Datasheet

USB 2.0 Hi-Speed Hub Controller
Datasheet
SMSC USB251xB/xBi 23 Revision 2.3 (06-11-13)
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 PRTPWR turned
on by the host system and the ports operate normally.
4.2 Battery Charging Configuration
The battery charging option can be configured in one of two ways:
 When the hub is brought up in the default configuration with strapping options enabled, with the
PRTPWR[x:1]/BC_EN[x:1] pins configured. See the following sections for details:
— Section 3.3:
Pin Descriptions (Grouped by Function) on page 17
— Section 3.3.1.2:
Internal Pull-Down (IPD) on page 20
 When the hub is initialized for configuration over I
2
C EEPROM or SMBus. Either of these interfaces
can be used to configure the battery charging option.
4.2.1 Battery Charging enabled via I
2
C 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, bit 2 represents port 2, etc. Each port with battery charging enabled
asserts the corresponding PRTPWR[x:1] pin.