The first USB power specification. Introduced in 2007, USB Battery Charging was fixed at 7.5 watts, 5 volts and 1.5 amps. When Version 1.2 was introduced in 2010, the following terms were coined to define USB port functionality. See
USB power.
Standard Downstream Port (SDP)
SDP provides downstream data transfer only.
Dedicated Charging Port (DCP)
DCP is a port in a power adapter for charging only and no data transfer.
Charging Downstream Port (CDP)
A CDP port is capable of transferring data and charging at the same time. Also called a "charge and sync" port.