MAX458-MAX459 MAXIM [Maxim Integrated Products], MAX458-MAX459 Datasheet - Page 14

• Manufacturer Part Number: MAX458-MAX459
• Description: 8x4 Video Crosspoint Switches with Buffers
• Manufacturer: MAXIM [Maxim Integrated Products]

When driving loads greater than 100pF, you may need
a capacitance compensating resistor in series with the
output of each affected amplifier. The required resistor
will depend on load as well as capacitance. For 150Ω
or higher load resistances and capacitance up to
1000pF, use a 2.4Ω resistor. For 100Ω loads, use a
4.7Ω resistor.
If an output amplifier is loaded with a pure capacitance
or with the inputs of other MAX458/MAX459s, the resis-
tors will cause no degradation of gain or other perfor-
mance because of the high impedance of the
crosspoints. However, resistive loads may cause a
reduction in gain.
The serial output, DOUT, allows cascading of two or
more crosspoint switches to create larger arrays. The
data at DOUT is the DIN data delayed by 16 cycles
plus one clock width. DOUT changes on SCLK’s falling
edge when
in the state of the last data bit.
Any number of MAX458/MAX459 crosspoint switches
can be daisy-chained by connecting the DOUT of one
device to the DIN of the next device in the chain, as
shown in Figure 12. For proper timing, ensure that both
t
t
DOUT is a TTL-compatible output with an active pull-
up. It does not become high impedance when C
high.
8x4 Video Crosspoint Switches with Buffers
14
CSS
DO
+ t
______________________________________________________________________________________
(C
—
DS
S
–
.
low to SCLK high) and t
–
C
—
S
–
is low. When C
Driving Capacitive Loads
Daisy-Chaining Devices
—
S
–
is high, DOUT remains
CL
are greater than
—
S
–
is
Figure 12. 16x4 Crosspoint Switch Using Serial "Daisy Chain"
Connection
SERIAL
DOUT
DOUT
INPUT
SCLK
DATA
DIN
CS
1
1
20
20
MAX458
MAX459
MAX458
MAX459
28
34
40
39
30
32
40
39
30
32
28
34
OUT3
OUT2
OUT1
OUT0