SMJ44C251B Datasheet, PDF (28/53 Pages) Texas Instruments – 262144 BY 4-BIT MULTIPORT VIDEO RAM

SMJ44C251B
262144 BY 4-BIT
MULTIPORT VIDEO RAM
SGMS058A – MARCH 1995 – REVISED JUNE 1995
PARAMETER MEASUREMENT INFORMATION
RAS
tc(rdW ₎
tw(RL)
td(RLCH)
td(CHRL)
td(RLCL)
CAS
th(RA)
tsu(RA)
tsu(CA)
td(RLCA)
th(RLCA)
A0 – A8
Row
Column
td(CLRH)
tw(CL)
th(CLCA)
td(CARH)
Don’t Care
th(SFR)
tsu(SFR)
DSF
1
th(RSF)
tsu(SFC)
th(SFC)
2
Don’t Care
TRG
th(RWM)
tsu( _WMR)
W
tsu(DQR)
Q0 –
Q3
th( _TRG)
tsu( _TRG)
td(DCL)
3
td(DGL)
ta(R)
th(RDQ)
4
tsu(rd)
td(CAWL)
tw( _TRG)
th( _WLG)
th(RLW ₎
th(CLW ₎
td(CLWL)
td(CLGH)
ta(CA)
td(RLWL)
td(GHD)
ta(C)
Valid
Output
tw( _WL)
tsu(DWL)
5
ta(G)
tdis(G)
Figure 16. Read-Write/Read-Modify-Write-Cycle Timing
tw(RH)
td(CHRL)
tw(CH)
tsu( _WCH)
tsu( _WRH)
th( _WLD)
Table 6. Write-Cycle State Table
CYCLE
Write operation
Write-mask load/use, write DQs to I/Os
Use previous write mask, write DQs to I/Os
Load write mask on later of W fall and CAS fall
1
2
L
L
L
L
H
L
H
L
STATE
3
H
L
L
H
4
Don’t care
Write mask
Don’t care
Don’t care
5
Valid data
Valid data
Valid data
Write mask
28
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