Electrical – STM32 Output current capabilities


In order to reduce the size of my board, I would like to connect directly my microcontroller to a current source which sink 9 mA (worst case). The datasheet above shows that it is possible. Nevertheless, I would like to have your opinion about this. I think that it will reduce the life time of the circuit as it heats up the microcontroller. What do you think ?

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Thank you very much and have a nice day !

Best Answer

The rules are simple.

If between Vss and Vdd you can to 25mA on one pin.
All pins together may do 80 mA. So 80mA in and 80mA out.
All currents should stay within 120mA, either way.

The current the chip itself uses subtracts from both ΣIvdd and ΣIvss.

Example: it is possible to sink 50ma and source 50mA with only 4 pins. (don't do that though)

If outside Vss to Vdd, 5mA max, polarity doesn't matter.

However, there is a caveat! Look at the Output voltage characteristics.
You may be looking at a 400 mV drop in voltage over the pin.

And every milliamp of current through the chip adds to the package power, see the chapter about thermals.

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