19-0373; Rev 1; 12/98 L MANUA ION KIT HEET T A U L EVA TA S WS DA FOLLO 375MHz Quad Closed-Loop Video Buffers, AV = +1 and +2 ____________________________Features The MAX496 and MAX497 are quad, closed-loop, ±5V video buffers that feature extremely high bandwidth and slew rate for both component video (RGB or YUV) and composite video (NTSC, PAL, SECAM). The MAX496 is a unity-gain (0dB) buffer with a 375MHz -3dB bandwidth and a 1600V/µs slew rate. The MAX497 gain of +2 (6dB) buffer, optimized for driving back-terminated coaxial cable, features a 275MHz -3dB bandwidth and a 1500V/µs slew rate. The MAX496/MAX497 are not slewrate limited, thus providing a high full-power bandwidth of 230MHz and 215MHz, respectively. The MAX496/MAX497 incorporate a unique two-stage architecture that combines the low offset and noise benefits of voltage feedback with the high bandwidth and slew-rate advantages of current-mode-feedback. ♦ MAX496 Fixed Gain: +1V/V MAX497 Fixed Gain: +2V/V ♦ High Speed: Small-Signal -3dB Bandwidth: 375MHz (MAX496) 275MHz (MAX497) Full-Power -3dB Bandwidth: 230MHz (MAX496) 215MHz (MAX497) ♦ 0.1dB Gain Flatness: 65MHz (MAX496) 120MHz (MAX497) ♦ 1600V/µs Slew Rate (MAX496) 1500V/µs Slew Rate (MAX497) ♦ Fast Settling Time: 12ns to 0.1% ♦ Lowest Differential Phase/Gain Error: 0.01°/0.01% ♦ 2pF Input Capacitance ♦ 5.6nV/√Hz Input-Referred Voltage Noise ♦ Low Distortion: 64dBc (f = 10MHz) ♦ Directly Drives 50Ω or 75Ω Back-Terminated Cables ♦ High ESD Protection: 5000V ♦ Output Short-Circuit Protected ________________________Applications Computer Workstations Surveillance Video Broadcast and High-Definition TV Systems _______________Ordering Information Multimedia Products PART Medical Imaging MAX496CPE High-Speed Signal Processing Video Switching and Routing _______________Frequency Response GAIN (dB) MAX496/97-A 8 0°C to +70°C PIN-PACKAGE 16 Plastic DIP MAX496CSE 0°C to +70°C 16 Narrow SO MAX496C/D 0°C to +70°C Dice* MAX497CPE 0°C to +70°C 16 Plastic DIP MAX497CSE 0°C to +70°C 16 Narrow SO MAX497C/D 0°C to +70°C Dice* * Dice are specified at TA = +25°C, DC parameters only. ___________________Pin Configuration MAX497 SMALL-SIGNAL GAIN vs. FREQUENCY 9 TEMP. RANGE TOP VIEW 7 GND 1 16 OUT0 6 IN0 2 15 VCC 5 GND 3 14 OUT1 4 IN1 4 3 GND 5 MAX496 MAX497 2 IN2 6 1 10 OUT3 IN3 8 -1 1M 10M 100M FREQUENCY (Hz) 12 OUT2 11 VEE GND 7 0 13 VEE 9 VCC 1G DIP/SO ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 1-800-835-8769. MAX496/MAX497 ________________General Description MAX496/MAX497 375MHz Quad Closed-Loop Video Buffers, AV = +1 and +2 ABSOLUTE MAXIMUM RATINGS Supply Voltage (VCC to VEE) ................................................. 12V Voltage on Any Input Pin to GND ....(VCC + 0.3V) to (VEE - 0.3V) Output Short-Circuit Current Duration ...............................60sec Continuous Power Dissipation (TA = +70°C) Plastic DIP (derate 10.53mW/°C above +70°C) ..........842mW Narrow SO (derate 8.70mW/°C above +70°C) ............696mW Operating Temperature Range...............................0°C to +70°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10sec) .............................+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. DC ELECTRICAL CHARACTERISTICS (VCC = +5V, VEE = -5V, VIN = 0V, RL = 150Ω, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER Input Voltage Range Input Offset Voltage Input Offset Voltage Drift Input Bias Current SYMBOL VIN MIN TYP MAX496 CONDITIONS ±2.8 ±3.2 MAX497 ±1.4 ±1.6 VOS VOUT = 0V ±1 TCVOS VOUT = 0V -10 IB VOUT = 0V ±1 Input Resistance RIN Input Capacitance CIN MAX496: -2V ≤ VIN ≤ +2V, MAX497: -1V ≤ VIN ≤ +1V AV MAX497 (Note 2) UNITS V ±3 mV µV/°C ±5 1.2 µA MΩ 2 MAX496 (Note 1) Voltage Gain 0.5 MAX pF RL = 150Ω 0.988 1.00 RL = 50Ω 0.983 1.00 RL = 150Ω 1.975 2.01 RL = 50Ω 1.965 2.01 V/V Positive Power-Supply Rejection Ratio (Change in VOS) PSRR+ VCC = ±4.5V to ±5.5V, VEE = -5.0V 55 74 dB Negative Power-Supply Rejection Ratio (Change in VOS) PSRR- VEE = ±4.5V to ±5.5V, VCC = 5.0V 60 78 dB Gain Linearity AVLIN AVCL = +2, VOUT = ±1mV to ±2V Positive Quiescent Supply Current (Total) ISY+ Negative Quiescent Supply Current (Total) ISY- Operating Supply Voltage Range VS 0.01 TA = +25°C 31 TA = TMIN to TMAX % 36 45 TA = +25°C 32 TA = TMIN to TMAX 37 45 ±4.50 ±5.50 RL = 150Ω ±2.8 ±3.7 RL = 50Ω ±2.5 ±3.3 mA mA V Output Voltage Swing VOUT Output Resistance ROUT DC 0.1 Ω Output Impedance ZOUT f = 10MHz 1.5 Ω Short to ground or either supply voltage 170 mA Short-Circuit Output Current 2 ISC _______________________________________________________________________________________ V 375MHz Quad Closed-Loop Video Buffers, AV = +1 and +2 (VCC = +5V, VEE = -5V, VIN = 0V, RL = 100Ω, TA = +25°C.) PARAMETER SYMBOL Small-Signal -3dB Bandwidth Small-Signal -3dB Bandwidth Full-Power Bandwidth Slew Rate BW-3dB FPBW SR Settling Time ts CONDITIONS MIN TYP MAX496CSE 375 MAX496CPE 375 MAX497CSE 275 MAX497CPE 275 VOUT = ±2V MAX496 230 MAX497 215 VOUT = 4V step, MAX496 1600 VOUT = 4V step, MAX497 1500 0.1% (VOUT = 2V step) MAX UNITS MHz MHz V/µs 12 ns Differential Gain Error DG f = 3.58MHz (Note 3) 0.01 % Differential Phase Error DP f = 3.58MHz (Note 3) 0.01 degrees Input Noise Voltage Density f = 10MHz 5.6 nV√Hz Input Noise Current Density f = 10MHz 2 pA√Hz Gain Flatness ±0.1dB Adjacent Channel Crosstalk (Note 4) All-Hostile Crosstalk (Note 4) Total Harmonic Distortion THD fC = 10MHz, VOUT = 2Vp-p Spurious-Free Dynamic Range SFDR fC = 5MHz MAX496CPE 80 MAX496CSE 80 MAX497CPE 100 MAX497CSE 120 MAX496 78 MAX497 72 MAX496 72 MAX497 65 MAX496 -64 MAX497 -58 MAX496 58 MAX497 60 MHz dB dB dBc dBc Note 1: Voltage Gain = (VOUT - VOS) / VIN, measured at VIN = ±1V. Note 2: Voltage Gain = (VOUT - VOS) / VIN, measured at VIN = ±2V. Note 3: Input test signal is a 3.58MHz sine wave of amplitude 40 IRE superimposed on a linear ramp (0 IRE to 100 IRE). RL = 150Ω, see Figure 2. Note 4: Input of channel under test grounded through 75Ω. Adjacent channel driven at f = 10MHz (Figure 4a). For All-Hostile Crosstalk, all inputs are driven except the channel under test (Figure 4b). _______________________________________________________________________________________ 3 MAX496/MAX497 AC ELECTRICAL CHARACTERISTICS __________________________________________Typical Operating Characteristics (VCC = +5V, VEE = -5V, RL = 100Ω, TA = +25°C, unless otherwise noted.) MAX496/97-02 1 0 -1 -0.1 -1 -2 -3 -4 GAIN (dB) 0 -0.2 -0.3 -0.4 -2 -3 -4 -5 -0.5 -5 -6 -0.6 -6 -7 -0.7 -7 -8 -0.8 10M 100M 1G -8 1M 10M 100M 1G 1M 10M 100M 1G FREQUENCY (Hz) FREQUENCY (Hz) FREQUENCY (Hz) MAX497 SMALL-SIGNAL GAIN vs. FREQUENCY MAX497 GAIN FLATNESS vs. FREQUENCY MAX497 LARGE-SIGNAL GAIN vs. FREQUENCY 6 5.9 4 3 2 SO 7 6 5 5.8 5.7 5.6 4 3 2 1 5.5 1 5.4 0 0 5.3 -1 -2 5.2 -1 1M 10M 100M 1G 1M 10M 100M FREQUENCY (Hz) MAX496 SMALL-SIGNAL GAIN vs. FREQUENCY DRIVING A 50Ω LOAD MAX497 SMALL-SIGNAL GAIN vs. FREQUENCY DRIVING A 50Ω LOAD 7 5 -2 -3 -4 0 -10 4 3 2 MAX497 -40 -50 -70 0 -1 -80 -8 -2 -90 100M FREQUENCY (Hz) 1G MAX496 -60 -7 10M VOUT = 2Vp-p -30 -6 1M 1G -20 1 -5 100M TOTAL HARMONIC DISTORTION (THD) vs. FREQUENCY DISTORTION (dB) 6 GAIN (dB) 0 -1 10M FREQUENCY (Hz) MAX496/97-08 8 MAX496/97-07 1 1M 1G FREQUENCY (Hz) 2 MAX496/97-06 8 MAX496/97-09 6.0 GAIN (dB) 7 5 DIP 6.1 GAIN (dB) 8 MAX496/97-05 6.2 MAX496/97-04 9 4 2 0 1M GAIN (dB) 0.1 GAIN (dB) GAIN (dB) 1 MAX496 LARGE-SIGNAL GAIN vs. FREQUENCY 0.2 MAX496/97-01 2 MAX496 GAIN FLATNESS vs. FREQUENCY MAX496/97-03 MAX496 SMALL-SIGNAL GAIN vs. FREQUENCY GAIN (dB) MAX496/MAX497 375MHz Quad Closed-Loop Video Buffers, AV = +1 and +2 1M 10M 100M FREQUENCY (Hz) 1G 10k 100k 1M 10M FREQUENCY (Hz) _______________________________________________________________________________________ 100M 375MHz Quad Closed-Loop Video Buffers, AV = +1 and +2 (VCC = +5V, VEE = -5V, RL = 100Ω, TA = +25°C, unless otherwise noted.) MAX497 CROSSTALK vs. FREQUENCY ALL-HOSTILE -60 -70 -80 ADJACENT CHANNEL -90 -40 ADJACENT CHANNEL -50 -60 -70 ALL-HOSTILE -80 -50 -60 -70 -80 -90 -90 -110 -100 -100 100 10M 1M 200 MAX496 GAIN MATCH vs. FREQUENCY CH 3–CH 1 0.1 CH 3–CH 2 CH 1–CH 0 CH 3–CH 0 0.1 0 -0.1 -0.3 -0.6 -0.4 -0.7 -0.5 10M 100M 1G 0.995 0.994 0.992 0.991 CH 2–CH 1 0.990 1M 10M 100M -40 1G -20 0 VIN = -1.0V 1.97 60 80 0.10 0 -0.10 RL = NO LOAD 38 SUPPLY CURRENT (mA) 1.99 40 MAX496/97-16 0.20 OFFSET VOLTAGE (mV) VIN = +1.0V 2.00 40 100 SUPPLY CURRENT vs. TEMPERATURE 0.30 MAX496/97-15 2.02 20 TEMPERATURE (°C) INPUT OFFSET VOLTAGE vs. TEMPERATURE 2.03 1.98 VIN = -1.0V 0.996 0.993 CH 3–CH 2 MAX497 GAIN vs. TEMPERATURE 2.01 VIN = -1.0V 0.999 0.998 FREQUENCY (Hz) 2.04 100M 1.000 CH 3–CH 0 FREQUENCY (Hz) 2.05 10M 0.997 CH 3–CH 1 -0.2 1M MAX496 GAIN vs. TEMPERATURE CH 1–CH 0 0.2 -0.5 1M CH 2–CH 0 0.4 GAIN MATCH (dB) -0.1 -0.4 100k FREQUENCY (Hz) 0.5 0.3 0.0 -0.2 -0.3 20k GAIN (V/V) CH 2–CH 1 CH 2–CH 0 1G MAX497 GAIN MATCH vs. FREQUENCY MAX496/97-13a 0.3 0.2 100M MAX496 FREQUENCY (Hz) MAX496/97-13b 10 FREQUENCY (MHz) GAIN MATCH (dB) MAX497 -40 -100 1 GAIN (V/V) -30 MAX496/97-14 -30 -20 MAX496/97-17 -40 CROSSTALK (dB) -20 -10 MAX496/97-12 -10 -30 -50 MAX496/97-11 -20 CROSSTALK (dB) 0 MAX496/97-10 -10 POWER-SUPPLY REJECTION (PSR) vs. FREQUENCY POWER-SUPPLY REJECTION (dB) MAX496 CROSSTALK vs. FREQUENCY 36 IEE 34 32 30 ICC 28 26 24 -0.20 22 1.96 20 -0.30 1.95 -40 -20 0 20 40 60 TEMPERATURE (°C) 80 100 -40 -20 0 20 40 60 TEMPERATURE (°C) 80 100 -10 0 10 20 30 40 50 60 70 80 TEMPERATURE (°C) _______________________________________________________________________________________ 5 MAX496/MAX497 _____________________________Typical Operating Characteristics (continued) _____________________________Typical Operating Characteristics (continued) (VCC = +5V, VEE = -5V, RL = 100Ω, TA = +25°C, unless otherwise noted.) MAX496 SMALL-SIGNAL PULSE RESPONSE MAX497 SMALL-SIGNAL PULSE RESPONSE MAX496/97-19 MAX496/97-18 0.05 to 0.50 VOLTAGE (V) VOLTAGE (V) IN -0.05 IN -0.50 to 0.10 0.05 OUT OUT -0.10 -0.05 TIME (10ns/div) TIME (10ns/div) MAX496 LARGE-SIGNAL PULSE RESPONSE MAX496/97-21 MAX497 LARGE-SIGNAL PULSE RESPONSE MAX496/97-20 1.0 1.0 IN VOLTAGE (V) IN VOLTAGE (V) MAX496/MAX497 375MHz Quad Closed-Loop Video Buffers, AV = +1 and +2 -1.0 1.0 -1.0 2.0 OUT OUT -2.0 -1.0 TIME (10ns/div) 6 TIME (10ns/div) _______________________________________________________________________________________ 375MHz Quad Closed-Loop Video Buffers, AV = +1 and +2 (VCC = +5V, VEE = -5V, RL = 100Ω, TA = +25°C, unless otherwise noted.) MAX496 SMALL-SIGNAL PULSE RESPONSE (CL = 47pF 0.05 0.50 IN IN VOLTAGE (V) VOLTAGE (V) MAX496/97-23 MAX496/97-22 MAX497 SMALL-SIGNAL PULSE RESPONSE (CL = 47pF) -0.05 -0.50 0.10 0.05 OUT OUT -0.10 -0.05 10ns/div 10ns/div MAX496/97-24 1.0 1.0 IN IN VOLTAGE (V) VOLTAGE (V) MAX496/97-25 MAX497 LARGE-SIGNAL PULSE RESPONSE (CL = 47pF) MAX496 LARGE-SIGNAL PULSE RESPONSE (CL = 47pF) -1.0 -1.0 2.0 1.0 OUT OUT -2.0 -1.0 10ns/div 10ns/div _______________________________________________________________________________________ 7 MAX496/MAX497 _____________________________Typical Operating Characteristics (continued) MAX496/MAX497 375MHz Quad Closed-Loop Video Buffers, AV = +1 and +2 _____________________Pin Description PIN NAME FUNCTION 1, 3, 5, 7 GND Ground. All ground pins are internally connected. Connect all ground pins externally to minimize the ground impedance. 2 4 6 8 IN0 IN1 IN2 IN3 Channel 0 Input Channel 1 Input Channel 2 Input Channel 3 Input 9, 15 VCC Positive Power Supply. Connect to +5V. VCC pins are internally connected. Connect both pins to +5V externally to minimize the supply impedance. 10 OUT3 11, 13 VEE 12 14 16 OUT2 OUT1 OUT0 _______________Detailed Description The MAX496/MAX497 are quad, high-speed, closed-loop voltage-feedback video amplifiers with fixed gain settings of +1 and +2, respectively (Figure 1). These amplifiers use a unique two-stage voltage-feedback architecture that combines the benefits of conventional voltage-feedback and current-mode-feedback topologies. They achieve wide bandwidths and high slew rates while maintaining precision. A resistively loaded first stage provides low input-referred noise even with low supply currents of 8mA per amplifier. The above features, along with the ability to drive 50Ω or 75Ω back-terminated cables to ±2.8V and low differential phase and gain errors, make these amplifiers ideal for the most demanding component and composite video applications. Channel 3 Output __________Applications Information Negative power supply. Connect to -5V. VEE pins are internally connected. Connect both pins to -5V externally to minimize the supply impedance. The feedback elements of the MAX496/MAX497 are included internally in the device to set the closed-loop gain to AV = +1 and AV = +2, respectively. Closing the loop internally on the chip minimizes problems associated with the board and package parasitics influencing the amplifier’s frequency response. Channel 2 Output Channel 1 Output Channel 0 Output VCC 0.10µF VEE 0.10µF +5V 75Ω 9 0.10µF 10µF 75Ω CABLE 2 RED 15 11 IN0 13 OUT0 0.10µF 16 75Ω -5V 10µF 75Ω CABLE 75Ω 75Ω MAX496* MAX497* 75Ω 75Ω CABLE 4 GREEN IN1 OUT1 AV = * 14 75Ω 75Ω CABLE 75Ω 75Ω 75Ω CABLE 75Ω 6 BLUE IN2 OUT2 AV = * 12 75Ω 75Ω CABLE 75Ω 75Ω 75Ω CABLE 75Ω 8 SYNC IN3 OUT3 AV = * 10 75Ω 75Ω CABLE 75Ω 75Ω GND *AV = +1 (MAX496) *AV = +2 (MAX497) 3 5 7 Figure 1. Typical Operating Circuit 8 _______________________________________________________________________________________ 375MHz Quad Closed-Loop Video Buffers, AV = +1 and +2 MAX496/MAX497 75Ω CABLE a) 75Ω 75Ω MAX497 75Ω CABLE 75Ω CABLE DUT 75Ω SOURCE: TEKTRONIX 1910 DIGITAL GENERATOR 75Ω MEASUREMENT: TEKTRONIX VM700 VIDEO MEASUREMENT SET b) 75Ω 75Ω CABLE MAX496 DUT 75Ω 150Ω Figure 2. Differential Phase and Gain Error Test Circuits: a) MAX497, Gain of +2 Amplifier; b) MAX496 Unity-Gain Amplifier Power Dissipation The maximum output current of the MAX496/MAX497 is limited by the packages maximum allowable power dissipation. The maximum junction temperature should not exceed +150°C. The power dissipation increases with load, and this increase can be approximated by the following: For VOUT > 0V: |VCC - VOUT| ILOAD OR For VOUT < 0V: |VEE - VOUT| ILOAD. These devices can drive 100Ω loads connected to each of the outputs over the entire rated output swing and temperature range. When driving 50Ω loads with each of the four outputs simultaneously, the output swing must be limited to ±1.25V at TA = +70°C. While the output is short-circuit protected to 170mA, this does not necessarily guarantee that, under all conditions, the maximum junction temperature will not be exceeded. Do not exceed the derating values given in the absolute maximum ratings. MAX496/MAX497 IN0 75Ω OUT1 75Ω 75Ω 75Ω OUT2 75Ω 75Ω OUT3 75Ω 75Ω OUT4 75Ω Figure 3. One-to-Four Distribution Amplifier _______________________________________________________________________________________ 9 MAX496/MAX497 375MHz Quad Closed-Loop Video Buffers, AV = +1 and +2 MAX496/MAX497 50Ω VIN = 4Vp-p, f = 10MHz, RS = 75Ω MAX496/MAX497 50Ω 100Ω 100Ω 50Ω 100Ω 50Ω 100Ω 50Ω 100Ω 50Ω 100Ω 50Ω 100Ω a) ADJACENT CHANNEL VIN = 4Vp-p, f = 10MHz, RS = 75Ω 100Ω 50Ω b) ALL-HOSTILE Figure 4. Crosstalk: a) Adjacent Channel; b) All-Hostile Total Noise Coaxial Cable Drivers The MAX496/MAX497’s low input current noise of 2pA/√Hz and voltage noise of 5.6nV/√Hz provide for lower total noise compared to typical current-modefeedback amplifiers, which usually have significantly higher input current noise. The input current noise multiplied by the feedback resistor is the dominant noise source of current-mode-feedback amplifiers. High-speed performance, excellent output current capability, and an internally fixed gain of +2 make the MAX497 ideal for driving back-terminated 50Ω or 75Ω coaxial cables to ±2.8V. In a typical application, the MAX497 drives a back-terminated 75Ω video cable (Figure 1). The back-termination resistor (at the MAX497’s output) matches the impedance of the cable’s driven end to the cable’s impedance, to eliminate signal reflections. This, along with the load-termination resistor, forms a voltage divider with the load impedance, which attenuates the signal at the cable output by one-half. The MAX497 operates with an internal +2V/V closed-loop gain to provide unity gain at the cable’s output. Differential Gain and Phase Errors Differential gain and phase errors are critical specifications for a buffer in composite (NTSC, PAL, SECAM) video applications, because these errors correspond directly to color changes in the displayed picture of composite video systems. The MAX496/MAX497’s ultra-low differential gain and phase errors (0.01%/ 0.01°) make them ideal in broadcast-quality composite video applications. Distribution Amplifier The circuit in Figure 3 is a one-to-four distribution amplifier using a single MAX496 or MAX497 IC. A one-to-eight distribution amplifier can be implemented with a MAX496 or MAX497 by driving an additional cable from each of the four outputs. When driving more than four outputs from a single device, see the Continuous Power Dissipation specifications in the Absolute Maximum Ratings. 10 Capacitive Load Driving In most amplifier circuits, driving large capacitive loads increases the likelihood of oscillation. This is especially true for circuits with high loop gains, such as voltage followers. The amplifier’s output resistance and the capacitive load form an RC filter that adds a pole to the loop response. If the pole frequency is low enough (as when driving a large capacitive load), the circuit phase margin is degraded and oscillation may occur. ______________________________________________________________________________________ 375MHz Quad Closed-Loop Video Buffers, AV = +1 and +2 4 CL = 47pF CL = 22pF 5 4 2 GAIN (dB)* GAIN (dB) 2 0 -2 CL = 0pF -4 -1 -8 -3 -10 -4 10M 100M CL = 47pF CL = 60pF -5 * -3dB ATTENUATION DUE TO RISO NOT SHOWN 1G CL = 10pF 0 -2 -12 CL = 22pF 1 -6 1M RL = 50Ω RISO = 20Ω 3 CL = 10pF 1M 10M 10 CL = 20pF 20 15 CL = 47pF 5 GAIN (dB) GAIN (dB) RL = RISO = 20Ω 10 5 MAX496/97-5d 8 CL = 47pF 8 CL = 68pF RL = RISO = 0Ω 1G Figure 5b. MAX496 Small-Signal Gain vs. Frequency and Load Capacitor (RL = 50Ω, RISO = 20Ω) MAX496/97-5c Figure 5a. MAX496 Small-Signal Gain vs. Frequency and Load Capacitor (RL = 50Ω, RISO = 0Ω) 15 100M FREQUENCY (Hz) FREQUENCY (Hz) 20 MAX496/97-5b CL = 60pF RL = 50Ω RISO = 0Ω MAX496/97-5a 6 MAX496/MAX497 8 0 CL = 10pF -5 -10 CL = 0pF -15 0 -15 -20 -25 -25 -30 -30 10M 100M CL = 22pF -10 -20 1M CL = 68pF -5 1G FREQUENCY (Hz) CL = 10pF 1M 10M 100M 1G FREQUENCY (Hz) Figure 5c. MAX496 Small-Signal Gain vs. Frequency and Load Capacitor (RL = ∞, RISO = 0Ω) Figure 5d. MAX496 Small-Signal Gain vs. Frequency and Load Capacitor (RL = ∞, RISO = 20Ω) The MAX496/MAX497 drive capacitive loads up to 75pF without sustained oscillation, although some peaking may occur. When driving larger capacitive loads, or to reduce peaking, add an isolation resistor (RISO) between the output and the capacitive load (Figures 5a–5d). Connect both positive power-supply pins together and bypass with a 0.10µF ceramic capacitor at each power supply pin, as close to the device as possible. Repeat the same for the negative power-supply pins. The capacitor lead lengths should be as short as possible to minimize lead inductance; surface-mount chip capacitors are ideal. A large-value (4.7µF or greater) tantalum or electrolytic bypass capacitor on each supply may be required for high-current loads. The location of this capacitor is not critical. The MAX496/MAX497’s analog input pins are isolated with ground pins to minimize parasitic coupling, which can degrade crosstalk and/or amplifier stability. Keep signal paths as short as possible to minimize inductance. Ensure that all input channel traces are the same length to maintain the phase relationship between the four channels. To further reduce crosstalk, connect the coaxial-cable shield to the ground side of the 75Ω terminating resistor at the ground plane, and terminate all unused inputs ground and outputs with a 100Ω or 150Ω resistor to ground. Grounding and Layout The MAX496/MAX497 bandwidths are in the RF frequency range. Depending on the size of the PC board used and the frequency of operation, it may be necessary to use Micro-strip or Stripline techniques. To realize the full AC performance of these high-speed buffers, pay careful attention to power-supply bypassing and board layout. The PC board should have at least two layers (wire-wrap boards are too inductive, bread boards are too capacitive), with one side a signal layer and the other a large, low-impedance ground plane. With multilayer boards, locate the ground plane on the layer that is not dedicated to a specific signal trace. The ground plane should be as free from voids as possible. Connect all ground pins to the ground plane. ______________________________________________________________________________________ 11 ___________________Chip Topography GND IN0 OUT0 VCC GND IN1 OUT1 VEE 0.101" (2.56mm) OUT2 GND VEE IN2 GND IN3 VCC OUT3 0.076" (1.930mm) TRANSISTOR COUNT: 544 SUBSTRATE CONNECTED TO VEE ________________________________________________________Package Information SOICN.EPS MAX496/MAX497 375MHz Quad Closed-Loop Video Buffers, AV = +1 and +2 12 ______________________________________________________________________________________