KS8993-EVAL Micrel Inc, KS8993-EVAL Datasheet - Page 32

• Manufacturer Part Number: KS8993-EVAL
• Description: BOARD EVAL EXPERIMENT FOR KS8993
• Manufacturer: Micrel Inc

Specifications of KS8993-EVAL

• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 576-1011

KS8993
MLT3 Coding
For 100BaseTX operation the NRZI (Non-Return to Zero Invert on ones) signal is line coded as MLT3. The net result of using
MLT3 is to reduce the EMI (Electro Magnetic Interference) of the signal over twisted pair media. In NRZI coding, the level
changes from high to low or low to high for every “1” bit. For a “0” bit there is no transition. MLT3 line coding transitions through
three distinct levels. For every transition of the NRZI signal the MLT3 signal either increments or decrements depending on
the current state of the signal. For instance if the MLT3 level is at its lowest point the next two NRZI transitions will change the
MLT3 signal initially to the middle level followed by the highest level (second NRZI transition). On the next NRZI change, the
MLT3 level will decrease to the middle level. On the following transition of the NRZI signal the MLT3 level will move to the lowest
level where the cycle repeats. The diagram below describes the level changes. Note that in the actual 100BaseTX circuit there
is a scrambling circuit and that scrambling is not shown in this diagram.
The MAC (Media Access Control) fields are described in the table below.
KS8993
Field
Preamble/SFD
DA
SA
802.1p tag
Length
Protocol/Data
Frame CRC
ESD
Idle
Octect Length
8
6
6
4
2
46 to 1500
4
1
Variable
Hex Value
Binary 4B
Binary 5B
NRZI
MLT3
NRZ
A
1010 0011 1000 1110 1001 0100 UUUU UUUU UUUU UUUU
10110101011001011100100110101001101001111111111111
3
Table 11. MAC Frame for 802.3
8
Figure 11. MLT3 coding
VLAN and priority tag (optional)
Frame Length
Higher Layer Protocol and Frame Data
Description
Preamble and Start of Frame Delimiter
48-bit Destination MAC Address
48-bit Source MAC Address
32-bit Cyclical Redundancy Check
End of Stream Delimiter
Inter Frame Idles
E
9
32
4
T3
R3
I1
I1
May 2005
Micrel