Introduction
The NE555 is a highly popular and versatile integrated circuit (IC) used as a timer, oscillator, and flip-flop in various electronic applications. Invented in 1972 by Hans R. Camenzind for Signetics, it has since become a staple in both hobbyist and professional electronics projects due to its reliability, simplicity, and low cost.
The NE555 operates in three primary modes:
- Monostable mode: Produces a single output pulse of a precise duration after being triggered.
- Astable mode: Functions as an oscillator, generating a continuous square wave.
- Bistable mode: Acts as a flip-flop with two stable states controlled by external signals.
With just a few external components (resistors and capacitors), the NE555 can achieve functions like delay timing, pulse generation, waveform creation, and frequency modulation. It works over a wide range of voltages (4.5V to 15V) and can drive loads up to 200mA, making it suitable for applications like LED flashers, tone
Pinout of NE555
| Pin Number | Pin Name & Description |
|---|---|
| 1 | GND - Ground connection (0V). |
| 2 | TRIG - Trigger input; starts the timing cycle when voltage drops below 1/3 of VCC. |
| 3 | OUT - Output pin; provides high or low signal based on the mode of operation. |
| 4 | RESET - Resets the timing cycle; active low. Connect to VCC if unused. |
| 5 | CV - Control Voltage; adjusts internal thresholds. Typically connected to GND via a 10nF capacitor. |
| 6 | THR - Threshold input; ends the timing cycle when voltage exceeds 2/3 of VCC. |
| 7 | DISCH - Discharge pin; used to discharge the external capacitor. |
| 8 | VCC - Positive power supply (4.5V to 15V). |
Key Features
- Operating Voltage: 4.5V to 15V (some variants work up to 18V).
- Output Current: Up to 200mA.
- Operating Modes:
- Monostable Mode: Generates a single pulse of a specific duration when triggered.
- Astable Mode: Operates as an oscillator, generating a continuous square wave.
- Bistable Mode: Functions as a flip-flop with two stable states.
- Adjustable Frequency and Duty Cycle: Configurable using external resistors and capacitors.
Applications
- Timers: Delaying or timing events.
- Oscillators: Generating square waves or PWM signals.
- Pulse Width Modulators: Used in motor control and signal processing.
- Tone Generators: For audio and alarms.
- LED/Lamp Flashers: Flashing lights for indicators or decorative purposes.
{getButton} $text={Dowload Datasheet} $icon={download} $color={#346eeb}