48
3286P–MICRO–3/10
AT89S8253
31. AC Characteristics
The values shown in this table are valid for T
A = -40°C to 85°C and VCC = 2.7 to 5.5V, unless otherwise noted.
Under operating conditions, load capacitance for Port 0, ALE/PROG, and PSEN = 100 pF; load capacitance for all other
outputs = 80 pF.
31.1
External Program and Data Memory Characteristics
Symbol
Parameter
Variable Oscillator
Units
Min
Max
1/tCLCL
Oscillator Frequency
0
24
MHz
tLHLL
ALE Pulse Width
2tCLCL - 12
ns
t
AVLL
Address Valid to ALE Low
t
CLCL - 12
ns
tLLAX
Address Hold after ALE Low
tCLCL - 16
ns
tLLIV
ALE Low to Valid Instruction In
4tCLCL - 50
ns
t
LLPL
ALE Low to PSEN Low
t
CLCL - 12
ns
tPLPH
PSEN Pulse Width
3tCLCL - 12
ns
tPLIV
PSEN Low to Valid Instruction In
3tCLCL - 50
ns
t
PXIX
Input Instruction Hold after PSEN
-10
ns
tPXIZ
Input Instruction Float after PSEN
tCLCL - 20
ns
tPXAV
PSEN to Address Valid
tCLCL - 4
ns
t
AVIV
Address to Valid Instruction In
5t
CLCL - 50
ns
tPLAZ
PSEN Low to Address Float
20
ns
t
RLRH
RD Pulse Width
6t
CLCL
ns
t
WLWH
WR Pulse Width
6t
CLCL
ns
tRLDV
RD Low to Valid Data In
5tCLCL - 50
ns
t
RHDX
Data Hold after RD
0ns
t
RHDZ
Data Float after RD
2t
CLCL - 20
ns
tLLDV
ALE Low to Valid Data In
8tCLCL - 50
ns
t
AVDV
Address to Valid Data In
9t
CLCL - 50
ns
t
LLWL
ALE Low to RD or WR Low
3t
CLCL - 24
3t
CLCL
ns
tAVWL
Address to RD or WR Low
4tCLCL - 12
ns
t
QVWX
Data Valid to WR Transition
2t
CLCL - 24
ns
t
QVWH
Data Valid to WR High
8t
CLCL - 24
ns
tWHQX
Data Hold after WR
2tCLCL - 24
ns
t
RLAZ
RD Low to Address Float
0ns
t
WHLH
RD or WR High to ALE High
t
CLCL - 10
t
CLCL + 20
ns
tWHAX
Address Hold after RD or WR High
tCLCL - 10
ns