at89c51re2-slsem ATMEL Corporation, at89c51re2-slsem Datasheet - Page 152

• Manufacturer Part Number: at89c51re2-slsem
• Description: At89c51re2 8-bit Flash Microcontroller
• Manufacturer: ATMEL Corporation

External Program Memory
Characteristics
7663B–8051–03/07
Table 99, Table 100 and Table 106 give the frequency derating formula of the AC
parameter for each speed range description. To calculate each AC symbols. take the x
value in the correponding column (-M or -L) and use this value in the formula.
Example: T
x = 35 ns
T 50 ns
T
Table 98. Symbol Description
Table 99. AC Parameters for a Fix Clock
CCIV
Symbol
T
T
T
T
T
T
T
T
T
T
T
PLPH
PLAZ
LHLL
AVLL
LLAX
LLPL
PXIX
AVIV
LLIV
PLIV
PXIZ
T
= 4T - x = 165 ns
Symbol
T
T
T
T
T
T
T
T
T
T
T
PLPH
PLAZ
LHLL
AVLL
LLAX
LLPL
PLIV
PXIX
PXIZ
AVIV
LLIV
T
LLIU
for -M and 20 MHz, Standard clock.
Parameter
Oscillator clock period
ALE pulse width
Address Valid to ALE
Address Hold After ALE
ALE to Valid Instruction In
ALE to PSEN
PSEN Pulse Width
PSEN to Valid Instruction In
Input Instruction Hold After PSEN
Input Instruction Float After PSEN
Address to Valid Instruction In
PSEN Low to Address Float
Min
25
35
50
5
5
5
0
-M
Max
n 65
30
10
80
10
Min
25
35
50
5
5
5
0
-L
Max
65
30
10
80
10
Units
135
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns