FLLXT1000BA.C4QE000 Intel, FLLXT1000BA.C4QE000 Datasheet - Page 48

• Manufacturer Part Number: FLLXT1000BA.C4QE000
• Manufacturer: Intel

Specifications of FLLXT1000BA.C4QE000

• Lead Free Status / RoHS Status: Not Compliant

LXT1000 — Gigabit Ethernet Transceiver
2.5.2.1
2.5.2.2
2.5.2.3
2.5.2.4
2.5.2.5
2.5.2.6
48
8B/10B Decoder
The 8B/10B is used only when the MAC interface is configured for TBI mode. In that case, it
converts 10B codes transmitted by the MAC into 8B (GMII) data. Note that only data codes are
decoded; non-data codes are ignored.
Scrambler
The scrambler randomizes the transmitted data. The purpose of scrambling is twofold:
The scrambler is driven by a 33-bit Linear Feedback Shift Register (LFSR), which is randomly
loaded at power-up. The LFSR function used by the Master differs from that used by the Slave,
giving each direction its own unique signature. The LFSR, in turn, generates twelve mutually
uncorrelated outputs. Eight of these are used to randomize the inputs to the 4DPAM5 and Trellis
encoders. The remaining four outputs randomize the sign of the 4DPAM5 outputs.
Transmit FIFO
The transmit FIFO re-synchronizes data transmitted by the MAC to the transmit reference used by
the LXT1000. The FIFO is large enough to support a frequency differential of up to +/- 1000 ppm
over a packet size of 10 KB (jumbo frame).
Transmit Phase-Locked Loop PLL
This function generates the 125 MHz timing reference used by the LXT1000 to transmit 4DPAM5
symbols. When the LXT1000 is the Master side of the link, the XI input is the reference for the
transmit PLL. When the LXT1000 is the Slave side of the link, the recovered receive clock is the
reference for the transmit PLL.
Trellis Encoder
The Trellis Encoder uses the two high-order bits of data and its previous output to generate a ninth
bit, which determines if the next 4DPAM5 pattern should be even or odd. For data, this function is:
Trellis
enhances the signal-to-noise (SNR) ratio by a factor of 6dB.
4DPAM5 Encoder
The 4DPAM5 encoder translates 8B codes transmitted by the MAC into 4DPAM5 symbols. The
encoder operates at 125 Mhz, which is both the frequency of the MAC interface and the baud rate
used by 1000BASE-T.
Each 8B code represents one of 2
five signal levels (-2,-1,0,1,2) on each of the four twisted-pair (A,B,C,D) representing 5
possible patterns per baud period. Of these, 113 patterns are reserved for control codes, leaving 512
patterns for data. These data patterns are divided into two groups of 256 even and 256 odd data
patterns. Thus, each 8B octet has two possible 4DPAM5 representations—one even and one odd
pattern.
•
•
Scrambling eliminates repeating data patterns, also known as “spectral lines” from the
4DPAM5 waveform in order to reduce EMI.
Each channel (A, B, C, D) has a unique signature that the receiver uses for identification.
n
= Data7
n-1
XOR Data6
n-2
8
XOR Trellis
or 256 data patterns. Each 4DPAM5 symbol consists of one of
n-3
This provides forward error correction and
Document #: 249276
Rev. Date: 07/20/01
Revision #: 002
Datasheet
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or 625