is42s16400b1 Integrated Silicon Solution, Inc., is42s16400b1 Datasheet - Page 33

• Manufacturer Part Number: is42s16400b1
• Description: 1 Meg Bits X 16 Bits X 4 Banks 64-mbit Synchronous Dynamic Ram - Integrated Silicon Solution, Inc
• Manufacturer: Integrated Silicon Solution, Inc.

IS42S16400B1
BURST READ/SINGLE WRITE
The burst read/single write mode is entered by programming
the write burst mode bit (M9) in the mode register to a logic 1.
In this mode, all WRITE commands result in the access of a
single column location (burst of one), regardless of the
programmed burst length. READ commands access
columns according to the programmed burst length and
sequence, just as in the normal mode of operation (M9 = 0).
CONCURRENT AUTO PRECHARGE
An access command (READ or WRITE) to another bank
while an access command with auto precharge enabled is
executing is not allowed by SDRAMs, unless the SDRAM
supports CONCURRENT AUTO PRECHARGE. ISSI
SDRAMs support CONCURRENT AUTO PRECHARGE.
Fig CAP 1 - READ With Auto Precharge interrupted by a READ
Integrated Silicon Solution, Inc. — www.issi.com —
Rev. A
12/09/03
Fig CAP 2 - READ With Auto Precharge interrupted by a WRITE
Internal States
Internal States
COMMAND
COMMAND
ADDRESS
ADDRESS
BANK m
BANK m
BANK n
BANK n
DQM
CLK
CLK
DQ
DQ
WRITE - AP
BANK n,
BANK n,
T0
Page Active
T0
BANK n
NOP
COL a
COL a
Page Active
CAS Latency - 3 (BANK n)
READ - AP
T1
BANK n
T1
NOP
Page Active
Page Active
READ with Burst of 4
READ with Burst of 4
CAS Latency - 3 (BANK n)
T2
T2
NOP
NOP
READ - AP
BANK m
T3
T3
NOP
1-800-379-4774
D
OUT
a
CAS Latency - 3 (BANK m)
Four cases where CONCURRENT AUTO PRECHARGE
occurs are defined below.
READ with Auto Precharge
1. Interrupted by a READ (with or without auto precharge):
2. Interrupted by a WRITE (with or without auto precharge):
Interrupt Burst, Precharge
A READ to bank m will interrupt a READ on bank n, CAS
latency later. The PRECHARGE to bank n will begin
when the READ to bank m is registered.
A WRITE to bank m will interrupt a READ on bank n
when registered. DQM should be used two clocks prior
to the WRITE command to prevent bus contention. The
PRECHARGE to bank n will begin when the WRITE to
bank m is registered.
WRITE - AP
BANK m,
BANK m,
BANK m
T4
T4
NOP
COL b
COL b
D
D
IN
t
OUT
RP - BANK n
READ with Burst of 4
b
a
Interrupt Burst, Precharge
WRITE with Burst of 4
T5
T5
D
NOP
NOP
D
IN
OUT
t
RP - BANK n
b+1
a+1
T6
T6
D
NOP
NOP
D
IN
OUT
b+2
b
DON'T CARE
DON'T CARE
Idle
T7
T7
D
NOP
D
NOP
IN
Write-Back
Precharge
OUT
b+3
t
t
RP - BANK m
RP - BANK m
b+1
Idle
ISSI
33
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