Datasheet

USB 2.0 Hi-Speed Hub Controller
Datasheet
SMSC USB251xB/xBi 19 Revision 2.3 (06-11-13)
DATASHEET
SUSP_IND/ I/O Active/Suspend Status LED: indicates USB state of the hub.
Negated = unconfigured; or configured and in USB suspend
Asserted = hub is configured and is active (i.e., not in suspend)
LOCAL_PWR/ 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
the upstream USB VBus)
High = self/local power source is available
NON_REM0 Non-Removable 0 Strap Option: when enabled by package and configuration
settings (see Table 5.1 on page 24), 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:
Note: When implementing an external LED on this pin, the active state is
outlined below and detailed in Section 3.3.1.3, on page 21.
NON_REM[1:0] = 00 : all ports are removable; LED is active high
NON_REM[1:0] = 01 : port 1 is non-removable; LED is active low
NON_REM[1:0] = 10 : ports 1 and 2 are non-removable; LED is active high
NON_REM[1:0] = 11 : (when available) ports 1, 2, and 3 are non-removable;
LED is active low
TEST IPD Test Pin: treat as a no connect pin or connect to ground. No trace or signal
should be routed or attached to this pin.
POWER, GROUND, and NO CONNECTS
CRFILT VDD Core Regulator Filter Capacitor: this pin can have up to a 0.1 μF low-ESR
capacitor to VSS, or be left unconnected.
VDD33 3.3 V Power
PLLFILT PLL Regulator Filter Capacitor: this pin can have up to a 0.1 μF low-ESR
capacitor to VSS, or be left unconnected.
VSS Ground Pad/ePad: the package slug is the only VSS for the device and must be
tied to ground with multiple vias.
NC No Connect: no signal or trace should be routed or attached to all NC pins.
Table 3.2 USB251xB/xBi Pin Descriptions (continued)
SYMBOL
BUFFER
TYPE DESCRIPTION