STM32L031X4 datasheet(27/118 Pages) STMICROELECTRONICS

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STM32L031x4/6

Functional overview

The ADC can be served by the DMA controller. It can operate from a supply voltage down to

1.65 V.

The ADC features a hardware oversampler up to 256 samples, this improves the resolution

to 16 bits (see AN2668).

An analog watchdog feature allows very precise monitoring of the converted voltage of one,

some or all scanned channels. An interrupt is generated when the converted voltage is

outside the programmed thresholds.

The events generated by the general-purpose timers (TIMx) can be internally connected to

the ADC start triggers, to allow the application to synchronize A/D conversions and timers.

3.11

Temperature sensor

The temperature sensor (TSENSE) generates a voltage VSENSE that varies linearly with

temperature.

The temperature sensor is internally connected to the ADC_IN18 input channel which is

used to convert the sensor output voltage into a digital value.

The sensor provides good linearity but it has to be calibrated to obtain good overall

accuracy of the temperature measurement. As the offset of the temperature sensor varies

from chip to chip due to process variation, the uncalibrated internal temperature sensor is

suitable for applications that detect temperature changes only.

To improve the accuracy of the temperature sensor measurement, each device is

individually factory-calibrated by ST. The temperature sensor factory calibration data are

stored by ST in the system memory area, accessible in read-only mode.

3.11.1

Internal voltage reference (VREFINT)

The internal voltage reference (VREFINT) provides a stable (bandgap) voltage output for the

ADC and Comparators. VREFINT is internally connected to the ADC_IN17 input channel. It

enables accurate monitoring of the VDD value (since no external voltage, VREF+, is available

for ADC). The precise voltage of VREFINT 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.

Table 7. Temperature sensor calibration values

Calibration value name

Description

Memory address

TSENSE_CAL1

TS ADC raw data acquired at

temperature of 30 °C, VDDA= 3 V

0x1FF8 007A - 0x1FF8 007B

TSENSE_CAL2

TS ADC raw data acquired at

temperature of 130 °C, VDDA= 3 V

0x1FF8 007E - 0x1FF8 007F

Table 8. Internal voltage reference measured values

Calibration value name

Description

Memory address

VREFINT_CAL

Raw data acquired at

temperature of 25 °C

VDDA = 3 V

0x1FF8 0078 - 0x1FF8 0079

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