2.4.1. Sampling Clock Frequency
To achieve the recommended frequency for the sampling clock, follow these steps:
- The SYNC_MODE and SAMPLE_SIZE parameters determine the sampling clock factor, which is then used to determine the required PLL settings. Use the Table 19 to identify the sampling clock factor for your configuration.
- Use the sampling clock factor identified in the previous step to determine the PLL settings. Table 22 lists the settings for Stratix® V PLL Intel® FPGA IP.
- In the case where the sampling clock factor is not achievable using the current PLL, Intel recommends that you use an alternative sampling clock frequency of 80 MHz.
- Sampling clock granularity determines the accuracy of synchronization where smaller granularity gives better accuracy. Table 20 and Table 21 show the granularity for each recommended sampling clock.
SYNC_MODE | Reference Clock Frequency (MHz) |
Sampling Clock Factor | ||
---|---|---|---|---|
SAMPLE_SIZE = 64 | SAMPLE_SIZE = 128 | SAMPLE_SIZE = 256 | ||
0, 1 | 125 | 16/63 | 32/33 | 64/63 |
156.25 | 64/315 | 128/155 | 256/375 | |
2 | Master/slave frequency | 64/63 | 128/153 | 256/375 |
3, 4 | 156.25 | 64/63 | 128/153 | 256/375 |
312.5 | 32/33 | 64/63 | 128/153 | |
5, 6 | 125 | 32/63 | 64/63 | 128/63 |
312.5 | 64/315 | 128/155 | 256/375 | |
7, 8 | 125 | N/A | N/A | 32/13 |
390.625 | N/A | N/A | 256/375 | |
9, 10 | 156.25 | 32/33 | 64/31 | 128/63 |
390.625 | 64/155 | 128/185 | 256/375 | |
11, 12 | 312.5 | 16/15 | 32/33 | 64/63 |
390.625 | 64/75 | 128/185 | 256/253 | |
13 | 62.5 | 64/63 | 128/153 | 256/253 |
125 | 32/33 | 64/63 | 128/153 | |
14 | 62.5 | 32/33 | 64/63 | 128/153 |
156.25 | 64/155 | 128/155 | 256/375 | |
15 | 62.5 | 64/63 | 128/153 | 256/253 |
312.5 | 64/155 | 128/155 | 256/375 |
SYNC_MODE | Reference Clock Frequency (MHz) |
Sampling Clock Granularity (ns) | ||
---|---|---|---|---|
SAMPLE_SIZE = 64 | SAMPLE_SIZE = 128 | SAMPLE_SIZE = 256 | ||
0, 1 | 125 | 0.5 | 0.25 | 0.125 |
156.25 | ||||
2 | Master/slave frequency | Ref clock period/64 | Ref clock period/128 | Ref clock period/256 |
3, 4 | 156.25 | 0.1 | 0.05 | 0.025 |
312.5 | ||||
5, 6 | 125 | 0.25 | 0.125 | 0.0625 |
312.5 | ||||
7, 8 | 125 | N/A | N/A | 0.25 |
390.625 | ||||
9, 10 | 156.25 | 0.2 | 0.1 | 0.05 |
390.625 | ||||
11, 12 | 312.5 | 0.2 | 0.1 | 0.05 |
390.625 | ||||
13 | 62.5 | 0.25 | 0.125 | 0.0625 |
125 | ||||
14 | 62.5 | 0.5 | 0.25 | 0.125 |
156.25 | ||||
15 | 62.5 | 0.25 | 0.125 | 0.0625 |
312.5 |
SYNC_MODE | Time of Day Frequency (MHz) |
Sampling Clock Granularity (ns) | ||
---|---|---|---|---|
SAMPLE_SIZE = 64 | SAMPLE_SIZE = 128 | SAMPLE_SIZE = 256 | ||
0, 1 | 125 | 0.5 | 0.5 | 0.5 |
156.25 | ||||
2 | 62.5 | 0.5 | 0.5 | 0.5 |
125 | 0.5 | 0.5 | 0.5 | |
156.25 | 0.1 | 0.1 | 0.1 | |
312.5 | 0.1 | 0.1 | 0.1 | |
390.625 | N/A | 0.02 | 0.02 | |
402.83 | N/A | N/A | N/A | |
3, 4 | 156.25 | 0.1 | 0.1 | 0.1 |
312.5 | ||||
5, 6 | 125 | 0.5 | 0.5 | 0.5 |
312.5 | ||||
7, 8 | 125 | N/A | 0.5 | 0.5 |
390.625 | ||||
9, 10 | 156.25 | N/A | 0.1 | 0.1 |
390.625 | ||||
11, 12 | 312.5 | N/A | 0.1 | 0.1 |
390.625 | ||||
13 | 62.5 | 0.5 | 0.5 | 0.5 |
125 | ||||
14 | 62.5 | 0.5 | 0.5 | 0.5 |
156.25 | ||||
15 | 62.5 | 0.5 | 0.5 | 0.5 |
312.5 |
Sampling Clock Factor | PLL Counter | ||
---|---|---|---|
M | N | C | |
16/15 | 16 | 5 | 3 |
16/63 | 16 | 3 | 21 |
32/13 | 32 | 13 | 1 |
32/33 | 32 | 3 | 11 |
32 | 11 | 3 | |
32/63 | 32 | 3 | 21 |
64/31 | 64 | 31 | 1 |
64/63 | 64 | 9 | 7 |
64 | 21 | 3 | |
64/75 | 64 | 25 | 3 |
64/155 | 64 | 31 | 5 |
64/315 | 64 | 21 | 15 |
128/63 | 128 | 21 | 3 |
128/153 | 128 | 51 | 3 |
128 | 17 | 9 | |
128 | 9 | 17 | |
128/155 | 128 | 31 | 5 |
128/185 | 128 | 37 | 5 |
256/253 | 256 | 11 | 23 |
256/375 | 256 | 75 | 5 |
256 | 25 | 15 |