MAX4359-MAX4456 Maxim, MAX4359-MAX4456 Datasheet - Page 9

• Manufacturer Part Number: MAX4359-MAX4456
• Description: Low-Cost 4x4 / 8x4 / 8x8 Video Crosspoint Switches
• Manufacturer: Maxim

Figure 2 shows a typical application of the MAX4456
(PDIP) with MAX497 quad, gain-of-two buffers at the
outputs to drive 75Ω loads. This application shows the
MAX4456 digital-switch control interface set up in the 7-
bit parallel mode. The MAX4456 uses seven data lines
and two control lines (WR and LATCH). Two additional
lines may be needed to control CE and LOAD when
using multiple MAX4456s.
The input/output information is presented to the chip at
A2, A1, A0, and D3–D0 by a parallel printer port. The
data is stored in the 1st-rank registers on the rising
edge of WR. When the LATCH line goes high, the
switch configuration is loaded into the 2nd-rank regis-
ters, and all eight outputs enter the new configuration at
the same time. Each 7-bit word updates only one out-
put buffer at a time. If several buffers are to be updat-
ed, the data is individually loaded into the 1st-rank reg-
isters. Then, a single LATCH pulse is used to reconfig-
ure all channels simultaneously.
Figure 2. MAX4456 (plastic DIP) Typical Application Circuit
14
19
22
23
24
25
18
20
21
DB–25
CHANNELS
_______________________________________________________________________________________
8 INPUT
VIDEO
1
2
3
6
4
5
7
8
Typical Application
22
21
11
13
15
17
19
38
36
2
1
6
4
3
7
9
5
IN0
IN1
IN2
IN3
A0
IN4
IN5
IN6
IN7
LATCH
WR
D0/SER IN
D1/SER OUT
D2
D3
A1
A2
MAX4456
EDGE/LEVEL
SER/PAR
AGND
DGND
OUT0
OUT1
OUT2
OUT3
OUT4
OUT5
OUT6
OUT7
LOAD
CE
CE
V+
V+
V+
V-
V-
39
37
35
33
29
27
25
24
26
28, 30, 32
10, 12
20
34
23
18
16
31
14
40
8
Video Crosspoint Switches
+5V
9,15
2
4
6
8
The short BASIC program in Figure 3 loads program-
ming data into the MAX4456 from any IBM PC or com-
patible. It uses the computer’s “LPT1” output to interface
to the circuit, then automatically finds the address for
LPT1 and displays a table of valid input values to be
used. The program does not keep track of previous
commands, but it does display the last data sent to
LPT1, which is written and latched with each transmis-
sion. A similar application is possible with the
MAX4359/MAX4360.
MAX4359 TRANSISTOR COUNT: 2372
MAX4360 TRANSISTOR COUNT: 2372
MAX4456 TRANSISTOR COUNT: 3820
V
Low-Cost 4x4, 8x4, 8x8
IN0
IN1
IN2
IN3
CC
MAX497
+5V
GND
1, 3, 5, 7 11,13
A
V
OUT0
OUT1
OUT2
OUT3
-5V
= 2
V
EE
NOTE: ALL BYPASS CAPACITORS ARE 0.1µF CERAMIC.
16
14
12
10
-5V
75Ω
Chip Information
Z
0
= 75Ω
75Ω
9