Use STM32H743II with an external ldo for vcore @ 400MHz

[michael2399]

We would use a STM32H743II with an external ldo for vcore. 

In the datasheet are tables (page 114, table 31) with regulator on but no tables with regulator off.

In the datasheet at page 114 is a table (table 31) for maximum current vs. junction temperature and running frequency. The current is increasing by higher junction temperature. More current means more power lost for the ldo, so we have a self-reinforcing effect.

Our idea is to supply the STM32 with an external LDO in order to be able to achieve a higher clock rate without violating the junction temperature. We want to achieve 400MHz at an ambient temperature of 85 ° C with a life time of 20 years.

[Amel NASRI]

Hi @michael2399​ ,

Referring to the product datasheet, it is possible to run the STM32H743II device @400MHz using an external LDO with Power scale = VOS1 giving that the maximum of junction temperature is 125 °C. This is what we can conclude from the table "Table 123. Supply voltage and maximum frequency configuration" of the datasheet.

The regulator consumption is very low, so you can refer to the tables with LDO regulator ON to estimate your power consumption.

Regarding the lifetime estimation, I recommend you to have a look to the application note AN5337: STM32H7 Series lifetime estimates.

In your case, the application note AN5036: Thermal management guidelines for STM32 applications can be helpful as well.

If further details are required, please let me know. It may be required to have an FAE contact to handle some of your questions.

-Amel