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USB 2.0 Hi-Speed Hub Controller
Datasheet
Revision 1.0 (3-11-09) 42 SMSC USB251x
DATASHEET
8.2.1.13 Register 0Ch: Max Power For Self-Powered Operation
8.2.1.14 Register 0Dh: Max Power For Bus-Powered Operation
8.2.1.15 Register 0Eh: Hub Controller Max Current For Self-Powered Operation
BIT
NUMBER BIT NAME DESCRIPTION
7:0 MAX_PWR_SP Max Power Self_Powered: Value in 2 mA increments that the hub consumes
from an upstream port (VBUS) when operating as a self-powered hub. This
value includes the hub silicon along with the combined power consumption
(from VBUS) of all associated circuitry on the board. This value also includes
the power consumption of a permanently attached peripheral if the hub is
configured as a compound device, and the embedded peripheral reports 0
mA in its descriptors.
Note: The USB 2.0 specification does not permit this value to exceed 100
mA
BIT
NUMBER BIT NAME DESCRIPTION
7:0 MAX_PWR_BP Max Power Bus_Powered: Value in 2 mA increments that the hub consumes
from an upstream port (VBUS) when operating as a bus-powered hub. This
value includes the hub silicon along with the combined power consumption
(from VBUS) of all associated circuitry on the board. This value also includes
the power consumption of a permanently attached peripheral if the hub is
configured as a compound device, and the embedded peripheral reports 0
mA in its descriptors.
BIT
NUMBER BIT NAME DESCRIPTION
7:0 HC_MAX_C_SP Hub Controller Max Current Self-Powered: Value in 2 mA increments that the
hub consumes from an upstream port (VBUS) when operating as a self-
powered hub. This value includes the hub silicon along with the combined
power consumption (from VBUS) of all associated circuitry on the board.
This value does NOT include the power consumption of a permanently
attached peripheral if the hub is configured as a compound device.
Note: The USB 2.0 specification does not permit this value to exceed 100
mA
A value of 50 (decimal) indicates 100 mA, which is the default value.