
AUTOMOTIVE 87C51FAFBFCFC-20
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
TAVLL e Time from Address Valid to ALE Low
TLLPL e Time from ALE Low to PSEN Low
AC CHARACTERISTICS (TA eb40 Cto a125 C VCC e 5V g 20% VSS e 0V Load Capacitance
for Port 0 ALEPROG and PSEN e 100 pF Load Capacitance for All Other Outputs e 80 pF)
ADVANCED INFORMATIONCONTACT INTEL FOR DESIGN-IN INFORMATION
EXTERNAL PROGRAM MEMORY CHARACTERISTICS
Symbol
Parameter
12 MHz
Variable Oscillator
Units
Oscillator
Min
Max
87C51FAFBFC 87C51FC-20
Min
Max
1TCLCL
Oscillator Frequency
35
1620
MHz
TLHLL
ALE Pulse Width
127
2TCLCL b 40
ns
TAVLL
Address Valid to ALE Low
43
TCLCL b 40
ns
TLLAX
Address Hold After ALE Low
53
TCLCL b 30
ns
TLLIV
ALE Low to Valid
234
4TCLCL b 100
ns
Instruction In
4TCLCL b 75
TLLPL
ALE Low to PSEN Low
53
TCLCL b 30
ns
TPLPH
PSEN Pulse Width
205
3TCLCL b 45
ns
TPLIV
PSEN Low to Valid
145
3TCLCL b 105
ns
Instruction In
3TCLCL b 90
TPXIX
Input Inst Hold After
0
ns
PSEN Trans
TPXIZ
Input Inst Float After
59
TCLCL b 25
ns
PSEN Trans
TCLCL b 20
TAVIV
Address Valid to Valid
312
5TCLCL b 105
ns
Instruction In
TPLAZ
PSEN Low to Address
10
ns
Float
TRLRH
RD Pulse Width
400
6TCLCL b 100
ns
TWLWH
WR Pulse Width
400
6TCLCL b 100
ns
10