USB ports are convenient for charging battery powered devices, but this can be slow on a standard USB downstream port (SDP), which only supplies a maximum of 500 mA @ 5V.
To meet the demands of high-current and battery-powered USB devices, the battery charging specification (BC v1.2 adopted in 2010) defines two types of charging ports: dedicated charging ports (DCP) and charging downstream ports (CDP). Mechanically, the USB charging ports use the same standard Type A USB connector. The only difference is the power available on the USB ports.
A DCP is used strictly for power, requires no host connection and offers no data transfer capabilities. This has resulted in the proliferation of USB chargers that provide a USB Type A connector. DCPs are also finding their way into cars, AC wall outlets and portable chargers.
A CDP on the other hand supports data transfers and can provide up to 1.5A to USB peripheral devices, which is three times the power available on a standard USB port. This opens up possibilities for USB-powered industrial sensors and devices that previously required a separate power supply.
Sealevels latest USB 2.0 4-port hubs support the BC v1.2 specification and provide a full 1.5A to each CDP port. This allows them to easily power or charge CDP compliant devices. Additionally, they can provide up to 1.5A of current to any USB peripheral that requires additional power.