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

TWHQX

Data Hold After WR

87C51BH

33

TCLCLb50

ns

87C51-24BH-24

7

TCLCLb35

ns

TQVWH

Data Valid to WR High

87C51BH

433

7TCLCLb150

ns

87C51-24BH-24

222

7TCLCLb70

ns

TRLAZ

RD Low to Address Float

0

0

0

ns

TWHLH

RD or WR High to ALE High

87C51BH

43

123

TCLCLb40

TCLCLa40

ns

87C51-24BH-24

12

71

TCLCLb30

TCLCLa30

ns

EXTERNAL PROGRAM MEMORY READ CYCLE

272335 – 12

EXTERNAL DATA MEMORY READ CYCLE

272335 – 13

14