MCS@51 CONTROLLER
L: ~level
LOW, or ALE
P: PSEN
Q: Output data
R: ~ signal
T: Time
V: Valid
W: WR signal
X: No longer a valid logic level
Z: Float
For example,
TAVLL = Time from Address Valid to ALE Low.
TLLPL = Time from ALE Low to PSEN Low.
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
1:Instruction (program memory contents)
AC CHARACTERISTICS
(Under Operating Conditions; Load Capacitance for Port O,ALE/PROG, and
PSEN = 100 pF; Load Capacitance for All Other Outputs = 80 pF)
EXTERNAL PROGRAM MEMORY CHARACTERISTICS
Symbol
1/TCLCL
TLHLL
TAVLL
TLLAX
TLLIV
Parameter
Oscillator Frequency
ALE Pulse Width
Address Valid to ALE Low
Address Hold after ALE Low
ALE Low to Valid Instr In
8751 H
All Others
ALE
LOW
to PSEN
LOW
PSEN Pulse Width
8751H
All Others
PSEN Low to Valid Instr In
8751H
All Others
Input Instr Hold after PSEN
Input Instr Float after PSEN
PSEN to Address Valid
Address to Valid Instr In
8751 H
All Others
PSEN Low to Address Float
~
~
Pulse Width
Low to Valid Data In
o
97
I
I
517
.,. -
DUD I
I
400
400
252
0
2TCLCL–70
8TCLCL–1 50
nl-n, n,
103
Y
I ~LUL—
.ec
WR Pulse Width
Data Hold after ~
Data Float after ~
ALE Low to Valid Data In
. ,,
. ,–,. , -—.—
,.–
I
Aaaress 10valla Ua[a m
o
63
75
287
302
20
6TCLCL– 100
6TCLCL– 100
5TCLCL– 165
TCLCL–8
5TCLCL–1 50
5TCLCL–1 15
20
58
190
215
100
125
0
TCLCL–20
12 MHz Oscillator
Max
Min
127
43
48
183
233
TCLCL–25
3TCLCL–60
3TCLCL–35
3TCLCL– 150
3TCLCL– 125
Variable Oscillator
Max
Min
12.0
3.5
2TCLCL–40
TCLCL–40
TCLCL–35
4TCLCL– 150
4TCLCL– 100
Units
MHz
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
--
rm
TLLPL
TPLPH
TPLIV
TPXIX
TPXIZ
TPXAV
TAVIV
TPLAZ
TRLRH
TWLWH
TRLDV
TRHDX
TRHDZ
TLLDV
-.. .. . .
I AVUV
I
9
INTEL [ INTEL CORPORATION ]
