POEPHYTEREV-E National Semiconductor, POEPHYTEREV-E Datasheet - Page 25

• Manufacturer Part Number: POEPHYTEREV-E
• Description: BOARD EVAL LM5072, DP83848I
• Manufacturer: National Semiconductor
• Series: PHYTER®r

Specifications of POEPHYTEREV-E

• Main Purpose: Special Purpose DC/DC, Power Over Ethernet
• Outputs And Type: 1, Isolated
• Power - Output: 24W
• Voltage - Output: 3.3V
• Current - Output: 7.3A
• Voltage - Input: 39 ~ 57V
• Regulator Topology: Flyback
• Frequency - Switching: 250kHz
• Board Type: Fully Populated
• Utilized Ic / Part: DP83848, LM5072
• Lead Free Status / RoHS Status: Not applicable / Not applicable

The code-group encoder converts 4-bit (4B) nibble data
generated by the MAC into 5-bit (5B) code-groups for
transmission. This conversion is required to allow control
data to be combined with packet data code-groups. Refer
to Table 5 for 4B to 5B code-group mapping details.
The code-group encoder substitutes the first 8-bits of the
MAC preamble with a J/K code-group pair (11000 10001)
upon transmission. The code-group encoder continues to
replace subsequent 4B preamble and data nibbles with
corresponding 5B code-groups. At the end of the transmit
packet, upon the deassertion of Transmit Enable signal
from the MAC, the code-group encoder injects the T/R
DATA CODES
IDLE AND CONTROL CODES
INVALID CODES
Note: Control code-groups I, J, K, T and R in data fields will be mapped as invalid codes, together with RX_ER as-
serted.
C
D
H
R
0
1
2
3
4
5
6
7
8
9
A
B
E
F
K
T
V
V
V
V
V
V
V
V
J
I
Table 5. 4B5B CCode-group Encoding and Injection
6.
11110
01001
10100
10101
01010
01011
01110
01111
10010
10011
10110
10111
11010
11011
11100
11101
00100
11111
11000
10001
01101
00111
00000
00001
00010
00011
00101
00110
01000
01100
25
code-group pair (01101 00111) indicating the end of the
frame.
After the T/R code-group pair, the code-group encoder
continuously injects IDLEs into the transmit data stream
until the next transmit packet is detected (reassertion of
Transmit Enable).
4.1.1 Scrambler
The scrambler is required to control the radiated emissions
at the media connector and on the twisted pair cable (for
HALT code-group - Error code
Inter-Packet IDLE - 0000 (
First Start of Packet - 0101 (
Second Start of Packet - 0101 (
First End of Packet - 0000 (
Second End of Packet - 0000 (
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
Note 1)
Note 1)
Note 1)
Note 1)
Note 1)
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