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MIC4826
Micrel
MIC4826
Low Input Voltage, 160VPP Output Voltage, EL Driver Final Information
General Description
Micrel's MIC4826 is a high output voltage, DC to AC converter, designed for driving EL (Electroluminescent) lamps. The device operates from an input voltage range of 1.8V to 5.5V, making it suitable for 1-cell Li Ion and 2- or 3-cell alkaline/NiCad/NiMH battery applications. The MIC4826 converts a low voltage DC input to a 160VPP AC output signal that drives the EL lamp. The MIC4826 is comprised of two stages: a boost stage, and an H-bridge, lamp driver, stage. The boost stage steps the input voltage up to +80V. The H-bridge stage then alternately switches the +80V output to each terminal of the EL lamp, thus creating a 160VPP AC signal to drive the EL lamp and generate light. The MIC4826 features separate oscillators for the boost- and H-bridge stages. External resistors independently set the operating frequency of each stage. This flexibility allows the EL lamp circuit to be optimized for maximum efficiency and brightness. The MIC4826 uses a single inductor and a minimum number of external components, making it ideal for portable, spacesensitive applications. The MIC4826 is available in an 8-pin MSOP package with an ambient temperature range of -40C to +85C.
Features
* * * * * * * * * * * * 1.8V to 5.5V DC input voltage 160VPP regulated AC output waveform Independently adjustable EL lamp frequency Independently adjustable boost converter frequency 0.1A shutdown current LCD panel backlight Cellular phones PDAs Pagers Calculators Remote controls Portable phones
Applications
Ordering Information
Part Number Standard Pb-Free Temp. Range Package
MIC4826BMM MIC4826YMM -40C to +85C MSOP-8
Typical Application
1
VDD RSW REL GND
SW CS VA VB
5 6 8 7
442k 2M
2 3 4
2in2 EL LAMP
TIME (2ms/div)
High Voltage EL Driver
Micrel, Inc. * 1849 Fortune Drive * San Jose, CA 95131 * USA * tel + 1 (408) 944-0800 * fax + 1 (408) 474-1000* http://www.micrel.com
August 2004
1
VA -- VB (50V/div)
VB (50V/div)
CIN 10F
MIC4826
COUT 0.01F/100V
VA (50V/div)
VIN
L1 220H
D1 1N4148
MIC4826
MIC4826
Micrel
Pin Configuration
VDD 1 RSW 2 REL 3 GND 4 8 VA 7 VB 6 CS 5 SW
8-Pin MSOP Package (MM)
Pin Description
Pin Number 1 2 Pin Name VDD RSW Pin Function Supply (Input): 1.8V to 5.5V for internal circuitry. Switch Resistor (External Component): Set switch frequency of the internal power MOSFET by connecting an external resistor to VDD. Connecting the external resistor to GND disables the switch oscillator and shutdown the device. EL Resistor (External Component): Set EL frequency of the internal H-bridge driver by connecting an external resistor to VDD. Connecting the external resistor to GND disables the EL oscillator. Ground Return. Switch Node (Input): Internal high-voltage power MOSFET drain. Regulated Boost Output (External Component): Connect to the output capacitor of the boost regulator and connect to the cathode of the diode. EL Output: Connect to one end of the EL lamp. Polarity is not important. EL Output: Connect to the other end of the EL lamp. Polarity is not important.
3
REL
4 5 6 7 8
GND SW CS VB VA
MIC4826
2
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MIC4826
Micrel
Absolute Maximum Rating (Note 1)
Supply Voltage (VDD) ..................................... -0.5V to +6V Output Voltage (VCS) ................................. -0.5V to +100V Frequency Control Voltage (VRSW, VREL) ... -0.5V to (VDD + 0.3V) Power Dissipation @ TA = 85C ............................. 200mW Storage Temperature (TS) ....................... -65C to +150C ESD Rating .............................................................. Note 3
Operating Ratings (Note 2)
Supply Voltage (VDD) ...................................... 1.8V to 5.5V Lamp Drive Frequency (fEL) ...................... 60Hz to 1000Hz Switching Transistor Frequency (fSW) ........ 8kHz to 200kHz Ambient Temperature (TA) ......................... -40C to +85C Package Thermal Resistance 8-pin MSOP (JA) .............................................. 206C/W
Electrical Characteristics
VIN = VDD = 3.0V, RSW = 560K, REL = 1.0M. TA = 25C unless otherwise specified. Bold values indicate -40C TA +85C Symbol RDS(ON) VCS VA - VB VEN-L VEN-H ISD IVDD ICS IIN fEL fSW D
Note 1. Note 2. Note 3. Note 4.
Parameter On-resistance of switching transistor Output voltage regulation
Condition ISW = 100 mA, VCS = 75V VDD = 1.8V to 5.5V VDD = 1.8V to 5.5V VDD = 1.8V to 5.5V VDD = 1.8V to 5.5V RSW = LOW; REL = LOW; VDD = 5.5V RSW = HIGH; REL = HIGH; VCS = 75V; VA, VB OPEN RSW = HIGH; REL = HIGH; VCS = 75V; VA, VB OPEN VIN = VDD = 1.8V (See Test Circuit)
Min
Typ 3.8
Max 7.0 85 87
Units V V V V V V A A A A mA
75 73
80
Output peak-to-peak voltage
150 146
160
170 174 0.5
Input low voltage (turn off) Input high voltage (turn on) Shutdown current, Note 4 Input supply current Boosted supply current Input current including inductor current VA-VB output drive frequency Switching transistor frequency Switching transistor duty cycle
VDD-0.5 0.01 21 200 28 285 53 360 66 90 435 79 0.1 0.5 75 400
Hz kHz %
Exceeding the absolute maximum rating may damage the device. The device is not guaranteed to function outside its operating rating. Devices are ESD sensitive. Handling precautions recommended. Shutdown current is defined as the sum of current going into pin 1, 5, and 6 when the device is disabled.
Test Circuit
VIN L1 220H D1 1N4148 COUT 0.01F/100V
5 6 8 7
CIN 10F 442k 2M
MIC4826
1 2 3 4
VDD RSW REL GND
SW CS VA VB
100 10nF
August 2004
3
MIC4826
MIC4826
Micrel
Typical Characteristics
Total Input Current vs. Input Voltage
50 INPUT CURRENT (mA)
INPUT CURRENT (mA)
Total Input Current vs. Temperature
50 R = 562k 45 SW REL = 1M 40 35 30 25 20
VIN = 3.0V 15 Lamp = 2in2 10 R = 332k SW L = 220H D = BAV19WS 5 REL = 3.32M COUT = 0.1F 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
Output Voltage vs. Input Voltage
200 180 RSW= 2M EL 160
VA -VB (VPP)
R = 442k
45 40 35 30 25 20 15 10 5 0 0
RSW = 442k R
EL
R
SW
= 562k, R
EL
= 1M
= 2M
RSW = 442k REL = 2M
140 120 100 R = 332k SW 80 REL = 3.32M 60 40 20 0 1
RSW = 562k REL = 1M
RSW = 332k REL = 3.32M Lamp = 2in2 L = 220H D = BAV19WS C = 0.1F OUT
Lamp = 2in2 L = 220H D = BAV19WS C = 0.1F
OUT
1 2 3 4 5 INPUT VOLTAGE (V)
6
2 3 4 5 INPUT VOLTAGE (V)
6
Output Voltage vs. Temperature
200 OUTPUT VOLTAGE (VPP) 180 160 140 R = 332k RSW = 442k SW 120 R = 3.32M REL = 2M EL 100 RSW = 562k 80 VIN = 3.0V REL = 1M 60 40
VCS (VAVG)
CS Voltage vs. Input Voltage
100 R =442k 90 SW REL = 2M 80 RSW = 562k REL = 1M RSW = 332k REL = 3.32M
Lamp = 2in2 L = 220H COUT = 0.1F D = BAV19WS
CS Voltage vs. Temperature
100 90 80
VCS (VAVG)
70 60 50 40 30 20 10 0 1
70 R = 332k SW 60 REL = 3.32M 50 40 R = 562k
SW
RSW = 442k REL = 2M
VIN = 3.0V Lamp = 2in2 L = 220H COUT = 0.1F D = BAV19WS
20 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
Lamp = 2in2 L = 220H COUT = 0.1F D = BAV19WS
30 20
REL = 1M
2 3 4 5 INPUT VOLTAGE (V)
6
10 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
Switch Resistance vs. Input Voltage
6 5 4 3 2 1 0 1 2 3 4 5 INPUT VOLTAGE (V) 6 SWITCHING FREQUENCY (kHz) 7 1000
Switching Frequency vs. Switch Resistor
10000 EL FREQUENCY (Hz)
EL Frequency vs. EL Resistor
SWITCH RESISTANCE ()
100
1000
10
100
1 100
1000 10000 SWITCH RESISTOR (k)
10 0.1
1 EL RESISTOR (M)
10
Switching Frequency vs. Input Voltage
SWITCHING FREQUENCY (Hz)
120 EL FREQUENCY (Hz) 100 80 60 RSW = 562k 40 20 0 1 2 3 4 5 INPUT VOLTAGE (V) 6 RSW = 332k RSW = 442k 400 350 300 250 200 150 100 50 0 1
EL Frequency vs. Input Voltage
120 FREQUENCY (KHz) REL = 1M REL = 2M 100 80 60 40 20
Switching Frequency vs. Temperature
RSW = 332k RSW = 442k RSW = 562k
REL = 3.32M 2 3 4 5 INPUT VOLTAGE (V) 6
VIN = 3.0V 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
MIC4826
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MIC4826
Micrel
EL Frequency vs. Temperature
400
OUTPUT VOLTAGE (VPP)
Output Voltage vs. Lamp Size
180 160 140 120 100 80 60 40 20 0 0 1 VIN = 3.0V L = 220H COUT = 0.1F D = BAV19WS 2 3 4 5 6 LAMP SIZE (sq. in.) 7 RSW = 332k REL = 3.32M
INPUT CURRENT (mA)
Total Input Current vs. Lamp Size
20 18 16 14 12 10 8 6 4 2 0 0 RSW = 332k REL = 3.32M
350 FREQUENCY (KHz) 300 250 200 150 100 50
RSW =1M
RSW = 2M
RSW = 3.32M
VIN = 3.0V
0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
VIN = 3.0V L = 220H D = BAV19WS COUT = 0.1F 1 2 3 4 5 6 LAMP SIZE (sq. in.) 7
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MIC4826
MIC4826
Micrel
Functional Diagram
VIN
1
L1 220H VDD
5
D1
CIN
RSW
2
SW RWS Switch Oscillator Q1 REL Q2 EL Oscillator Q3
7 3 8 6
COUT
CS
VA
VREF
EL LAMP
VB Q4
REL
4
GND
Figure 1. MIC4826 Block Diagram
Functional Description
See "Application Information" for component selection and pre-designed circuits. Overview The MIC4826 is a high voltage EL driver with an AC output voltage of 160V peak-to-peak capable of driving EL lamps up to 6 in2 . Input supply current for the MIC4826 is typically 21A with a typical shutdown current of 10nA. The high voltage EL driver has two internal oscillators to control the switching MOSFET and the H-bridge driver. Both of the internal oscillators' frequencies can be individually programmed through the external resistors to maximize the efficiency and the brightness of the lamps. Regulation Referring to Figure 1, initially power is applied to VDD. The internal feedback voltage is less than the reference voltage causing the internal comparator to go low which enables the switching MOSFET's oscillator. When the switching MOSFET turns on, current flows through the inductor and into the switch. The switching MOSFET will typically turn on for 90% of the switching frequency. During the on-time, energy is stored in the inductor. When the switching MOSFET turns off, current flowing into the inductor forces the voltage across the inductor to reverse polarity. The voltage across the inductor rises until the external diode conducts and clamps the voltage at VOUT+VD1. The energy in the inductor is then discharged into the COUT capacitor. The internal comparator continues to turn the switching MOSFET on and off until the internal feedback voltage is above the reference voltage. Once the internal feedback voltage is above the reference voltage, the internal comparator turns off the switching MOSFET's oscillator. MIC4826 6
When the EL oscillator is enabled, VA and VB switch in opposite states to achieve a 160V peak-to-peak AC output signal. The external resistor that connects to the REL pin determines the EL frequency.
VA (50V/div)
VA -- VB (50V/div)
VB (50V/div)
VIN = 3.0V L = 220H COUT = 0.01F Lamp = 2in2 RSW = 332k REL = 3.32M
TIME (2ms/div)
Figure 2. 108Hz Typical Output Waveform Switching Frequency The switching frequency of the converter is controlled via an external resistor between RSW pin and VDD pin of the device. The switching frequency increases as the resistor value decreases. For resistor value selections, see "Typical Characteristics: Switching Frequency vs. Switch Resistor" or use the equation below. The switching frequency range is 8kHz to 200kHz, with an accuracy of 20%. fSW (kHz) = 36 RSW (M)
August 2004
MIC4826
EL Frequency The EL lamp frequency is controlled via an external resistor connected between REL pin and VDD pin of the device. As the lamp frequency increases, the resistor value decreases. For resistor value selections, see the "Typical Characteristics: EL Frequency vs. EL Resistor" or use the equation below. The EL frequency range is 60Hz to 1000Hz, with an accuracy of 20%. fEL (Hz) = 360 REL (M)
Micrel
In general, as the EL lamp frequency increases, the amount of current drawn from the battery will increase. The color of the EL lamp and the intensity are dependent upon its frequency.
VA (50V/div)
VA (50V/div)
VB (50V/div)
VIN = 3.0V L = 220H COUT = 0.01F Lamp = 2in2 RSW = 442k REL = 2M
VA -- VB (50V/div)
VB (50V/div)
VIN = 3.0V L = 220H COUT = 0.01F Lamp = 2in2 RSW = 562k REL = 1M
TIME (2ms/div)
Figure 4. 360Hz Output Waveform Enable Function The enable function of the MIC4826 is implemented by switching the RSW and REL resistor between ground and VDD. When RSW and REL are connected to ground, the switch and the EL oscillators are disabled; therefore the EL driver becomes disabled. When these resistors connect to VDD, both oscillators will function and the EL driver is enabled.
VA -- VB (50V/div)
TIME (2ms/div)
Figure 3. 180Hz Output Waveform
August 2004
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MIC4826
MIC4826
Micrel
Diode The application circuit specifies the 1N4148 or equivalent. It has a forward current of 150mA and a typical forward voltage of 950mV. For applications that are not cost driven, a fast switching diode with lower forward voltage and higher reverse voltage can be used to enhance the efficiency, such as BAV19WS and BAV20WS. Output Capacitor Low ESR capacitors should be used at the regulated boost output (CS pin) of the MIC4826 to minimize the switching output ripple voltage. Selection of the capacitor value will depend upon the peak inductor current, inductor size, and the load. MuRata offers the GRM40 series with up to 0.015F at 100V, with a X7R temperature coefficient in 0805 surfacemount package. Typically, values ranging from 0.01F to 0.1F at 100V can be used for the regulated boost output capacitor.
L1 D1 220H Vishay Telefunken Murata MCL4148 LQH4C221K04 COUT 0.01F/100V GRM40X7R103K
5 6 7 8
Application Information
Inductor In general, smaller value inductors, which can handle more current, are more suitable to drive larger size lamps. As the inductor value decreases, the switching frequency (controlled by RSW) should be increased to avoid saturation or the input voltage should be increased. Typically, inductor values ranging from 220H to 560H can be used. Murata offers the LQH3C series up to 560H and LQH4C series up to 470H, with low DC resistance. A 220H Murata (LQH4C221K04) inductor is recommended for driving a lamp size of 3 square inches. It has a maximum DC resistance of 4.0.
Pre-designed Application Circuits
Li-Ion Battery VIN 3.0V to 4.2V C2 10F/6.3V Murata GRM42-6X5R106K6.3 C1 0.22F/10V Murata GRM39X7R 224K10 R2 3.32M R1 322k
MIC4826
1 2 3 4
VDD RSW REL GND
SW CS VB VA
3in2 LAMP
VIN 3.3V
IIN 20mA
VA-VB 160VPP
FEL 100Hz
Lamp Size 3in2
VA -- VB (50V/div)
VB (50V/div)
VA (50V/div)
TIME (2ms/div)
Figure 5. Typical 100Hz EL Driver for 3in2 Lamp
MIC4826
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August 2004
MIC4826
Micrel
VIN 2.5V to 5.5V C2 10F/6.3V Murata GRM42-6X5R106K6.3 R2 3.32M R1 332k
L1 220H Murata LQH4C221K04
D1 Diodes BAV20WS COUT 0.1F/100V GRM42-2X7R104K100
5 6 7 8
MIC4826
1 2 3 4
VDD RSW REL GND
SW CS VB VA
EL LAMP LSI X533-13
VIN 3.3V
IIN 14mA
VA-VB 160VPP
FEL 100Hz
Lamp Size 2in2
VA -- VB (50V/div)
VB (50V/div)
VA (50V/div)
TIME (2ms/div)
Figure 6. Typical EL Driver for 2in2 Lamp with CS = 0.1F
August 2004
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MIC4826
MIC4826
Micrel
VIN 3.3V to 5.5V C2 10F/6.3V Murata GRM42-6X5R106K6.3 R2 3.32M R1 332k
L1 560H Murata LQ32CN561K21
D1 Diodes BAV20WS COUT 0.01F/100V GRM40X7R103K100
5 6 7 8
MIC4826
1 2 3 4
VDD RSW REL GND
SW CS VB VA
EL LAMP LSI X533-13
VIN 3.3V
IIN 13.2mA
VA-VB 160VPP
FEL 100Hz
Lamp Size 2in2
VA -- VB (50V/div)
VB (50V/div)
VA (50V/div)
TIME (2ms/div)
Figure 7. Typcial EL Driver for 2in2 Lamp with 560H inductor
MIC4826
10
August 2004
MIC4826
L1 220H Murata LQH4C221K04 C2 10F/6.3V Murata GRM42-6X5R106K6.3 R1 C1 0.01F/50V Murata GRM40-X7R103K50 442k R2 3.32M
Micrel
VIN 1.5V
D1 Diodes BAV20WS COUT 0.01F/100V GRM40X7R103K100
VDD 1.8V to 5.5V
MIC4826
1 2 3 4
VDD RSW REL GND
SW CS VB VA
5 6 7 8
EL LAMP
VIN 1.5V
IIN 22mA
VDD 3.0V
IDD 36A
VA-VB 160VPP
FEL 100Hz
Lamp Size 1.6in2
VA -- VB (50V/div)
VB (50V/div)
VA (50V/div)
TIME (2ms/div)
Figure 8. Typical Split Power Supplies Applications
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MIC4826
MIC4826
Micrel
Package Information
0.122 (3.10) 0.112 (2.84)
0.199 (5.05) 0.187 (4.74)
DIMENSIONS: INCH (MM)
0.120 (3.05) 0.116 (2.95) 0.036 (0.90) 0.032 (0.81) 0.043 (1.09) 0.038 (0.97) 0.012 (0.30) R
0.007 (0.18) 0.005 (0.13)
0.012 (0.3) 0.0256 (0.65) TYP
0.008 (0.20) 0.004 (0.10)
5 MAX 0 MIN
0.012 (0.03) R 0.039 (0.99) 0.035 (0.89) 0.021 (0.53)
8-Lead MSOP (MM)
MICREL INC. 1849 FORTUNE DRIVE
TEL
SAN JOSE, CA 95131
WEB
USA
+ 1 (408) 944-0800
FAX
+ 1 (408) 474-1000
http://www.micrel.com
This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc. (c) 2004 Micrel Incorporated
MIC4826
12
August 2004

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