lan9420 Standard Microsystems Corp., lan9420 Datasheet - Page 66

• Manufacturer Part Number: lan9420
• Description: Lan9420/lan9420i Single-chip Ethernet Controller With Hp Auto-mdix Support And Pci Interface
• Manufacturer: Standard Microsystems Corp.

Revision 1.1 (03-31-08)
3.6.1.2
GROUP
CODE
10010
10011
10110
11010
11000
10001
01101
00100
00110
11001
00000
00001
00010
00011
00101
01000
01100
10000
10111
11011
11100
11101
00111
01111
11111
Scrambling
Repeated data patterns (especially the IDLE code-group) can have power spectral densities with large
narrow-band peaks. Scrambling the data helps eliminate these peaks and spread the signal power
more uniformly over the entire channel bandwidth. This uniform spectral density is required by FCC
regulations to prevent excessive EMI from being radiated by the physical wiring.
SYM
A
B
C
D
E
R
H
V
V
V
7
8
9
F
K
T
V
V
V
V
V
V
V
J
I
IDLE
First nibble of SSD, translated to “0101”
following IDLE, else RX_ER
Second nibble of SSD, translated to
“0101” following J, else RX_ER
First nibble of ESD, causes de-assertion
of CRS if followed by /R/, else assertion
of RX_ER
Second nibble of ESD, causes de-
assertion of CRS if following /T/, else
assertion of RX_ER
Transmit Error Symbol
INVALID, RX_ER if during RX_DV
INVALID, RX_ER if during RX_DV
INVALID, RX_ER if during RX_DV
INVALID, RX_ER if during RX_DV
INVALID, RX_ER if during RX_DV
INVALID, RX_ER if during RX_DV
INVALID, RX_ER if during RX_DV
INVALID, RX_ER if during RX_DV
INVALID, RX_ER if during RX_DV
INVALID, RX_ER if during RX_DV
A
B
C
D
E
7
8
9
F
Table 3.21 4B/5B Code Table (continued)
INTERPRETATION
RECEIVER
Single-Chip Ethernet Controller with HP Auto-MDIX Support and PCI Interface
1000
1001
1010
1011
1100
1101
0111
1110
1111
DATASHEET
66
Sent after /T/R until TX_EN
Sent for rising TX_EN
Sent for rising TX_EN
Sent for falling TX_EN
Sent for falling TX_EN
Sent for rising TX_ER
INVALID
INVALID
INVALID
INVALID
INVALID
INVALID
INVALID
INVALID
INVALID
INVALID
A
B
C
D
E
7
8
9
F
INTERPRETATION
TRANSMITTER
1000
1001
1010
0111
1011
1100
1101
1110
1111
SMSC LAN9420/LAN9420i
Datasheet