19-3216; Rev 0; 1/08 KIT ATION EVALU E L B AVAILA Adaptive Equalizer for Video Over Twisted Pair Features 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. 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 Ordering Information PART TEMP RANGE PIN-PACKAGE MAX7474EAE+ -40C to +85C 16 SSOP (5.3mm x 6.2mm) PKG CODE A16+2 +Denotes a lead-free package. Applications Security Video Systems Pin Configuration and Typical Application Circuit appear at end of data sheet. Video Switching Systems Home Automation Functional Diagram +5V +5V 0.1F 0.1F VCC VCC 0.022F INP UNSHIELDED TWISTED PAIR (0 TO 300m) MAX7474 CLAMP CAMERA ADAPTIVE EQUALIZER OUT ADC INN 50 BACK-PORCH CLAMP 0.022F 50 FEQ0 FEQ1 AGC AND AEQ CONTROL BPLVL (1.0V TO 1.6V) LOB LOS GND ________________________________________________________________ Maxim Integrated Products 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. 1 MAX7474 General Description MAX7474 Adaptive Equalizer for Video Over Twisted Pair 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 SYMBOL VIN-DIFF Maximum Differential Input Operating Voltage Output Voltage CONDITIONS AC-coupled, measured from sync tip to 100% white level (Note 1) AC-coupled, measured from sync tip to 100% white level VOUT MIN TYP MAX 1.0 VP-P 2.4 Measured from sync tip to 100% white level UNITS VP-P 1.0 VP-P Output Sync Accuracy VSYNC_OUT 210mVP-P < VSYNC_IN-DIFF < 600mVP-P 263 293 323 mVP-P Output Burst Accuracy VBURST_OUT 76mVP-P < VBURST_IN-DIFF < 300mVP-P, fSC = 3.58MHz 242 293 344 mVP-P Differential Phase DP 0.3 Degrees Differential Gain DG 0.3 % Clamp Settling Time tCLAMP Back-Porch Level Input Operating Range VBPLVL Output Blank Level Accuracy VOUT-BL Output blank level settles to < 5 IRE of final value from an initial 100 IRE input error 9 1.0 (Note 2) 30 H Lines 1.6 V 55 mV Line-Time Distortion LTD 18s, 100 IRE bar, DC-coupled output 1.2 % LOS Threshold VLOS Measured differentially between INP and INN (Note 3) 40 mVP-P LOB Threshold VLOB Measured at OUT with maximum equalizer gain (Note 4) 80 mVP-P 16,384 H Lines Equalizer Response Time tEQ Within 10% of final value of the combined AGC and AEQ gain from minimum to maximum OUT Leakage Current ILEAK LOS mode, OUT is three-stated Fixed Equalizer Gain AFEQ fSC = 3.58MHz 2 0.01 10 +1.5 FEQ1 = GND, FEQ0 = GND -1.5 0 FEQ1 = GND, FEQ0 = VCC 2.5 4.5 6.5 FEQ1 = VCC, FEQ0 = GND 8.5 10.5 12.5 _______________________________________________________________________________________ A dB Adaptive Equalizer for Video Over Twisted Pair (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 TYP MAX UNITS DIGITAL INPUTS (FEQ0, FEQ1) Input High Voltage VIH Input Low Voltage VIL Input Leakage Current Input Capacitance 0.7 x VCC Digital inputs = 0 or VCC V 0.01 CIN 0.3 x VCC V 10 A 15 pF DIGITAL OUTPUTS (LOS, LOB) Output Low Voltage VOL ISINK = 500A Output High Voltage VOH ISOURCE = 500A 0.4 VCC - 0.4 V V POWER SUPPLY Supply Voltage Range Supply Current DC Power-Supply Rejection Ratio VCC ICC PSRR 4.75 No load 5.0 5.25 Normal mode 47 59 LOS mode 24 20log(VCC/VOUT-BlackLevel), black video input with no color burst 65 V mA dB 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. _______________________________________________________________________________________ 3 MAX7474 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (VCC = 5V, RL = high impedance, fSC = 3.58MHz, Category 5e cable with active driver, TA = +25C.) MULTIBURST (0.5m CABLE) 75% COLOR BAR VECTOR DIAGRAM (0.5m CABLE) MULTIBURST (300m CABLE) MAX7474 toc01 MAX7474 toc02 MAX7474 toc03 VINP-VINN 200mV/div VINP-VINN 200mV/div VOUT 200mV/div VOUT 200mV/div 10s/div 75% COLOR BAR VECTOR DIAGRAM (300m CABLE) DIFFERENTIAL GAIN AND PHASE (300m CABLE) 0.4 MAX7474 toc05 MAX7474 toc04 0.2 0 -0.2 -0.4 0.4 0.2 0 -0.2 -0.4 0 1 2 3 4 DIFFERENTIAL PHASE () DIFFERENTIAL GAIN (%) DIFFERENTIAL GAIN AND PHASE (0.5m CABLE) 0.4 0.2 0 -0.2 -0.4 1 2 3 5 MAX7474 toc09 VINP-VINN 200mV/div VOUT 200mV/div 200ns/div 4 12.5T RESPONSE (0.5m CABLE) VINP-VINN 200mV/div VOUT 200mV/div 4 -0.4 MAX7474 toc08 VINP-VINN 200mV/div 200ns/div 0 -0.2 MODULATED STEP 2T RESPONSE (300m CABLE) MAX7474 toc07 0.2 0 5 MODULATED STEP 2T RESPONSE (0.5m CABLE) 0.4 MAX7474 toc06 10s/div DIFFERENTIAL PHASE () DIFFERENTIAL GAIN (%) MAX7474 Adaptive Equalizer for Video Over Twisted Pair VOUT 200mV/div 500ns/div _______________________________________________________________________________________ Adaptive Equalizer for Video Over Twisted Pair 18s LINE-TIME DISTORTION (300m CABLE) 18s LINE-TIME DISTORTION (0.5m CABLE) 12.5T RESPONSE (300m CABLE) MAX7474 toc10 MAX7474 toc12 MAX7474 toc11 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 (300m CABLE) MAX7474 toc13 0 -5 -10 -15 -20 -25 -30 -40 -45 -50 -55 -60 -65 -70 -75 -80 -85 -90 -95 -100 NOISE LEVEL (dB) NOISE LEVEL (dB) NOISE SPECTRUM (0.5m CABLE) 1 2 3 4 FREQUENCY (MHz) 5 MAX7474 toc14 0 -5 -10 -15 -20 -25 -30 -40 -45 -50 -55 -60 -65 -70 -75 -80 -85 -90 -95 -100 1 2 3 4 5 FREQUENCY (MHz) _______________________________________________________________________________________ 5 MAX7474 Typical Operating Characteristics (continued) (VCC = 5V, RL = high impedance, fSC = 3.58MHz, Category 5e cable with active driver, TA = +25C.) Adaptive Equalizer for Video Over Twisted Pair MAX7474 Pin Description PIN NAME 1, 2, 3, 5, 10, 13 GND Ground. Connect all GND terminals together. 4, 9 VCC 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. 6 LOB 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. 7 BPLVL 8 OUT 11 FEQ0 12 FEQ1 FUNCTION 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. 14 INP Noninverted Video Input. AC-couple video signal with a 0.022F capacitor. 15 INN Inverted Video Input. AC-couple video signal with a 0.022F capacitor. LOS 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. 16 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. 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). 6 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). _______________________________________________________________________________________ Adaptive Equalizer for Video Over Twisted Pair 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. 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. 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. 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. 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 Fixed Equalization Mode (LOB Is High) Differential UTP Input Interface 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). 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. Table 1. Fixed Equalization Level Settings PART MAX7474 TYP (dB) CABLE LENGTH RANGE (m) FEQ1 FEQ0 GND GND 0 0 to 75 GND VCC 4.5 75 to 225 VCC X 10.5 225 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. 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 MAX7474 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. MAX7474 Adaptive Equalizer for Video Over Twisted Pair CAMERA +0.5VP-P 1VP-P 50 0.022F MAX7474 CAT 5e (0 TO 600m) 1VP-P ADC CVBS 0.022F 50 -0.5VP-P 50 CAMERA +0.5VP-P 1VP-P 50 BPLVL 50 0.022F MAX7474 CAT 5e (0 TO 600m) 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. 8 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 _______________________________________________________________________________________ Adaptive Equalizer for Video Over Twisted Pair MAX7474 Pin Configuration TOP VIEW GND 1 16 LOS GND 2 15 INN GND 3 14 INP 13 GND VCC 4 GND 5 12 FEQ1 LOB 6 11 FEQ0 BPLVL 7 10 GND OUT 8 9 MAX7474 VCC SSOP Typical Application Circuit VCC VCC JU2 1 2 JU1 1 2 3 3 J1 11 12 13 VCC VCC 4 9 C6 0.1F C3 0.1F 5 GND 10 14 VIN-8 VIN-7 VIN-6 R1 49.9 1% VIN-3 VIN-2 VIN-1 GND U1 LOS MAX7474 GND GND VCC GND 15 J1-1 16 J1-2 J1-3 1 2 3 VCC JU4 GND GND OUT VOUT 8 R3 0 C7 470F INP BP_LVL C5 V_INN 0.022F BPLVL INN JU3 7 3 2 1 R2 49.9 1% VIN-5 VIN-4 FREQ1 LOB C4 0.022F V_INP VIN FREQ0 6 VCC GND 3 4 C1 1F 2 SHDN IN GND U2 OUT 5 1 C2 1F MAX6037 N.C. 2 3 R4 10k 1 _______________________________________________________________________________________ 9 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 SSOP.EPS MAX7474 Adaptive Equalizer for Video Over Twisted Pair 1 INCHES E H MILLIMETERS DIM MIN MAX MIN MAX A 0.068 0.078 1.73 1.99 A1 0.002 0.008 0.05 0.21 B 0.010 0.015 0.25 0.38 C 0.20 0.09 0.004 0.008 SEE VARIATIONS D E e 0.205 0.212 0.0256 BSC 5.20 MILLIMETERS INCHES D D D D D 5.38 MIN MAX MIN MAX 0.239 0.239 0.278 0.249 0.249 0.289 6.07 6.07 7.07 6.33 6.33 7.33 0.317 0.397 0.328 0.407 8.07 10.07 8.33 10.33 N 14L 16L 20L 24L 28L 0.65 BSC H 0.301 0.311 7.65 7.90 L 0.025 0 0.037 8 0.63 0 0.95 8 N A C B e A1 L D 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. 21-0056 REV. C 1 1 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 Heaney is a registered trademark of Maxim Integrated Products, Inc.