AN2680

Digital temperature sensor

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1

Digital temperature sensor

The STDS75 and STLM75 are digital temperature sensors that measure the ambient

temperature and give the digital output. Both the STDS75 and STLM75 are 8-pin ICs

available in two packages, SO-8 and TSSOP-8. The measurable temperature range of the

sensors is -55 °C to 125 °C.

The STLM75 and STDS75 differ only in terms of the resolution of the temperature data. The

STLM75 has a fixed 9-bit resolution whereas the STDS75 has configurable resolution

starting from 9 to 12 bits. In the present application, we move with the default resolution

settings of the sensor that is 9 bits and thus both the STDS75 and STLM75 are dealt with in

the same manner.

Figure 1.

Temperature sensor pin description

1.1

Theory of operation

This temperature sensor is a high-precision CMOS IC with a delta-sigma analog-to-digital

converts the measured temperature to a digital value that is calibrated in degree Celsius.

Negative temperature is shown in two's compliment form. The sensor also has an alarm

output signal.

Table 1.

Pin description

Name

Description

SDA

Serial data input output pin

SCL

Serial clock input pin

Alarm

Alarm output pin

GND

DC ground

A0,A1,A2

Address lines

VCC

Supply voltage (2.7 V- 5.5 V)