TLK6002 Datasheet, PDF (31/96 Pages) Texas Instruments – Dual Channel 0.47Gbps to 6.25Gbps Multi-Rate Transceiver

TLK6002
www.ti.com
SLLSE34 – MAY 2010
In full rate mode, the latency measurement function runs off of an internal clock which is equal to the
frequency of the transmit serial bit rate divided by four. In half rate mode, the latency measurement
function runs off of an internal clock which is equal to the serial bit rate divided by two. In quarter rate
mode, the latency measurement function runs off of an internal clock which is equal to the serial bit rate.
In eighth rate mode, the latency measurement function runs off of a clock which is equal to twice the serial
bit rate. The latency measurement accuracy in all cases is equal to plus or minus one latency
measurement clock period. The measurement clock can be divided down if a longer duration
measurement is required, in which case the accuracy of the measurement is accordingly reduced. The
high speed latency measurement clock is divided by either 1, 2, 4, or 8 via register 16.5:4. The
measurement clock used is always selected by the channel under test. The high speed latency
measurement clock may only be used when operating at one of the eight serial rates specified in the
CPRI/OBSAI specifications. It is also possible to run the latency measurement function off of the
recovered byte clock for the channel under test (and gives a latency measurement clock frequency equal
to the serial bit rate divided by 10) via register bit 16.2 (where the 16.5:4 divider value setting is ignored).
The accuracy for the standard based CPRI/OBSAI application rates is shown in Table 2-6, and assumes
the latency measurement clock is not divided down per user selection (division is required to measure a
duration greater than 682 µs). For each division of 2 in the measurement clock, the accuracy is also
reduced by a factor of two.
Table 2-6. CPRI/OBSAI Latency Measurement Function Accuracy
(Undivided Measurement Clock)
Gbps
0.6144
0.768
1.2288
1.536
2.4576
3.072
4.9152
6.144
Rate
Eighth
Eighth
Quarter
Quarter
Half
Half
Full
Full
Clock Frequency
(GHz)
1.2288
1.536
1.2288
1.536
1.2288
1.536
1.2288
1.536
Accuracy
(± ns)
0.8138
0.6510
0.8138
0.6510
0.8138
0.6510
0.8138
0.6510
Copyright © 2010, Texas Instruments Incorporated
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