Atmel AT89C51ID2 Data Sheet - Keil

External Program Memory
Characteristics
4289A–8051–09/03
AT89C51ID2
Table 98, Table 99 and Table 105 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: TLLIU for -M and 20 MHz, Standard clock.
x = 35 ns
T 50 ns
TCCIV = 4T - x = 165 ns
Table 97. Symbol Description
Symbol Parameter
T Oscillator clock period
T LHLL
T AVLL
T LLAX
T LLIV
T LLPL
T PLPH
T PLIV
T PXIX
T PXIZ
T AVIV
T PLAZ
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
Table 98. AC Parameters for a Fix Clock
Symbol -M -L Units
Min Max Min Max
T 25 25 ns
T LHLL 35 35 ns
T AVLL 5 5 ns
T LLAX 5 5 ns
T LLIV n 65 65 ns
T LLPL 5 5 ns
T PLPH 50 50 ns
T PLIV 30 30 ns
T PXIX 0 0 ns
T PXIZ 10 10 ns
T AVIV 80 80 ns
T PLAZ 10 10 ns
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