STM32WLE4JC datasheet(41/146 Pages) STMICROELECTRONICS

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DS13105 Rev 9

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STM32WLE5/E4xx

Functional overview

3.18.3

VBAT battery voltage monitoring

This embedded hardware feature allows the application to measure the VBAT(a) battery

voltage using the ADC VIN[14] input channel. As VBAT may be higher than VDDA, and thus

outside the ADC input range, the VBAT pin is internally connected to a bridge divider by

three. As a consequence, the converted digital value is one third the VBAT voltage.

3.19

Digital-to-analog converter (DAC)

The 1-channel 12-bit buffered DAC converts a digital value into an analog voltage available

on the channel output. The architecture of each channel is based on an integrated resistor

string and an inverting amplifier. The digital circuitry is common for both channels.

DAC main features:

•

1 DAC output channel

•

8-bit or 12-bit output mode

•

buffer offset calibration (factory and user trimming)

•

left or right data alignment in 12-bit mode

•

synchronized update capability

•

noise-wave generation

•

triangular-wave generation

•

independent or simultaneous conversion for DAC channels

•

DMA capability for either DAC channel

•

triggering with timer events, synchronized with DMA

•

triggering with external events

Sample-and-hold low-power mode, with internal or external capacitor

3.20

Voltage reference buffer (VREFBUF)

The devices embed a voltage reference buffer that can be used as voltage reference for

ADC, and also as voltage reference for external components through the VREF+ pin.

VREFBUF supports two voltages: 2.048 V and 2.5 V.

An external voltage reference can be provided through the VREF+ pin when VREFBUF

is off.

Table 13. Internal voltage reference calibration values

Calibration value name

Description

Memory address

VREFINT_CAL

Raw data acquired at 30 °C (± 5 °C),

VDDA = VREF+ = 3.3 V (± 10 mV)

0x1FFF 75AA - 0x1FFF 75AB

a. VDD on STM32WLE5/E4UxYx devices.

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