HD74LS191 Datasheet, PDF (6/11 Pages) Hitachi Semiconductor – Synchronous Up/Down 4-bit Binary Counters(single clock line)

HD74LS191
Count Sequences
Load
A
B
C
D
Clock
Down/Up
Enable G
Q_A
Q_B
Q_C
Q_D
Max/Min
Ripple
Clock
13 14 15 0 1 2
2
1 0 15 14 13
Load
Count Up
Inhibit
Count Down
Illustrated below is the following sequence:
1. Load (preset) to binary thirteen.
2. Count up to fourteen, fifteen (maximum), zero, one and two.
3. Inhibit
4. Count down to one, zero (minimum), fifteen, fourteen, and thirteen.
Rev.2.00, Feb.18.2005, page 6 of 10