External Program and Data Memory Characteristics
Symbol
Parameter
12 MHz Oscillator
Variable Oscillator
Units
Min
Max
Min
Max
1/t
CLCL
Oscillator Frequency
0
24
MHz
t
LHLL
ALE Pulse Width
127
2t
CLCL
-40
ns
t
AVLL
Address Valid to ALE Low
28
t
CLCL
-13
ns
t
LLAX
Address Hold After ALE Low
48
t
CLCL
-20
ns
t
LLIV
ALE Low to Valid Instruction In
233
4t
CLCL
-65
ns
t
LLPL
ALE Low to PSEN Low
43
t
CLCL
-13
ns
t
PLPH
PSEN Pulse Width
205
3t
CLCL
-20
ns
t
PLIV
PSEN Low to Valid Instruction In
145
3t
CLCL
-45
ns
t
PXIX
Input Instruction Hold After PSEN
0
0
ns
t
PXIZ
Input Instruction Float After PSEN
59
t
CLCL
-10
ns
t
PXAV
PSEN to Address Valid
75
t
CLCL
-8
ns
t
AVIV
Address to Valid Instruction In
312
5t
CLCL
-55
ns
t
PLAZ
PSEN Low to Address Float
10
10
ns
t
RLRH
RD Pulse Width
400
6t
CLCL
-100
ns
t
WLWH
WR Pulse Width
400
6t
CLCL
-100
ns
t
RLDV
RD Low to Valid Data In
252
5t
CLCL
-90
ns
t
RHDX
Data Hold After RD
0
0
ns
t
RHDZ
Data Float After RD
97
2t
CLCL
-28
ns
t
LLDV
ALE Low to Valid Data In
517
8t
CLCL
-150
ns
t
AVDV
Address to Valid Data In
585
9t
CLCL
-165
ns
t
LLWL
ALE Low to RD or WR Low
200
300
3t
CLCL
-50
3t
CLCL
+50
ns
t
AVWL
Address to RD or WR Low
203
4t
CLCL
-75
ns
t
QVWX
Data Valid to WR Transition
23
t
CLCL
-20
ns
t
QVWH
Data Valid to WR High
433
7t
CLCL
-120
ns
t
WHQX
Data Hold After WR
33
t
CLCL
-20
ns
t
RLAZ
RD Low to Address Float
0
0
ns
t
WHLH
RD or WR High to ALE High
43
123
t
CLCL
-20
t
CLCL
+25
ns
A.C. Characteristics
Under operating conditions, load capacitance for Port 0, ALE/PROG, and PSEN = 100 pF; load capacitance for all
other outputs = 80 pF.
AT89C52
17
