W641GG2JB Datasheet, PDF (87/109 Pages) Winbond – 1-Gbit GDDR3 Graphics SDRAM

6.19.2 Auto Refresh Cycle
W641GG2JB
1-Gbit GDDR3 Graphics SDRAM
6.20 Self-Refresh
6.20.1 Self-Refresh Entry (SREFEN)
The Self-Refresh mode can be used to retain data in the GDDR3 Graphics RAM even if the rest of the system is powered down.
When in the Self-Refresh mode, the GDDR3 Graphics RAM retains data without external clocking. The Self-Refresh command is
initiated like an Auto-Refresh command except CKE is disabled (LOW). Self Refresh Entry is only possible if all banks are
precharged and t_RP is met.The GDDR3 Graphics RAM has a build-in timer to accommodate Self-Refresh operation. The Self-
Refresh command is defined by having CS#, RAS#, CAS# and CKE held low with WE# high at the rising edge of the clock. Once
the command is registered, CKE must be held LOW to keep the device in Self- Refresh mode. When the GDDR3 Graphics RAM has
entered the Self-Refresh mode, all external control signals, except CKE are disabled. For power saving, the DLL and the clock are
internally disable; and the address and command terminators are turned off. But the Data terminators remain on. The user may halt
the external clock while the device is in Self-Refresh mode the next clock after Self-Refresh entry, however the clock must be
restarted before the device can exit Self-Refresh operation.
In 2-CS-mode, SR may only be entered for both ranks in parallel. Therefore CS0# and CS1# will have to be set to Low Level.
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Publication Release Date: Apr, 22, 2011
Revision A01-002