![](/images/backgrounds/136088/136088-16965x1.png)
Datasheet
TX_CLK 100M
PLL
MAC
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| 4B/5B |
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| Scrambler |
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| Internal |
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| MII |
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| 25MHz |
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| 25MHz by |
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| MII 25 MHz by 4 bits |
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| by 4 bits |
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| Encoder |
| 5 bits |
| and PISO |
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| 125 Mbps Serial |
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| NRZI |
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| Tx |
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| Magnetics |
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| NRZI |
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| Converter |
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| Converter |
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| Driver |
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RJ45
Figure 3.25 100BASE-TX Data Path
3.6.1The data path of the
3.6.1.14B/5B Encoding
The transmit data passes from the MII block to the 4B/5B encoder. This block encodes the data from
The first 16
The encoding process may be bypassed by clearing bit 6 of register 31. When the encoding is bypassed, the 5th transmit data bit is equivalent to TX_ER.
Table 3.21 4B/5B Code Table
CODE |
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| RECEIVER |
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| TRANSMITTER |
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GROUP | SYM |
| INTERPRETATION |
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| INTERPRETATION |
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11110 | 0 | 0 |
| 0000 |
| DATA | 0 |
| 0000 |
| DATA |
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01001 | 1 | 1 |
| 0001 |
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| 1 |
| 0001 |
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10100 | 2 | 2 |
| 0010 |
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| 2 |
| 0010 |
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10101 | 3 | 3 |
| 0011 |
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| 3 |
| 0011 |
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01010 | 4 | 4 |
| 0100 |
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| 4 |
| 0100 |
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01011 | 5 | 5 |
| 0101 |
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| 5 |
| 0101 |
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01110 | 6 | 6 |
| 0110 |
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| 6 |
| 0110 |
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01111 | 7 | 7 |
| 0111 |
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| 7 |
| 0111 |
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SMSC LAN9420/LAN9420i | 65 | Revision 1.22 |
| DATASHEET |
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