Datasheet

117
4235K–8051–05/08
AT89C51RD2/ED2
Figure 25-4. Clock Signal Waveform for I
CC
Tests in Active and Idle Modes
25.3 AC Parameters
25.3.1 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 sta-
tus 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.
(Load Capacitance for port 0, ALE and PSEN = 100 pF; Load Capacitance for all other outputs =
80 pF.)
Table 25-1 Table 25-4, and Table 25-7 give the description of each AC symbols.
Table 25-2, Table 25-3, Table 25-5 and Table 25-8 gives the range for each AC parameter.
Table 25-2, Table 25-3 and Table 25-9 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 corre-
ponding column (-M) and use this value in the formula.
Example: T
LLIU
for -M and 20 MHz, Standard clock.
x = 35 ns
T 50 ns
T
CCIV
= 4T - x = 165 ns
V
CC
-0.5V
0.45V
0.7V
CC
0.2V
CC
-0.1
T
CLCH
T
CHCL
T
CLCH
= T
CHCL
= 5ns.