HD74LS390 Datasheet, PDF (2/6 Pages) Hitachi Semiconductor – Dual Decade Counters

HD74LS390
Function Table
BCD Count Sequence (Notes 1)
Count
Outputs
Q_D
Q_C
Q_B
Q_A
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
L
H
L
H
6
L
H
H
L
7
L
H
H
H
8
H
L
L
L
9
H
L
L
H
Bi-quinary (Notes 2)
Count
Outputs
Q_A
Q_D
Q_C
Q_B
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
H
L
H
L
8
H
L
H
H
9
H
H
L
L
Notes: 1. Output Q_A is connected to input B for BCD count.
2. Output Q_D is connected to input A for bi-quinary count.
3. H; high level, L; low level, X; irrelevant
Rev.4.00, May 10, 2006, page 2 of 5