AT89C51ID2-SLSIM Atmel, AT89C51ID2-SLSIM Datasheet - Page 143

• Manufacturer Part Number: AT89C51ID2-SLSIM
• Description: C51ID2 64KF TWI 32KHZ PLCC44 3-5.5V IND.
• Manufacturer: Atmel

AC Parameters
Explanation of the AC
Symbols
External Program Memory
Characteristics
143
AT89C51ID2
Each timing symbol has 5 characters. The first character 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.
Example:T
(Load Capacitance for port 0, ALE and PSEN = 100 pF; Load Capacitance for all other
outputs = 80 pF.)
Table 98 Table 101, and Table 104 give the description of each AC symbols.
Table 99, Table 100, Table 102 and Table 105 gives the range for each AC parameter.
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
CCIV
T
LLPL
= 4T - x = 165 ns
= Time for ALE Low to PSEN Low.
Symbol
T
T
T
T
T
T
T
T
T
T
T
PLPH
LHLL
AVLL
LLAX
PLAZ
AVLL
LLPL
PLIV
PXIX
PXIZ
AVIV
LLIV
T
LLIU
= Time for Address Valid to ALE Low.
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
4289C–8051–11/05