Preliminary
VG37648041AT
256M:x4, x8, x16
VIS
CMOS Synchronous Dynamic RAM
3. Current state definitions:
Idle: The bank has been precharged, and RP has been met.
t
Row Active: A row in the bank has been activated, and tRCD has been met. No data bursts/accesses
and no register accesses are in progress.
Read: A READ burst has been initiated, with AUTO PRECHARGE disabled, and has not yet termi-
nated or been terminated.
Write: A WRITE burst has been initiated, with AUTO PRECHARGE disabled, and has not yet termi-
nated or been terminated.
Read with Auto
Precharge Enabled: See following text
Write with Auto
Precharge Enabled: See following text
The Read with Auto Precharge Enabled or Write with Auto Precharge Enabled states can each be
broken into two parts: the access period and the precharge period. The precharge period is defined
as if the same burst was executed with Auto Precharge disabled and then followed with the earliest
possible PRECHARGE command that still accesses all of the data in the burst. The access period
starts with registration of the command and ends where the precharge period (or tRP) begins.
During the precharge period of the Read with Auto Precharge Enabled or Write with Auto Precharge
Enabled states, ACTIVE, PRECHARGE, READ and WRITE commands to the other bank may be
applied; during the access period, only ACTIVE and PRECHARGE commands to the other bank may
be applied. In either case, all other related limitations apply (e.g. following a Read with Auto Pre-
charge by a Write command to another bank is subject to the same data path limitations as when fol-
lowing a Read by a Write).
4. AUTO REFERESH, LOAD MODE REGISTER and PRECHARGE ALL commands may only be issued
when all banks are idle.
5. A BURST TERMINATE command cannot be issued to another bank; it applies to the bank represented
by the current state only.
6. All states and sequences not shown are illegal or reserved.
7. READs or WRITEs listed in the Command/Action column include READs or WRITEs with AUTO PRE-
CHARGE enabled and READs or WRITEs with AUTO PRECHARGE disabled.
Document : 1G5-0157
Rev.1
Page66
VML [ VANGUARD INTERNATIONAL SEMICONDUCTOR ]
