USB2512 datasheet(23/72 Pages) SMSC

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USB 2.0 Hi-Speed Hub Controller

Datasheet

SMSC USB251x

Revision 1.0 (3-11-09)

DATASHEET

DOWNSTREAM USB 2.0 INTERFACES (continued)

LED_A_N[x:1] /

PRTSWP[x:1]

I/O12

Port LED Indicators

This pin will be active low when LED support is enabled via EEPROM or

SMBus.

Port Swap Strapping Option

If this strap is enabled by package and configuration settings (see Table 8.1,

"Hub Configuration Options"), this pin will be sampled at RESET_N negation

to determine the electrical connection polarity of the downstream USB port

pins (USB_DP and USB_DM).

Also, the active state of the LED will be determined as follows:

‘0’ = Port polarity is normal, LED is active high.

‘1’ = Port polarity (USB_DP and USB_DM) is swapped, LED is active low.

LED_B_N[7:4]

I/O12

Enhanced Indicator Port LED for ports 4-7

Enhanced indicator LED for ports 4-7. This pin will be active low when LED

support is enabled via EEPROM or SMBus.

LED_B_N[3] /

GANG_EN

I/O12

Enhanced Indicator Port LED for Port 3

Ganged Power and Over-current strap option

This signal selects between ganged or individual port power and over-current

sensing. If this strap is enabled by package and configuration settings (see

Table 8.1, "Hub Configuration Options"), this pin will be sampled at RESET_N

negation to determine the mode as follows:

‘0’ = Individual sensing and switching, LED_B_N[3] is active high.

‘1’ = Ganged sensing and switching, LED_B_N[3] is active low.

Table 5.2 USB251x Pin Descriptions (continued)

SYMBOL

BUFFER

TYPE

DESCRIPTION

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