RAS/CAS timinggreenspun.com : LUSENET : ece342 : One Thread
I was just wondering about the timing constaraints for RAS and CAS. On the data sheets it says the maximum RAS to CAS (trcd) delay is 60 ns. If we assert RAS then assert CAS on the next clock cycle, that is a delay of 100ns. Is this a problem??? Does this mean we have to assert RAS and CAS on the same clock edge and add appropriate delay to CAS???
-- John Oh (firstname.lastname@example.org), February 01, 1999
If you look at the note attached to Trcd, you'll notice that the 60ns maximum is listed for reference only. You don't need to hold to the limit, you just need to keep an eye on the timing constraints that become important if you go over the limit, such as Tcac and Tcaa.
Steven Truelove COMP 0T0
-- Steven Truelove (email@example.com), February 02, 1999.