TLK6002 datasheet(23/96 Pages) TI

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TXCLK _A

TDA_ [19:0]

Data

SourceCentered (DDR)

Source Aligned (DDR)

Data

FallingEdge Aligned (RisingEdgeSampled )(SDR)

RisingEdge Aligned (FallingEdgeSampled )(SDR)

TDA_ [19:0]

TDA_[19:0]

TDA_ [19:0]

tSETUP

tHOLD

tSETUP

tHOLD

Data

TLK6002

www.ti.com

SLLSE34 – MAY 2010

Figure 2-5. Transmit Interface Timing (Channel A is shown).

2.9

Scrambler and De-scrambler

TLK6002 incorporates a scrambling function located before the 8b/10b encoder in the transmit datapath,

and a de-scrambling function located after the 8b/10b decoder in the receive datapath. The scrambler and

de-scrambler can be enabled/disabled using the MDIO management serial interface.

The transmitter applies a 7-degree polynomial to data bytes (not control), and the inverse operation is

performed by the receiver.

The scrambler/descrambler should be disabled if the 8b/10b encoder/decoder is disabled.

To achieve randomness between transmitting lanes, transmitters can be programmed to have differing

scrambling offset. Each transmitter seed value is programmed into a register which will be used by that

transmitter. The user should program unique seed values for adjacent TX links.

The receivers also have their own de-scrambling seed value registers. The receiver’s de-scrambling seed

value must be programmed to be the same as the corresponding transmitting end of the link. There is no

training sequence for transmitting the seed values to the receiver.

The scrambler is a 7-degree polynomial, linear feedback shift register (LFSR). The polynomial is; (X7 + X6

+ 1). K28.1, K28.5, or K28.7 characters reset the LFSR to the seed value. The bit pattern repeats every

127 bits.

Description

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