DRAM REFRESH COMMAND OPERATION

Burst operation establishes command sequences that include Nop command intervals Some of these Nop intervals are used to perform operations on a bank other than the one under access for the burst that provide a refresh. ACTIVE followed by PRECHARGE commands are inserted into the command intervals addressed to a refresh address The refresh addresses are generated externally of the SDRAM and provided to a multiplexer that sequences them with the data addresses. A secondary timer checks that required refresh has occurred and prioritises the refresh addresses over data addresses in the multiplexer in the event that a refresh has not been completed shortly before a maximum refresh interval