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USB 2.0 Hi-Speed Hub Controller
Datasheet
Revision 1.0 (3-11-09) 26 SMSC USB251x
DATASHEET
MISC
XTALIN ICLKx Crystal Input
24 MHz crystal
This pin connects to either one terminal of the crystal or to an external
24 MHz clock when a crystal is not used.
CLKIN External Clock Input
This pin connects to either one terminal of the crystal or to an external
24 MHz clock when a crystal is not used.
XTALOUT OCLKx Crystal Output
24 MHz Crystal
This is the other terminal of the crystal, or a no connect pin, when an external
clock source is used to drive XTALIN/CLKIN.
SUSP_IND /
LOCAL_PWR /
NON_REM[0]
I/O Active/Suspend status LED
Suspend Indicator: Indicates USB state of the hub.
‘negated’ = Unconfigured, or configured and in USB Suspend
‘asserted’ = the hub is configured, and is active (i.e., not in suspend)
Local Power: Detects availability of local self-power source.
Low = Self/local power source is NOT available (i.e., the hub gets all power
from Upstream USB VBus).
High = Self/local power source is available.
NON_REM[0] Strap Option:
If this strap is enabled by package and configuration settings (see Table 8.1,
"Hub Configuration Options"), this pin will be sampled (in conjunction with
NON_REM[1]) at RESET_N negation to determine if ports [x:1] contain
permanently attached (non-removable) devices. Also, the active state of the
LED will be determined as follows:
NON_REM[1:0] = ‘00’, All ports are removable, and the LED is active high
NON_REM[1:0] = ‘01’, Port 1 is non-removable, and the LED is active low
NON_REM[1:0] = ‘10’, Ports 1 & 2 are non-removable, and the LED is active
high
NON_REM[1:0] = ‘11’, When available, ports 1, 2 & 3 are non-removable, and
the LED is active low
TEST IPD TEST pin
User must treat as a no connect pin or connect to ground. No trace or signal
should be routed or attached to this pin.
Table 5.2 USB251x Pin Descriptions (continued)
SYMBOL
BUFFER
TYPE DESCRIPTION