Choosing Appropriate Capacitance Value on C Pin for FM0+ Series MCUs (KA-03431)
For FM0+ series devices, the instantaneous peak current value is largely related to the capacitance value applied on the C pin, when the device is woken up from DeepStandby mode.
The capacitance on the C pin gets charged and discharged whenever the device enters and returns from the DeepStandby mode. This means that smaller capacitance values may cause a smaller current. However, the minimum value of the capacitance is 1 µF, and normal operation of the device cannot be guaranteed if the value is less than 1 µF. Meanwhile, the capacitance value has a temperature dependency; it drifts with change in ambient temperature. Therefore, you should ensure that the capacitance value is always higher than 1 µF, while taking temperature drifts into consideration.