USB charging

A USB port is convenient for charging portable devices. The amount of power which can be drawn from an ordinary
USB port depends on its state and varies between 2 and 500 mA. In order to allow higher charging currents, a new standard was
developed especially for portable device charging. The portable device has to detect if it is connected to a charging USB port before it starts
drawing excessive current.

Details can be downloaded here: http://www.usb.org/developers/devclass_docs/Battery_Charging_V1_2.zip

Specifications for a Dedicated Charging Port (DCP):
  • Voltage: 4.75-5.25
  • Current: max.1.5 A