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Ultra Fast USB 2.0 Multi-Format Flash Media Controller/USB Hub Combo
Revision 2.0 (10-03-08) 42 SMSC USB2640/USB2641
DATASHEET
7.3.3.25 ECh: Hub Controller Max Current For Self-Powered Operation
7.3.3.26 EDh: Hub Controller Max Current For Bus-Powered Operation
7.3.3.27 EEh: Power-On Time
BIT
NUMBER BYTE 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.
BIT
NUMBER BYTE NAME DESCRIPTION
7:0 HC_MAX_C_BP Hub Controller Max Current 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 will include the hub silicon along with the combined
power consumption (from VBUS) of all associated circuitry on the board.
This value will NOT include the power consumption of a permanently
attached peripheral if the hub is configured as a compound device.
A value of 50 (decimal) would indicate 100 mA, which is the default value.
BIT
NUMBER BYTE NAME DESCRIPTION
7:0 POWER_ON_TIME Power-On Time: The length of time that it takes (in 2 ms intervals) from the
time the host initiated power-on sequence begins on a port until power is
adequate on that port. System software uses this value to determine how
long to wait before accessing a powered-on port.