AT89C51RC2-3CSIM datasheet(111/127 Pages) ATMEL

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111

AT89C51RB2/RC2

4180C–8051–12/03

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:TAVLL = Time for Address Valid to ALE Low.

TLLPL = 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 75 Table 78, and Table 80 give the description of each AC symbols.

Table 77, Table 79 and Table 81 give the AC parameterfor each range.

Table 76, Table 77 and Table 82 gives the frequency derating formula of the AC param-

eter 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

LLIU for -M and 20 MHz, Standard clock.

x = 35 ns

T 50 ns

CCIV = 4T - x = 165 ns

External Program Memory

Characteristics

Table 75. Symbol Description

Symbol

Parameter

Oscillator clock period

TLHLL

ALE pulse width

TAVLL

Address Valid to ALE

TLLAX

Address Hold after ALE

TLLIV

ALE to Valid Instruction In

TLLPL

ALE to PSEN

TPLPH

PSEN Pulse Width

TPLIV

PSEN to Valid Instruction In

TPXIX

Input Instruction Hold after PSEN

TPXIZ

Input Instruction Float after PSEN

TAVIV

Address to Valid Instruction In

TPLAZ

PSEN Low to Address Float

AT89C51RC2-3CSIM Datasheet(PDF) 111 Page - ATMEL Corporation

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