STM32MP157D datasheet(41/259 Pages) STMICROELECTRONICS

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DS12504 Rev 5

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STM32MP157A/D

Functional overview

3.27

Voltage reference buffer (VREFBUF)

The STM32MP157A/D devices embed a voltage reference buffer which can be used as

voltage reference for ADC, DACs and also as voltage reference for external components

through the VREF+ pin.

The internal voltage reference buffer supports four voltages:

•

1.5 V

•

1.8 V

•

2.048 V

•

2.5 V

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

voltage reference buffer is off.

Figure 4. Voltage reference buffer

3.28

Digital filter for sigma delta modulators (DFSDM1)

The device embeds one DFSDM with support for 6 digital filters modules and 8 external

input serial channels (transceivers) or alternately 8 internal parallel inputs.

The DFSDM peripheral is dedicated to interface external Σ∆ modulators to

STM32MP157A/D and perform digital filtering of the received data streams. Σ∆ modulators

are used to convert analog signals into digital serial streams that constitute the inputs of the

DFSDM. The DFSDM can also interface PDM (pulse density modulation) microphones and

perform the PDM to PCM conversion and filtering (hardware accelerated). The DFSDM

features optional parallel data stream inputs from internal ADC peripherals or

STM32MP157A/D memory (through DMA/CPU transfers into DFSDM).

The DFSDM transceivers support several serial interface formats (to support various Σ∆

modulators). DFSDM digital filter modules perform digital processing according user-defined

filter parameters with up to 24-bit final ADC resolution.

MSv40197V1

VREFBUF

Low frequency

cut-off capacitor

DAC, ADC

Bandgap

VDDA

100 nF

VREF+

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