74LS121 Monostable Multivibrator IC With Schmitt Trigger Inputs

74LS121 Monostable Multivibrator IC With Schmitt Trigger Inputs

The 74LS121 is a monostable Multi-vibrator with Schmitt-trigger inputs that features dual negative-transition-triggered inputs and a single positive-transition-triggered input which can be used as an inhibit input. The 74LS121 IC has a wide range of working voltage, a wide range of working conditions, and directly interfaces with CMOS, NMOS, and TTL. The output of the IC always comes in TTL which makes it easy to work with other TTL devices and microcontrollers.

What is a Monostable Multivibrator?

A monostable multivibrator (MMV), often called a one-shot multivibrator, is a pulse generator circuit in which the duration of the pulse is determined by the R-C network, connected externally to the 555 timers. In such a vibrator, one state of output is stable while the other is quasi-stable (unstable). For auto-triggering of output from a quasi-stable state to a stable state, energy is stored by an externally connected capaci­tor to a reference level. The time taken in storage determines the pulse width.

74LS121 Key Features & Specifications

  • Logic Family / Base Number: TTL121 
  • Multivibrator Type: Monostable 
  • Output Current: 16mA 
  • Supply Voltage Min: 4.75V 
  • Supply Voltage Max: 5.25V 
  • Logic Case Style: DIP 
  • No. of Pins: 14Pins 
  • Propagation Delay: 45ns 
  • Logic IC Family: TTL 
  • Logic IC Base Number: 74121 
  • Operating Temperature Min: 0°C 
  • Operating Temperature Max: 70°C

74LS121 Pinout

Pin No.Pin NameDescription
1Q’Active low output pin
2NCNot used
3A1′Active Low Multivibrator input 1
4A2′Active Low Multivibrator input 2
5BSchmitt Trigger Input
6QActive high output
7GNDGround pin
8NCNot used
9RintPin to connect Rint resistance
10CextPin to connect Cext capacitance
11Rext/CextPin to connect Rext/Cext resistance/capacitance
12NCNot Used
13NCNot Used
14VccChip Supply Voltage
74ls121 pinout


The 74LS121 IC has a number of uses , some of them are listed as below:

  • monostable multivibrators are used as timers, delay circuits, gated circuits, etc.

74LS121 Datasheet

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  • Views: 161
  • Product Code: 74LS121
  • Availability: In Stock
  • KES 200.00

Tags: 74LS121, Monostable Multivibrator

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