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19-0016; Rev 1; 1/95
140MHz, 2-Channel Video Multiplexer/Amplifier
_______________General Description
The MAX442 combines a 140MHz video amplifier with a high-speed, 2-channel multiplexer in an 8-pin package. With its 36ns switching time and low differential gain (0.07%) and phase (0.09) errors, it is ideal for broadcast-quality video applications. The device is designed to drive both 50 and 75 cables, and can directly drive a 75 load to 3V. The MAX442 video amplifier is compensated for unitygain stability, and features a 140MHz bandwidth and a 250V/s slew rate. The multiplexer's low input capacitance (4pF with the channel on or off) maximizes highspeed performance, and a ground pin separating the two input channels minimizes crosstalk and simplifies board layout. The MAX442 operates from 5V supplies and typically consumes 300mW. For applications that require more input channels, see the data sheets for the MAX440 8channel mux/amp and the MAX441 4-channel mux/amp.
____________________________Features
o 140MHz Unity-Gain Bandwidth o 250V/s Slew Rate o 0.07%/0.09 Differential Gain/Phase Error o 36ns Channel Switch Time o No External Compensation Components o 8-Pin DIP and SO Packages o Directly Drives 50 and 75 Cables
MAX442
______________Ordering Information
PART MAX442CPA MAX442CSA MAX442C/D MAX442EPA MAX442ESA TEMP. RANGE 0C to +70C 0C to +70C 0C to +70C -40C to +85C -40C to +85C PIN-PACKAGE 8 Plastic DIP 8 SO Dice* 8 Plastic DIP 8 SO
________________________Applications
Broadcast-Quality Video-Signal Multiplexing Coaxial-Cable Drivers Video Editing Video Security Systems Medical Imaging High-Speed Signal Processing
*Dice are specified at TA = +25C, DC parameters only.
__________Typical Operating Circuit
+5V
__________________Pin Configuration
TOP VIEW
0.1F
V+
MAX442
VOUT VIDEO SIGNALS IN IN0 270 IN270 75 75 75 CABLE VIDEO OUTPUT
IN0 1 GND 2 IN1 3 V- 4
8 7
A0 V+ VOUT IN-
IN1 A0 GND V0.1F
MAX442
6 5
DIP/SO
CHANNEL SELECT
-5V
________________________________________________________________ Maxim Integrated Products
1
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140MHz, 2-Channel Video Multiplexer/Amplifier MAX442
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (V+ to V-).......................................................12V Analog Input Voltage ............................(V+ + 0.3V) to (V- - 0.3V) Digital Input Voltage .....................................-0.3V to (V+ + 0.3V) Short-Circuit Current Duration ........................................1 minute Input Current to Any Pin, Power On or Off........................50mA Continuous Power Dissipation (TA = +70C) Plastic DIP (derate 9.09mW/C above +70C) ............727mW SO (derate 5.88mW/C above +70C) .........................471mW Operating Temperature Ranges MAX442C_A........................................................0C to +70C MAX442E_A .....................................................-40C to +85C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10sec) .............................+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
(V+ = 5V, V- = -5V, RL = 150, TA = TMIN to TMAX, unless otherwise noted.) PARAMETER DC PERFORMANCE Input Voltage Range Input Offset Voltage (All Channels) Offset Matching (VOS0-VOS1) Input Bias Current (Channel On) Input Leakage Current (Channel Off) Input Resistance (Channel On) (Note 1) Input Capacitance DC Output Resistance Open-Loop Voltage Gain Common-Mode Rejection Ratio Power-Supply Rejection Ratio Output Voltage Swing IB ILKG RIN CIN ROUT AVOL CMRR PSRR VOUT VIN TA = +25C VOS MAX442C MAX442E TA = +25C TA = TMIN to TMAX VIN = 0V VIN = 0V -2V VCM 2V Channel on or off AV = 0dB AV = 6dB RL = 75, -2V VOUT +2V -2V VIN +2V 4.75V to 5.25V RL = 75 TA = +25C TA = TMIN to TMAX TA = +25C TA = TMIN to TMAX TA = +25C TA = TMIN to TMAX TA = +25C TA = TMIN to TMAX 50 46 46 46 54 54 2.5 2.0 3.0 80 50 TA = +25C TA = TMIN to TMAX TA = +25C TA = TMIN to TMAX TA = +25C TA = TMIN to TMAX 0.5 0.2 4 25 50 60 2.0 0.5 0.6 1 -2 1.5 2 7.0 10 12 2.5 5.0 2 5 50 1 mV A nA A M pF m dB dB dB V mV V SYMBOL CONDITIONS MIN TYP MAX UNITS
2
_______________________________________________________________________________________
140MHz, 2-Channel Video Multiplexer/Amplifier
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 5V, V- = -5V, RL = 150, TA = TMIN to TMAX, unless otherwise noted.) PARAMETER DYNAMIC PERFORMANCE -3dB Bandwidth Slew Rate Differential Phase Error Differential Gain Error Settling Time Crosstalk Input Noise-Voltage Density POWER REQUIREMENTS Operating Supply-Voltage Range Positive Supply Current VS TA = +25C ICC VIN = 0V MAX442C MAX442E TA = +25C Negative Supply Current SWITCHING CHARACTERISTICS Logic Low Voltage Logic High Voltage Address Propagation Delay Channel Switching Time VIL VIH tAPD tSW Figure 7 Figure 7 (Note 2) 2.4 24 36 0.8 V V ns ns IEE VIN = 0V MAX442C MAX442E 4.75 25 22 19 23 20 17 28 30 5.25 35 38 41 35 38 41 mA mA V BW SR1 DP DG ts XTALK en Figure 1 Figure 1 To 0.1% of final value, AV = 0dB, RL = 150, 2V step input f = 10MHz, RS = 75, AV = 0dB, Figure 6 f = 10kHz AV = 0dB, RL = 100 140 250 0.09 0.07 50 76 12 MHz V/s degrees % ns dB nV/Hz SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX442
Note 1: Incremental resistance for a common-mode voltage between 2V. Note 2: Channel Switching Time specified between two grounded input channels; does not include signal rise/fall times for switching between channels with different input voltages.
__________________________________________Typical Operating Characteristics
(TA = +25C, unless otherwise noted.)
OPEN-LOOP GAIN AND PHASE vs. FREQUENCY
80 70 OPEN-LOOP GAIN (dB) 60 50 40 30 20 10 0 -10 -20 0.001 0.1 10 PHASE GAIN 135 90 CLOSED-LOOP GAIN (dB) PHASE SHIFT (Degrees) 45 0 -45 -90 -135 -180 -225 -270 -315 1000 30 25 20 15 10 5 0 -5 -10 -15 -20 0.1 1 10 100 1000 FREQUENCY (MHz) 0.01 10k 100k 1M FREQUENCY (Hz) 10M 100M AVCL = 20dB AVCL = 6dB AVCL = 0dB
CLOSED-LOOP GAIN vs. FREQUENCY
MAX442-02
UNITY-GAIN OUTPUT IMPEDANCE vs. FREQUENCY
MAX442-03
100
OUTPUT IMPEDANCE ()
10
1
0.1
FREQUENCY (MHz)
_______________________________________________________________________________________
3
140MHz, 2-Channel Video Multiplexer/Amplifier MAX442
____________________________Typical Operating Characteristics (continued)
(TA = +25C, unless otherwise noted.)
VOLTAGE-NOISE DENSITY vs. FREQUENCY
MAX442-04
CROSSTALK vs. FREQUENCY
MAX442-05
OUTPUT VOLTAGE SWING vs. LOAD RESISTANCE
4 3 OUTPUT VOLTAGE (V) 2 1 0 -1 -2 -3 -4
MAX442-06
1000 VOLTAGE-NOISE DENSITY (nV/Hz)
0 -20 CROSSTALK (dB)
5
100
-40 -60 -80 -100
10
1 1 10 100 1k 10k 100k FREQUENCY (Hz)
-120 1 10 100 1000 FREQUENCY (MHz)
-5 10 100 1k 10k LOAD RESISTANCE ()
SUPPLY CURRENT vs. TEMPERATURE
MAX442-07
INPUT OFFSET VOLTAGE vs. TEMPERATURE
MAX442-08
INPUT BIAS CURRENT vs. TEMPERATURE
0.9 INPUT BIAS CURRENT (A) 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 VCM = 0V
MAX442-09
40 30 SUPPLY CURRENT (mA) 20 10 0 -10 -20 -30 -40 -40 -20 0 20 40 60 80 IEE ICC
5 4 INPUT OFFSET VOLTAGE (mV) 3 2 1 0 -1 -2 -3 -4 -5
1.0
100
-40 -20
0
20
40
60
80
100
-40 -20
0
20
40
60
80
100
TEMPERATURE (C)
TEMPERATURE (C)
TEMPERATURE (C)
OPEN-LOOP VOLTAGE GAIN vs. TEMPERATURE
MAX442-10
COMMON-MODE REJECTION RATIO vs. TEMPERATURE
DIFFERENTIAL INPUT OFFSET VOLTAGE (mV) COMMON-MODE REJECTION RATIO (dB) 70 60 50 40 30 20 10 0 -40 -20 0 20 40 60 80 100
MAX442-11
DIFFERENTIAL INPUT OFFSET VOLTAGE vs. TEMPERATURE
MAX442-12
80 OPEN-LOOP VOLTAGE GAIN (dB) 70 60 50 40 30 20 10 0 -40 -20 0 20 40 60 80
80
3 2 1 0 -1 -2 -3 -40 -20 0 20 40 60 80
100
100
TEMPERATURE (C)
TEMPERATURE (C)
TEMPERATURE (C)
4
_______________________________________________________________________________________
140MHz, 2-Channel Video Multiplexer/Amplifier
_____________________Pin Description
PIN 1 2 3 4 5 6 7 8 NAME IN0 GND IN1 VINVOUT V+ A0 FUNCTION Analog Input, channel 0 Ground Analog Input, channel 1 Negative Power Supply, -5V Amplifier Inverting Input Amplifier Output Positive Power Supply, +5V Channel Address Input: A0 = logic 0 selects channel 0, A0 = logic 1 selects channel 1
__________Applications Information
The MAX442's bipolar construction results in a typical channel input capacitance of only 4pF, whether the channel is on or off. As with all ICs, the mux's input capacitance forms a single-pole RC lowpass filter with the signal source's output impedance. This filter can limit the system's signal bandwidth if the RC product becomes too large. However, the MAX442's low channel input capacitance allows full AC performance of the amplifier, even with source impedances as great as 250--a significant improvement over common mux or switch alternatives. Feedback resistors should be limited to no more than 500 to ensure that the RC time constant formed by the resistors, the circuit board's capacitance, and the capacitance of the amplifier input pins does not limit the system's high-speed performance.
To prevent oscillation and unwanted signal coupling, minimize trace area at the circuit's critical high-impedance nodes, especially the amplifier summing junction (the amplifier's inverting input). Surround these critical nodes with a ground trace, and include ground traces between all signal traces to minimize parasitic coupling that can degrade crosstalk and/or amplifier stability. Keep signal paths as short as possible to minimize inductance, and keep all input channel traces at equal lengths to maintain the phase relationship between the input channels. Bypass all power-supply pins directly to the ground plane with 0.1F ceramic capacitors, placed as close to the supply pins as possible. For high-current loads, it may be necessary to include 1F tantalum or aluminum-electrolytic capacitors in parallel with the 0.1F ceramic bypass capacitors. Keep capacitor lead lengths as short as possible to minimize series inductance; surface-mount (chip) capacitors are ideal for this application.
MAX442
Differential Gain and Phase Errors
In color video applications, lowest differential gain and phase errors are critical for an IC, because they cause changes in contrast and color of the displayed picture. Typically, the MAX442's multiplexer/amplifier combination has a differential gain and phase error of only 0.07% and 0.09, respectively. This low differential gain and phase error makes the MAX442 ideal for use in broadcast-quality color video systems.
Coaxial-Cable Drivers
High-speed performance and excellent output current capability make the MAX442 ideal for driving 50 or 75 coaxial cables. The MAX442 will drive 50 and 75 coaxial cables to 3V.
75 CABLE 75 75 75 CABLE
Power-Supply Bypassing and Board Layout
Realizing the full AC performance of high-speed amplifiers requires careful attention to power-supply bypassing and board layout. Use a low-impedance ground plane with the MAX442. With multilayer boards, the ground plane should be located on the PC board's component side to minimize impedance between the components and the ground plane. For single-layer boards, components should be mounted on the board's copper side and the ground plane should include the entire portion of the board that is not dedicated to a specific signal trace.
MAX442
75 470 SOURCE: TEKTRONIX 1910 DIGITAL GENERATOR 470
75 CABLE 75
MEASUREMENT: TEKTRONIX VM700 VIDEO MEASUREMENT SET
Figure 1. Differential Gain and Phase Error Test Circuit
_______________________________________________________________________________________ 5
140MHz, 2-Channel Video Multiplexer/Amplifier
The Typical Operating Circuit shows the MAX442 driving a back-terminated 75 video cable. The back-termination resistor (at the MAX442 output) is included to match the impedance of the cable's driven end to the characteristic impedance of the cable itself. This, plus the load-termination resistor, eliminates signal reflections from the cable's ends. The back-termination resistor forms a voltage divider with the load impedance, which attenuates the signal at the cable output by onehalf. The amplifier is operated with a 2V/V closed-loop gain to provide unity gain at the cable's video output. lowers. The amplifier's output impedance 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. With capacitive loads greater than approximately 50pF and the MAX442 configured as a unity-gain buffer, use an isolation resistor in series with the load, as shown in Figure 2. The resistor removes the pole from the loop response caused by the load capacitance.
MAX442
Capacitive-Load Driving
Driving large capacitive loads increases the likelihood of oscillation in most amplifier circuits. This is especially true for circuits with high loop gains, like voltage fol-
Channel Switching Time/Transient
When the MAX442 multiplexer is switched from one channel to another, a small glitch will appear at the output. Figure 3 shows the results of putting a 0V to 5V pulse 100ns wide into A0.
MAX442
IN 22 OUT CLOAD > 50pF
INPUT 1V/div
GND
CABLE OUTPUT 500mV/div
GND
Figure 2. Capacitive-Load-Driving Circuit
Figure 4. Pulse Response with RL = 100 (50 back-terminated cable), AVCL = +1V/V
A0 INPUT 5V/div AMP OUTPUT 200mV/div
GND INPUT 1V/V GND CABLE OUTPUT 1V/V GND
GND
Figure 3. Output Switching Transient when Switching Between Two Grounded Inputs with RL = 100
6
Figure 5. Pulse Response with RL = 100 (50 back-terminated cable), AVCL = +2V/V
_______________________________________________________________________________________
140MHz, 2-Channel Video Multiplexer/Amplifier
___________________Chip Topography
A0
MAX442
MAX442
IN0 75 IN1
(MEASURED WITH CHANNEL 0 SELECTED) OUT 150
IN0 V+ 0.066" (1.676mm) GND V OUT INV0.066" (1.676mm)
A0
IN1
VIN = 1Vp-p at 10MHz, RS = 75
V CROSSTALK = 20 log10 OUT V IN
TRANSISTOR COUNT: 137 SUBSTRATE CONNECTED TO V-
Figure 6. Crosstalk Test Circuit
tAPD A0
VOUT tSW
Figure 7. Switch Timing
_______________________________________________________________________________________
7
140MHz, 2-Channel Video Multiplexer/Amplifier MAX442
________________________________________________________Package Information
E D A3 A A2 E1
DIM A A1 A2 A3 B B1 C D1 E E1 e eA eB L INCHES MAX MIN 0.200 - - 0.015 0.175 0.125 0.080 0.055 0.022 0.016 0.065 0.045 0.012 0.008 0.080 0.005 0.325 0.300 0.310 0.240 - 0.100 - 0.300 0.400 - 0.150 0.115 INCHES MIN MAX 0.348 0.390 0.735 0.765 0.745 0.765 0.885 0.915 1.015 1.045 1.14 1.265 MILLIMETERS MIN MAX - 5.08 0.38 - 3.18 4.45 1.40 2.03 0.41 0.56 1.14 1.65 0.20 0.30 0.13 2.03 7.62 8.26 6.10 7.87 2.54 - 7.62 - - 10.16 2.92 3.81 MILLIMETERS MIN MAX 8.84 9.91 18.67 19.43 18.92 19.43 22.48 23.24 25.78 26.54 28.96 32.13
21-0043A
L A1 e B D1
0 - 15 C B1 eA eB
Plastic DIP PLASTIC DUAL-IN-LINE PACKAGE (0.300 in.)
PKG. DIM PINS P P P P P N D D D D D D 8 14 16 18 20 24
DIM
D A e B
0.101mm 0.004in.
0-8
A1
C
L
A A1 B C E e H L
INCHES MAX MIN 0.069 0.053 0.010 0.004 0.019 0.014 0.010 0.007 0.157 0.150 0.050 0.244 0.228 0.050 0.016
MILLIMETERS MIN MAX 1.35 1.75 0.10 0.25 0.35 0.49 0.19 0.25 3.80 4.00 1.27 5.80 6.20 0.40 1.27
E
H
Narrow SO SMALL-OUTLINE PACKAGE (0.150 in.)
DIM PINS D D D 8 14 16
INCHES MILLIMETERS MIN MAX MIN MAX 0.189 0.197 4.80 5.00 0.337 0.344 8.55 8.75 0.386 0.394 9.80 10.00
21-0041A
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.
8 ___________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600 (c) 1995 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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