
Datasheet
Table 4.4 - Biasing and Clock Oscillator Signals
NAME | BUFFER | ACTIVE |
| DESCRIPTION |
TYPE | LEVEL |
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RBIAS | N/A | External 1% bias resistor. Requires a 12KΩ resistor to ground. Used for | ||
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| setting HS transmit current level and | |
XTAL1/CLKIN | ICLKx | N/A | External crystal. 24MHz crystal or external clock input when a crystal is not | |
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| used. | |
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| Connect a 5M ohm resistor from this pin to XTAL2 when a crystal is used. | |
XTAL2 | OCLKx | N/A | External crystal. 24MHz crystal. Not connected when using an external clock. | |
CLKIN_EN | I | High | Clock Input Enable. When high, an external CMOS clock drives XTAL1. | |
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| Table 4.5 - Power and Ground Signals | |
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NAME | BUFFER | ACTIVE |
| DESCRIPTION |
TYPE | LEVEL |
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VDD3.3 | N/A | N/A | 3.3V | Digital Supply. Powers digital pads. |
VDD1.8 | N/A | N/A | 1.8V | Digital Supply. Powers digital core. |
VSS | N/A | N/A | Signal Ground. | |
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. |
4.2Buffer Type Descriptions
Table 4.6 – USB20H04 Buffer Type Descriptions
BUFFER | DESCRIPTION |
I | Input |
IPU | Input with weak internal |
IPD | Input with weak internal |
IS | Input with Schmitt trigger |
IO8 | Input/Output with 8mA drive |
IOSD12 | Open drain with 12mA sink with Schmitt |
| trigger. Meets |
O8 | Output with 8mA drive |
OD8 | Open drain with 8mA sink |
ICLKx | XTAL clock input |
OCLKx | XTAL clock output |
Defined in USB specification | |
AO | Analog Output |
3.3V Tolerant Analog Pin |
SMSC USB20H04 | Page 11 | Revision 1.63 |
DATASHEET