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
Active low output pin
Active Low Multivibrator input 1
Active Low Multivibrator input 2
Schmitt Trigger Input
Active high output
Pin to connect Rint resistance
Pin to connect Cext capacitance
Pin to connect Rext/Cext resistance/capacitance
Chip Supply Voltage
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.