How much can I overclock the STM32F303xx MCUs when powered by 3.3v and running at room temperature?

[briankaz]

I'm using the STM32F303xx MCU in an application with a 24.576MHz crystal. The MCU is powered from 3.3v. I am currently clocking the processor at 3x 24.576MHZ, or just slightly under 74MHz. I realize this is above the rated maximum processor clock of 72MHz but I thought it will work anyway, especially since the MCU is rated down to 2.0v and I am using 3.3v and only using it at ambient room temperature.

What I'm wondering is, can I reliably increase the processor clock to 4x 24.576MHz = 98.304MHz under these conditions? I tried it and it seems to work but I don't want to run into any unexpected reliability issues down the road. In my understanding increasing the supply voltage should definitely increase the maximum operating frequency but there is no such information in the datasheet.

I would appreciate any more helpful information you can provide.

Thanks!

-Brian

[waclawek.jan]

> can I reliably increase the processor clock

No.

All ST guarantees you is the 72MHz, that's reliable.

Supply voltage probably won't have that much influence as the core runs most probably from an internal regulator anyway. Ambient temperature might play role, but how would you know where's the margin. To the manufacturer, typically, it takes several levels of characterization, down to the transistors level, to find out the safe margins, so it's not just that they tried some pieces in a clima chamber finding out the spot when they failed, and then threw some arbitrary margin on it.

ST might be willing to work on assurance for you at relaxed constraints, if you represent a significant buying power (as expressed in $M++); but then you probably wouldn't ask here.

Try to have a look at other STM32 families, maybe you'll find a mix of features that will suit your application. The new 'G4 family is said to be the next 'F3.

JW

[Tesla DeLorean]

Additional flash wait states are typically the way to increase speed. This will eat into incremental gains as there is no ART cache on the F3, but you could run from CCM as I recall.

Also certainly runs at 1.25V internally, so mucking with the external VDD probably not going to change anything.