Rainbow Electronics MAX31723 - Manual (Page 7)

MAX31722/MAX31723
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
7
Detailed Description
The MAX31722/MAX31723 are factory-calibrated tem-
perature sensors that require no external components.
The user can alter the configuration/status register to
place the device in a continuous temperature conversion
mode or into a one-shot conversion mode. In the continu-
ous conversion mode, the devices continuously convert
the temperature and store the result in the temperature
register. As conversions are performed in the back-
ground, reading the temperature register does not affect
the conversion in progress. In the one-shot temperature
conversion mode, the devices perform one temperature
conversion, store the result in the temperature register,
and then return to the shutdown state. This conversion
mode is ideal for power-sensitive applications. The
temperature conversion results have a default resolution
of 9 bits. In applications where small incremental tem-
perature changes are critical, the user can change the
conversion resolution from 9 bits to 10, 11, or 12. This is
accomplished by programming the configuration/status
register.
The devices can be configured as a thermostat, allow-
ing for the TOUT pin to behave as an interrupt, trigger-
ing when the programmed limits, T
HIGH and T LOW , are
surpassed. The devices can communicate using either a
serial peripheral interface (SPI) or standard 3-wire inter-
face. The user can select either communication standard
through the SERMODE pin, connecting it to V
DD for SPI
and to GND for 3-wire.
Pin Configuration
Pin Description
µMAX
2 7 SERMODE CE
1 8 V DD TOUT
+
SDI SCLK 3 6
SDO GND 4 5
MAX31722
MAX31723
TOP VIEW
PIN NAME FUNCTION
1 TOUT Thermostat Output. Open-drain output indicator for internal thermal alarm limits.
2 CE
Chip Enable. Must be asserted high for communication to take place for either the SPI or 3-wire
interfaces.
3 SCLK
Serial-Clock Input. Used to synchronize data movement on the serial interface for either SPI or
3-wire interfaces.
4 GND Ground. Ground connection.
5 SDO
Serial-Data Output. When SPI communication is selected, the SDO pin is the serial-data output for
the SPI bus. When 3-wire communication is selected, this pin must be connected to the SDI pin.
The SDI and SDO pins function as a single I/O pin when connected together.
6 SDI
Serial-Data Input. When SPI communication is selected, the SDI pin is the serial-data input for the
SPI bus. When 3-wire communication is selected, this pin must be connected to the SDO pin. The
SDI and SDO pins function as a single I/O pin when connected together.
7 SERMODE
Serial-Interface Mode Input. This pin selects which interface is used. When connected to V DD , SPI
communication is selected. When connected to GND, 3-wire communication is selected.
8 V DD Supply Voltage. Power-supply input.