USB 2.0 Hi-Speed Hub Controller

Datasheet

8.2.1.7Register 06h: CONFIG_BYTE_1

BIT

 

 

NUMBER

BIT NAME

DESCRIPTION

 

 

 

7

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 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 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.

 

 

This field is set by the OEM using either the SMBus or EEPROM interface

 

 

options.

 

 

Please see the description under dynamic power for the self-/bus- power

 

 

functionality when dynamic power switching is enabled.

 

 

'0' = Bus-powered operation

 

 

’1’ = Self-powered operation

 

 

If dynamic power switching is enabled, this bit is ignored and the

 

 

LOCAL_PWR pin is used to determine if the hub is operating from self or

 

 

bus power.

 

 

 

6

Reserved

Reserved

 

 

 

5

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).

 

 

'0' = Hi-/Full-speed

 

 

‘1’ = Full-speed-Only (Hi-speed disabled!)

 

 

 

4

MTT_ENABLE

Multi-TT enable: Enables one transaction translator per port operation.

 

 

(Not available on the USB2512A/12Ai.)

 

 

Selects between a mode where only one transaction translator is available

 

 

for all ports (Single-TT), or each port gets a dedicated transaction translator

 

 

(Multi-TT).

 

 

'0' = Single TT for all ports

 

 

‘1’ = One TT per port (when multiple TT's are supported)

 

 

 

3

EOP_DISABLE

EOP Disable: Disables EOP generation at 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 for additional details.

 

 

'0' = EOP generation is normal

 

 

‘1’ = EOP generation is disabled

 

 

 

Revision 1.0 (3-11-09)

38

SMSC USB251x

DATASHEET