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DS000002250A-page 13

USB2504/USB2504A

5.1.1.7

Multiple-TT Support

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) {Note: The host may force Single-TT mode only}.

This field is set by the OEM using either the SMBus or EEPROM interface options. When using the internal default

option, the MTT_EN pin enables/disables MTT support.

5.1.1.8

EOP Disable

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.

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

5.1.1.9

Current Sensing

Selects current sensing on a port-by-port basis, all ports ganged, or none(only for bus-powered hubs)The ability to sup-

port current sensing on a port or ganged basis is hardware implementation dependent.

This field can be set by the OEM using either the SMBus or EEPROM interface options.When using the internal default

option, the SELF_PWR pin determines if current sensing will be ganged, or none (ganged if self-powered, none if bus-

powered).

5.1.1.10

Downstream Port Power Enabling

Enables all ports simultaneously (ganged), or port power is individually switched on and off on a port-by-port basis. The

ability to support power enabling on a port or ganged basis is hardware implementation dependent.

This field is set by the OEM using either the SMBus or EEPROM interface options. When using the internal default

option, the GANG_EN pin will configure the hub for ganged or individual port-by-port port power switching.

5.1.1.11

Compound Device

Allows the OEM to indicate that the Hub is part of a compound (see the USB Specification for definition) device. The

applicable port(s) must also be defined as having a “Non-Removable Device”.

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

Note: When configured via strapping options, declaring a port as non-removable automatically causes the hub controller

to report that it is part of a compound device.

5.1.1.12

Non-Removable Device

Informs the Host if one of the active ports has a permanent device that is undetachable from the Hub. (Note: The device

must provide its own descriptor data.)

This field is set by the OEM using either the SMBus or EEPROM interface options. When using the internal default

option, the NON_REM[1:0] pins will designate the appropriate ports as being non-removable.

5.1.1.13

Self-Powered Port DISABLE

During Self-Powered operation, this selects the ports which will be permanently disabled, and are not available to be

enabled or enumerated by a Host Controller. The disabled ports must be contiguous, and must be in decreasing order

starting with port 4.

This field is set by the OEM using either the SMBus or EEPROM interface options. When using the internal default

option, the PRT_DIS[1:0] pins will disable the appropriate ports.

5.1.1.14

Bus-Powered Port DISABLE

During Bus-Powered operation, this selects the ports which will be permanently disabled, and are not available to be

enabled or enumerated by a Host Controller. The disabled ports must be contiguous, and must be in decreasing order

starting with port 4.

This field is set by the OEM using either the SMBus or EEPROM interface options. When using the internal default

option, the PRT_DIS[1:0] pins will disable the appropriate ports.