GX434 Datasheet, PDF (9/9 Pages) Gennum Corporation – GX434 Monolithic 4x1 Video Multiplexer

APPLICATIONS INFORMATION
The GX434 multiplexer is a very high performance,
wideband circuit requiring careful external circuit design.
Good power supply regulation and decoupling are
necessary to achieve optimum results. The circuit designer
must use proper lead dress, component placement and
PCB layout as in any high frequency circuit.
Functionally, the video switches are non-inverting, unity
gain bipolar switches with buffered inputs requiring DC
coupling and 75Ω line terminating resistors when directly
driven from 75Ω cable. The output must be buffered to
drive 75Ω lines. This is usually accomplished with the
addition of an operational amplifier/ buffer which also
allows adjustments to be made to the gain, offset and
frequency response of the overall circuit.
A typical video routing application is shown in Figure 11.
Four ICs are used in a 16 x 1 multiplexer switching circuit.
An external address decoder is shown which generates
the 16 address and chip enable codes from a binary
number. The address inputs to each chip are active high
while the chip select inputs are active low. Depending on
the application and speed of the logic family used,
latches may be required for synchronization where timing
and delays are critical. Since the individual crosspoint
switching circuits are unidirectional bipolar elements, low
crosstalk and high isolation are inherent. The make-
before-break switching characteristics of the GX434
means virtually 'glitch' free switching.
VIDEO INPUTS
GX434 SWITCHES
0.1
+8V
BINARY ADDRESS
DECODER
V0
V1
V2
V3
75
75
75
75
V4
V5
V6
V7
75
75
75
75
V8
V9
V 10
V 11
75
75
75
75
1 _{IN 0 +V} 14
2 _GND
3 _{IN 1}
A 0 ¹³
A 1 ¹²
4 _{GND CS} 11
5 _{IN 2 OUT} 10
6 _GND
7 _{IN 3}
R9
EXT
-V
8
33K
1%
0.1
-8V
+8V
0.1
1 _{IN 0 +V} 14
2 _{GND A 0} 13
3 _{IN 1} A 1 ¹²
4 _GND
11
CS
5 _{IN 2 OUT} 10
6 _GND
7 _{IN 3}
R
EXT
-V
9
8
33K
0.1
1%
-8V
0.1
+8V
1 _{IN 0 +V} 14
2 _GND
3 _{IN 1}
A
A
0
1
13
12
4 _{GND CS} 11
5 _{IN 2}
6 _GND
7 _{IN 3}
10
OUT
R
9
EXT
-V
8
33K
0.1
1%
-8V
0.1
+8V
A0
A1
4
3
A2
5
1
2
2
A3
6
74HC139
1 _ENABLE
7
8 16
+5V
0.1
330
2-10pF
+5V
3
+
7
0.1
6
75
100 _{2 -}
4
250
3500
Video
Out
-5V
DOCUMENT
IDENTIFICATION
0.1
CLC 410 (comlinear)
V 12
V 13
V14
V15
75
75
75
75
1 _{IN 0}
14
+V
2 _GND
3 _{IN 1}
13
A 0 ₁₂
A1
4 _GND
5 _{IN 2}
6 _GND
7
IN 3
CS
11
10
OUT
R
9
EXT ₈
-V
33K
1%
0.1
-8V
All resistors in ohms, all capacitors in
microfarads unless otherwise stated.
Fig.11 16 x 1 Video Multiplexer Circuit
PRODUCT PROPOSAL
This data has been compiled for market investigation purposes
only, and does not constitute an offer for sale.
ADVANCE INFORMATION NOTE
This product is in development phase and specifications are
subject to change without notice. Gennum reserves the right to
remove the product at any time. Listing the product does not
constitute an offer for sale.
PRELIMINARY DATA SHEET
The product is in a preproduction phase and specifications are
subject to change without notice.
DATA SHEET
The product is in production. Gennum reserves the right to make
changes at any time to improve reliability, function or design, in
order to provide the best product possible.
Gennum Corporation assumes no responsibility for the use of any circuits described herein and makes no representations that they are free from patent infringement.
©Copyright August 1989 Gennum Corporation. Revision date: January 1993. All rights reserved. Printed in Canada.
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