CD74AC191 Datasheet, PDF (9/10 Pages) Texas Instruments – Presettable Synchronous 4-Bit Binary Up/Down Counter

CD74AC191, CD74ACT191
LOAD
P0
PRESET ^P1
INPUTS _P2
P3
CLOCK
DOWN/UP
ENABLE
Q0
Q1
Q2
Q3
TERMINAL COUNT
RIPPLE CLOCK
H
L
H
H
L
L
H
H
L
H
L
13 14 15 0 1 2
H
L
2 2 1 0 15 14 13
COUNT UP INHIBIT
LOAD
COUNT DOWN
Sequence:
1. Load (preset) to binary thirteen.
2. Count up to fourteen, fifteen, zero, one, and two.
3. Inhibit.
4. Count down to one, zero, fifteen, fourteen, and thirteen.
FIGURE 10. CD74AC191 DECODE COUNTERS TYPICAL LOAD, COUNT, AND INHIBIT SEQUENCES
DIRECTION
CONTROL
ENABLE
CLOCK
U/D
CE
CP TC
U/D
CE
CP TC
U/D
CE
CP TC
FIGURE 11. SYNCHRONOUS N-STAGE COUNTER WITH PARALLEL GATED TC/RC
DIRECTION
CONTROL
ENABLE
CLOCK
U/D RC
CE
CP
U/D RC
CE
CP
U/D RC
CE
CP
FIGURE 12. SYNCHRONOUS N-STAGE COUNTER USING RIPPLE TC/RC
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