TLK3104SA_09 Datasheet, PDF (12/43 Pages) Texas Instruments – QUAD 3.125 Dbps SERIAL TRANSCEIVER

TLK3104SA
QUAD 3.125 Gbps SERIAL TRANSCEIVER
SCAS651B-− AUGUST 2000 − REVISED SEPTEMBER 2001
8-B/10-B encoder (continued)
Table 4. Transmit Data Controls
TDx[7:0]
XX
BC
F7
3C
1C
FB
FD
FE
FC
7C
TDx8
(KGENx)
0
1
1
1
1
1
1
1
1
1
K CODE
TRANSMITTED
X
K28.5
K23.7
K28.1
K28.0
K27.7
K29.7
K30.7
K28.7
K28.3
DESCRIPTION
Normal data transmission
IdleE/not-busy
IdleO/not-busy
IdleE/busy
IdleO/busy
SOP(S)
EOP(T)
Error propagation
Code violation or parity error
Channel alignment precursor
comma detect and 8-B/10-B decoding
When parallel data is clocked into a parallel to serial converter, the byte boundary that was associated with the
parallel data is lost in the serialization of the data. When the serial data is received and converted to parallel
format again, a method is needed to be able to recognize the byte boundary again. Generally this is
accomplished through the use of a synchronization pattern. This is a unique a pattern of 1s and 0s that either
cannot occur as part of valid data or is a pattern that repeats at defined intervals. 8-B/10-B encoding contains
a character called the comma (b’0011111’) which is used by the comma detect circuit to align the received serial
data back to its original byte boundary. The decoder detects the K28.5 comma, generating a synchronization
signal aligning the data to their 10-bit boundaries for decoding. It then converts the data back into 8-bit data.
It is important to note that the comma can be either a (b’0011111’) or the inverse (b’1100000’) depending on the
running disparity. The TLK3104SA decoder detects only the (b’0011111’) pattern. Therefore, since
synchronization is achieved on the positive comma, two consecutive K-codes containing commas are required
to assure byte boundary synchronization (see Table 6 for K-codes containing positive commas). Comma detect
is not active in PRBS mode.
The reception of K-characters is reported by the assertion of RDx8(KFLAG) on each channel. When a code
word error or running disparity error is detected in the decoded data on a channel, RDx9(ERROR DETECT)
and KFLAG is asserted and all 1s (0xFF) are placed on the receive data bus for that channel. When a loss of
signal (LOS) is detected on the differential receive inputs, ERROR DETECT is low, KFLAG is asserted, and 1s
(0xFF) is placed on the receive data bus for that channel, as shown in Table 5. The LOS signal can be disabled
using MDIO (see Table 15).
Table 5. Receive Data Controls
EVENT
Normal data
Normal K-character
Loss of signal (LOS)
Code word error or running disparity error
† _{Does not comply with P802.3ae D2.0.}
RECEIVE DATA BUS
(RDx[7−0])
XX
Valid K-code (see Table 6)
0xFF
0xFF†
KFLAG
(RDx8)
Low
High
High
High
ERROR DETECT
(RDx9)
Low
Low
Low
High
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