STM32CubeMX 6.8 Changes VOS on STM32H745 again

[jgauthier]

I'm building several projects based on STM32H745 and upgraded to STM32CubeMX 6.8. Upon doing so, VOS0 no longer is an option when using PWR_DIRECT_SMPS_SUPPLY:

6.7:

 

Now with 6.8:

 

Of course, this changes all the peripheral speeds and causes many problems with existing applications. I don't think this is correct.

I have an incredibly simply project that does nothing other than initialize FDCAN using generated code which immediately goes into Hardware Fault. Using 6.7, this does not happen at all.

[christop · Accepted solution]

There was an issue in the previous STM32CubeMX v6.7.0. It shouldn't have allow SMPS with VOS0.

STM32CubeMX v6.8.0 is following the device datasheet.

On STM32H745, VOS0 cannot be used with SMPS.

This is specified in the datasheet.

See section 3.5.3 (extract below):

Run mode (VOS0 to VOS3)

– Scale 0: boosted performance (available only with LDO regulator)

– Scale 1: high performance

– Scale 2: medium performance and consumption

– Scale 3: optimized performance and low-power consumption

[jgauthier]

So the previous version was wrong. Does this document cover the differences between SMPS, LDO, and External? Because I have not had much luck reading about how each of those are applied in hardware. I do know that setting those modes does not work on my design nor on the Nucleo. :)

[DTomi.1]

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