Philips Semiconductors

Product specification

80C31/80C51/87C51

CMOS single-chip 8-bit microcontrollers

1996 Aug 16

13

AC ELECTRICAL CHARACTERISTICS FOR SC87C51 12–33MHz PHILIPS NORTH AMERICA DEVICES

SYMBOL

FIGURE

PARAMETER

MIN

MAX

UNIT

Oscillator frequency:

Speed Versions

SC87C51

C

G

P

Y

3.5

3.5

3.5

3.5

12

16

24

33

MHz

MHz

MHz

MHz

1

ALE pulse width

ns

1

Address valid to ALE low

ns

1

Address hold after ALE low

ns

1

ALE low to valid instruction in

ns

1

ALE low to PSEN low

ns

1

PSEN pulse width

ns

1

PSEN low to valid instruction in

ns

1

Input instruction hold after PSEN

0

ns

1

Input instruction float after PSEN

ns

1

Address to valid instruction in

ns

1

PSEN low to address float

10

ns

Data Memory

2, 3

RD pulse width

ns

2, 3

WR pulse width

ns

2, 3

RD low to valid data in

ns

2, 3

Data hold after RD

0

ns

2, 3

Data float after RD

ns

2, 3

ALE low to valid data in

ns

2, 3

Address to valid data in

ns

2, 3

ALE low to RD or WR low

ns

2, 3

Address valid to WR low or RD low

ns

2, 3

Data valid to WR transition

ns

2, 3

Data hold after WR

ns

2, 3

RD low to address float

0

ns

2, 3

RD or WR high to ALE high

ns

External Clock

5

High time

12

ns

5

Low time

12

ns

5

Rise time

20

ns

5

Fall time

20

ns

NOTES:

1. Parameters are valid over operating temperature range unless otherwise specified.

2. Load capacitance for port 0, ALE, and PSEN = 100pF, load capacitance for all other outputs = 80pF.

3. For all Philips North America speed versions only.

4. Interfacing the 87C51 to devices with float times up to 50ns is permitted. This limited bus contention will not cause damage to port 0 drivers.