AT89C51IC2-RLTIM ATMEL [ATMEL Corporation], AT89C51IC2-RLTIM Datasheet - Page 132

• Manufacturer Part Number: AT89C51IC2-RLTIM
• Description: 8-bit Flash Microcontroller with 2-wire Interface
• Manufacturer: ATMEL [ATMEL Corporation]

AC Parameters
Explanation of the AC
Symbols
External Program Memory
Characteristics
132
AT89C51IC2
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 94 Table 97, and Table 99 give the description of each AC symbols.
Table 96, Table 98 and Table 100 give the AC parameterfor each range.
Table 95, Table 96 and Table 101 gives 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 94. 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
LLPL
PLAZ
AVLL
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
4301C–8051–06/06