Datasheet

MAX4550/MAX4570
Serially Controlled, Dual 4x2, Clickless
Audio/Video Analog Crosspoint Switches
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Figures 3, 4, and Table 6 show the details of the
3-wire protocol, as it applies to the MAX4570. DOUT is
the shift register’s output. Data at DOUT is simply the
input data delayed by 16 clock cycles, with data
appearing synchronous with SCLK’s falling edge.
Transitions at DIN and SCLK have no effect when CS is
high, and DOUT holds the last bit in the shift register.
Daisy Chaining
To program several MAX4570s, “daisy chain” the
devices by connecting DOUT of the first device to DIN of
the second, and so on. The CS pins of all devices are
connected together, and data is shifted through the
MAX4570s in series. 16 bits of data per device are
required for proper programming of all devices. When
CS is brought high, all devices are updated simultane-
ously.
CS
SCLK
DIN
COMMAND BYTE DATA BYTE
16
1
C7 D0
C0 D7
Figure 3. 3-Wire Serial-Interface Communication
• • •
• • •
• • •
• • •
CS
SCLK
DIN
DOUT
t
CSH
t
CSS
t
CL
t
DS
t
DH
t
DV
t
CH
t
DO
t
TR
t
CSH
Figure 4. 3-Wire Serial-Interface Timing Details