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2-Port USB 2.0 Hub Controller
Datasheet
Revision 2.3 (08-27-07) 12 SMSC USB2502
DATASHEET
2-PORT USB 2.0 HUB INTERFACE
High-Speed USB
Data
USBDN[2:1]
USBDP[2:1]
IO-U These pins connect to the downstream USB peripheral
devices attached to the Hub’s ports.
USB Power
Enable
PRTPWR O8 Enables power to USB peripheral devices (downstream).
The active signal level of the PRTPWR pin is determined by
the Power Polarity Strapping function of the PRTPWR_POL
pin.
Port [2:1] Green
LED
&
Port Non-
Removable
strapping option.
GR[2:1]/
NON_REM[1:0]
I/O8 Green indicator LED for ports 2 and 1. Will be active low
when LED support is enabled via EEPROM or SMBus.
If the hub is configured by the internal default configuration,
these pins will be sampled at the rising edge of RESET_N
(see the applicable RESET_N timing table in Section 5.6.1)
to determine if ports [2:1] contain permanently attached
(non-removable) devices. Also, the active state of the LED’s
will be determined as follows:
NON_REM[1:0] = ‘00’, All ports are removable,
GR2 is active high,
GR1 is active high.
NON_REM1:0] = ‘01’, Port 1 is non-removable,
GR2 is active high,
GR1 is active low.
NON_REM[1:0] = ‘10’, Ports 1 & 2 are non-removable,
GR2 is active low,
GR1 is active high.
NON_REM[1:0] = ‘11’, Ports 1 & 2 are non-removable,
GR2 is active low,
GR1 is active low.
Port Power
Polarity strapping.
PRTPWR_POL I/O8 Port Power Polarity strapping determination for the active
signal polarity of the PRTPWR pin.
While RESET_N is asserted, the logic state of this pin will
(though the use of internal combinatorial logic) determine
the active state of the PRTPWR pin in order to ensure that
downstream port power is not inadvertently enabled to
inactive ports during a hardware reset.
On the rising edge of RESET_N (see the applicable
RESET_N timing table in Section 5.6.1), the logic value will
be latched internally, and will retain the active signal polarity
for the PRTPWR pin.
‘1’ = PRTPWR pin has an active ‘high’ polarity
‘0’ = PRTPWR pin has an active ‘low’ polarity
Over Current
Sense
OCS_N IPU Input from external current monitor indicating an over-
current condition. {Note: Contains internal pull-up to 3.3V
supply}
USB Transceiver
Bias
RBIAS I-R A 12.0kΩ (+/− 1%) resistor is attached from ground to this
pin to set the transceiver’s internal bias settings.
Table 4.1 2-Port Hub Pin Descriptions (continued)
NAME SYMBOL TYPE FUNCTION