STM32WLE4JC datasheet(40/146 Pages) STMICROELECTRONICS

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Functional overview

STM32WLE5/E4xx

40/146

DS13105 Rev 9

The ADC frequency is independent from the CPU frequency, allowing maximum sampling

rate of ~2 Msps even with a low CPU speed. An auto-shutdown function guarantees that the

ADC is powered off except during the active conversion phase.

The ADC can be served by the DMA controller. It can operate in the whole VDD supply

range.

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

16 bits. Refer to the application note Improving STM32F1 Series, STM32F3 Series and

STM32Lx Series ADC resolution by oversampling (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 with timers.

3.18.1

Temperature sensor

The temperature sensor (TS) generates a VTS voltage that varies linearly with temperature.

The temperature sensor is internally connected to the ADC VIN[12] input channel, 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 may

vary from part to part due to process variation, the uncalibrated internal temperature sensor

is suitable only for relative temperature measurements.

To improve the accuracy of the temperature sensor, each part is individually factory-

calibrated by ST. The resulting calibration data is stored in the device engineering bytes,

accessible in read-only mode.

3.18.2

Internal voltage reference (VREFINT)

VREFINT provides a stable (bandgap) voltage output for the ADC and comparators. VREFINT

is internally connected to the ADC VIN[13] input channel.

VREFINT is individually and precisely measured, for each part, by ST, during production test

and stored in the device engineering bytes. It is accessible in read-only mode.

Table 12. Temperature sensor calibration values

Calibration value

name

Description

Memory address

TS_CAL1

TS ADC raw data acquired at 30 °C (± 5 °C),

VDDA = VREF+ = 3.3 V (± 10 mV)

0x1FFF 75A8 - 0x1FFF 75A9

TS_CAL2

TS ADC raw data acquired at 130 °C (± 5 °C),

VDDA = VREF+ = 3.3 V (± 10 mV)

0x1FFF 75C8 - 0x1FFF 75C9

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