TLK2711-SP Datasheet, PDF (6/21 Pages) Texas Instruments – 1.6-Gbps to 2.5-Gbps Class V Transceiver

TLK2711-SP
SGLS307D – JULY 2006 – REVISED JULY 2009 .............................................................................................................................................................. www.ti.com
TXCLK
TXD0−TXD15
t_su
t_h
TKLSB, TKMSB
Figure 2. Transmit Timing Waveform
Data Transmission Latency
The data transmission latency of the TLK2711 is defined as the delay from the initial 16-bit word load to the
serial transmission of bit 0. The transmit latency is fixed once the link is established. However, due to silicon
process variations and implementation variables such as supply voltage and temperature, the exact delay varies
slightly. The minimum transmit latency t_{d(Tx latency)} is 34 bit times; the maximum is 38 bit times. Figure 3 shows the
timing relationship between the transmit data bus, the TXCLK, and the serial transmit terminals.
Transmitted 20-Bit Word
TXP,
TXN
TXD0−TXD15
t_{d(Tx latency)}
16-Bit Word to Transmit
TXCLK
Figure 3. Transmitter Latency
8-Bit/10-Bit Encoder
All true serial interfaces require a method of encoding to ensure minimum transition density, so that the receiving
phase-locked loop (PLL) has a minimal number of transitions to stay locked on. The encoding scheme maintains
the signal dc balance by keeping the number of ones and zeros the same. This provides good transition density
for clock recovery and improves error checking. The TLK2711 uses the 8-bit/10-bit encoding algorithm that is
used by fibre channel and gigabit ethernet. This is transparent to the user, as the TLK2711 internally encodes
and decodes the data such that the user reads and writes actual 16-bit data.
The 8-bit/10-bit encoder converts 8-bit-wide data to a 10-bit-wide encoded data character to improve its
transmission characteristics. Since the TLK2711 is a 16-bit-wide interface, the data is split into two 8-bit-wide
bytes for encoding. Each byte is fed into a separate encoder. The encoding is dependent upon two additional
input signals, TKMSB and TKLSB.
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