The NE555 is a highly stable controller capable of producing accurate time delays or oscillation. It is arguably the most famous and widely used integrated circuit in the history of electronics. Since its introduction, it has become a staple for hobbyists and engineers alike due to its versatility, ease of use, and low cost. The IC can operate in three distinct modes: Monostable (one-shot), Astable (free-running), and Bistable (schmitt trigger). Whether you need to blink an LED, generate a Pulse Width Modulation (PWM) signal, or create a simple tone generator, the NE555 provides a reliable solution across a wide voltage range.
NE555 Pinout (DIP-8)
The NE555 is most commonly found in the 8-pin Dual In-line Package (DIP). When looking at the chip from the top with the notch or dot at the top, the pins are numbered 1 to 8 in a counter-clockwise direction.
| Pin | Terminal | Function |
| 1 | Ground (GND) | Connected to the negative supply (0V) |
| 2 | Trigger (TRIG) | Initiates the timing cycle when voltage drops below 1/3 Vcc |
| 3 | Output (OUT) | The output signal; can sink or source up to 200mA |
| 4 | Reset (RESET) | Resets the timer when connected to ground (active low) |
| 5 | Control Voltage (CONT) | Allows access to the internal voltage divider (usually bypassed) |
| 6 | Threshold (THRESH) | Ends the timing cycle when voltage exceeds 2/3 Vcc |
| 7 | Discharge (DISCH) | Used to discharge the timing capacitor through an open collector |
| 8 | VCC | Positive supply voltage (typically 4.5V to 15V) |
Technical Specifications
- Supply Voltage (VCC): 4.5V to 15V (up to 18V for some versions)
- Output Current (IOUT): 200mA (maximum sink or source)
- Power Dissipation (PD): 600mW
- Timing Range: Microseconds to hours
- Temperature Stability: 0.005% per °C
- Operating Temperature: 0°C to 70°C (NE series)
- Maximum Duty Cycle: Adjustable from 50% to 100% (Astable mode)
Key Features & Benefits
- High Drive Capability: The 200mA output allows the IC to drive small speakers, LEDs, and relays directly.
- Versatile Modes: Functions perfectly as a timer, oscillator, or flip-flop.
- Wide Supply Range: Operates on common voltages like 5V, 9V, and 12V.
- Adjustable Duty Cycle: Pulse widths can be precisely controlled using external resistors and capacitors.
Common Applications
- LED Flashers: Creating simple blinking lights or automotive turn signals.
- PWM Generation: Controlling the speed of DC motors or the brightness of LEDs.
- Tone Generators: Producing audible frequencies for alarms or musical instruments.
- Time Delay Circuits: Automatically turning off a device after a set duration.
NE555 Equivalent & Substitutes
- LM555 (Standard equivalent)
- TLC555 (CMOS version for low power/high frequency)
- NA555 (Industrial temperature version)
- NE556 (Dual version – two 555 timers in one 14-pin chip)
Related Tutorials on ElxHub
- Basics: Learn more in Integrated Circuits – Basics and Working
- PWM Control: Learn how to use timers in our DC Motor Speed Control Tutorial
- Selection Guide: Compare power options in our Ultimate IC Selection Guide
- Timer Tutorial: Learn how to use 555 IC in our Digital Timers and Oscillators Tutorial
- Calculator: Find the exact frequency and pulse width with our NE555 Timer Calculator
Conclusion
The NE555 timer is a masterpiece of analog design that remains relevant even in the age of microcontrollers. Its ability to provide precise timing with minimal external components makes it an essential chip for any electronics library. Whether you are a student learning the basics of oscillation or a professional building a robust industrial timer, the NE555 is a component you will reach for time and again.
Download the IC’s Datasheet pdf
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