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19-3216; Rev 0; 1/08
KIT ATION EVALU LE B AVAILA
Adaptive Equalizer for Video Over Twisted Pair
General Description Features
Automatically Equalizes Up to 600m (Fully Recovers Losses Up to 300m) of UTP Cable Carrying CVBS Automatic Switchover to Fixed Equalization for CVBS Without Color Burst Integrated Video Driver with Adjustable Back-Porch Clamp Level LOS and LOB Output NTSC and PAL Compatible 16-Pin SSOP Package
MAX7474
The MAX7474 adaptive equalizer recovers losses incurred in the transmission of a composite video (CVBS) signal over unshielded twisted-pair (UTP) cable. The device fully recovers losses for cable lengths of up to 300m and greatly improves signal quality for cable lengths of up to 600m. The device automatically adapts to all cable lengths for CVBS signals with color burst and allows fixed-equalization settings for video signals without burst. The MAX7474 is optimized to provide compensation for losses that occur when transmitting composite video signals over UTP cables such as Category 5e. The device compensates for low frequency and chroma band losses. The MAX7474 is compatible with NTSC and PAL standards. The MAX7474 accepts differential input and provides a single-ended output. The output is capable of driving two AC- or DC-coupled standard 150 video loads. The output back-porch DC level is adjustable with an externally applied DC voltage at the BPLVL input. The device also features loss-of-sync (LOS) and loss-of-burst (LOB) logic outputs. The MAX7474 is available in a 16-pin SSOP package and is fully specified over the extended (-40C to +85C) temperature range.
Ordering Information
PART MAX7474EAE+ TEMP RANGE PIN-PACKAGE -40C to +85C 16 SSOP (5.3mm x 6.2mm) PKG CODE A16+2
Applications
Security Video Systems Video Switching Systems Home Automation
+Denotes a lead-free package.
Pin Configuration and Typical Application Circuit appear at end of data sheet.
Functional Diagram
+5V +5V
0.1F VCC 0.022F UNSHIELDED TWISTED PAIR (0 TO 300m) CAMERA INN 50 0.022F 50 FEQ0 FEQ1 INP CLAMP
0.1F VCC MAX7474 ADAPTIVE EQUALIZER OUT ADC
BACK-PORCH CLAMP AGC AND AEQ CONTROL GND
BPLVL (1.0V TO 1.6V)
LOB LOS
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
Adaptive Equalizer for Video Over Twisted Pair MAX7474
ABSOLUTE MAXIMUM RATINGS
VCC to GND ..............................................................-0.3V to +6V All Other Pins to GND.............-0.3V to (min of 6V or VCC + 0.3V) Maximum Continuous Current into Any Input or Output .....50mA Continuous Power Dissipation (TA = +70C) 16-Pin SSOP (derate 7.1mW/C above +70C) ........571.4mW Operating Temperature Range ...........................-40C to +85C Maximum Junction Temperature .....................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VCC = +4.75V to +5.25V, RL = 150 (AC-coupled), FEQ1 = GND, FEQ0 = GND, VBPLVL = 1.4V, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.)
PARAMETER Differential Input Operating Voltage Maximum Differential Input Operating Voltage Output Voltage Output Sync Accuracy Output Burst Accuracy Differential Phase Differential Gain Clamp Settling Time Back-Porch Level Input Operating Range Output Blank Level Accuracy Line-Time Distortion LOS Threshold LOB Threshold Equalizer Response Time OUT Leakage Current Fixed Equalizer Gain VOUT VSYNC_OUT VBURST_OUT DP DG tCLAMP VBPLVL VOUT-BL LTD VLOS VLOB tEQ ILEAK AFEQ (Note 2) 18s, 100 IRE bar, DC-coupled output Measured differentially between INP and INN (Note 3) Measured at OUT with maximum equalizer gain (Note 4) Within 10% of final value of the combined AGC and AEQ gain from minimum to maximum LOS mode, OUT is three-stated FEQ1 = GND, FEQ0 = GND fSC = 3.58MHz FEQ1 = GND, FEQ0 = VCC FEQ1 = VCC, FEQ0 = GND -1.5 2.5 8.5 1.2 40 80 16,384 0.01 0 4.5 10.5 10 +1.5 6.5 12.5 dB Output blank level settles to < 5 IRE of final value from an initial 100 IRE input error 1.0 SYMBOL VIN-DIFF CONDITIONS AC-coupled, measured from sync tip to 100% white level (Note 1) AC-coupled, measured from sync tip to 100% white level Measured from sync tip to 100% white level 210mVP-P < VSYNC_IN-DIFF < 600mVP-P 76mVP-P < VBURST_IN-DIFF < 300mVP-P, fSC = 3.58MHz 263 242 2.4 1.0 293 293 0.3 0.3 9 30 1.6 55 323 344 MIN TYP 1.0 MAX UNITS VP-P VP-P VP-P mVP-P mVP-P Degrees % H Lines V mV % mVP-P mVP-P H Lines A
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Adaptive Equalizer for Video Over Twisted Pair
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +4.75V to +5.25V, RL = 150 (AC-coupled), FEQ1 = GND, FEQ0 = GND, VBPLVL = 1.4V, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.)
PARAMETER SYMBOL CONDITIONS MIN 0.7 x VCC 0.3 x VCC Digital inputs = 0 or VCC CIN VOL VOH ISINK = 500A ISOURCE = 500A VCC - 0.4 4.75 No load Normal mode LOS mode 5.0 47 24 65 5.25 59 0.01 15 0.4 10 TYP MAX UNITS
MAX7474
DIGITAL INPUTS (FEQ0, FEQ1) Input High Voltage Input Low Voltage Input Leakage Current Input Capacitance Output Low Voltage Output High Voltage POWER SUPPLY Supply Voltage Range Supply Current DC Power-Supply Rejection Ratio VCC ICC PSRR V mA dB VIH VIL V V A pF V V
DIGITAL OUTPUTS (LOS, LOB)
20log(VCC/VOUT-BlackLevel), black video input with no color burst
Note 1: VIN-DIFF = VINP - VINN. Note 2: VOUT-BL = VBPLVL + VOUT-BL. Note 3: LOS is high when the input video sync amplitude goes below VLOS for 32 consecutive horizontal lines. LOS goes low when the input video sync amplitude exceeds VLOS for 32 consecutive horizontal lines. Note 4: LOB is high when the output color burst amplitude goes below VLOB for 32 consecutive horizontal lines when at maximum equalizer gain. LOB goes low when the output color burst amplitude exceeds VLOB for 32 consecutive horizontal lines.
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Adaptive Equalizer for Video Over Twisted Pair MAX7474
Typical Operating Characteristics
(VCC = 5V, RL = high impedance, fSC = 3.58MHz, Category 5e cable with active driver, TA = +25C.)
MULTIBURST (0.5m CABLE)
MAX7474 toc01
MULTIBURST (300m CABLE)
MAX7474 toc02
75% COLOR BAR VECTOR DIAGRAM (0.5m CABLE)
MAX7474 toc03
VINP-VINN 200mV/div
VINP-VINN 200mV/div
VOUT 200mV/div
VOUT 200mV/div
10s/div
10s/div
75% COLOR BAR VECTOR DIAGRAM (300m CABLE)
DIFFERENTIAL PHASE () DIFFERENTIAL GAIN (%)
MAX7474 toc04
DIFFERENTIAL GAIN AND PHASE (0.5m CABLE)
MAX7474 toc05
DIFFERENTIAL GAIN AND PHASE (300m CABLE)
DIFFERENTIAL PHASE () DIFFERENTIAL GAIN (%) 0.2 0 -0.2 -0.4 0.4 0.2 0 -0.2 -0.4 0 1 2 3 4 5 MODULATED STEP
MAX7474 toc06
0.4 0.2 0 -0.2 -0.4 0.4 0.2 0 -0.2 -0.4 0 1 2 3 4 5 MODULATED STEP
0.4
2T RESPONSE (0.5m CABLE)
MAX7474 toc07
2T RESPONSE (300m CABLE)
MAX7474 toc08
12.5T RESPONSE (0.5m CABLE)
MAX7474 toc09
VINP-VINN 200mV/div
VINP-VINN 200mV/div
VINP-VINN 200mV/div
VOUT 200mV/div
VOUT 200mV/div
VOUT 200mV/div
200ns/div
200ns/div
500ns/div
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Adaptive Equalizer for Video Over Twisted Pair
Typical Operating Characteristics (continued)
(VCC = 5V, RL = high impedance, fSC = 3.58MHz, Category 5e cable with active driver, TA = +25C.)
18s LINE-TIME DISTORTION (0.5m CABLE)
MAX7474 toc11
MAX7474
12.5T RESPONSE (300m CABLE)
MAX7474 toc10
18s LINE-TIME DISTORTION (300m CABLE)
MAX7474 toc12
VINP-VINN 200mV/div
VINP-VINN 200mV/div
VINP-VINN 200mV/div
VOUT 200mV/div
VOUT 200mV/div
VOUT 200mV/div
500ns/div
5s/div
5s/div
NOISE SPECTRUM (0.5m CABLE)
0 -5 -10 -15 -20 -25 -30 -40 -45 -50 -55 -60 -65 -70 -75 -80 -85 -90 -95 -100 1 2 3 4 FREQUENCY (MHz)
MAX7474 toc13
NOISE SPECTRUM (300m CABLE)
0 -5 -10 -15 -20 -25 -30 -40 -45 -50 -55 -60 -65 -70 -75 -80 -85 -90 -95 -100 1 2 3 4 FREQUENCY (MHz)
MAX7474 toc14
NOISE LEVEL (dB)
NOISE LEVEL (dB)
5
5
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Adaptive Equalizer for Video Over Twisted Pair MAX7474
Pin Description
PIN 1, 2, 3, 5, 10, 13 4, 9 NAME GND VCC Ground. Connect all GND terminals together. Power-Supply Input. Connect a +4.75V to +5.25V supply to VCC. Connect both VCC inputs together. Bypass each VCC input with a 0.1F capacitor to GND as close as possible to the device. Loss-of-Burst Logic Output. LOB goes high when the output color burst goes below the LOB threshold (VLOB) for 32 consecutive horizontal lines when the equalizer is at its maximum gain. LOB goes low when the output color burst exceeds VLOB for 32 consecutive horizontal lines. When LOB is active, the device enters the fixed equalization mode. LOB is valid only when LOS is low. Back-Porch Level Input. The voltage applied to BPLVL sets the output back-porch voltage level. Composite Video Output Fixed-Cable Equalization inputs. FEQ0 and FEQ1 set the fixed equalization level. See Table 1. Noninverted Video Input. AC-couple video signal with a 0.022F capacitor. Inverted Video Input. AC-couple video signal with a 0.022F capacitor. Loss-of-Sync Logic Output. LOS goes high when the input sync amplitude goes below the loss-of-sync threshold (VLOS) for 32 consecutive horizontal lines. LOS is pulled low when the input sync amplitude exceeds VLOS for 32 consecutive horizontal lines. When LOS is active, the output enters a highimpedance state. FUNCTION
6
LOB
7 8 11 12 14 15
BPLVL OUT FEQ0 FEQ1 INP INN
16
LOS
Detailed Description
The MAX7474 compensates for cable losses that occur when transmitting a composite video signal over unshielded twisted-pair cable (see the Typical Application Circuit). The device automatically adapts to cable length by monitoring the sync and color-burst amplitudes of the color video signal at the output (OUT) and adjusting the gains accordingly. Video signals without burst are automatically detected and a user-selectable fixed equalization is applied to the signal. The MAX7474 provides full equalization up to 300m of Category 5e cable and greatly improves performance up to 600m. The MAX7474 accepts differential video input signals in NTSC or PAL standards. The MAX7474 includes an output unity-gain video driver and adjustable backporch DC level. The device also features LOS and LOB logic outputs.
Input Clamp The MAX7474 clamps the sync tip of the input signal to internally set DC levels effectively correcting, on a lineby-line basis, any shift in the sync-tip level of the input video signal. The sync-tip of the positive video input signal (VINP) is clamped to typically 2.0V and the negative video input signal (VINN) is clamped to typically 3.2V. The input clamp enables capacitive coupling of the input, permitting a large common-mode DC difference between the line driver (camera) and the device.
Adaptive Equalizer
The adaptive equalizer in the MAX7474 provides the appropriate inverse frequency response needed to compensate for UTP cable loss. The equalizer adjusts the low-frequency amplitude and chroma amplitude of the input CVBS signal. The low-frequency component of the CVBS is adjusted according to the feedback information obtained from the internal automatic gaincontrol (AGC) circuit, which monitors the sync pulse amplitude of the output signal (see the Automatic Gain Control (AGC) section). The chroma gain of the video signal is adjusted according to the feedback information obtained from the internal automatic equalization control circuit, which monitors the color-burst amplitude of the output signal (see the Automatic Equalization Control (AEQ) section).
Video Input
The MAX7474 accepts a differential video input with a maximum 2.4VP-P voltage swing. A twisted-pair cable carries the differential video signal to the positive (INP) and negative (INN) inputs, which are AC-coupled with 0.022F capacitors. Each input is internally clamped to a DC level (see the Input Clamp section).
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Adaptive Equalizer for Video Over Twisted Pair
The chroma gain for the MAX7474 is automatically adjusted between 0dB and +12dB, while the low-frequency gain is automatically adjusted between -6dB and +3.6dB, providing full equalization for cable losses that can occur when using up to 300m of UTP cable to transmit CVBS signal with color burst. When using cable lengths greater than 75m, set the fixed equalization level according to Table 1, or higher, to ensure the device comes out of the fixed equalization mode. If the fixed equalization is set to a lower gain setting than specified in Table 1, the amplitude of the color-burst signal at the output may remain smaller than the LOB threshold (V LOB ) of 80mV P-P , keeping the device in LOB mode (see the Automatic Equalization Control (AEQ) section). If the conditions in Table 1 are not met, set FEQ1 to high to ensure the device always comes out of LOB mode for longer cable lengths.
MAX7474
Automatic Gain Control (AGC)
The automatic gain control circuit corrects low-frequency signal losses such that the output signal obtains a nominal sync level (VSYNC_OUT) of 293mV. Differential input sync pulse amplitude in the 210mV P-P and 600mVP-P range is automatically adjusted to the nominal output sync level (VSYNC_OUT). If the sync is lost for 32 consecutive horizontal lines, the LOS output goes high and OUT is set to a high-impedance state.
Output Video Driver
The MAX7474 features a single-ended video output driver with 0dB gain. The typical output voltage swing of the output driver is 1.2VP-P. The output driver is capable of driving two AC-coupled or DC-coupled 150 video loads. The output back-porch DC level is set by an internal back-porch clamp circuit (see the BackPorch Clamp section). OUT enters a high-impedance state when sync is lost for 32 consecutive horizontal lines, asserting LOS.
Automatic Equalization Control (AEQ)
The automatic equalization control circuit corrects the chroma signal attenuation such that the output-signal burst amplitude is 293mV (subcarrier frequency, fSC = 3.58MHz or 4.43MHz). Differential input color-burst amplitude in the 76mVP-P and 300mVP-P range is automatically adjusted to the nominal output color-burst level (VBURST_OUT). The AGC and AEQ equalization take approximately 1s (16,384 lines) to change from the lowest gain to the highest gain. During this time, the chroma amplitude is gradually increased from minimum to maximum.
Back-Porch Clamp
The MAX7474 features a back-porch clamp to set the output blanking level. This clamp shifts the DC level of the video signal so that the back-porch level is approximately equal to the voltage level on the BPLVL input. The voltage range allowed at the BPLVL input is 1V to 1.6V.
Applications Information
Differential UTP Input Interface
Applications with differential input interface require proper input voltage levels, termination, and AC-coupling (Figure 1). The maximum differential input voltage swing allowed is 2.4V. Use active drivers to drive the cable as shown in Figure 1. For Category 5e cables, the proper termination resistance is 50 to ground at INN and INP inputs. Apply a 0.022F coupling capacitor at each input.
Fixed Equalization Mode (LOB Is High)
If the color-burst amplitude at the output of the MAX7474 (OUT) is less than 80mVP-P with the equalizer gain set to maximum for 32 consecutive horizontal lines, the loss-of-burst output (LOB) goes high. LOB returns low when color bursts with amplitude greater than 80mVP-P are present at OUT for 32 consecutive horizontal lines. For applications where the input signal has no color burst, or the input burst amplitude is lower than the LOB threshold voltage (VLOB), the MAX7474 asserts LOB and automatically applies a user-defined fixed equalization set by logic inputs FEQ1 and FEQ0 (see Table 1).
Output Interface
The video output is capable of driving an AC-coupled or DC-coupled load. Use a 220F or larger coupling capacitor for AC-coupling. Figure 1 shows applications with AC- and DC-coupled output interface.
Table 1. Fixed Equalization Level Settings
PART FEQ1 GND MAX7474 GND VCC FEQ0 GND VCC X TYP (dB) 0 4.5 10.5 CABLE LENGTH RANGE (m) 0 to 75 75 to 225 225
Security Systems Application
Security systems typically consist of many cameras that are viewed and recorded on a relatively smaller number
X = VCC or GND.
_______________________________________________________________________________________ 7
Adaptive Equalizer for Video Over Twisted Pair MAX7474
CAMERA +0.5VP-P 1VP-P 50 CAT 5e (0 TO 600m)
0.022F
MAX7474
1VP-P ADC CVBS
0.022F 50 -0.5VP-P 50 50 BPLVL
CAMERA +0.5VP-P 1VP-P 50 CAT 5e (0 TO 600m)
0.022F
MAX7474
1VP-P 220F 75 CVBS
0.022F 50 -0.5VP-P 50 50
Figure 1. Typical Input and Output Connections
of monitors or recording devices. Cabling is a significant part of a CCTV installation cost. Low-cost unshielded twisted-pair (UTP) cable has increasingly replaced coaxial cable in security systems. Most cameras and switchers use single-channel coax connectors, and therefore require some type of single-ended-to-differential video conversion such as active drivers. Active cable compensation is required for longer cable lengths. Active compensation can occur on the receive side, camera side, or both. The MAX7474 provides active compensation on the receive side that is superior to balun, or active fixed cable equalization.
Power Supply, Grounding, and Layout
The MAX7474 operates from a +4.75V to +5.25V single supply. Connect both VCC inputs together and bypass each one with a 0.1F capacitor to GND. Connect the 0.1F capacitors as close as possible to the device to minimize the loop formed when the bypass capacitor is connected to the device, thus avoiding additional inductance that could resonate with the capacitor. For optimum performance, use a ground plane and keep the input and output traces away from each other.
Chip Information
PROCESS: BiCMOS
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_______________________________________________________________________________________
Adaptive Equalizer for Video Over Twisted Pair
Pin Configuration
TOP VIEW
GND GND GND VCC GND LOB BPLVL OUT 1 2 3 4 5 6 7 8 16 LOS 15 INN 14 INP
MAX7474
MAX7474
13 GND 12 FEQ1 11 FEQ0 10 GND 9 VCC
SSOP
Typical Application Circuit
VCC 1 2 3 VCC 1 2 3 J1 11 12 13 VCC VCC C3 0.1F GND V_INP C4 0.022F 14 R1 49.9 1% C5 V_INN 0.022F 15 R2 49.9 1% VCC GND C1 1F 3 4 SHDN IN INN BPLVL INP 3 2 1 C6 0.1F 4 9 5 10 FREQ0 FREQ1 GND LOB 6 16 1 2 3 JU4 OUT 8 R3 0 C7 470F BP_LVL VOUT J1-1 J1-2 J1-3
JU2
JU1
U1 MAX7474
LOS GND GND
VCC VCC GND GND
GND
VIN VIN-8 VIN-7 VIN-6 VIN-5 VIN-4 VIN-3 VIN-2 VIN-1
7
JU3
U2 MAX6037
OUT
5 C2 1F
1
2 R4 10k
3
2
GND
N.C.
1
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Adaptive Equalizer for Video Over Twisted Pair MAX7474
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
2 1
SSOP.EPS
INCHES DIM A A1 B C E H D E e H L MIN 0.068 0.002 0.010 MAX 0.078 0.008 0.015
MILLIMETERS MIN 1.73 0.05 0.25 MAX 1.99 0.21 0.38 D D D D D INCHES MIN 0.239 0.239 0.278 0.317 0.397 MAX 0.249 0.249 0.289 0.328 0.407 MILLIMETERS MIN 6.07 6.07 7.07 8.07 10.07 MAX 6.33 6.33 7.33 8.33 10.33 N 14L 16L 20L 24L 28L
0.20 0.09 0.004 0.008 SEE VARIATIONS 0.205 0.301 0.025 0 0.212 0.311 0.037 8 5.20 7.65 0.63 0 5.38 7.90 0.95 8 0.0256 BSC 0.65 BSC
N
A C B e D A1 L
NOTES: 1. D&E DO NOT INCLUDE MOLD FLASH. 2. MOLD FLASH OR PROTRUSIONS NOT TO EXCEED .15 MM (.006"). 3. CONTROLLING DIMENSION: MILLIMETERS. 4. MEETS JEDEC MO150. 5. LEADS TO BE COPLANAR WITHIN 0.10 MM.
PROPRIETARY INFORMATION TITLE:
PACKAGE OUTLINE, SSOP, 5.3 MM
APPROVAL DOCUMENT CONTROL NO. REV.
21-0056
1 1
C
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
10 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.
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