USB2642 datasheet(29/56 Pages) MICROCHIP

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 2014-2015 Microchip Technology Inc.

DS00001578C-page 29

USB2642

7.4.3.14

E4h: Configuration Data Byte 1 (CFG_DAT_BYT1)

Bit

Name

Description

SELF_BUS_PWR

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

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

available 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

rsvd

HS_DISABLE

Hi-Speed Disable: Disables the capability to attach as either a Hi-/Full-Speed

device, and forces attachment as Full-Speed only (i.e., no Hi-Speed support).

: Hi-/Full-Speed

: Full-Speed-Only (Hi-Speed disabled!)

rsvd

EOP_DISABLE

EOP Disable: Disables EOP generation of EOF1 when in Full-Speed mode.

During FS operation only, this permits the hub to send EOP if no

downstream traffic is detected at EOF1. See Section 11.3.1 of the USB 2.0

Specification (References) for additional details.

: An EOP is generated at the EOF1 point if no traffic is detected.

: EOP generation at EOF1 is disabled (normal USB operation).

Generation of an EOP at the EOF1 point may prevent a host controller

(operating in FS mode) from placing the USB bus in suspend.

2:1

CURRENT_SNS

Over-Current Sense: Selects current sensing on a port-by-port basis, all

ports ganged, or none (only for bus-powered hubs). The ability to support

current sensing on a per port or ganged basis is dependent upon the

hardware implementation.

: ganged sensing (all ports together)

: individual (port-by-port)

: over-current sensing is not supported (must only be used with bus-

powered configurations)

PORT_PWR

Port Power Switching: Enables power switching on all ports simultaneously

(ganged), or port power is individually switched on and off on a port-by-port

basis (individual). The ability to support power enabling on a port or ganged

basis is dependent upon the hardware implementation.

: ganged switching (all ports together)

: individual port-by-port switching

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