SN54HC191J ,Synchronous 4-Bit Up/Down Binary Counters SCLS121D − DECEMBER 1982 − REVISED OCTOBE ..
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SN54HC191J-SNJ54HC191J
Synchronous 4-Bit Up/Down Binary Counters
±4-mA Output Drive at 5 V
Low Input Current of 1 µA Max Single Down/Up Count-Control Line Look-Ahead Circuitry Enhances Speed ofCascaded Counters Fully Synchronous in Count Modes Asynchronously Presettable With Load
Control
description/ordering informationThe ’HC191 devices are 4-bit synchronous,
reversible, up/down binary counters.
Synchronous counting operation is provided by
having all flip-flops clocked simultaneously so that
the outputs change coincident with each other
when instructed by the steering logic. This mode
of operation eliminates the output counting spikes
normally associated with asynchronous
(ripple-clock) counters.
The outputs of the four flip-flops are triggered on
a low- to high-level transition of the clock (CLK)
input if the count-enable (CTEN) input is low. A
high at CTEN inhibits counting. The direction of
the count is determined by the level of the
down/up (D/U) input. When D/U is low, the counter
counts up, and when D/U is high, it counts down.
ORDERING INFORMATION†Package drawings, standard packing quantities, thermal data, symbolization, and PCB design guidelines are
available at www.ti.com/sc/package.
CTEN
D/UC
GND
CLK
RCO
MAX/MIN
LOAD
CLK
RCO
MAX/MIN
LOAD
CTEN
D/UCBNCCA
GND
SN54HC191... FK PACKAGE
(TOP VIEW)NC − No internal connection
