The 74LS series of integrated circuits (ICs) was one of the most popular logic families of transistor-transistor logic (TTL) logic chips. 74LS series is a bipolar, low-power Schottky IC. The 74LS221 device is a dual multivibrator with performance characteristics virtually identical to those of the ’121 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.
74LS221 Features
- Dual, Highly Stable One-Shot
- Pinout Identical to 74LS123
- Hysteresis Inputs
- Direct Reset Terminated Output Pulse
- Standard TTL Switching Voltages
74LS221 Specifications
| Supply Voltage | 4.75 – 5.25Vdc |
| Maximum Clock Frequency | 40Mhz |
| Power Dissipation | 2mW/gate @100kHz |
| Minimum Output Current | 8mA |
| Propagation Delay | 10nS |
| Fan Out (TTL Loads) | 20 |
74LS221 Pinout Diagram
74LS221 Pin Description
| Pin No | Pin Name | Description |
| 1 | 1A | Input 1 Of Schmitt Trigger 1 |
| 2 | 1B | Input 2 Of Schmitt Trigger 1 |
| 3 | 1 CLR | Clear Pin 1 |
| 4 | 1Q | Output Of Schmitt Trigger 1 |
| 5 | 2Q | Output Of Schmitt Trigger 2 |
| 6 | 2 C(ext) | External Capacitor 2 |
| 7 | 2 R(ext)/C(ext) | External Capacitor/Resistor 2 |
| 8 | GND | Ground |
| 9 | 2A | Input 1 Of Schmitt Trigger 2 |
| 10 | 2B | Input 2 Of Schmitt Trigger 2 |
| 11 | 2 CLR | Clear Pin 2 |
| 12 | 2Q’ | Invert Output Of Schmitt Trigger 2 |
| 13 | 1Q’ | Invert Output Of Schmitt Trigger 1 |
| 14 | 1 C(ext) | External Capacitor 1 |
| 15 | 1 R(ext)/C(ext) | External Capacitor/Resistor 1 |
| 16 | VCC | Positive Supply |
Applications
- Increase the noise immunity in a circuit with only a single input threshold
74LS221 Alternative Equivalent
Download 74LS221 Dual Mono. Multivibrator Schmitt Trigger Datasheet from the link given below.
