NE555 PDF – Timer IC ( Datasheet, Pinout ) – Philips

A Timer IC, short for Timer Integrated Circuit, is an electronic component that is designed to generate accurate and stable time delays or timing signals. Timer ICs are widely used in various electronic applications where precise timing is essential, such as in oscillators, pulse generators, frequency dividers, and time-delay circuits.

One of the most well-known and commonly used timer ICs is the 555 Timer IC, which comes in different variations such as the NE555, LM555, and more. The 555 Timer IC is versatile and can be configured in various modes, making it suitable for a wide range of timing applications. It’s often referred to as a “universal timer” due to its popularity and widespread use.

The 555 Timer IC has three operating modes:

1. Monostable Mode (One-Shot): In this mode, the 555 timer acts as a one-shot pulse generator. When triggered, it produces a single output pulse with a duration determined by external components. This mode is often used for generating precise time delays.

2. Astable Mode (Oscillator): In this mode, the 555 timer operates as an oscillator, generating a continuous square wave output. The frequency and duty cycle of the output waveform are determined by external components. This mode is commonly used for generating clock signals or square wave oscillations.

3. Bistable Mode (Flip-Flop): In this mode, the 555 timer functions as a flip-flop circuit with two stable states. External signals trigger the transition between these states. It can be used for applications like toggling between two states.

Part Number: NE555, NE555D, NE555N

Function: Timer

Package: DIP, SO 8 Pin type

Manufacturer: Philips

Images:NE555 pdf pinout


The NE555 monolithic timing circuit is a highly stable controller capable of producing accurate time delays, or oscillation. In the time delay mode of operation, the time is precisely controlled by one external resistor and capacitor. For a stable operation as an oscillator, the free running frequency and the duty cycle are both accurately controlled with two external resistors and one capacitor. The circuit may be triggered and reset on falling waveforms, and the output structure can source or sink up to 200 mA.


• Turn-off time less than 2 ms

• Max. operating frequency greater than 500 kHz

• Timing from microseconds to hours

• Operates in both astable and monostable modes

• High output current

• Adjustable duty cycle

• TTL compatible

• Temperature stability of 0.005% per °C

Block Diagram:

NE555 timer datasheet


• Precision timing

• Pulse generation

• Sequential timing

• Time delay generation

• Pulse width modulation […]

NE555 PDF Datasheet

NE555 pdf