Maximum Frequencies
The Semi-Ternary CAM Search IP is designed to run at up to 500 MHz (low voltage)/600 MHz (mid voltage) for -2 speed grade devices.
Latency
The STCAM lookup latency depends on the size of the STCAM, the TDM factor and memory type. The lookup latency is constant for fixed rate STCAM and some examples are shown in the following table.
| Entries | TDM Factor = 1 | TDM Factor = 4 | TDM Factor = 16 | TDM Factor = 32 |
|---|---|---|---|---|
| 256 | 29/29 | 13/13 | 9/9 | 9/9 |
| 1K | 29/29 | 13/13 | 9/9 | 9/9 |
| 4K | 30/29 | 13/13 | 9/9 | 9/9 |
| 16K | 32/29 | 13/13 | 10/10 | NA/9 |
Note: Latency values are measured in
lookup interface frequency cycles:
KEY_WIDTH = 32, RESPONSE_WIDTH = 16, NUM_MASKS = 32, LOOKUP_RATE = LOOKUP_INTERFACE_FREQ.
The lookup latency is not constant for variable rate STCAM. The latency value shown in the GUI represents the minimum lookup latency.