19-3267; Rev 2; 11/04 Video-Signal Conditioners with AGC and Back-Porch Clamp Features The MAX7450/MAX7451/MAX7452 complete front-end video-signal conditioners are designed to improve the quality of standard-definition video signals. The devices restore the DC level of the video input, correct for amplitude errors up to ±6dB, detect fault conditions, and filter out-of-band noise. The MAX7450/MAX7451/ MAX7452 optimize the signal quality for further video processing through a crosspoint switch or video decoder (ADC). Each device integrates an input video clamp, automatic gain control (AGC), loss-of-sync (LOS) detector, and an out-of-band noise/lowpass filter. These devices also incorporate a user-selectable buffer gain (0 or +6dB) and an AGC-disable function. The MAX7450 and MAX7451 operate from dual power supplies of ±5V or ±3.3V respectively, and they restore the video blanking level to GND. The MAX7452 operates from a single +5V supply and features a user-adjustable clamp level. ♦ Back-Porch Clamp to GND (MAX7450/MAX7451) ♦ Adjustable Back-Porch Clamp (MAX7452) ♦ Automatic Gain Control (±6dB Range) Normalizes Signals to Standard Video Level ♦ Input Fault Detection with LOS Output ♦ Inherent 50Hz/60Hz Input Rejection of 60dB ♦ Single-Supply Operation: MAX7452 (+5V) ♦ Out-of-Band Noise Filter ♦ Output Buffer Drives Standard 150Ω Video Load with 0dB or +6dB Gain ♦ Dual-Supply Operation MAX7450 (±5V) MAX7451 (±3.3V) ♦ Tiny 8-Pin SO Package The devices are available in an 8-pin SO package with an exposed pad and are specified for operation over the extended (-40°C to +85°C) temperature range. Ordering Information PART† Applications Signal Conditioner for Standard-Definition Video Inputs Security Video Systems TEMP RANGE PINSUPPLY PACKAGE VOLTAGE (V) MAX7450ESA -40°C to +85°C 8 SO-EP* ±5 MAX7451ESA -40°C to +85°C 8 SO-EP* ±3.3 MAX7452ESA -40°C to +85°C 8 SO-EP* +5 *EP = Exposed pad. †Package code = S8E-12. Video-Switching Systems Functional Diagram VCC VIDEO INPUT IN NOISE FILTER GAIN SET (0dB OR +6dB) ±6dB 0 OR +6dB 75Ω OUT 75Ω SYNC SEPARATOR AND AMPLITUDE DETECTOR LOS AGCD MAX7450 MAX7451 VSS GND ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX7450/MAX7451/MAX7452 General Description MAX7450/MAX7451/MAX7452 Video-Signal Conditioners with AGC and Back-Porch Clamp ABSOLUTE MAXIMUM RATINGS VCC to GND MAX7450/MAX7452...........................................................+6V MAX7451 ...........................................................................+4V VSS to GND MAX7450.............................................................................-6V MAX7451.............................................................................-4V OUT MAX7450/MAX7451 ..........................................-2.5V to +3.5V MAX7452 ................................................-0.3V to (VCC + 0.3V) GSET, AGCD, LOS .....................................-0.3V to (VCC + 0.3V) All Other Pins MAX7450/MAX7451...................(-0.3V + VSS) to (VCC + 0.3V) MAX7452 ................................................-0.3V to (VCC + 0.3V) Maximum Current into Any Pin ............……………………±50mA Continuous Power Dissipation (TA = +70°C) 8-Pin SO (derate 18.9mW/°C above +70°C)..............1509mW Operating Temperature Range ...........................-40°C to +85°C Storage Temperature Range .............................-65°C to +150°C Junction Temperature ......................................................+150°C Lead temperature (soldering, 10s) ..................................+300°C 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 (VSUPPLY = ±5V ±5% (MAX7450), VSUPPLY = ±3.3V ±5% (MAX7451), VSUPPLY = +5V ±5% (MAX7452), RL=150Ω to GND, CL = 0 to 20pF, GSET = 1, AGCD = 1, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL Clamp Accuracy CONDITIONS ±50 ±50 GSET = 0 1.5 2.4 GSET = 1 1.2 2.0 MAX7452 Clamp Response Time tCLAMP Blanking level at the output to 1% of final value AGCD = 0, VIN = 0.5VP-P to 2VP-P Gain Flatness GF Noise-Filter Cutoff Fc Low-Frequency Gain MAX MAX7450/MAX7451, relative to GND VBPLVL AGC Input Range TYP MAX7452, relative VBPLVL = 1.5V Back-Porch Level Input Range AGC Accuracy MIN mV V Lines 70 GSET = 0, relative to VOUT = 1VP-P ±10 GSET = 1, relative to VOUT = 2VP-P ±10 % AGCD = 0, relative to VIN = 1VP-P -6.0 f = 5MHz relative to 100kHz -0.3 +6.0 +0.3 10 f = 100kHz UNITS dB dB MHz GSET = 0 0.95 1 1.05 GSET = 1 1.85 2 2.05 V/V Group-Delay Deviation ∆tG 3.58/4.43MHz relative to 100kHz 15 ns Differential Gain dG Five-step modulated staircase (VIN = 1VP-P) 0.2 0.6 % Differential Phase dθ Five-step modulated staircase (VIN = 1VP-P) 0.2 0.6 Degrees 2 _______________________________________________________________________________________ Video-Signal Conditioners with AGC and Back-Porch Clamp (VSUPPLY = ±5V ±5% (MAX7450), VSUPPLY = ±3.3V ±5% (MAX7451), VSUPPLY = +5V ±5% (MAX7452), RL=150Ω to GND, CL = 0 to 20pF, GSET = 1, AGCD = 1, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER Signal-to-Noise Ratio SYMBOL SNR CONDITIONS Output signal peak-to-peak to RMS noise (100Hz to 5MHz) 68 GSET = 1, VOUT = 2VP-P 65 Line Time Distortion HDIST 18µs, 100 IRE bar Field Time Distortion VDIST 130 lines, 18µs, 100IRE bar Input Leakage Current PSRR Supply Current VIH Logic-Low Input VIL MAX 0.2 UNITS % 0.5 % 1 5 µA VIN = 1VP-P, dG / dP < 3% / degrees 2 2.4 VP-P AGCD = 1 30 AGCD = 0 with maximum gain 20 VCC + 100mVP-P, f = 3.5MHz dB MAX7450 35 MAX7451 30 MAX7452 Logic-High Input TYP dB IIN Output Dynamic Range Power-Supply Rejection Ratio MIN GSET = 0, VOUT = 1VP-P 20 0.7 x VCC V 0.3 x VCC Logic-High Output VOH ISOURCE = 500µA Logic-Low Output VOL mA VCC 0.5 V V ISINK = 500µA 0.4 V Input Current Logic-High IIH Logic input sink 10 µA Input Current Logic-Low IIL Logic input source 10 µA _______________________________________________________________________________________ 3 MAX7450/MAX7451/MAX7452 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics VSUPPLY = ±5V ±5% (MAX7450), VSUPPLY = ±3.3V ±5% (MAX7451), VSUPPLY = +5V ±5% (MAX7452), RL= 150Ω to GND, CL = 0 to 20pF, GSET = 1, AGCD = 1. TA = +25°C, unless otherwise noted. GROUP DELAY vs. FREQUENCY 2T RESPONSE DIFFERENTIAL GAIN 40 IN 200mV/div 30 20 OUT 200mV/div 10 1 10 t = 200ns/div FREQUENCY (MHz) PASSBAND AMPLITUDE vs. FREQUENCY 6 2 0 GAIN = 1V / V -4 4th -20 1st 2nd 3rd 4th GAIN = 1V / V -30 -40 -50 -8 -60 -70 1 10 0.1 1 100 10 FREQUENCY (MHz) SUPPLY CURRENT vs. TEMPERATURE BACK-PORCH VOLTAGE vs. TEMPERATURE 33 31 29 27 0 MAX7450 BACK-PORCH VOLTAGE (mV) MAX7450 MAX7450 toc06 FREQUENCY (MHz) 35 -1 -2 -3 -4 -5 25 -6 -40 -15 10 35 TEMPERATURE (°C) 60 85 -40 -15 5th 6th 0.3 0.2 0.1 0 -0.1 -0.2 -0.3 GAIN = 2V / V -6 0.1 SUPPLY CURRENT (mA) 3rd DIFFERENTIAL PHASE -10 -10 4 2nd 0 GAIN = 2V / V -2 1st AMPLITUDE vs. FREQUENCY AMPLITUDE (dB) AMPLITUDE (dB) 4 -0.4 10 MAX7450 toc04 8 0 -0.2 MAX7450 toc07 0.1 0.2 MAX7450 toc05 50 0.4 MAX7450 toc03 MAX7450 toc01 DIFFERENTIAL PHASE (DEGREES) DIFFERENTIAL GAIN (%) MAX7450 toc02 60 GROUP DELAY (ns) MAX7450/MAX7451/MAX7452 Video-Signal Conditioners with AGC and Back-Porch Clamp 10 35 60 85 TEMPERATURE (°C) _______________________________________________________________________________________ 5th 6th Video-Signal Conditioners with AGC and Back-Porch Clamp OUTPUT BACK-PORCH LEVEL (MAX7450) AGC RESPONSE ENVELOPE (VIN = 0.5VP-P) MAX7450 toc08 AGC RESPONSE ENVELOPE (VIN = 2VP-P) MAX7450 toc10 MAX7450 toc09 AGCD = 0 VOUT = 2VP-P AGCD = 0 VOUT = 2VP-P IN AC-COUPLED 200mV/div 500mV/div 500mV/div OUT 200mV/div BACK-PORCH = 0V 1µs 400ms/div 400ms/div Pin Description PIN NAME FUNCTION 1 VCC Positive Power Supply. Connect +5V to VCC for the MAX7450/MAX7452. Connect +3.3V to VCC for the MAX7451. Bypass to GND with 1µF and 0.1µF capacitors as close to the pin as possible. 2 2 IN 3 3 GND Ground 4 — VSS Negative Power Supply. Connect -5V to VSS for the MAX7450. Connect -3.3V to VSS for the MAX7451. Bypass to GND with 1µF and 0.1µF capacitors as close to the pin as possible. — 4 BPLVL Back-Porch Level Input. When gain = 2V/V (GSET = 1), output back-porch level is equal to BPLVL input. When gain = 1V/V (GSET = 0), output back-porch level is equal to VBPLVL/1.5. 5 5 AGCD Automatic Gain-Control Disable Input. Disable AGC by driving AGCD to VCC. Enable AGC by driving AGCD to GND. 6 6 OUT Video Output 7 7 GSET Gain-Setting Input. Drive GSET high to set buffer gain to +6dB. Drive GSET low to set buffer gain to 0dB. 8 8 LOS Loss-of-Sync Logic Output. LOS is high when video sync is lost for more than 15 horizontal lines. LOS goes low when video sync is present. — — EP MAX7450/ MAX7451 MAX7452 1 Video Input. AC-couple video signal through a 0.1µF capacitor. Exposed Pad. Connect to VSS (MAX7450/MAX7451). Connect to GND (MAX7452). _______________________________________________________________________________________ 5 MAX7450/MAX7451/MAX7452 Typical Operating Characteristics (continued) VSUPPLY = ±5V ±5% (MAX7450), VSUPPLY = ±3.3V ±5% (MAX7451), VSUPPLY = +5V ±5% (MAX7452), RL= 150Ω to GND, CL = 0 to 20pF, GSET = 1, AGCD = 1. TA = +25°C, unless otherwise noted. MAX7450/MAX7451/MAX7452 Video-Signal Conditioners with AGC and Back-Porch Clamp VCC GAIN SET (0dB OR +6dB) VIDEO INPUT IN NOISE FILTER ±6dB 0 OR +6dB OUT 75Ω 75Ω MAX7452 SYNC SEPARATOR AND AMPLITUDE DETECTOR LOS AGCD GND BPLVL Figure1. MAX7452 Functional Diagram Detailed Description As shown in Figure 1, the devices include a 2nd-order lowpass filter intended to reject out-of-band noise. The MAX7450/MAX7451 clamp the back-porch voltage to ground, and the MAX7452 clamps to a user-supplied reference voltage. These devices also include an automatic gain control (AGC), which automatically adjusts the gain to ensure the sync amplitude is normalized to a standard video level; an AGC disable function; and an output driver that drives a standard video load (150Ω) with a full 2VP-P video signal (GSET = 1) or 1VPP video signal (GSET = 0). The clamp and the AGC work concurrently. Interaction between the two different control loops is eliminated by the large difference in time constants. The time constant of the clamp settles within 100 lines, while the AGC loop is digitally stepped so that it settles between 1000–64,000 lines. The AGC control works independently of the gain setting of the output buffer. The overall gain is the multiplication of the AGC gain and the output buffer gain. The maximum overall gain is +12dB and the minimum gain is -6dB. 6 Back-Porch Clamp The MAX7450/MAX7451/MAX7452 feature a backporch clamp to set the output blanking level. The devices sense the voltage during back porch and feed back into a control system. The control system provides the appropriate DC-level shift to clamp the output to ground (MAX7450/MAX7451) or to a voltage set by VBPLVL (MAX7452). This restores the DC level for further video processing such as on-screen display (OSD) insertion and analog-to-digital conversion. The backporch clamp to ground also eliminates the need for large output-coupling capacitors that can introduce unwanted line-time distortion (tilt) and cost. This can also reduce board space. The feedback network and the on-chip capacitors introduce a finite settling time after power-up or after any dramatic shift in input voltage (see the Electrical Characteristics section). Back-Porch Level Input (MAX7452) The MAX7452 features an adjustable back-porch level at the output as shown in Figure 1. VBPLVL sets the back-porch clamp level. The back-porch clamp-output level is defined by the following equations. GSET = 1 (Gain = 2V / V), VBACKPORCHLEVEL = VBPLVL GSET = 0 (Gain = 1V / V), VBACKPORCHLEVEL = VBPLVL / 1.5 _______________________________________________________________________________________ Video-Signal Conditioners with AGC and Back-Porch Clamp The MAX7450/MAX7451/MAX7452 feature a simple 2ndorder lowpass filter to reject out-of-band noise that may be introduced by the long cable connection between the cameras and the switching matrix. AGCD GSET OUTPUT 0 0 1VP-P fixed 0 1 2VP-P fixed 1 0 VOUT = VIN LOS Detector 1 1 VOUT = 2VIN The LOS detector of the MAX7450/MAX7451/MAX7452 outputs a logic high when the sync is not present (loss of video signal) for at least 15 horizontal lines on the input. This can be used to indicate a fault condition of the camera or cable. Automatic Gain Control (AGC) The MAX7450/MAX7451/MAX7452 have an integrated automatic gain-control circuit to ensure the sync amplitude is normalized to the standard level, thus normalizing the overall amplitude to a standard level. The accuracy of the normalized amplitude assumes the ratio of active video to sync amplitude is correct in the input video signal. The gain is adjusted automatically by detecting and comparing the amplitude of the sync pulse to a fixed internal reference. If the sync amplitude is less than this value, the overall gain is increased until the sync amplitude equals this reference. However, if the sync amplitude is high, the overall gain is reduced accordingly. Disable the AGC loop by driving AGCD high. When designing the overall system, it is important to note that the AGC can correct for termination problems. First, disable the AGC and verify that the terminations are correct, and then enable the AGC for proper operation. Output Buffer The output buffer of the MAX7450/MAX7451/MAX7452 is designed to drive either standard video loads or high-impedance loads, independent of the buffer gain. Logic levels on GSET and AGCD set the gain of the MAX7450/MAX7451/MAX7452. Table 1 shows the different gain-setting configurations. CAM 1 Applications Information Connecting the MAX7450/MAX7451 to a Crosspoint Switch The MAX7450/MAX7451/MAX7452 are designed to directly interface to a video crosspoint switching device such as those used in security systems (see Figure 2). The MAX7450/MAX7451 clamp the video output to GND, making the devices an ideal interface to the MAX4358 crosspoint switches and the MAX4455 OSD. The MAX7450/MAX7451 and the MAX4455 have their outputs referenced to ground, ensuring the amplitudes and the brightness of the OSD relative to the video signal are accurate. Interfacing the MAX7452 to an ADC The MAX7452 can be directly connected to an ADC or video decoder as shown in Figure 3. The video output of the MAX7452 is DC-coupled to a single-ended video input on the ADC. The voltage on the BPLVL pin sets the black level of the video signal at the output of the MAX7452. Use a stable voltage reference for the BPLVL voltage, ideally the same reference that is used MAX7450 MAX7451 MONITOR 1 MAX4358 32 x 16 CROSSPOINT CAM 32 MAX7450 MAX7451 MONITOR 16 MAX4455 OSD MAX4455 OSD Figure 2. MAX7450/MAX7451 in a 32 x 16 Crosspoint Application _______________________________________________________________________________________ 7 MAX7450/MAX7451/MAX7452 Noise Filter Table 1. Gain-Control Settings MAX7450/MAX7451/MAX7452 Video-Signal Conditioners with AGC and Back-Porch Clamp VCC GAIN SET (0dB OR +6dB) VIDEO INPUT IN NOISE FILTER ±6dB 0 OR +6dB OUT ADC DSP REF MAX7452 SYNC SEPARATOR AND AMPLITUDE DETECTOR VIDEO DECODER LOS AGCD BPLVL VSS Figure 3. MAX7452 Interfaced to a Video Decoder for the analog-to-digital conversion. This voltage must be scaled by a ratio of two resistors to set the black level of the video signal to the appropriate level (to match the input range of the converter). If the ADC or video decoder has a built-in clamp circuit, the output of the MAX7452 must be AC-coupled into the ADC with the capacitor value recommended for the converter. In this situation, set the BPLVL on the MAX7452 to the midpoint of the specified range for optimum performance. In addition, the stability of this voltage is not critical, provided that it stays within the specified range. Power-Supply Bypassing and Layout Bypass all supply pins to GND with 0.1µF and 1µF capacitors. These capacitors filter higher frequencies in the MHz range. Place all external components as close to the devices as possible. Connect EP to V SS for the MAX7450/MAX7451. Connect EP to GND for the MAX7452. Placing the IC onto a copper area the size of the pad is recommended for proper power dissipation. Refer to the MAX7450 Evaluation Kit for a proven PCboard layout example. 8 Chip Information TRANSISTOR COUNT: 6316 PROCESS: BiCMOS Pin Configuration TOP VIEW VCC 1 IN 2 GND 3 MAX7450 MAX7451 MAX7452 VSS (MAX7450/MAX7451) 4 BPLVL (MAX7452) SO-EP* *CONNECT EP TO VSS FOR THE MAX7450/MAX7451 _______________________________________________________________________________________ 8 LOS 7 GSET 6 OUT 5 AGCD Video-Signal Conditioners with AGC and Back-Porch Clamp 8L, SOIC EXP. PAD.EPS PACKAGE OUTLINE 8L SOIC, .150" EXPOSED PAD 21-0111 B 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. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 9 © 2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. MAX7450/MAX7451/MAX7452 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.)