19
4173ES–USB–09/07
AT89C5132
6.3
AC Characteristics
6.3.1
External 8-bit Bus Cycles
6.3.1.1
Definition of Symbols
Table 6. External 8-bit Bus Cycles Timing Symbol Definitions
6.3.1.2
Timings
Test conditions: capacitive load on all pins = 50 pF.
Table 7. External 8-bit Bus Cycle – Data Read AC Timings
V
DD
= 2.7 to 3.3V, T
A
= -40
°
to +85
°
C
Signals
Conditions
A
Address
H
High
D
Data In
L
Low
L
ALE
V
Valid
Q
Data Out
X
No Longer Valid
R
RD
Z
Floating
W
WR
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
LLRL
ALE Low to RD Low
3·T
CLCL
-30
1.5·T
CLCL
-30
ns
T
RLRH
RD Pulse Width
6·T
CLCL
-25
3·T
CLCL
-25
ns
T
RHLH
RD high to ALE High
T
CLCL
-20
T
CLCL
+20
0.5·T
CLCL
-20
0.5·T
CLCL
+20
ns
T
AVDV
Address Valid to Valid Data In
9·T
CLCL
-65
4.5·T
CLCL
-65
ns
T
AVRL
Address Valid to RD Low
4·T
CLCL
-30
2·T
CLCL
-30
ns
T
RLDV
RD Low to Valid Data
5·T
CLCL
-30
2.5·T
CLCL
-30
ns
T
RLAZ
RD Low to Address Float
0
0
ns
T
RHDX
Data Hold After RD High
0
0
ns
T
RHDZ
Instruction Float After RD High
2·T
CLCL
-25
T
CLCL
-25
ns