at89c51rd2-smsum ATMEL Corporation, at89c51rd2-smsum Datasheet - Page 117

• Manufacturer Part Number: at89c51rd2-smsum
• Description: 8-bit Flash Microcontroller
• Manufacturer: ATMEL Corporation

25.3
25.3.1
4235J–8051–01/08
AC Parameters
Explanation of the AC Symbols
Figure 25-4. Clock Signal Waveform for I
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
(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
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
x = 35 ns
T 50 ns
T
CCIV
= 4T - x = 165 ns
T
25-2, Table 25-3, Table 25-5 and Table 25-8 gives the range for each AC parameter.
LLPL
AVLL
LLIU
= Time for ALE Low to PSEN Low.
= Time for Address Valid to ALE Low.
for -M and 20 MHz, Standard clock.
V
CC
T
-0.5V
0.45V
CHCL
T
CLCH
= T
CHCL
CC
Tests in Active and Idle Modes
= 5ns.
T
CLCH
0.7V
0.2V
CC
CC
-0.1
AT89C51RD2/ED2
117