Rainbow Electronics DS1722 - Manual (Page 3)

DS1722
3 of 13
The DS1722 can communicate using either a Motorola Serial Peripheral Interface (SPI) or standard 3-
wire interface. The user can select either communication standard through the SERMODE pin, tying it to
V
DDD
for SPI and to ground for 3-wire.
The device contains both an analog supply voltage and a digital supply voltage (V
DDA
and V
DDD
,
respectively). The analog supply powers the device for operation while the digital supply provides the
top rails for the digital inputs and outputs. The DS1722 was designed to be 1.8V Logic-Ready.
DS1722 FUNCTIONAL BLOCK DIAGRAM Figure 1
OPERATION-Measuring Temperature
The core of DS1722 functionality is its direct-to-digital temperature sensor. The DS1722 measures
temperature through the use of an on-chip temperature measurement technique with an operating range
from -55
° =to +120 °
C. The device powers up in a power-conserving shutdown mode. After power-up, the
DS1722 may be placed in a continuous conversion mode or in a one-shot conversion mode. In the
continuous conversion mode, the device continuously computes the temperature and stores the most
recent result in the temperature register at addresses 01h (LSB) and 02h (MSB). In the one-shot
conversion mode, the DS1722 performs one temperature conversion and then returns to the shutdown
mode, storing temperature in the temperature register. Details on how to change the setting after power-
up are contained in the “OPERATION-Programming” section.