USB 2.0 Hi-Speed Hub Controller
Datasheet
behaviors provide battery charging even when the hub is not enumerated and protect the hub from
sustained short circuit conditions. If the short circuit condition persists when the hub is plugged into a
host system the user is notified that a port has an over-current condition. Otherwise the PRTPWR is
turned on by the host system and the port operates normally.
7.3
Battery Charging Configuration
Configuration of ports to support battery charging is done through a strap option on the corresponding
ports PRTPWR[x] / BC_EN[x] pin. see Chapter 5, Pin Descriptions, or through EEPROM or SMBus
configuration load.
7.3.1
Battery Charging enabled via EEPROM or SMBus
Register memory map location 0xD0 is allocated for battery charging support. The "Battery Charging"
register at location 0xD0 starting from Bit 1 enables battery charging for each downstream port when
asserted. Bit 1 represents port 1 and so on. Each port with battery charging enabled asserts the
corresponding PRTPWR[x:0] pin.
Revision 1.0 (3-11-09)
32
SMSC USB251x
DATASHEET
SMSC [ SMSC CORPORATION ]
