TLK2208B Datasheet, PDF (22/40 Pages) Texas Instruments – 8-PORT GIGABIT ETHERNET TRANCSEIVER

TLK2208B
8ĆPORT GIGABIT ETHERNET TRANSCEIVER
SLLS578D − AUGUST 2003 − REVISED SEPTEMBER 2006
receive logic (continued)
RBCG
RCLK/RBCH
RDxx[9:0]
CH[G,E,C,A]
CH[H,F,D,B]
NOTE: RX timing is always source centered.
Figure 6. Multiplexed Channel Receive Timing
In the nibble interface channel mode, channels B, D, F, and H are output on the high-order nibble RDxx[9:5],
while channels A, C, E, G are output on the low-order nibble RDxx[4:0] as shown in Figure 7.
In the nibble interface channel mode, parallel data to be transferred to the protocol device on channel A
(RDBA[4:0]) is output referenced to both the rising and falling edges of RBCA, and channel B (RDBA[9:5]) is
output referenced to both the rising and falling edges of RBCB. Channels C through H are output the same way
with their respective clocks.
RCLK/RBCH, RBCx
RDxx[4:0]
CH[A,C,E,G]
Least-Significant
Nibble
CH[A,C,E,G]
Most-Significant
Nibble
RDxx[9:5]
CH[B,D,F,H]
Least-Significant
Nibble
CH[B,D,F,H]
Most-Significant
Nibble
NOTE: RX timing is always source centered.
Figure 7. Nibble Mode Receive Timing
clock recovery
A baud-rate clock is extracted from the 10-bit encoded serial data stream independently on each channel. The
receive clock locks to the input within 2 µs after a valid input data stream is applied. The received data is
deserialized and byte aligned. In the absence of input data, the clock recovery circuit locks onto the reference
clock frequency REFCLK.
deserializer
For each channel, serial data is received on the RXx+/RXx– terminals. The interpolator and clock recovery
circuit locks to the data stream if the clock to be recovered is within ±100 ppm of the internally generated bit-rate
clock. The recovered clock is used to retime the input data stream. The serial data is then clocked into the
serial-to-parallel shift registers. If enabled, the 10-bit-wide parallel data is then fed into 8b/10b decoders. The
parallel data for each channel is fed into a FIFO buffer where the output is synchronized to REFCLK.
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