STM32F103 NRST PIN CAPACITOR VALUE?

[cbyun.1]

There was a phenomenon that booting was not possible during the low temperature test.

The NRST external switch is equipped with a 100pF capacitor.

The datasheet recommends installing 100nF.

However, I don't think it will be a problem because the MIN value is more than 300ns.

If you install 100nF, it will boot normally.

Why can't I mount 100pF?

RC= 8K (40K (internal pull-up resistor) // 10K (external pull-up resistor)) * 100pF

Over 300ns.

[Uwe Bonnes]

100 pF will release NRST very fast, Probably some internal "TEMPORIZATION" timing is not meet.

[ONadr.1]

The capacitor should also block superimposed interference and prevent unwanted resets. That's why there is a recommended capacitance of 100nF.