USB2504/USB2504A

DS000002250A-page 12

 2007 - 2016 Microchip Technology Inc.

5.0

FUNCTIONAL BLOCK DESCRIPTION

5.1

4-Port Hub

Microchip’s USB 2.0 4-Port Hub is fully specification compliant to the Universal Serial Bus Specification Revision 2.0

April 27,2000 (12/7/2000 and 5/28/2002 Errata). Please reference Chapter 11 (Hub Specification) for general details

regarding Hub operation and functionality.

For performance reasons, the 4-Port Hub provides 1 Transaction Translator (TT) per port (defined as Multi-TT configu-

ration), divided into 4 non-periodic buffers per TT.

5.1.1

HUB CONFIGURATION OPTIONS

The Microchip Hub supports a large number of features (some are mutually exclusive), and must be configured in order

to correctly function when attached to a USB host controller. There are three principal ways to configure the hub: SMBus,

EEPROM, or by internal default settings (with or without pin strapping option over-rides). In all cases, the configuration

method will be determined by the CFG_SEL2, CFG_SEL1 and CFG_SEL0 pins immediately after RESET_N negation.

5.1.1.1

Vendor ID

Is a 16-bit value that uniquely identifies the Vendor of the user device (assigned by USB-Interface Forum). This field is

set by the OEM using either the SMBus or EEPROM interface options. When using the internal default option, Micro-

chip’s VID (see Table 5-1) will be reported.

5.1.1.2

Product ID

Is a 16-bit value that the Vendor can assign that uniquely identifies this particular product (assigned by OEM). This field

is set by the OEM using either the SMBus or EEPROM interface options. When using the internal default option, Micro-

chip’s PID designation of (see Table 5-1) will be reported.

5.1.1.3

Device ID

Is a 16-bit device release number in BCD format (assigned by OEM). This field is set by the OEM using either the SMBus

or EEPROM interface options. When using the internal default option, Microchip’s DID designation of (see Table 5-1)

will be reported.

5.1.1.4

Self-Powered/Bus-Powered

The Hub is either Self-Powered (draws less than 2mA of upstream bus power) or Bus-Powered (limited to a 100mA

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 100mA 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 100mA per externally available downstream port) must consume no more

than 500mA 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, <1mA of upstream VBUS current is consumed and all 7 ports are available,

with each port being capable of sourcing 500mA of current.

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

option, the SELF_PWR pin determines the Self-powered or Bus-powered status.

Please see the description under Dynamic Power for the self/bus power functionality when dynamic power switching is

enabled.

5.1.1.5

Port Indicators

Controls the use of LED indicator for Port status information. See Section 11.5.3 of the USB 2.0 Specification for addi-

tional details.

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

option, the LED_EN pin enables/disables LED Indicator support.

5.1.1.6

High-Speed Disable

Allows an OEM to force the Hub to configure as a Full-Speed device only (i.e. High-Speed not available).

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