ic42s32400 ETC-unknow, ic42s32400 Datasheet - Page 13

• Manufacturer Part Number: ic42s32400
• Description: 1m X 32 Bit X 4 Banks 128-mbit Sdram
• Manufacturer: ETC-unknow

IC42S32400
IC42S32400L
Integrated Circuit Solution Inc.
DR038-0C 02/01/2005
6
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.
ICSI SDRAMs support CONCURRENT AUTO PRECHARGE. Four cases where CONCURRENT AUTO
PRECHARGE occurs are defined below.
READ with Auto Precharge
· Interrupted by a READ (with or without auto precharge): A READ to bank m will interrupt a READ on bank n,
· Interrupted by a WRITE (with or without auto precharge): A WRITE 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 regis-tered.
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.
Internal
States
Internal
States
NOTE: 1. DQM is HIGH at T2 to prevent D
NOTE: DQM is LOW.
READ With Auto Precharge Interrupted by a WRITE
READ With Auto Precharge Interrupted by a READ
COMMAND
ADDRESS
COMMAND
BANK m
BANK n
ADDRESS
BANK m
BANK n
CLK
DQM
DQ
CLK
DQ
1
Active
Page
READ - AP
Page Active
BANK n,
T0
BANK n
NOP
COL a
T0
READ with Burst of 4
CAS Latency = 3 (BANK n)
READ - AP
Page Active
BANK n,
Page Active
T1
NOP
BANK n
COL a
T1
OUT
READ with Burst of 4
CAS Latency = 3 (BANK n)
-a+1 from contending with D
T2
NOP
T2
NOP
T3
D
NOP
OUT
a
BANK m,
READ - AP
T3
BANK m
COL d
Interrupt Burst, Precharge
CAS Latency = 3 (BANK m)
READ with Burst of 4
BANK m,
WRITE - AP
COL d
BANK m
T4
D
d
IN
IN
Interrupt Burst, Precharge
WRITE with Burst of 4
-d at T4.
T4
NOP
D
T5
OUT
a
t
d + 1
RP - BANK n
NOP
D
IN
t
RP - BANK n
T5
NOP
T6
D
a + 1
d + 2
NOP
D
OUT
IN
DON’T CARE
T6
NOP
T7
t WR - BANK m
d + 3
NOP
D
D
IN
OUT
d
Write-Back
Idle
DON T CARE
Idle
T7
NOP
t RP - BANK m
Precharge
D
d + 1
OUT
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