In many systems, the contents of the memory system have to be maintained during low-power sleep modes. The MPMC provides two features to enable this:

Self-refresh mode can be entered automatically by hardware or manually by software:

The PMU can be used to enable self-refresh mode to be entered automatically. To do this, the PMU asserts the MPMCSREFREQ signal when self-refresh mode is to be entered. The memory controller then closes any open memory banks and puts the external memory into self-refresh mode. The MPMC then asserts the MPMCSREFACK signal to indicate to the PMU that self-refresh mode is entered. The system must ensure that the memory subsystem is idle before asserting MPMCSREFREQ. The memory controller accepts transactions to dynamic memory even in self-refresh mode, if the accesses are targeted to chip selects that are populated with SyncFlash and its variants. This is required to aid booting from a SyncFlash device. Deasserting MPMCSREFREQ returns the memory to normal operation. See the memory data sheet for refresh requirements.