Preliminary
VG37648041AT
256M:x4, x8, x16
VIS
CMOS Synchronous Dynamic RAM
TRUTH TABLE 3-Current State Bank n - Command to Bank n
(Notes: 1-6; notes appear below and on next page)
CURRENT STATE CS# RAS# CAS# WE#
COMMANDACTION
NOTES
Any
H
L
L
L
L
L
L
L
L
L
L
L
L
L
L
X
H
L
X
H
H
L
L
L
L
H
L
L
H
H
L
L
H
X
H
H
H
L
H
L
L
H
L
L
L
H
L
L
COMMAND INHBIT (NOP/continue previous operation
NO OPERATION (NOP/continue previous operation)
ACTIVE (select and activate row)
L
AUTO REFRESH
7
7
Idle
L
LOAD MODE REGISTER
H
H
L
READ (select column and start READ burst)
WRITE (select column and start WRITE burst)
PRECHARGE (deactivate row in bank or banks)
READ (select column and start new READ burst)
WRITE (select column and start WRITE burst)
PRECHARGE(truncate READ burst, start PRECHARGE)
BURST TERMINATE
10
10
8
Row Active
Read
(Auto-
Precharge
Disabled)
H
H
L
10
10
8
H
H
H
L
9
Write
(Auto-
Precharge
Disabled)
READ (select column and start READ burst)
WRITE (select column and start new WRITE burst)
PRECHARGE (truncate WRITE burst, start PRECHARGE)
10
10
8
NOTE:
1. This table applies when CKEn-1 was HIGH and CKEn Is HIGH (see Turn Table 2) and after tXSR has
been met (if the previous state was self refresh).
2. This table is bank-specific, except where noted, i.e., the current state is for a specific bank and the
commands shown are those allowed to be issued to that bank when in that state, Exceptions are
covered in the notes below.
3.Current state definitions:
Idle: The bank has been precharged, and tRP has been met.
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 ter-
minated or been terminated.
Document : 1G5-0157
Rev.1
Page63
VML [ VANGUARD INTERNATIONAL SEMICONDUCTOR ]
