STDS75 Datasheet, PDF (6/37 Pages) STMicroelectronics – Digital temperature sensor and thermal watchdog

Summary description
1
Summary description
STDS75
The STDS75 is a high-precision CMOS (Digital) temperature sensor IC with a Delta-Sigma
analog-to-digital (ADC) converter and an I²C-compatible serial digital interface (see Figure 1
on page 7). It is targeted for general applications such as personal computers, system
thermal management, electronics equipment, and industrial controllers, and is packaged in
the industry standard 8-lead TSSOP and SO8 packages (see Figure 2 on page 8).
The device contains a band gap temperature sensor and programmable 9-to 12-bit ADC
which monitor and digitize the temperature to a resolution up to 0.0625°C. The STDS75 is
typically accurate to (±3°C - max) over the full temperature measurement range of –55°C to
125°C with ±2°C accuracy in the –25°C to +100°C range. At power-up, the STDS75 defaults
to 9-bit resolution for software compatibility with the STLM75.
STDS75 is specified for operating at supply voltages from 2.7V to 5.5V. Operating at 3.3V,
the supply current is typically (125µA).
The on-board delta sigma analog-to-digital converter (ADC) converts the measured
temperature to a digital value that is calibrated in °C; for Fahrenheit applications a lookup
table or conversion routine is required.
The STDS75 is factory-calibrated and requires no external components to measure
temperature.
1.1
Serial communications
The STDS75 has a simple 2-wire I²C-compatible digital serial interface which allows the
user to access the data in the temperature register at any time. It communicates via the
serial interface with a master controller which operates at speeds up to 400kHz. Three pins
(A0, A1, and A2) are available for address selection, and enable the user to connect up to 8
devices on the same bus without address conflict.
In addition, the serial interface gives the user easy access to all STDS75 registers to
customize operation of the device.
1.2
Temperature sensor output
The STDS75 Temperature Sensor has a dedicated open drain Over-Limit Signal/Alert
(OS/INT/Alert) output which features a thermal Alarm function. This function provides a
user-programmable trip and turn-off temperature. It can operate in either of two selectable
modes:
● Comparator mode, and
● Interrupt mode.
At power-up the STDS75 comes up in 9-bit mode and immediately begins measuring the
temperature and converting the temperature to a digital value. The resolution of the digital
output data is user-configurable to 9, 10, 11, or 12 bits which correspond to temperature
increments of 0.5°C, 0.25°C, 0.125°C, and 0.0625°C, respectively.
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