Q4 to Q5 of the clamp circuits are also switched on holding the system outputs near to GND. When capacitor C49 is fully charged transistors Q10 and Q4 to Q5 are switched off setting the outputs active. When the +VS power supply is removed, PNP transistor Q11 of the trigger circuit is switched on. In turn, transistors Q4 to Q5 of the clamp circuits are switched on holding the outputs of the evaluation board near to GND until the rest of the circuitry on the board has settled. Note: It is recommended that low Vcesat switching transistors should be used in this circuit to ensure that the clamp is applied before the rest of the circuitry has time to power down. Important: If a trigger circuit such as the one shown is to be used, it is important that the +VS supply drops quicker than any other supply to ensure that the outputs are clamped during the period when `pop' noise may occur.
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WM8776 PACKAGE DIMENSIONS
FT: 48 PIN TQFP (7 x 7 x 1.0 mm) DM004.C
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b
e
25
36
37
24
E1
E
48
13
1
12
c
D1 D
L
A A2
A1 -Cccc C
SEATING PLANE
Symbols A A1 A2 b c D D1 E E1 e L ccc REF:
Dimensions (mm) MIN NOM MAX --------1.20 0.05 ----0.15 0.95 1.00 1.05 0.17 0.22 0.27 0.09 ----0.20 9.00 BSC 7.00 BSC 9.00 BSC 7.00 BSC 0.50 BSC 0.45 0.60 0.75 o o o 0 3.5 7 Tolerances of Form and Position 0.08 JEDEC.95, MS-026
NOTES: A. ALL LINEAR DIMENSIONS ARE IN MILLIMETERS. B. THIS DRAWING IS SUBJECT TO CHANGE WITHOUT NOTICE. C. BODY DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSION, NOT TO EXCEED 0.25MM. D. MEETS JEDEC.95 MS-026, VARIATION = ABC. REFER TO THIS SPECIFICATION FOR FURTHER DETAILS.
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Product Preview
WM8776
IMPORTANT NOTICE
Wolfson Microelectronics plc (WM) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current. All products are sold subject to the WM terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability.
WM warrants performance of its products to the specifications applicable at the time of sale in accordance with WM's standard warranty. Testing and other quality control techniques are utilised to the extent WM deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed, except those mandated by government requirements.
In order to minimise risks associated with customer applications, adequate design and operating safeguards must be used by the customer to minimise inherent or procedural hazards. Wolfson products are not authorised for use as critical components in life support devices or systems without the express written approval of an officer of the company. Life support devices or systems are devices or systems that are intended for surgical implant into the body, or support or sustain life, and whose failure to perform when properly used in accordance with instructions for use provided, can be reasonably expected to result in a significant injury to the user. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness.
WM assumes no liability for applications assistance or customer product design. WM does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right of WM covering or relating to any combination, machine, or process in which such products or services might be or are used. WM's publication of information regarding any third party's products or services does not constitute WM's approval, license, warranty or endorsement thereof.
Reproduction of information from the WM web site or datasheets is permissible only if reproduction is without alteration and is accompanied by all associated warranties, conditions, limitations and notices. Representation or reproduction of this information with alteration voids all warranties provided for an associated WM product or service, is an unfair and deceptive business practice, and WM is not responsible nor liable for any such use.
Resale of WM's products or services with statements different from or beyond the parameters stated by WM for that product or service voids all express and any implied warranties for the associated WM product or service, is an unfair and deceptive business practice, and WM is not responsible nor liable for any such use.
ADDRESS:
Wolfson Microelectronics plc Westfield House 26 Westfield Road Edinburgh EH11 2QB United Kingdom
Tel :: +44 (0)131 272 7000 Fax :: +44 (0)131 272 7001 Email :: sales@wolfsonmicro.com
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