STM32L151VBT6DTR datasheet(25/121 Pages) STMICROELECTRONICS

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STM32L151x6/8/B, STM32L152x6/8/B

Functional overview

Doc ID 17659 Rev 8

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3.10.2

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 (when 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.

3.11

DAC (digital-to-analog converter)

The two 12-bit buffered DAC channels can be used to convert two digital signals into two

analog voltage signal outputs. The chosen design structure is composed of integrated

resistor strings and an amplifier in non-inverting configuration.

This dual digital Interface supports the following features:

●

two DAC converters: one for each output channel

●

left or right data alignment in 12-bit mode

●

synchronized update capability

●

noise-wave generation

●

triangular-wave generation

●

dual DAC channels’ independent or simultaneous conversions

●

DMA capability for each channel (including the underrun interrupt)

●

external triggers for conversion

●

input reference voltage VREF+

Eight DAC trigger inputs are used in the STM32L15xxx. The DAC channels are triggered

through the timer update outputs that are also connected to different DMA channels.

3.12

Ultra-low-power comparators and reference voltage

The STM32L15xxx embeds two comparators sharing the same current bias and reference

voltage. The reference voltage can be internal or external (coming from an I/O).

●

one comparator with fixed threshold

●

one comparator with rail-to-rail inputs, fast or slow mode. The threshold can be one of

the following:

–

DAC output

–

External I/O

–

Internal reference voltage (VREFINT) or VREFINT submultiple (1/4, 1/2, 3/4)

Table 7.

Internal voltage reference measured values

Calibration value name

Description

Memory address

VREFINT_CAL

Raw data acquired at

temperature of 30 °C

VDDA= 3 V

0x1FF8 0078-0x1FF8 0079

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