W9725G8JB Datasheet, PDF (29/86 Pages) Winbond – 8M  4 BANKS  8 BIT DDR2 SDRAM

W9725G8JB
Table 5 – Precharge & Auto-precharge clarifications
From
Command
To Command
Minimum Delay between “From Unit Notes
Command” to “To Command”
Read
Precharge (to same Bank as Read)
AL + BL/2 + max(RTP, 2) - 2
clks 1, 2
Precharge All
AL + BL/2 + max(RTP, 2) - 2
clks 1, 2
Read w/AP Precharge (to same Bank as Read w/AP)
AL + BL/2 + max(RTP, 2) - 2
clks 1, 2
Precharge All
AL + BL/2 + max(RTP, 2) - 2
clks 1, 2
Write
Precharge (to same Bank as Write)
WL + BL/2 + tWR
clks
2
Precharge All
WL + BL/2 + tWR
clks
2
Write w/AP Precharge (to same Bank as Write w/AP)
WL + BL/2 + WR
clks
2
Precharge All
WL + BL/2 + WR
clks
2
Precharge Precharge (to same Bank as Precharge)
1
clks
2
Precharge All
1
clks
2
Precharge
All
Precharge
Precharge All
1
clks
2
1
clks
2
Notes:
1. RTP[cycles] = RU{ tRTP[nS] / tCK(avg)[nS] }, where RU stands for round up.
2. For a given bank, the precharge period should be counted from the latest precharge command, either one bank precharge or
precharge all, issued to that bank. The precharge period is satisfied after tRP depending on the latest precharge command
issued to that bank.
7.8 Refresh Operation
Two types of Refresh operation can be performed on the device: Auto Refresh and Self Refresh. By
repeating the Auto Refresh cycle, each bank in turn refreshed automatically. The Refresh operation
must be performed 8192 times (rows) within 64mS. The period between the Auto Refresh command
and the next command is specified by tRFC.
Self Refresh mode enters issuing the Self Refresh command (CKE asserted "LOW") while all banks
are in the idle state. The device is in Self Refresh mode for as long as CKE held "LOW". In the case of
8192 burst Auto Refresh commands, 8192 burst Auto Refresh commands must be performed within
7.8 µS before entering and after exiting the Self Refresh mode. In the case of distributed Auto Refresh
commands, distributed auto refresh commands must be issued every 7.8 µS and the last distributed
Auto Refresh commands must be performed within 7.8 µS before entering the self refresh mode. After
exiting from the Self Refresh mode, the refresh operation must be performed within 7.8 µS. In Self
Refresh mode, all input/output buffers are disable, resulting in lower power dissipation (except CKE
buffer). (Example timing waveform refer to 10.29 Self Refresh diagram in Chapter 10)
7.9 Power Down Mode
Power-down is synchronously entered when CKE is registered LOW, along with NOP or Deselect
command. CKE is not allowed to go LOW while mode register or extended mode register command
time, or read or write operation is in progress. CKE is allowed to go LOW while any other operation
such as row activation, Precharge or Auto-precharge or Auto Refresh is in progress, but power down
IDD specification will not be applied until finishing those operations.
The DLL should be in a locked state when power-down is entered. Otherwise DLL should be reset
after exiting power-down mode for proper read operation.
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Publication Release Date: Oct. 12, 2010
Revision A01