The DS1621 Digital Thermometer and Thermostat
provides 9-bit temperature readings, which indicate the temperature of the
device. The thermal alarm output, TOUT, is active when the temperature of the
device exceeds a user-defined temperature TH:- The output remains active until
the temperature drops below user defined temperature TL, allowing for any
hysteresis necessary.
User-defined temperature settings are stored in nonvolatile memory so
parts may be programmed prior to insertion in a system. Temperature settings
and temperature readings are all communicated to/from the DS1621 over a simple
2-wire serial interface.
Operation
Measuring Temperature
The DS1621 measures temperature using a band gap-based temperature
sensor. A delta-sigma analog-to digital converter (ADC) converts the measured
temperature to a digital value that is calibrated in °C; for °F applications, a
lookup table or conversion routine must be used.
The temperature reading is provided in a 9-bit, two’s complement reading
by issuing the READ TEMPERATURE command. Table 2 describes the exact
relationship of output data to measured temperature. The data is transmitted
through the 2-wire serial interface, MSB first. The DS1621 can measure
temperature over the range of -55_C to +125_C in 0.5_C increments.
DS1621
FUNCTIONAL BLOCK DIAGRAM
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| Block Diagram DS1621 |
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