STM32F030 PC13,14,15 current sink limits?

[Andrew Neil]

Is it OK to use these pins as current sinks for driving LEDs ?

[STTwo-32]

Hello @Andrew Neil 

As it is mentionned on the 3rd line of the note on the screenshot:

"These GPIOs must not be used as current sources (e.g. to drive an LED)." For Curent sink, i will check this and get back to you ASAP.

Best Regards.

STTwo-32 

[Tesla DeLorean]

Good question, the P/N gates probably the same size, but the ground ring is probably more robust, and not gated like VDD/VBAT path

I'd tend toward it being Ok, but will watch for the official response.

Slack pins for LEDs, the PA13/PA14 often can be used and still facilitate debug connectivity if the code is aware.

[Andrew Neil]

plus the reason stated for the limitation is that these pins are fed  "through the power switch", and that's what limits their sourcing capabilities.

I presume this is "the power switch":

On that basis, if it's the whole story, sinking should be OK ... ?

"the switch only sinks (sic?) a limited amount of current" sounds like a typo, though?

[Tesla DeLorean]

>>plus the reason stated for the limitation is that these pins are fed "through the power switch", and that's what limits their sourcing capabilities.

What's gating it, or how robust the wiring/metalization is feeding it across the die.

That was definitely my "hot-take" on the documentations wording, and that the return-path on the common VSS side was significantly more substantial, and not switched/gated.

The geometry of the IOCELL's transistor might also be smaller/slower, I vaguely recall a +/- 3mA specification in some STM32 family docs.

[AScha.3]

Sinking some mA ( < 3 mA ) should be ok...is done on all these blue-pill boards, so if thats a problem, you could see thousands of "my blue-pill died..." messages ; :)

But for a 100% reliable design, i would use these pins only as inputs - if possible.

[Tesla DeLorean]

Yes the design that sank a thousand ships..

[STTwo-32 · Accepted solution]

Hello @Andrew Neil @Tesla DeLorean @AScha.3 

Sorry for my late replay, I just received this answer from the concerned person:

" The switch is only impacting GPIO source capabilities. No limitations if IO is set in output low level."

Best Regards.

STTwo-32

[Andrew Neil]

Thanks - it would be helpful if that could be clarified in the datasheet.

[Andrew Neil]

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@Tesla DeLorean wrote:

the design that sank a thousand ships..

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But I only want to sink a dozen milliamps - to light my LEDs!