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Ac characteristics, External program and data memory characteristics, At89c51rc – Rainbow Electronics AT89C51RC User Manual

Page 19

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AT89C51RC

19

AC Characteristics

Under operating conditions, load capacitance for Port 0, ALE/PROG, and PSEN = 100 pF; load capacitance for all other
outputs = 80 pF.

External Program and Data Memory Characteristics

Symbol

Parameter

12 MHz Oscillator

Variable Oscillator

Units

Min

Max

Min

Max

1/t

CLCL

Oscillator Frequency

0

33

MHz

t

LHLL

ALE Pulse Width

127

2t

CLCL

-40

ns

t

AVLL

Address Valid to ALE Low

43

t

CLCL

-25

ns

t

LLAX

Address Hold after ALE Low

48

t

CLCL

-25

ns

t

LLIV

ALE Low to Valid Instruction In

233

4t

CLCL

-65

ns

t

LLPL

ALE Low to PSEN Low

43

t

CLCL

-25

ns

t

PLPH

PSEN Pulse Width

205

3t

CLCL

-45

ns

t

PLIV

PSEN Low to Valid Instruction In

145

3t

CLCL

-60

ns

t

PXIX

Input Instruction Hold after PSEN

0

0

ns

t

PXIZ

Input Instruction Float after PSEN

59

t

CLCL

-25

ns

t

PXAV

PSEN to Address Valid

75

t

CLCL

-8

ns

t

AVIV

Address to Valid Instruction In

312

5t

CLCL

-80

ns

t

PLAZ

PSEN Low to Address Float

10

10

ns

t

RLRH

RD Pulse Width

400

6t

CLCL

-100

ns

t

WLWH

WR Pulse Width

400

6t

CLCL

-100

ns

t

RLDV

RD Low to Valid Data In

252

5t

CLCL

-90

ns

t

RHDX

Data Hold after RD

0

0

ns

t

RHDZ

Data Float after RD

97

2t

CLCL

-28

ns

t

LLDV

ALE Low to Valid Data In

517

8t

CLCL

-150

ns

t

AVDV

Address to Valid Data In

585

9t

CLCL

-165

ns

t

LLWL

ALE Low to RD or WR Low

200

300

3t

CLCL

-50

3t

CLCL

+50

ns

t

AVWL

Address to RD or WR Low

203

4t

CLCL

-75

ns

t

QVWX

Data Valid to WR Transition

23

t

CLCL

-30

ns

t

QVWH

Data Valid to WR High

433

7t

CLCL

-130

ns

t

WHQX

Data Hold after WR

33

t

CLCL

-25

ns

t

RLAZ

RD Low to Address Float

0

0

ns

t

WHLH

RD or WR High to ALE High

43

123

t

CLCL

-25

t

CLCL

+25

ns