USB 2.0 Hi-Speed Hub Controller
Datasheet
Table 5.2 USB251x Pin Descriptions (continued)
DESCRIPTION
BUFFER
TYPE
SYMBOL
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.
Port Swap Strapping Option
PRTSWP[x:1]
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.
Enhanced Indicator Port LED for ports 4-7
LED_B_N[7:4]
I/O12
I/O12
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
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.
SMSC USB251x
23
Revision 1.0 (3-11-09)
DATASHEET
SMSC [ SMSC CORPORATION ]
