87C5180C51BH80C31BH

EXTERNAL MEMORY CHARACTERISTICS

All parameter values apply to all devices unless otherwise indicated In this table 87C51BH refers to

87C51BH 87C51-1BH-1 and 87C51-2BH-2 (Continued)

Symbol

Parameter

Oscillator

Units

12 MHz

24 MHz

Variable

Min

Max

Min

Max

Min

Max

TPXIX

Input Instr Hold After PSEN

00

0

ns

TPXIZ

Input Instr Float After PSEN

87C51BH

59

TCLCLb25

ns

87C51-24BH-24

21

TCLCLb20

ns

TAVIV

Address to Valid Instr In

312

103

5TCLCLb105

ns

TPLAZ

PSEN Low to Address Float

10

10

10

ns

TRLRH

RD Pulse Width

400

150

6TCLCLb100

ns

TWLWH

WR Pulse Width

400

150

6TCLCLb100

ns

TRLDV

RD Low to Valid Data In

87C51BH

252

5TCLCLb165

ns

87C51-24BH-24

113

5TCLCLb95

ns

TRHDX

Data Hold After RD

00

0

ns

TRHDZ

Data Float After RD

107

23

2TCLCLb60

ns

TLLDV

ALE Low to Valid Data In

87C51BH

517

8TCLCLb150

ns

87C51-24BH-24

243

8TCLCLb90

ns

TAVDV

Address to Valid Data In

87C51BH

585

9TCLCLb165

ns

87C51-24BH-24

285

9TCLCLb90

ns

TLLWL

ALE Low to RD or WR Low

200

300

75

175

3TCLCLb50

3TCLCLa 50

ns

TAVWL

Address to RD or WR Low

87C51BH

203

4TCLCLb130

ns

87C51-24BH-24

77

4TCLCLb90

ns

TQVWX

Data Valid to WR Transition

87C51BH

33

TCLCLb50

ns

80C51-24BH-24

12

TCLCLb30

ns

13