High Speed Inter-Chip USB 2.0 Hub and Flash Media Controller

Datasheet

 

 

8.4.1.17

9Ah: USB BmAttribute (1 byte)

 

 

 

BIT

NAME

DESCRIPTION

 

 

 

7:0

USB_BM_ATT

Self- or Bus-Power: Selects between self- and bus-powered operation.

 

 

The hub is either self-powered (draws less than 2 mA) or bus-powered

 

 

(limited to 100 mA maximum power prior to being configured by the host

 

 

controller).

 

 

When configured as a bus-powered device, the SMSC hub consumes less

 

 

than 100 mA of current prior to being configured. After configuration, the bus-

 

 

powered SMSC hub (along with all associated hub circuitry, any embedded

 

 

devices if part of a compound device, and 100 mA per externally available

 

 

downstream port) must consume no more than 500 mA of current. The

 

 

current consumption is system dependent, and the OEM must ensure that

 

 

the USB 2.0 Specification is not violated.

 

 

When configured as a self-powered device, <1 mA of current is consumed

 

 

and all ports are available, with each port being capable of sourcing 500 mA

 

 

of current.

 

 

80 = Bus-powered operation (default)

 

 

C0 = Self-powered operation

 

 

A0 = Bus-powered operation with remote wake-up

 

 

E0 = Self-powered operation with remote wake-up

 

 

 

8.4.1.189Bh: USB MaxPower (1 byte)

BIT

NAME

DESCRIPTION

 

 

 

7:0

USB_MAX_PWR

USB Max Power per the USB 2.0 Specification. Do NOT set this value

 

 

greater than 100 mA.

 

 

 

SMSC USB4640/USB4640i

35

Revision 1.0 (06-01-09)

DATASHEET