STM32H7R3 power design: VDDXSPI, VREF+/-, VDDA ?

[oysteikr]

Hi

Do QUAD SPI require power on the VDDXSPI power pins?

ADCs, what is the voltage reference buffer, VREF+ and VREF- , voltages? Can the internal reference buffer be used if VDDA is 3.3V and I want full scale 0-3.3V ADC conversion range?

kr

Øystein

[mƎALLEm · Accepted solution]

Hello,

1- According to the AN5935 "Getting started with STM32H7Rx/7Sx MCUs hardware development" / Table 4:

Normally you need to power supply the XSPI IOs no matter the memory configuration, QSPI etc .. It's more related to the memory power domain:

2- The internal reference buffer (VREFBUF) in STM32 cannot provide a 3.3V reference; its maximum is typically 2.5V.

From the reference manual RM0477:

[TDK]

> Do QUAD SPI require power on the VDDXSPI power pins?

Yes.

> ADCs, what is the voltage reference buffer, VREF+ and VREF- , voltages? Can the internal reference buffer be used if VDDA is 3.3V and I want full scale 0-3.3V ADC conversion range?

No, the highest voltage selected by VREFBUF is 2.5 V. If you want the full range, either connect VREF+ to VDDA or create your own 3.3V voltage reference. Note that VREF+ can't be above VDDA. VREF- must be connected to VSSA.

General hardware tips:

Getting started with STM32H7Rx/7Sx MCUs hardware development - Application note