Networking Silicon — GD82559ER
A 25 MHz crystal or a 25 MHz oscillator is used to drive the PHY unit’s X1 and X2 pins. The PHY unit derives its internal transmit digital clocks from this crystal or oscillator input. The internal Transmit Clock signal is a derivative of the 25 MHz internal clock. The accuracy of the external crystal or oscillator must be ± 0.0005% (50 PPM).
The transmit subsection of the PHY unit accepts
The 4B/5B encoder accepts
The 4B/5B encoder complies with the IEEE 802.3u
The table below illustrates the 4B/5B encoding scheme associated with the given symbol.
Symbol | 5B Symbol Code | 4B Nibble Code |
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0 | 11110 | 0000 |
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1 | 01001 | 0001 |
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2 | 10100 | 0010 |
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3 | 10101 | 0011 |
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4 | 01010 | 0100 |
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5 | 01011 | 0101 |
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6 | 01110 | 0110 |
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7 | 01111 | 0111 |
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8 | 10010 | 1000 |
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9 | 10011 | 1001 |
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A | 10110 | 1010 |
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B | 10111 | 1011 |
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C | 11010 | 1100 |
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D | 11011 | 1101 |
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Datasheet | 37 |