MAX442CPA Maxim Integrated Products, MAX442CPA Datasheet - Page 6

• Manufacturer Part Number: MAX442CPA
• Description: IC MUX/VIDEO AMP 2CH 140MHZ 8DIP
• Manufacturer: Maxim Integrated Products

Specifications of MAX442CPA

• Applications: 2:1 Multiplexer-Amplifier
• Number Of Circuits: 1
• -3db Bandwidth: 140MHz
• Slew Rate: 250 V/µs
• Current - Supply: 30mA
• Voltage - Supply, Single/dual (±): ±4.75 V ~ 5.25 V
• Mounting Type: Through Hole
• Package / Case: 8-DIP (0.300", 7.62mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

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 chan-
nel input capacitance allows full AC performance of the
amplifier, even with source impedances as great as
250Ω—a significant improvement over common mux or
switch alternatives.
Feedback resistors should be limited to no more than
500Ω 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.
Realizing the full AC performance of high-speed ampli-
fiers requires careful attention to power-supply bypass-
ing 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.
_____________________Pin Description
__________Applications Information
PIN
1
2
3
4
5
6
7
8
NAME
V
GND
IN0
IN1
IN-
OUT
V+
A0
V-
_______________________________________________________________________________________
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
Power-Supply Bypassing
FUNCTION
and Board Layout
Video Multiplexer/Amplifier
To prevent oscillation and unwanted signal coupling,
minimize trace area at the circuit’s critical high-imped-
ance 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 0.1µF ceramic capacitors, placed as close
to the supply pins as possible. For high-current loads,
it may be necessary to include 1µF tantalum or alu-
minum-electrolytic capacitors in parallel with the 0.1µF
ceramic bypass capacitors. Keep capacitor lead
lengths as short as possible to minimize series induc-
tance; surface-mount (chip) capacitors are ideal for this
application.
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 combina-
tion 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.
High-speed performance and excellent output current
capability make the MAX442 ideal for driving 50Ω or
75Ω coaxial cables. The MAX442 will drive 50Ω and
75Ω coaxial cables to ±3V.
Figure 1. Differential Gain and Phase Error Test Circuit
SOURCE:
TEKTRONIX
1910 DIGITAL GENERATOR
75
140MHz, 2-Channel
CABLE
Differential Gain and Phase Errors
75
MAX442
Coaxial-Cable Drivers
470
470
CABLE
75
75
CABLE
75
MEASUREMENT SET
MEASUREMENT:
VM700 VIDEO
TEKTRONIX
75
75
5