SMSC USB3250 - Manual (Page 7)

Hi-Speed USB Device Transceiver with UTMI Interface
SMSC USB3250 7 Revision 1.7 (05-11-07)
PRODUCT PREVIEW
Note 2.1 A Ferrite Bead (with DC resistance <.5 Ohms) is recommended for filtering between both
the VDD3.3 and VDDA3.3 supplies and the VDD1.8 and VDDA1.8 Supplies.
Note 2.2 All VSS and VSSA are bonded to the exposed pad under the IC in the package. The
exposed pad must be connected to solid GND plane on printed circuit board.
Table 3 USB I/O Pins
NAME DIRECTION
ACTIVE
LEVEL DESCRIPTION
DP I/O N/A USB Positive Data Pin.
DM I/O N/A USB Negative Data Pin.
Table 4 Biasing and Clock Oscillator Pins
NAME DIRECTION
ACTIVE
LEVEL DESCRIPTION
RBIAS Input N/A External 1% bias resistor. Requires a 12K Ω resistor to ground.
Used for setting HS transmit current level and on-chip termination
impedance.
XI/XO Input N/A External crystal. 12MHz crystal connected from XI to XO.
Table 5 Power and Ground Pins
NAME DIRECTION
ACTIVE
LEVEL DESCRIPTION
VDD3.3 N/A N/A 3.3V Digital Supply. Powers digital pads. See Note 2.1
VDD1.8 N/A N/A 1.8V Digital Supply. Powers digital core.
VSS N/A N/A Digital Ground. See Note 2.2
VDDA3.3 N/A N/A 3.3V Analog Supply. Powers analog I/O and 3.3V analog
circuitry.
VDDA1.8 N/A N/A 1.8V Analog Supply. Powers 1.8V analog circuitry. See Note 2.1
VSSA N/A N/A Analog Ground. See Note 2.2