Main Site Documentation

0.22F supercap on cellular radio module


#1

Why is there a 0.22F (220,000u) capacitor on the SIM900 cellular module? It seems a bit excessive, especially since the datasheet only calls for a 330u capacitor to stabilize the MIC29302 regulator.


#2

Sim900 data sheet indicates the module can draw up to 2A at times. I’ve bypassed the 5V line going through from the main board tapping it to an external 5V@ 4A supply. I was having trouble with it even using a powered USB port.