VRAM
SMJ44C251B
MT42C4256
Austin Semiconductor, Inc.
TIMING REQUIREMENTS OVER RECOMMENDED RANGES OF
SUPPLY VOLTAGESAND OPERATING FREE-AIR TEMPERATURE1
-10
-12
PARAMETER
SYM/ALT. SYM MIN
/t
MAX
MIN
MAX
UNIT
2
t
190
190
250
60
105
190
190
30
20
25
80
100
25
25
10
10
35
35
30
100
0
220
ns
c(rd) RC
Cycle time, read
2
t
/t
220
290
70
125
220
220
35
30
30
90
120
25
30
12
12
40
40
20
120
0
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
c(W) WC
Cycle time, write
2
t
/t
c(rdW) RMW
Cycle time, read-modify-write
2
t
/t
c(P) PC
Cycle time, page-mode read or write
2
t
/t
c(rdWP) PRMW
Cycle time, page-mode read-modify-write
2
t
t
/t
c(TRD) RC
Cycle time, read transfer
2
/t
c(TW) WC
Cycle time, write transfer
2
t
/t
c(SC) SCC
Cycle time, serial clock
Pulse duration, CAS\ high
t
/t
w(CH) CPN
4
t
/t
75000
75000
75000
75000
w(CL) CAS
Pulse duration, CAS\ low
Pulse duration, RAS\ high
t
/t
w(RH) RP
5
t
/t
w(RL) RAS
Pulse duration, RAS\ low
Pulse duration,W\ low
t
/t
w(WL) WP
Pulse duration, TRG\ low
t
w(TRG)
Pulse duration, SC high
t
/t
w(SCH) SC
Pulse duration, SC low
t
/t
w(SCL) SCP
Pulse duration, SE\ low
t
/t
w(SEL) SE
Pulse duration, SE\ high
t
/t
w(SEH) SEP
Pulse duration, TRG\ high
Pulse duration, RAS\ low (page mode)
Setup time, column address
Setup time, DSF before CAS\ low
Setup time, row address
t
/t
w(GH) TP
t
75000
75000
w(RL)P
t
/t
su(CA) ASC
t
/t
0
0
su(SFC) FSC
t
/t
0
0
su(RA) ASR
Setup time, W\ before RAS\ low
Setup time, DQ before RAS\ low
Setup time, TRG\ before RAS\ low
t
/t
0
0
su(WMR) WSR
t
/t
0
0
su(DQR) MS
t
/t
0
0
su(TRG) THS
6
t
/t
0
0
su(SE) ESR
Setup time, SE\ before RAS\ low
Setup time, serial write disable
t
/t
10
0
15
0
su(SESC) SWIS
Setup time, DSF before RAS\ low
Setup time, data before CAS\ low
Setup time, data before W\ low
t
/t
su(SFR) FSR
t
/t
0
0
su(DCL) DSC
t
/t
0
0
su(DWL) DSW
Setup time, read command
t
/t
0
0
su(rd) RCS
Setup time, early write command before CAS\ low
Setup time, write before CAS\ high
t
t
/t
0
0
su(WCL) WCS
/t
25
30
su(WCH) CWL
Setup time, write before RAS\ high with
TRG\ = W\ = low
t
/t
25
30
ns
su(WRH) RWL
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
SMJ44C251B/MT42C4256
Rev. 0.1 12/03
19
AUSTIN [ AUSTIN SEMICONDUCTOR ]
