USB2512 datasheet(26/63 Pages) MICROCHIP

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USB 2.0 Hi-Speed Hub Controller

Datasheet

Revision 2.2 (02-17-12)

SMSC USB251xB/xBi

DATASHEET

Chapter 5 Initial Interface/Configuration Options

The hub must be configured in order to correctly function when attached to a USB host controller. The

hub can be configured either internally or externally by setting the CFG_SEL[1:0] pins (immediately

after RESET_N negation) as outlined in the table below.

Note:

See Chapter 11 (Hub Specification) of the USB specification for general details regarding hub

operation and functionality.

To configure the hub externally, there are two principal ways to interface to the hub: over SMBus or

I2C EEPROM. The hub can be configured internally, where several default configurations are available

as described in the table below. When configured internally, additional configuration is available using

the strap options (listed in Section 3.3.1 on page 22).

Note:

Strap options are not available when configuring the hub over I2C or SMBus.

Table 5.1 Initial Interface/Configuration Options

CFG_SEL[1]

CFG_SEL[0]

DESCRIPTION

Default configuration:

Strap options enabled

Self-powered operation enabled

Individual power switching

Individual over-current sensing

The hub is configured externally over SMBus (as an SMBus slave

device):

Strap options disabled

All registers configured over SMBus

Default configuration with the following overrides:

Bus-powered operation

The hub is configured over 2-wire I2C EEPROM:

Strap options disabled

All registers configured by I2C EEPROM

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