Datasheet

124
AT89C51AC3
4383D–8051–02/08
AC Parameters
Explanation of the AC
Symbols
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
AVLL
= Time for Address Valid to ALE Low.
T
LLPL
= Time for ALE Low to PSEN Low.
T A = -40°C to +85°C; V
SS
= 0V; V
CC
= 3V to 5.5V; F = 0 to 40 MHz.
(Load Capacitance for port 0, ALE and PSEN = 60 pF; Load Capacitance for all other
outputs = 60 pF.)
Table 73, Table 76 and Table 79 give the description of each AC symbols.
Table 74, Table 78 and Table 80 give for each range the AC parameter.
Table 75, Table 78 and Table 81 give the frequency derating formula of the AC parame-
ter for each speed range description. To calculate each AC symbols: Take the x value
and use this value in the formula.
Example: T
LLIV
and 20 MHz, Standard clock.
x = 30 ns
T = 50 ns
T
CCIV
= 4T - x = 170 ns