Not able to make STM32H745i Disco board running after a modification from SMPS to LDO

[mridul_xalten]

New question from this thread.

So in order to use both SMPS and LDO, given in board schematics,
I mounted SB6 and SB17 (SB44, SB46, L4 already mounted)
and removed SB5 and SB18 (rest already not mounted).

After than i flashed it with keeping the following settings.

Im still getting the same error. 

[LCE]

> So basically the HW is configured in SMPS.
> So in order to obtain 480MHz, what changes should i do to the hardware.
> Or is there any way i could do it without changing the hardware?

I think the SMPS is there exactly for using the maximum CPU speed of 480 MHz, because usually at fmax the power consumption is the highest, and the SMPS should have lower loss and thus heat generation than the internal LDO.

So my guess: after using the LDO the MCU is getting warmer than with SMPS.

[mƎALLEm]

Check the VCORE voltage.

[mƎALLEm]

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@LCE wrote:

I think the SMPS is there exactly for using the maximum CPU speed of 480 MHz,

---

No. SMPS is not available in VOS0 (maximum 480Mhz). See this thread.

[LCE]

Thanks for the info!

Very interesting, why's that so? Any internal interference between SMPS and CPU at that clock rate?

@mƎALLEm  

[mƎALLEm]

Frankly, I don't have that information but VOS0 came after in rev V and it was not available in older die revisions like rev Y which have maximum CPU freq at 400MHz at VOS1.

[aniruddh]

Iam facing the same problem as the OP, Could you please elaborate further on measurement of Vcore and or any other things i should be wary of?

[aniruddh]

The issue was resolved when the supply source was changed from LDO only to LDO and SMPS.

[mridul_xalten · Accepted solution]

Thanks,
It was indeed the issue i guess. It is working fine when i chose 

HAL_PWREx_ConfigSupply(PWR_SMPS_2V5_SUPPLIES_LDO); 

/** Configure the main internal regulator output voltage */
__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE0);

instead of 

HAL_PWREx_ConfigSupply(PWR_LDO_SUPPLY); 

/** Configure the main internal regulator output voltage */
__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE0);