Datasheet

MAX31913
Industrial, Octal, Digital Input
Translator/Serializer
11Maxim Integrated
Serial-Port Operation
Serial output of the device functions in one of two
modes, depending on the MODESEL setting (Table 3).
With MODESEL = 0, the device output includes a 5-bit
CRC, an undervoltage alarm, and an overtemperature
alarm. See the Detailed Description for CRC, undervolt-
age, and overtemperature functional descriptions. With
MODESEL = 1, the device outputs only the state of the
IN1–IN8 inputs and omits the CRC, undervoltage alarm,
and overtemperature alarm.
Daisy-Chain Operation
For systems with more than eight sensor inputs, multiple
devices can be daisy-chained to allow access to all data
inputs through a single serial port. When using a daisy-
chain configuration, connect SOUT of one of the devices
to the SIN input of another upstream device. CS and SCK
of all devices in the chain should be connected together
in parallel (see Figure 2). In a daisy-chain configuration,
external components used to enhance EMC robustness
do not need to be duplicated for each device of a circuit
board. Figure 3 illustrates a 16-input application.
SPI Waveforms
The serial output of the device adheres to the SPI proto-
col, running with CPHA = 0 and CPOL = 0. Input states
on IN1–IN8 are latched in on the falling edge of CS. The
transfer of data out of the slave output, SOUT, starts
immediately when CS is asserted (i.e., MSB is output
onto SOUT independent of CLK). The remaining data bits
are shifted out on the falling edge of CLK. The data bits
are written to the output SOUT with MSB first. When CS
is high, SOUT is high impedance. The resultant timing is
shown in Figure 4. Note that all bits after IN1 are invalid
if 8-bit operation mode is selected with the MODESEL
input. Figure 5, Figure 6, Figure 7, and Figure 8 illustrate
SPI timing specifications.
Figure 2. Daisy-Chain Operation
Table 3. MODESEL Settings
MODESEL SETTING FUNCTIONALITY
0 16-bit output; [IN8–IN1][CRC (5 bit)][UV1][OT][UV2]
1 8-bit output; [IN8–IN1]
MAX31913 MAX31913MAX31913
SIN
SOUT
SIN
SOUT
SIN
SOUT
TO µCONTROLLER