USB2642 datasheet(24/56 Pages) MICROCHIP

24 / 56 page

USB2642

DS00001578C-page 24

 2014-2015 Microchip Technology Inc.

7.4.2.7

9Ah: USB BmAttribute (1 byte)

7.4.2.8

9Bh: USB MaxPower (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 of upstream bus power)

or bus-powered (limited to a 100 mA maximum of upstream power prior to

being configured by the host controller).

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

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

powered Microchip hub (along with all associated hub circuitry, any embed-

ded devices if part of a compound device, and 100 mA per externally avail-

able downstream port) must consume no more than 500 mA of upstream

VBUS current. The current consumption is system dependent, and the OEM

must ensure that the USB 2.0 specifications are not violated.

When configured as a self-powered device, <1 mA of upstream VBUS current

is consumed and all ports are available, with each port being capable of

sourcing 500 mA of current.

= Bus-powered operation

= Self-powered operation

= Bus-powered operation with remote wake-up

= Self-powered operation with remote wake-up

Bit

Name

Description

7:0

USB_MAX_PWR

USB Max Power per USB Specification (References). Do NOT set this value

greater than 100 mA.

USB2642 Datasheet(PDF) 24 Page - Microchip Technology