The USB Implementers Forum (USB-IF) has presented their new Battery Charging Revision 1.0 specification. Consumers currently use USB to charge batteries on their peripheral devices. With the announcement of the new Battery Charging specification, the USB-IF Battery Charging Workgroup has defined a standard way for portable devices to draw current from wall chargers or PCs. In addition, the Battery Charging specification allows PCs and hubs to provide increased levels of current, in order to shorten the charging time of connected portable devices.
“The USB-IF has responded to the growing trend among mobile devices to utilize USB for charging capabilities,” said Jeff Ravencraft, USB-IF president. “The Battery Charging specification allows multiple types of portable devices to charge from USB ports or from a standards charger, thus eliminating the need to carry multiple chargers for different kinds of devices.”
One of the issues addressed with the Battery Charging specification is defining a mechanism for portable devices to detect whether they are attached to a wall charger, high current host or hub, or to a regular host or hub. When connected to a wall charger or high current host or hub, portable devices are allowed to immediately draw currents in excess of 500mA. When connected to a PC or hub, portable devices are required to limit their current to 2.5mA, 100mA or 500mA, as required by the USB 2.0 specification.
The Battery Charging Workgroup has also defined a Dead Battery Provision in the new specification, which allows portable devices with dead batteries to draw 100 milliamp (mA) minutes or hours before connecting. This permits portable devices with dead batteries to be able to charge from a host, even if they are not able to power up.