STM32H745II VOS with SMPS supplying LDO

DTomi.1 · ‎2023-03-23

Greetings,

What is the reason for not being able to use the SMPS (or the SMPS supplying LDO) option for VOS0 on STM32H745II?

VOS0 means the highest voltage, so won't the dissipation on the LDO be the highest?

I have been using the PWR_SMPS_1V8_SUPPLIES_LDO option with VOS0 (core running at 480 MHz) and have seen no problem.

Can you please tell me what are the possible risks of using this configuration?

Best regards,

Domagoj

DTomi.1 · ‎2023-06-06

I have new info from the ST support, this option is ok and a fix will be provided in the STM32CubeMX 6.9.0.

View solution in original post

Foued_KH · ‎2023-03-23

Hello @Domagoj Tomić ,

As mentioned in the Table 24. Supply voltage and maximum frequency configuration in the datasheet 12923

VOS0 (power scale 0) is not available when the SMPS step-down converter directly supplies VCORE.

Foued

To give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

DTomi.1 · ‎2023-03-23

But I'm currently using this configuration (PWR_SMPS_1V8_SUPPLIES_LDO with PWR_REGULATOR_VOLTAGE_SCALE0) since older CubeMX version allowed it, and it works without any issues so far.

Why is that configuration not allowed, and what are the potential risks if I keep using it?

DTomi.1 · ‎2023-03-23

But I'm currently using this configuration (PWR_SMPS_1V8_SUPPLIES_LDO with PWR_REGULATOR_VOLTAGE_SCALE0) since older CubeMX version allowed it, and it works without any issues so far.

Why is that configuration not allowed, and what are the potential risks if I keep using it?

Foued_KH · ‎2023-03-23

Try to use the latest version STM32CubeMX 6.8.0 .

To give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

DTomi.1 · ‎2023-03-23

My question is regarding the existing FW configured with older CubeMX, what are the possible consequences of using the PWR_SMPS_1V8_SUPPLIES_LDO configuration with PWR_REGULATOR_VOLTAGE_SCALE0 since I already have MCUs shipped with that configuration to customers.

ROKAM.1 · ‎2023-03-24

I have the same problem.

Are you talking about PWR_DIRECT_SMPS_SUPPLY option?

Does SMPS supply VCORE directly on PWR_SMPS_1V8_SUPPLIES_LDO option too?

DTomi.1 · ‎2023-03-28

"Are you talking about PWR_DIRECT_SMPS_SUPPLY option?"

I think he is, but I'm talking about PWR_SMPS_1V8_SUPPLIES_LDO option.

My understanding is that with the "PWR_SMPS_1V8_SUPPLIES_LDO" configuration, the VCORE is sourced from the LDO, that's why I'm confused why that option is now not available and it was in the older CubeMX.

O'li · ‎2023-04-04

Hi @KHALSI_Foued,

I'm in the same situation, where both my hardware and my firmware are configured with PWR_SMPS_1V8_SUPPLIES_LDO and VOS0.

Could you please give us some insight regarding why SMPS_supplies_LDO and VOS0 shouldn't be used in conjunction, and what could be the consequences of such a configuration?

LCE · ‎2023-04-04

I'm curious about this:

If you find the time, please check with a scope: is the SMPS really active?

And maybe try comparing temperature from MCU-internal sensor, with LDO / SMPS active.