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| Table 3 USB I/O Pins | ||
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| ACTIVE |
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NAME | DIRECTION | LEVEL |
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| DESCRIPTION |
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DP | I/O | N/A |
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| USB Positive Data Pin. |
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DM | I/O | N/A |
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| USB Negative Data Pin. |
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| Table 4 Biasing and Clock Oscillator Pins | |||
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| ACTIVE |
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NAME | DIRECTION | LEVEL |
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| DESCRIPTION |
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RBIAS | Input | N/A |
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| External 1% bias resistor. Requires a 12KΩ resistor to ground. |
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| Used for setting HS transmit current level and |
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| impedance. |
XI/XO | Input | N/A |
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| External crystal. 12MHz crystal connected from XI to XO. |
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| Table 5 Power and Ground Pins | |||
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| ACTIVE |
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NAME | DIRECTION | LEVEL |
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| DESCRIPTION |
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VDD3.3 | N/A | N/A |
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| 3.3V Digital Supply. Powers digital pads. See Note 2.1 |
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VDD1.8 | N/A | N/A |
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| 1.8V Digital Supply. Powers digital core. |
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VSS | N/A | N/A |
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| Digital Ground. See Note 2.2 |
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VDDA3.3 | N/A | N/A |
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| 3.3V Analog Supply. Powers analog I/O and 3.3V analog |
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| circuitry. |
VDDA1.8 | N/A | N/A |
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| 1.8V Analog Supply. Powers 1.8V analog circuitry. See Note 2.1 |
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VSSA | N/A | N/A |
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| Analog Ground. See Note 2.2 |
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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.
SMSC USB3250 | PRODUCT7 PREVIEW | Revision 1.7 |