Clarification on STM32H7A3 Power Supply Configuration with LQFP64 Package

[GustavEckerbom]

Hi ST Community,

I’m working on a hardware design using the STM32H7A3 in an LQFP64 package, specifically STM32H7A3RIT and need some reassurance on the power supply configuration. I’ve been looking into the power domains outlined in the application note AN5307, particularly Figure 1 Power supplies, which illustrates the power supply routing.

Link to AN5307

Based on this figure and nearby text in the application note;

• The internal LDO voltage regulator connects to the VDDLDO pin.
• It seems there’s an option to bypass the internal LDO, allowing an external supply to be connected directly to the VCAP pins.

In the LQFP64 package, however, the VDDLDO pin is not available externally, which has me wondering: Does this mean I cannot use the internal LDO with this package?

Later in the document, I found Figure 3 suggesting that VDDLDO might be internally tied to the VDD pins.

If that’s correct, it would imply that the internal LDO is still accessible and can power the core domain even without an external VDDLDO pin. I would appreciate confirmation on this - Does the internal connection to VDD indeed allow the LDO to function for the core domain in the LQFP64 package?

If so, my understanding is that I should do the following to power my core through the VDD pins using the internal LDO:

• Connect the two VCAP pins together.
• Place a 2.2uF capacitor close to each VCAP pin as per the recommendation in the application note’s capacitor table

Thanks for any guidance on this setup!

Best regards,
Gustav Eckerbom

[SofLit · Accepted solution]

Hello,

If no VDDLDO is available on the package it's indeed tied internally to VDD.

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@GustavEckerbom wrote:

If so, my understanding is that I should do the following to power my core through the VDD pins using the internal LDO:

• Connect the two VCAP pins together.
• Place a 2.2uF capacitor close to each VCAP pin as per the recommendation in the application note’s capacitor table

That's correct.