Specification	SN74ALS191AN

Count Rate	30 MHz
Direction	Up, Down
Logic Type	Binary Counter
Mounting Type	Through Hole
Number of Bits per Element	4
Number of Elements	1
Operating Temperature [Max]	70 °C
Operating Temperature [Min]	0 °C
Package / Case	0.3 in
Package / Case	16-DIP
Package / Case	7.62 mm
Supplier Device Package	16-PDIP
Timing	Synchronous
Trigger Type	Positive Edge
Voltage - Supply [Max]	5.5 V
Voltage - Supply [Min]	4.5 V

SN74ALS191A Series

4-Bit Synchronous Up/Down Binary Counters

Part	Operating Temperature [Max]	Voltage - Supply [Min]	Voltage - Supply [Max]	Number of Elements	Mounting Type	Count Rate	Trigger Type	Supplier Device Package	Logic Type	Timing	Number of Bits per Element	Direction	Package / Case	Package / Case	Package / Case	Package / Case [x]	Package / Case [y]
Texas Instruments SN74ALS191ANG4	70 °C	4.5 V	5.5 V	1	Through Hole	30 MHz	Positive Edge	16-PDIP	Binary Counter	Synchronous	4	Down Up	0.3 in	16-DIP	7.62 mm
Texas Instruments SN74ALS191ANSR	70 °C	4.5 V	5.5 V	1	Surface Mount	30 MHz	Positive Edge	16-SO	Binary Counter	Synchronous	4	Down Up	0.209 "	16-SOIC	5.3 mm
Texas Instruments SN74ALS191AN	70 °C	4.5 V	5.5 V	1	Through Hole	30 MHz	Positive Edge	16-PDIP	Binary Counter	Synchronous	4	Down Up	0.3 in	16-DIP	7.62 mm
Texas Instruments SN74ALS191ADR	70 °C	4.5 V	5.5 V	1	Surface Mount	30 MHz	Positive Edge	16-SOIC	Binary Counter	Synchronous	4	Down Up		16-SOIC		0.154 in	3.9 mm

Pricing

Prices provided here are for design reference only. For realtime values and availability, please visit the distributors directly

Distributor	Package	Quantity	$

Arrow	N/A	25	$ 1.89
Digikey	Tube	375	$ 2.64
Texas Instruments	TUBE	1	$ 3.28
		100	$ 2.88
		250	$ 2.02
		1000	$ 1.63

Description

General part information

SN74ALS191A Series

The 'ALS191A are synchronous 4-bit reversible up/down binary counters. Synchronous counting operation is provided by having all flip-flops clocked simultaneously so that the outputs change coincidentally 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 () input is low. A high atinhibits 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, the counter counts down.

These counters feature a fully independent clock circuit. Changes at the control inputs (and D/U\) that modify the operating mode have no effect on the contents of the counter until clocking occurs. The function of the counter is dictated solely by the conditions meeting the stable setup and hold times.

Documents

Technical documentation and resources

Synchronous 4-Bit Up/Down Binary Counters datasheet (Rev. C)

Data sheet