standard downstream port (USB) (SDP)

The USB interface according to USB 2.0 knows different charging specifications, which differ in the current output: Besides the Standard DownstreamPort( SDP), there is the Charging Downstream Port( CDP) and the Dedicated Charging Port( DCP).

The Standard Downstream Port (SDP) is the same port as specified in USB 2.0. It is the typical port of desktops and laptops. The maximum load current is 2.5 mA when idle and 100 mA when active. 500 mA can be reached by appropriate configuration. Devices connected to the port detect if it is an SDP port by sensing the data lines (D+ and D-) and grounding them individually through a 15 kOhm resistor.