Ac characteristics, External program and data memory characteristics, At89s53 – Rainbow Electronics AT89S53 User Manual
Page 26
![background image](/manuals/281583/26/background.png)
AT89S53
26
AC Characteristics
Under operating conditions, load capacitance for Port 0, ALE/PROG, and PSEN = 100 pF; load capacitance for all other
outputs = 80 pF.
External Program and Data Memory Characteristics
Symbol
Parameter
12MHz 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
43
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