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Startseite > Other > The Ultimate Guide to NE555N Timer: Pinout, Datasheet, and Schematic D

The Ultimate Guide to NE555N Timer: Pinout, Datasheet, and Schematic Diagram

Updatezeit: 2023-11-29 13:37:14


The NE555N timer, a distinguished electronic element, has left an indelible imprint on the field because of its sturdy construction and multipurpose capabilities. In the realm of electronic components, each with its unique function, the NE555N emerges as a universally useful and crucial device. This piece takes a detailed look at the inner workings of the NE555N timer, exploring its pin configuration, technical specifications from its datasheet, and associated circuit diagrams.

What is the NE555N timer?

The NE555N monolithic timing circuit is an exceptionally reliable controller for generating precise time delays or oscillations. When set in the time delay function, the duration is meticulously regulated by an external resistor and capacitor. The self-sustained frequency and duty cycle are finely tuned for dependable oscillator performance using two external resistors and a single capacitor. The circuit can initiate and reset through descending signals, and its output mechanism can supply or drain up to 200 mA. The NE555N belongs to the NE555 series. It is a timing circuit that controls the duration through an oscillation circuit. It comes in an 8-PIN Dual In-line Package (DIP) made of plastic.

NE555N Pinout

NE555N Pinout.jpg

Pin Configuration

  • Pin 1 (GND): Ground terminal, connected to the negative supply.

  • Pin 2 (TRIG): Trigger terminal, the input to the lower comparator.

  • Pin 3 (OUT): Output terminal, can drive up to 200mA.

  • Pin 4 (RESET): Reset terminal, when connected to a low voltage, it can reset the timer.

  • Pin 5 (CV): Control Voltage terminal, used for modulation purposes.

  • Pin 6 (THRS): Threshold terminal, the input to the upper comparator.

  • Pin 7 (DISCH): Discharge terminal, connected directly to a transistor.

  • Pin 8 (VCC): Supply voltage terminal, typically ranges from 4.5V to 15V.

NE555N Features

  • Swift deactivation time

  • Peak operating frequency exceeds 500 kHz

  • Capable of timing durations ranging from microseconds to hours

  • Functions in both astable and monostable configurations

  • Output can either supply or drain up to 200 mA

  • Modifiable duty cycle

  • Compatible with TTL

  • Thermal stability at 0.005% per °C

  • Outputs include both default-on and default-off states

  • Serves as a direct alternative for SE555/NE555.

Technical Specifications

  • Operating Modes: Astable, Monostable

  • Number of Timers: 1

  • Clock, External Input: No

  • Frequency: 500kHz

  • Power Supply Voltage Range: 4.5-16V

  • Package Format: DIP

  • Pin Count: 8

  • Operating Temperature Range: 0°C to +70°C

  • SVHC (Substances of Very High Concern): No SVHC as of 20-Jun-2011

  • Device Marking: 555

  • Packaging Type: DIP

  • Working Temperature: 0-70°C

  • Maximum Operating Frequency: 0.5MHz

  • Temperature Range: Commercial

  • Maximum Power Supply Voltage: 16V

  • Minimum Power Supply Voltage: 4.5V

  • Chip Marking: 555

  • Surface Mount Device: Through-hole mounting

  • Number of Channels: 1

  • Logic Function Number: 555

NE555N Functional Block Diagram

NE555N Block Diagram.jpg

NE555N Schematic Diagram

NE555N Schematic Diagram.jpg

Key Functionalities of the NE555N Timer

Monostable Mode

In this configuration, the NE555N functions as a one-shot pulse generator. Upon receiving an input trigger, the timer generates a fixed pulse width.

Astable Mode

The NE555N operates as an oscillator, producing a continuous square wave. It's instrumental for applications like tone generation and LED flashing.

Bistable Mode

The NE555N in bistable mode serves as a flip-flop. It can be set or reset based on the inputs and has memory-related applications.

NE555N Equivalents

Part NumberDescription
NE555D1 Func, BIPolar. PDSO8, SOP-8
LM555CMXIC PULSE; RECTANGULAR. TIMER. PDSO8, SOIC-8. Analog Waveform Generation Function
SA555D1 Func, BIPolar. PDSO8, SOP-8
ICM7555CD-TIC PULSE. 0.5 MHz. TIMER. PDSO8, 3.90 MM. PLASTIC, MS-012, SOT96-1, SOP-8, Analog Waveform Generation Function
TLC555QDR2.1-MHz, 250-pA. Low-Pov/er Timer 8-SOIC -40 to 125

How to use NE555N

In its monostable configuration, the timer produces a singular pulse. As depicted in Figure 1, an internal transistor within the timer initially keeps the external capacitor discharged.

NE555N typical schematics in monostable operation.jpg

Figure 1. NE555N typical schematics in monostable operation

When the input signal descends to 1/3 VCC, the circuit is activated. After activation, it stays in this state for the predetermined duration, even if another trigger appears within this span. The HIGH state's output length is expressed by t = 1.1 R1C1, which can be gleaned from Figure 3.

It's essential to recognize that since both the charging rate and the comparator's threshold are directly linked to the power supply voltage, the timing interval remains unaffected by supply variations. Applying a negative pulse to both the reset (pin 4) and trigger terminals (pin 2) during a timing cycle empties the external capacitor, prompting the cycle to recommence. This new timing cycle begins at the rising edge of the reset pulse. Throughout the reset pulse duration, the output is directed to its LOW state.

Upon receiving a negative trigger pulse at pin 2, the flip-flop engages, disconnecting the short circuit from the external capacitor and pushing the output to HIGH. The capacitor's voltage escalates exponentially based on the time constant t = R1C1. When the capacitor's voltage hits 2/3 VCC, the comparator turns the flip-flop off. This action prompts a swift discharge of the capacitor, redirecting the output to a LOW state.

Figure 2 presents the waveforms produced during this operation mode.

If the Reset function isn't utilized, it should be connected to a high state to eliminate chances of unintended activations.

NE555N waveforms in monostable operation.jpg

Figure 2. NE555N waveforms in monostable operation

NE555N pulse duration versus R1C1.jpg

Figure 3. NE555N pulse duration versus R1C1

NE555N Applications

  • Accurate time measurement

  • Creation of pulses

  • Ordered timing sequences

  • Generation of time delays

  • Modulation of pulse width

  • Modulation of pulse positioning

  • Linear incline generation

NE555N Datasheet

Download NE555N Datasheet PDF from STMicroelectronics.


The NE555N timer is a shining example of electronic excellence. Its pin configuration, technical datasheet, and circuitry blueprint collectively offer an in-depth perspective of its functions. For both experienced electronic engineers and emerging enthusiasts, gaining insights into the NE555N enriches one's electronic knowledge base. Thus, as you set forth on your next electronic endeavor, don't overlook the unparalleled capabilities of the NE555N timer.

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  • What does a 555 timer do?
  • The 555 timer IC is an affordable, widely used, and versatile precision timing instrument. It can serve as a basic timer, creating individual pulses or extended delays, or function as a relaxation oscillator, generating a series of consistent waveforms with duty cycles ranging from 50% to 100%.

  • What is IC diagram?
  • An integrated circuit typically appears as a rectangle on an electronic schematic representation. Circuit connections radiate around this rectangle, positioned for clarity rather than mirroring the actual physical layout of the pins. Every pin connection bears a label.

  • What is the difference between NE555N and NE555P?
  • Apart from minor differences, they're largely the same. Any chip belonging to the 555 family will possess consistent pin configurations, though their specifications might vary. For instance, CMOS 555s, like the TI TLC555 available from Radio Shack or the 7555, feature distinct specifications, yet their pin configurations remain identical. Often, NE555N and NE555P can seamlessly replace each other in applications.

  • In which name the IC NE555N is known?
  • The 555 timer IC is a versatile integrated circuit (chip) employed in numerous timer, delay, pulse creation, and oscillator tasks. As of 2017, some sources estimated that over a billion 555 timers are manufactured yearly, making it arguably the most widely-used integrated circuit in history.

  • Is NE555 the same as LM555?
  • Several manufacturers produce their variant of the 555 timer. Numerous CMOS iterations exist, and they operate at voltages distinct from the LM555 and NE555, necessitating circuit modifications for their usage. To address your question, the LM555 and NE555 are fundamentally interchangeable.

  • What is the function of NE555N?
  • The NE555N is an exceptionally stable device that generates precise time delays or oscillations.

  • What is the basic principle of the 555 timer?
  • The trigger input is maintained in a High state by linking it to VCC via a resistor.

  • What are the advantages of the 555 timer circuit?
  • This device can generate precise timing signals. Not only can it function as a basic timer, but it's also capable of creating time delays. Recognized for its exceptional stability as a controller, it operates across a broad range of voltages.

  • What is the difference between NE555 and 555 timer?
  • Typically, in a 555 timer, the output turns high when pin 2 (trigger) dips below 1/3VCC, while the output becomes low when pin 6 (threshold) rises above 2/3VCC. With the NE555, should the trigger pin drop low while the threshold pin remains high, the output shifts to a low state.

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