After data is gathered from the memory, a command called Precharge needs to be issued, closing the memory row that was being used and allowing a new row to be activated. RAS Precharge time (tRP) is the time taken between when the Precharge command and the next Active command can be issued. As we learned from the previous page, the Active command starts a read or write cycle.

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Figure 6: RAS Precharge (tRP)

In Figure 6, we are giving an example of a memory with tRP = 3.

As with the other parameters, RAS Precharge works with the memory real clock (which is half of the labeled clock). The lower this parameter, the faster the memory will be, as it will issue the Active command earlier.

Adding everything we’ve seen, the time elapsed between issuing the Precharge command and actually getting the data will be tRP + tRCD + CL.