Xilinx Virtex-5 RocketIO GTP, User Manual

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206 www.xilinx.com Virtex-5 RocketIO GTP Transceiver User Guide
UG196 (v1.3) May 25, 2007
Chapter 10: GTP-to-Board Interface
R
When overriding the control value based on the calibration to an external precision
reference resistor, the process independence is lost. As a consequence, the termination
value has a tolerance of ± 25% given by the resistor tolerance of the semiconductor process.
Table 10-3 shows the encoding of the TERMINATION_CTRL attribute.
Table 10-3: TERMINATION_CTRL Attribute Encoding
TERMINATION_CTRL [4:0]
Nominal
Resistance [
Ω
]
+25% Resistance
[
Ω
]
-25% Resistance
[
Ω
]
0 0 0 0 0 103.0 128.8 77.3
0 0 0 0 1 97.8 122.3 73.4
0 0 0 1 0 93.2 116.4 69.9
0 0 0 1 1 88.9 111.1 66.7
0 0 1 0 0 85.0 106.3 63.8
0 0 1 0 1 81.5 101.9 61.1
0 0 1 1 0 78.2 97.8 58.7
0 0 1 1 1 75.2 94.0 56.4
0 1 0 0 0 72.4 90.5 54.3
0 1 0 0 1 69.8 87.3 52.4
0 1 0 1 0 67.4 84.2 50.5
0 1 0 1 1 65.1 81.4 48.9
0 1 1 0 0 63.0 78.8 47.3
0 1 1 0 1 61.1 76.3 45.8
0 1 1 1 0 59.2 74.0 44.4
0 1 1 1 1 57.5 71.8 43.1
1 0 0 0 0 55.8 69.8 41.9
1 0 0 0 1 54.3 67.8 40.7
1 0 0 1 0 52.8 66.0 39.6
1 0 0 1 1 51.4 64.3 38.6
1 0 1 0 0 50.1 62.6 37.6
1 0 1 0 1 48.8 61.0 36.6
1 0 1 1 0 47.6 59.5 35.7
1 0 1 1 1 46.5 58.1 34.9
1 1 0 0 0 45.4 56.8 34.1
1 1 0 0 1 44.4 55.5 33.3
1 1 0 1 0 43.4 54.2 32.5
1 1 0 1 1 42.5 53.1 31.8
1 1 1 0 0 41.5 51.9 31.2
1 1 1 0 1 40.7 50.9 30.5