Visible to Intel only — GUID: iga1401314930722
Ixiasoft
Visible to Intel only — GUID: iga1401314930722
Ixiasoft
33.3.2. Timing Page
Settings | Allowed Values | Default Value | Description |
---|---|---|---|
CAS latency | 1, 2, 3 | 3 | Latency (in clock cycles) from a read command to data out. |
Initialization refresh cycles | 1–8 | 2 | This value specifies how many refresh cycles the SDRAM controller performs as part of the initialization sequence after reset. |
Issue one refresh command every | — | 15.625 µs | This value specifies how often the SDRAM controller refreshes the SDRAM. A typical SDRAM requires 4,096 refresh commands every 64 ms, which can be achieved by issuing one refresh command every 64 ms / 4,096 = 15.625 μs. |
Delay after power up, before initialization | — | 100 µs | The delay from stable clock and power to SDRAM initialization. |
Duration of refresh command (t_rfc) | — | 70 ns | Auto Refresh period. |
Duration of precharge command (t_rp) | — | 20 ns | Precharge command period. |
ACTIVE to READ or WRITE delay (t_rcd) | — | 20 ns | ACTIVE to READ or WRITE delay. |
Access time (t_ac) | — | 17 ns | Access time from clock edge. This value may depend on CAS latency. |
Write recovery time (t_wr, No auto precharge) | — | 14 ns | Write recovery if explicit precharge commands are issued. This SDRAM controller always issues explicit precharge commands. |
Regardless of the exact timing values you specify, the actual timing achieved for each parameter is an integer multiple of the Avalon® clock period. For the Issue one refresh command every parameter, the actual timing is the greatest number of clock cycles that does not exceed the target value. For all other parameters, the actual timing is the smallest number of clock ticks that provides a value greater than or equal to the target value.