I have a problem with degign of SIM900R USB device.
SIM900R has 2A pick current and SIMCOM advices 2x1500uF for SIM900R suplly voltage. Also advices LM2596 with output current 3A.
If I put 2x1500uF capacitor for supply voltage, I should also add current limiter for protection of USB port because of the inrush current of capacitors. Beside this, the USB port has 50mA current limiter, how can I get supply current from USB port? Also I wonder how USB 2G/3G modems can get enough power from the USB port?