© Semiconductor Components Industries, LLC, 1999

December, 1999 – Rev. 6

1

Publication Order Number:

SN74LS221/D

SN74LS221

Dual Monostable

Multivibrators with

Schmitt-Trigger Inputs

Each multivibrator of the LS221 features a negative-transition-

triggered input and a positive-transition-triggered input either of

which can be used as an inhibit input.

Pulse triggering occurs at a voltage level and is not related to the

transition time of the input pulse. Schmitt-trigger input circuitry for B

input allows jitter-free triggering for inputs as slow as 1 volt / second,

providing the circuit with excellent noise immunity. A high immunity

Once triggered, the outputs are independent of further transitions of

the inputs and are a function of the timing components. The output

pulses can be terminated by the overriding clear. Input pulse width

may be of any duration relative to the output pulse width. Output pulse

width may be varied from 35 nanoseconds to a maximum of 70 s by

= 0, a typical output pulse of 30 nanoseconds is achieved. Output rise

and fall times are independent of pulse length.

Pulse width stability is achieved through internal compensation and

pulse stability will only be limited by the accuracy of external timing

components.

ranges for greater than six decades of timing capacitance (10 pF to 10

µF), and greater than one decade of timing resistance (2.0 to 100 kΩ

for the SN74LS221). Pulse width is defined by the relationship:

1000

µF and resistance as low as 1.4 kΩ may be used. The range of

temperature.

GUARANTEED OPERATING RANGES

Symbol

Parameter

Min

Typ

Max

Unit

Supply Voltage

4.75

5.0

5.25

V

Operating Ambient

Temperature Range

0

25

70

°C

Output Current – High

– 0.4

mA

Output Current – Low

8.0

mA

LOW

POWER

SCHOTTKY

Device

Package

Shipping

ORDERING INFORMATION

SN74LS221N

16 Pin DIP

2000 Units/Box

SN74LS221D

16 Pin

SOIC

D SUFFIX

CASE 751B

http://onsemi.com

2500/Tape & Reel

PLASTIC

N SUFFIX

CASE 648

16

1

16

1