RM0091 Analog-to-digital converter (ADC)
Doc ID 018940 Rev 1 189/742
12.9 Temperature sensor and internal reference voltage
The temperature sensor can be used to measure the junction temperature (T
J
) of the
device. The temperature sensor is internally connected to the ADC1_IN16 input channel
which is used to convert the sensor’s output voltage to a digital value. The sampling time for
the temperature sensor’s analog pin must be greater than 2.2 µs.
The internal voltage reference (V
REFINT) provides a stable (bandgap) voltage output for the
ADC and Comparators. V
REFINT is internally connected to the ADC_IN17 input channel. The
precise voltage of V
REFINT is individually measured for each part by ST during production
test and stored in the system memory area. It is accessible in read-only mode.
Figure 37 shows the block diagram of the temperature sensor.
When not in use, the sensor can be put in power down mode.
Note: The TSVREFE bit must be set to enable the conversion of both internal channels:
ADC1_IN16 (temperature sensor) and ADC1_IN17 (V
REFINT
).
The temperature sensor output voltage changes linearly with temperature. The offset of this
line varies from chip to chip due to process variation (up to 45 °C from one chip to another).
The internal temperature sensor is more suited for applications that detect temperature
variations instead of absolute temperatures. If accurate temperature readings are needed,
an external temperature sensor part should be used.
During the manufacturing process, the calibration data of the temperature sensor and the
internal voltage reference are stored in the system memory area. The user application can
then read them and use them to improve the accuracy of the temperature sensor or the
internal reference. Refer to the datasheet for additional information.
Main features
● Supported temperature range: –40 to 125 °C
● Linearity: ±2 °C max. , precision depending on calibration
Figure 37. Temperature sensor and V
REFINT
channel block diagram
sensor
Temperature
V
SENSE
TSEN control bit
ADC1
Address/data bus
converted data
V
REFINT
ADC1_IN16
ADC1_IN17
power
block
Internal
ai16065
VREFEN
control bit
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