AUTOMOTIVE 80C51FA83C51FA

EXPLANATION OF THE AC SYMBOLS

Each timing symbol has 5 characters The first char-

acter 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

A Address

C Clock

D Input Data

H Logic level HIGH

I Instruction (program memory contents)

L Logic level LOW or ALE

P PSEN

Q Output Data

R RD signal

T Time

V Valid

W WR signal

X No longer a valid logic level

Z Float

For example

for Port 0 ALEPROG and PSEN e 100 pF Load Capacitance for All Other Outputs e 80 pF)

EXTERNAL MEMORY CHARACTERISTICS

Symbol

Parameter

12 MHz Oscillator

Variable Oscillator

Units

Min

Max

Min

Max

Oscillator Frequency

35

16

MHz

ALE Pulse Width

127

ns

Address Valid to ALE Low

43

ns

Address Hold After ALE Low

53

ns

ALE Low to Valid Instruction In

224

ns

ALE Low to PSEN Low

53

ns

PSEN Pulse Width

205

ns

PSEN Low to Valid Instruction In

135

ns

Input Instr Hold After PSEN Trans

0

0

ns

Input Instr Float After PSEN Trans

59

ns

Address to Valid Instruction In

302

ns

PSEN Low to Address Float

10

10

ns

RD Pulse Width

400

ns

WR Pulse Width

400

ns

RD Low to Valid Data In

242

ns

Data Hold After RD High

b

10

b

10

ns

Data Float After RD High

107

ns

ALE Low to Valid Data In

507

ns

Address Valid to Valid Data In

575

ns

ALE Low to RD or WR Low

200

300

ns

Data Valid to WR Low

203

ns

Address Valid before WR Low

23

ns

Data Hold after WR High

33

ns

Data Valid to WE High

433

ns

RD Low to Address Float

0

0

ns

RD or WR High to ALE High

43

123

ns

10