NE555N Datasheet, Alternatives, and Last-Time Buy Guide

Introduction

The STMicroelectronics NE555N is a classic 555 type timer/oscillator IC in an 8-pin DIP (Dual In-line Package) package. According to the official STMicroelectronics datasheet (Doc ID 2182 Rev 6, January 2012), this device is a "highly stable controller capable of producing accurate time delays or oscillation" .

As confirmed by multiple distributor sources including DigiKey and Octopart, the NE555N from STMicroelectronics is now marked as Obsolete . This article provides verified specifications from the original datasheet, explains the obsolete status with authoritative sources, and offers practical replacement options for engineers and procurement professionals.

Intended Audience: Hardware engineers, procurement specialists, repair technicians, and hobbyists who currently use or plan to replace the NE555N in legacy designs.

Key Specifications (Source: STMicroelectronics Datasheet Doc ID 2182 Rev 6)

The following specifications are extracted from the official STMicroelectronics datasheet for the NE555/SA555/SE555 series 

Key Features from Official Datasheet :

• Low turn-off time
• Timing from microseconds to hours
• Operates in both astable and monostable modes
• Adjustable duty cycle
• TTL compatible
• Output can source or sink up to 200mA
• Direct replacement for SE555/NE555

Understanding the Obsolete Status (With Authoritative Sources)

According to multiple authoritative distributor sources, the STMicroelectronics NE555N has been discontinued.

Verification Sources:

Important Notes from Distributors:

• DigiKey explicitly states: "NE555N is obsolete and no longer manufactured" with available substitutes listed 
• Octopart shows lifecycle status as "Obsolete" with a last update confirmation 
• Win Source (via GlobalSpec) reports a "Fake Threat In the Open Market: 41 pct" for this part number, indicating significant counterfeit risk 

What This Means for Different Users:

NE555N Pinout Diagram and Pin Description (Source: STMicroelectronics Datasheet)

The following pinout is standardized across all 555 timers and is documented on page 1 of the STMicroelectronics datasheet

Pin Connections (top view):

              +---+--+---+ 

      GND   |1  +--+ 8| VCC 

     TRIG 2|          7| DISCH 

      OUT 3 |          6| THRES 

      RESET4|         5| CTRL

               +----------+

Pin Function Table:

Functional Block Diagram and Operating Modes

Based on the official STMicroelectronics datasheet, the NE555N contains two comparators, a resistive voltage divider (three 5kΩ resistors), a flip-flop, a discharge transistor, and an output stage.

Astable Mode (Oscillator)

In astable mode, the NE555N generates a continuous square wave without any external trigger. The output toggles between high and low at a frequency determined by two resistors (RA, RB) and one capacitor (C).

Frequency Formula (Source: Datasheet Application Information):

    f = 1.44 / ((RA + 2RB) × C)

Charge Time (HIGH output): t1 = 0.693 × (RA + RB) × C
Discharge Time (LOW output): t2 = 0.693 × RB × C
Duty Cycle: D = t1 / (t1 + t2) = (RA + RB) / (RA + 2RB)

Typical Applications: LED flashers, tone generators, clock sources, PWM signal generation.

Monostable Mode (One-Shot Timer)

In monostable mode, the NE555N produces a single output pulse of fixed width each time the trigger pin (pin 2) receives a low pulse. The pulse width is set by one resistor (R) and one capacitor (C).

Pulse Width Formula (Source: Datasheet Application Information):

  T = 1.1 × R × C

Example: R = 10kΩ, C = 100µF → T = 1.1 × 10,000 × 0.0001 = 1.1 seconds

Typical Applications: Delay circuits, switch debouncing, missing pulse detection, timed relay activation.

Bistable Mode (Schmitt Trigger / Flip-Flop)

In bistable mode, the NE555N acts as a set-reset flip-flop. The output stays high or low until triggered.

Configuration:

• A low pulse on pin 2 (TRIG) sets the output HIGH
• A low pulse on pin 4 (RESET) sets the output LOW
• No timing capacitor required

Typical Applications: Simple memory elements, switch debouncing, logic control.

Direct Replacements for NE555N (Pin-Compatible, Verified)

According to distributor cross-reference data, the following parts are direct, pin-to-pin replacements for the NE555N. No circuit changes are required

Recommendation: For most existing designs, the Texas Instruments NE555P is the safest and most available replacement. DigiKey lists NE555P as an "Upgrade" substitute for the obsolete NE555N

Comparison: NE555N vs. NE555P vs. LM555CN

Based on distributor and datasheet comparisons :

Key Finding: For applications requiring 500kHz operation, NE555P is the appropriate replacement. LM555CN is limited to 100kHz and may not be suitable for high-frequency applications 

Upgrade Options (Enhanced Performance, Not Always Pin-Compatible)

For new designs or redesigns, these modern timers offer superior performance. Note: These may not be 100% pin-compatible in all circuits.

Important Warning from Datasheets: CMOS versions (TLC555, LMC555) have different input impedance and output drive characteristics. Always prototype before replacing a bipolar NE555N in a production board

Counterfeit Risk and Identification Guide

According to supply chain data from Win Source (via GlobalSpec), the NE555N has a reported "Fake Threat In the Open Market: 41 pct" . This means over 40% of components sold under this part number may be counterfeit or substandard.

Verification Methods:

Recommended Test (from industry practice): Build a simple astable oscillator with RA=1kΩ, RB=10kΩ, C=0.1µF. Genuine NE555N will output approximately 650Hz stable frequency. Counterfeits may show erratic frequency or fail above 100kHz.

Purchasing Recommendation: Purchase only from authorized distributors (DigiKey, Mouser, Newark, Farnell) or trusted franchised suppliers. We guarantee that all NE555N parts supplied by us are sourced from authorized channels and tested for authenticity.

Frequently Asked Questions (FAQ)

Q1: Is the STMicroelectronics NE555N still in production?

No. According to DigiKey and Octopart, the product status is "Obsolete" . STMicroelectronics has stopped manufacturing this part.

Q2: What is the difference between NE555N and NE555P?

NE555N is manufactured by STMicroelectronics (obsolete). NE555P is manufactured by Texas Instruments (active). Both are DIP-8, same pinout, same electrical specifications (500kHz, 200mA output, 4.5V-16V supply) .

Q3: What is the maximum output current of NE555N?

According to the ST datasheet operating conditions: ±200 mA. Absolute maximum rating: ±225 mA

Q4: Can NE555N run on 3.3V?

No. The minimum supply voltage for NE555 is 4.5V per datasheet operating conditions . For 3.3V operation, use TLC555 or LMC555 (CMOS versions).

Q5: What is the maximum frequency of NE555N?

The datasheet specifies "maximum operating frequency greater than 500 kHz" . Practical astable operation up to 500kHz is reliable.

Q6: Does NE555N work with a crystal?

No. The 555 timer is an RC oscillator and does not accept a crystal. For crystal accuracy, use a microcontroller or dedicated crystal oscillator.

Q7: What is the temperature range for NE555N?

0°C to 70°C (commercial grade). For industrial temperature range (-40°C to 105°C), use SA555. For military range (-55°C to 125°C), use SE555

Q8: What is the typical supply current?

10mA at VCC=5V with no load . Quiescent current is approximately 3mA.

Q9: Is the NE555N RoHS compliant?

Yes. The terminal finish is "Matte Tin (Sn) - annealed" which is lead-free and RoHS compliant

Q10: What are the timing formulas?

Monostable: T = 1.1 × R × C. Astable frequency: f = 1.44 / ((RA + 2RB) × C). Source: STMicroelectronics datasheet application information 

Related Products and Categories

The NE555N belongs to the Clock/Timing - Programmable Timers and Oscillators category. Other related products available on our website include:

Direct Replacements (Pin-Compatible):

• NE555P (Texas Instruments) - Active, 500kHz, DIP-8
• LM555CN (Texas Instruments) - Active, 100kHz, DIP-8
• SA555P (Texas Instruments) - Active, -40°C to 105°C

Upgrade Options (CMOS):

• TLC555CP (Texas Instruments) - Low power, 2.1MHz, 2V-15V
• LMC555CN (Texas Instruments) - 3MHz, low power

Related Categories:

• Clock Generators and Synthesizers
• Real-Time Clocks (RTC)
• Oscillators and Crystals
• Delay Lines

Visit our Clock/Timing category page to browse all available timers and oscillators.

Last-Time Buy and Stock Availability

Current Stock Status (as of April 2026):

Verified Distributor Stock (for reference):

• DigiKey: NE555N Obsolete, recommends substitutes 
• ShinYua： NE555N in stock (3,073 units as of April 2026)
• Jameco Electronics: NE555P in stock (2,845 units as of April 2026) 

To request a quote, please provide:

• Part Number: NE555N (ST) or NE555P (TI)
• Quantity required
• Target unit price (if applicable)
• Shipping destination

Contact us via the RFQ button on the product page or email us directly.

References

1. STMicroelectronics. (January 2012). "NE555 - SA555 - SE555: General-purpose single bipolar timers." Datasheet Doc ID 2182 Rev 6. 
2. Octopart. (2026). "STMicroelectronics NE555N - Distributors, Price Comparison, and Datasheets." 
3. DigiKey. (2026). "NE555N STMicroelectronics - Product Details (497-1963-5-ND)." 
4. Jameco Electronics. (2026). "Texas Instruments NE555P Timer ICs (Part no. 27422)." 
5. GlobalSpec / Win Source. (2026). "STMicroelectronics NE555N - Clock/Timing - Programmable Timers and Oscillators." 
6. Datasheets.com. (2016). "NE555N Datasheet - STMicroelectronics." 
7. Utmel. (2021). "NE555N Timer: Pinout, Datasheet, and Schematic Diagram." 
8. FindIC. (2024). "LM555CN vs NE555P Comparison." 

Document Revision History

Summary and Action Items for NE555N Users

The STMicroelectronics NE555N is a well-documented single timer IC with a maximum frequency of 500kHz and a supply voltage range of 4.5V to 16V, as specified in the official STMicroelectronics datasheet (Doc ID 2182 Rev 6). However, according to DigiKey, Octopart, and other authorized distributors, the part is now obsolete and no longer in production.

Summary of Key Findings:

Recommendations by User Type:

For new designs: Do not use NE555N. Select active replacement NE555P (TI) or upgrade to TLC555CP for low-power applications.

For existing products using NE555N:

• Perform last-time buy of original ST stock while available, OR
• Switch to NE555P (TI) with no circuit changes, OR
• Upgrade to CMOS timer (TLC555, LMC555) with minor circuit adjustments

If you need assistance selecting the right replacement or want to check current stock and pricing for the NE555N or its alternatives, please submit an RFQ on our product page.