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AUTOMOTIVE 80C51FA/83C51FA
EXPLANATION OF THE AC SYMBOLS
Each timing symbol has 5 characters. The first char-
acter is always a `T' (stands for time). The other
characters, depending on their positions, stand for
the name of a signal or the logical status of that
signal. The following is a list of all the characters and
what they stand for.
A: Address
C: Clock
D: Input Data
H: Logic level HIGH
I: Instruction (program memory contents)
L: Logic level LOW, or ALE
P: PSEN
Q: Output Data
R: RD
signal
T: Time
V: Valid
W: WR
signal
X: No longer a valid logic level
Z: Float
For example,
T
AVLL
e
Time from Address Valid to ALE Low
T
LLPL
e
Time from ALE Low to PSEN Low
AC CHARACTERISTICS (T
A
eb
40
Cto
a
125
C, V
CC
e
5V
g
10%, V
SS
e
0V, Load Capacitance
for Port 0, ALE/PROG
and PSEN
e
100 pF, Load Capacitance for All Other Outputs
e
80 pF)
EXTERNAL MEMORY CHARACTERISTICS
Symbol Parameter
12 MHz Oscillator Variable Oscillator
Units
Min Max Min Max
1/T
CLCL
Oscillator Frequency 3.5 16 MHz
T
LHLL
ALE PulseWidth 127 2T
CLCL
b
40 ns
T
AVLL
Address Valid to ALE Low 43 T
CLCL
b
40 ns
T
LLAX
Address Hold After ALE Low 53 T
CLCL
b
30 ns
T
LLIV
ALE Low to ValidInstruction In 224 4T
CLCL
b
110 ns
T
LLPL
ALE Low to PSEN
Low 53 T
CLCL
b
30 ns
T
PLPH
PSENPulse Width 205 3T
CLCL
b
45 ns
T
PLIV
PSENLow to Valid Instruction In 135 3T
CLCL
b
115 ns
T
PXIX
Input Instr Hold After PSENTrans 0 0 ns
T
PXIZ
Input Instr Float After PSENTrans 59 T
CLCL
b
25 ns
T
AVIV
Address to Valid Instruction In 302 5T
CLCL
b
115 ns
T
PLAZ
PSENLow to Address Float 10 10 ns
T
RLRH
RD PulseWidth 400 6T
CLCL
b
100 ns
T
WLWH
WR PulseWidth 400 6T
CLCL
b
100 ns
T
RLDV
RD Low to Valid Data In 242 5T
CLCL
b
175 ns
T
RHDX
Data Hold After RD High
b
10
b
10 ns
T
RHDZ
Data Float After RD High 107 2T
CLCL
b
60 ns
T
LLDV
ALE Low to ValidData In 507 8T
CLCL
b
160 ns
T
AVDV
Address Valid to ValidData In 575 9T
CLCL
b
175 ns
T
LLWL
ALE Low to RD or WRLow 200 300 3T
CLCL
b
50 3T
CLCL
a
50 ns
T
AVWL
Data Validto WR Low 203 4T
CLCL
b
130 ns
T
QVWX
Address Valid before WR Low 23 T
CLCL
b
50 ns
T
WHQX
Data Hold after WR High 33 T
CLCL
b
50 ns
T
QVWH
Data Validto WE High 433 7T
CLCL
b
150 ns
T
RLAZ
RD Low to Address Float 0 0 ns
T
WHLH
RD or WR Highto ALE High 43 123 T
CLCL
b
40 T
CLCL
a
40 ns
10