MAX4358ECE MAXIM [Maxim Integrated Products], MAX4358ECE Datasheet - Page 37

• Manufacturer Part Number: MAX4358ECE
• Description: 32 x 16 Nonblocking Video Crosspoint Switch with On-Screen Display Insertion and I/O Buffers
• Manufacturer: MAXIM [Maxim Integrated Products]

Total capacitance is the sum of the capacitance of all
the disabled outputs and is a function of the size of the
matrix. Also, as the size of the matrix increases, the
length of the PC board traces increases, adding more
capacitance. The output buffers have been designed to
drive more than 30pF of capacitance while still main-
taining a good AC response. Depending on the size of
the array, the capacitance seen by the output can
exceed this amount. There are several ways to improve
the situation. The first is to use more building-block
crosspoint devices to reduce the number of outputs
that need to be wired together (see Figure 7).
Figure 8. Optimal Isolation Resistor vs. Capacitive Load
with On-Screen Display Insertion and I/O Buffers
Figure 7. 128 x 16 Nonblocking Matrix with Reduced Capacitive
Loading
INPUTS (96–127)
INPUTS (32–63))
INPUTS (64–95)
INPUTS (0–31)
32 x 16 Nonblocking Video Crosspoint Switch
30
25
20
15
10
5
0
32
IN
32
IN
32
IN
32
IN
0
MAX4358
MAX4358
MAX4358
MAX4358
OPTIMAL ISOLATION RESISTANCE
______________________________________________________________________________________
100
vs. CAPACITIVE LOAD
OUT
OUT
OUT
OUT
CAPACITIVE LOAD (pF)
16
16
16
16
200
16
IN
16
IN
300
MAX4358
400
OUT
16
500
OUTPUTS (0–15)
In Figure 7, the additional devices are placed in a sec-
ond bank to multiplex the signals. This reduces the
number of wired-OR connections. Another solution is to
put a small resistor in series with the output before the
capacitive load to limit excessive ringing and oscilla-
tions. Figure 8 shows the graph of the Optimal Isolation
Table 6. Input Selection Programming
(MSB)
B4
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
INPUT ADDRESS BIT
B3
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
B2
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
B1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
(LSB)
B0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
SELECTED
INPUT
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
0
1
2
3
4
5
6
7
8
9
37