Datasheet

MAX4359/MAX4360/MAX4456
Low-Cost 4x4, 8x4, 8x8
Video Crosspoint Switches
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Detailed Description
Output Buffers
The MAX4456 video crosspoint switch consists of 64
T-switches in an 8x8 grid (Figure 1). The eight matrix
outputs are followed by eight wideband buffers opti-
mized for driving 400Ω and 20pF loads. The
MAX4359’s core is a 4x4 switch matrix with each of its
outputs followed by a wideband buffer. The MAX4360
has an 8x4 matrix and four output buffers. Each buffer
has an internal active load on the output that can be
readily shut off through the LOAD input (off when LOAD
= 0V). The shut-off is useful when two or more cross-
points are connected in parallel to create more input
channels. With more input channels, only one set of
buffers can be active and only one set of loads can be
driven. When active, the buffer must have either 1) an
internal load, 2) the internal load of another buffer in
another MAX4359/MAX4360/MAX4456, or 3) an exter-
nal load.
Each output can be disabled under logic control. When
a buffer is disabled, its output enters a high-impedance
state. In multichip parallel applications, the disable
function prevents inactive outputs from loading lines
driven by other devices. Disabling the inactive buffers
reduces power consumption.
The outputs connect easily to MAX4395 quad, opera-
tional amplifiers when back-terminated 75Ω coaxial
cable must be driven.
A = +1
IN0
IN1 IN2 IN3
IN4 IN5
IN6 IN7
OUTPUT
BUFFERS
OUT0
400Ω
LOAD
LATCH
EDGE/LEVEL
2nd-RANK REGISTERS
1st-RANK REGISTERS
WR
CE
CE
A0
A1
A2
D3
D2
V+
V-
AGND
DGND
D1/SER OUT
D0/SER IN
SER/PAR
MAX4456
8x8
SWITCH
MATRIX
A = +1
OUT7
400Ω
Figure 1. MAX4456 Functional Diagram