The 74LS221 are monolithic dual multivibrators with performance characteristics virtually identical to those of the 74LS121 devices. Each multivibrator features a negative transition triggered input and a positive transition triggered input, either of which can be used as an inhibit input. The 74LS221 IC has a wide range of working voltage, a wide range of working conditions, and directly interfaces with CMOS, NMOS, and TTL configurations. 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.
74LS221 Pinout
74LS221 Pin Configuration
| Pin No | Pin Name | Description |
|---|---|---|
| 1 | 1A’ | Active Low 1st Multivibrator input A |
| 2 | 1B | 1st Multivibrator input B |
| 3 | CLR1′ | Active low clear pin 1 |
| 4 | 1Q’ | Active low output pin |
| 5 | 2Q | output pin |
| 6 | 2 Cext | Pin to connect Cext capacitance |
| 7 | 2Rext/Cext | Pin to connect Rext/Cext resistance/capacitance |
| 8 | GND | Ground Pin |
| 9 | 2A’ | Active Low 2nd Multivibrator input A |
| 10 | 2B | 2nd Multivibrator input B |
| 11 | 2CLR’ | Active low clear pin 2 |
| 12 | 2Q’ | Active low output pin |
| 13 | 1Q | output pin |
| 14 | Cext 1 | Pin to connect Cext capacitance |
| 15 | 1 Rext/Cext | Pin to connect Rext/Cext resistance/capacitance |
| 16 | Vcc | Chip Supply voltage |
74LS221 Features & Specifications
- Channels (#): 2
- Technology Family: LS
- VCC (Min): 4.75V
- VCC (Max): 5.25V
- Input type: Schmitt-Trigger
- Output type: Push-Pull
- IOL (Max): 8mA
- IOH (Max): -0.4mA
- Standard speed: (tpd > 50ns)
- Overriding Clear Terminates Output Pulse
- Propagation Delay: 45ns
- Logic IC Family: TTL
- Logic IC Base Number: 74221
- Operating Temperature Min: 0°C
- Operating Temperature Max: 70°C
Applications
- It is generally used in devices such as delay timers & gated circuits, etc.
You can download this datasheet for the 74LS221 Dual Monostable Multivibrator IC With Schmitt Trigger Inputs from the link given below:
See Also: 74LS68 Dual 4-Bit Decade/Binary Counter IC – Datasheet | 74LS46 BCD – 7 Segment Decoder IC – Datasheet | 74LS04 Hex Inverter IC / NOT Gate IC – Datasheet
