87C51 Intel Corporation, 87C51 Datasheet - Page 12

• Manufacturer Part Number: 87C51
• Description: CHMOS SINGLE-CHIP 8-BIT MICROCONTROLLER
• Manufacturer: Intel Corporation

87C51 80C51BH 80C31BH
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
AC CHARACTERISTICS
PSEN
EXTERNAL MEMORY CHARACTERISTICS
All parameter values apply to all devices unless otherwise indicated In this table 87C51 BH refers to
87C51 BH 87C51-1 BH-1 and 87C51-2 BH-2
12
1 TCLCL
TLHLL
TAVLL
TLLAX
TLLIV
TLLPL
TPLPH
TPLIV
Symbol
A Address
C Clock
D Input data
H Logic level HIGH
I Instruction (program memory contents)
e
100 pF Load Capacitance for All Other Outputs
Oscillator Frequency
ALE Pulse Width
Address Valid to ALE Low
Address Hold After ALE Low
ALE Low to Valid Instr In
ALE Low to PSEN Low
PSEN Pulse Width
PSEN Low to Valid Instr In
87C51 BH
87C51-1 BH-1
87C51-2 BH-2
87C51-24 BH-24
87C51 BH
87C51-24 BH-24
87C51 BH
87C51-24 BH-24
87C51 BH
87C51-24 BH-24
Parameter
(Over Operating Conditions Load Capacitance for Port 0 ALE and
Min
127
205
43
53
53
12 MHz
Max
234
145
For example
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
TAVLL
TLLPL
Min
43
12
12
12
80
24 MHz
e
80 pF)
Max
91
35
e
e
Oscillator
Time from ALE Low to PSEN Low
Time from Address Valid to ALE Low
2TCLCL
3TCLCL
TCLCL
TCLCL
TCLCL
TCLCL
Min
3 5
3 5
0 5
3 5
b
b
b
b
b
b
40
30
30
30
Variable
40
45
4TCLCL
3TCLCL
4TCLCL
3TCLCL
Max
12
16
12
24
b
b
b
b
100
105
75
90
Units
MHz
MHz
MHz
MHz
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns