SYNCHRONOUS 4-BIT UP/DOWN DECADE AND BINARY COUNTERSThe ALS190 and ALS191 are synchronous,
reversible up/down Counters The ALSL90 is a
4-bit decade Counter and the ALS191 is a 4-bit
binary Counter Synchronous counting operation
is provided by having all Flip-Flops clocked
simultaneously so that the outputs change
coincident with each other when so 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 input if
the enable input CTEN 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.
These Counters feature a fully independent Clock circuit. Changes at the control inputs (CTEN and D/U) that will
modify the operating mode have no effect on the contents of the Counter until clocking occurs. The function of
the Counter will be dictated solely by the condition meeting the stable setup and hold times.
These Counters are fully programmable; that is, the outputs may each be preset to either level by placing a low
on the load input and entering the desired data at the data inputs. The output will change to agree with the data
inputs independently of the level of the Clock input. This feature allows the Counters to be used as modulo-N
dividers by simply modifying the count length with the preset inputs.
The CLK, D/U, and LOAD inputs are buffered to lower the drive requirement, which significantly reduces the
loading on, or current required by, Clock Drivers etc., for long parallel words. By Texas Instruments
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SN74ALS190 Pb-Free | SN74ALS190 Cross Reference | SN74ALS190 Schematic | SN74ALS190 Distributor |
SN74ALS190 Application Notes | SN74ALS190 RoHS | SN74ALS190 Circuits | SN74ALS190 footprint |