USB 2.0 Hi-Speed Hub Controller

Datasheet

Table 5.2 USB251x Pin Descriptions (continued)

 

BUFFER

 

SYMBOL

TYPE

DESCRIPTION

 

 

 

 

DOWNSTREAM USB 2.0 INTERFACES (continued)

 

 

 

LED_A_N[x:1] /

I/O12

Port LED Indicators

 

 

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

 

 

SMBus.

 

 

 

PRTSWP[x:1]

 

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] /

I/O12

Enhanced Indicator Port LED for Port 3

 

 

 

GANG_EN

 

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.

 

 

 

SMSC USB251x

23

Revision 1.0 (3-11-09)

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