SMPS power Regulator is not being set in STM32U575.

[nilesh-dryad]

I am trying to set up SMPS power Regulator for low power operation. I am using Nucleo-U575ZI-Q board. I set the bit in CR3 register but bit in SVMSR is not being set.

Do anyone have idea what can be wrong? Is there something that I am missing?

[Bruno_ST]

Hello @nilesh-dryad​ 

Did you enable the RCC->AHB3ENR PWREN (bit 2) before poking the PWR->CR3 REGSEL to 1 ?

Then yes, you you see switch the SVMSR toggling to 1.

BR,

Bruno

[nilesh-dryad]

@Bruno_ST​ 

Thank you for your quick reply.

I am using the example from STM32CubeIDE for Nucleo-U575 without any change. Am I supposed to change anything in example?

BR,

Nilesh Vora

[Tesla DeLorean]

Typically the PWR peripheral is enabled via HAL_Init() and its call to HAL_MspInit() stm32u5xx_hal_msp.c

The SMPS settings via SystemPower_Config()

See example

STM32Cube_FW_U5_V1.1.0\Projects\NUCLEO-U575ZI-Q\Examples\CRC\CRC_Example\Src\main.c

[nilesh-dryad]

I checked Hal_Init function, it is set. Do I need to set any jumper or solder bridge on Nucleo board? I checked the user manual of the nucleo board. I didn't find anything related to SMPS.

[nilesh-dryad]

It is enabled. I checked it. I don't understand why the sample examples are not working on nucleo board.

I also checked TX_LOWPOWER example, it is also not working. Power consumption is always around 60ma. Tickless idle also does not seem to work. I didn't try all the examples.

[Bruno_ST]

Examples should work straight away without any change on the board.

For Tx_LowPower, LED_GREEN toggles every 500ms for 5 seconds each time user press the user button (consumption ~4/5uA). Something looks wrong on your Nucleo MB1449 board. Consumption under reset ~550uA (black button keep pressed and IDD measure on pin 2 of JP5 means on VDD_MCU side)

Bruno

[nilesh-dryad]

Strange. I have 3 Nuclen board with me. I tried on two. I didn't work but today I opened the 3rd one and the examples worked on the 3rd one. So the SMPS regulator worked on 3rd one.

[Bruno_ST]

Yes, strange... as the board is tested in production...

When you say the 2 first boards are not working, the issue is only on SMPS that doesn't start on the board ?

Is the on-board SMPS on JP4 @1.8V ok ?

60mA is so high ! The U575 doesn't consumes so much on LDO @160MHz at 25°C.... (cf datasheet)

[nilesh-dryad]

If you switch to LDO on those two boards then it works fine.

One more question: Do I need to switch to 1.8V if I enable SMPS power regulator?