DM7490A Просмотр технического описания (PDF) - Fairchild Semiconductor
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DM7490A Datasheet PDF : 5 Pages
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Function Tables (Note 1)
BCD Count Sequence (Note 2)
Count
Outputs
QD QC QB QA
0
L
L
L
L
1
L
L
L
H
2
L
L
H
L
3
L
L
H
H
4
L
H
L
L
5
LHLH
6
LHHL
7
L HHH
8
H
L
L
L
9
H
L
L
H
Logic Diagram
BCD Bi-Quinary (5-2) (Note 3)
Count
Outputs
QA QD QC QB
0
L
L
L
L
1
L
L
L
H
2
L
L
H
L
3
L
L
H
H
4
L
H
L
L
5
H
L
L
L
6
H
L
L
H
7
HLHL
8
H L HH
9
HH
L
L
Reset/Count Function Table
R0(1)
H
H
X
X
L
L
X
Reset Inputs
R0(2) R9(1)
H
L
H
X
X
H
L
X
X
L
X
X
L
L
R9(2)
X
L
H
L
X
L
X
Outputs
QD QC QB QA
LLLL
LLLL
HL LH
COUNT
COUNT
COUNT
COUNT
Note 1: H = High Level, L = Low Level, X = Don’t Care.
Note 2: Output QA is connected to input B for BCD count.
Note 3: Output QD is connected to input A for bi-quinary count.
The J and K inputs shown without connection are for
reference only and are functionally at a high level.
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