DS80C310

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AC ELECTRICAL CHARACTERISTICS (Note 1)

25MHz

VARIABLE

CLOCK

PARAMETER

SYMBOL

MIN

MAX

MIN

MAX

UNITS

External Oscillator

0

25

0

25

Oscillator

Frequency

External Crystal

1

25

1

25

MHz

ALE Pulse Width

40

5

ns

Port 0 Address Valid to ALE Low

10

5

ns

Address Hold after ALE Low

2

(Note 2)

18

(Note 2)

ns

ALE Low to Valid Instruction In

56

20

ns

ALE Low to

PSEN Low

7

13

ns

PSEN Pulse Width

55

ns

PSEN Low to Valid Instruction In

41

20

ns

Input Instruction Hold after

PSEN

0

0

ns

Input Instruction Float after

PSEN

26

ns

Port 0 Address to Valid Instruction In

71

20

ns

Port 2 Address to Valid Instruction In

81

25

ns

PSEN Low to Address Float

(Note 2)

(Note 2)

ns

Note 1:

All parameters apply to both commercial and industrial temperature operation unless otherwise noted. Specifications to -40

C

are guaranteed by design and not product tested. AC electrical characteristics assume 50% duty cycle for the oscillator, and

are not 100% tested but are guaranteed by design. All signals characterized with load capacitance of 80pF except Port 0, ALE,

PSEN, and WR with 100pF. Interfacing to memory devices with float times (turn-off times) over 25ns can cause contention.

This does not damage the parts, but rather causes an increase in operating current. Port 2 and ALE timing changes in relation

to duty cycle variation.

Note 2:

Address is held in a weak latch until overdriven by external memory.