At8xc51snd1c, 7 to 3.3 v, t – Rainbow Electronics AT89C51SND1C User Manual
Page 187
187
AT8xC51SND1C
4109E–8051–06/03
Table 161. External 8-bit Bus Cycle - Data Write AC Timings
V
DD
= 2.7 to 3.3 V, T
A
= -40 to +85
°
C
Waveforms
Figure 142. External 8-bit Bus Cycle - Data Read Waveforms
Symbol
Parameter
Variable Clock
Standard Mode
Variable Clock
X2 Mode
Unit
Min
Max
Min
Max
T
CLCL
Clock Period
50
50
ns
T
LHLL
ALE Pulse Width
2·T
CLCL
-15
T
CLCL
-15
ns
T
AVLL
Address Valid to ALE Low
T
CLCL
-20
0.5·T
CLCL
-20
ns
T
LLAX
Address hold after ALE Low
T
CLCL
-20
0.5·T
CLCL
-20
ns
T
LLWL
ALE Low to WR Low
3·T
CLCL
-30
1.5·T
CLCL
-30
ns
T
WLWH
WR Pulse Width
6·T
CLCL
-25
3·T
CLCL
-25
ns
T
WHLH
WR High to ALE High
T
CLCL
-20
T
CLCL
+20
0.5·T
CLCL
-20
0.5·T
CLCL
+20
ns
T
AVWL
Address Valid to WR Low
4·T
CLCL
-30
2·T
CLCL
-30
ns
T
QVWH
Data Valid to WR High
7·T
CLCL
-20
3.5·T
CLCL
-20
ns
T
WHQX
Data Hold after WR High
T
CLCL
-15
0.5·T
CLCL
-15
ns
T
AVDV
T
LLAX
T
RHDX
T
RHDZ
T
AVLL
T
AVRL
P2
P0
RD
ALE
T
LHLL
T
RLRH
Data In
A15:8
T
RLAZ
T
LLRL
T
RHLH
T
RLDV
D7:0
A7:0