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NE555P

Precision timer IC, astable/monostable, 4.5-16V, 200mA output, PDIP-8

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Manufacturer Part：

NE555P

Package：

PDIP-8 (9.81 x 6.35 x 4.57mm, 2.54mm pitch)

Brand：

Product Categories：

Integrated Circuits ICs, Interface ICs

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Description

Product Overview

The NE555P is a precision timer from Texas Instruments capable of producing accurate time delays or oscillation from microseconds to hours in a 8-pin PDIP through-hole package.

Key Specifications

Supply Voltage	4.5V to 16V
Output Current	200mA max (sink or source)
Timing Range	Microseconds to hours
Frequency (astable)	Up to 500kHz typical
Initial Timing Accuracy	1% typical
Temperature Drift	50ppm/°C typical
Supply Current	6mA typical at 15V
Trigger Voltage	1/3 VCC
Threshold Voltage	2/3 VCC
Reset Voltage	0.7V typical (active low)
Operating Temperature	0°C to +70°C
Package	PDIP-8 (9.81 x 6.35mm)

Features

Operates in both astable and monostable modes
Adjustable duty cycle in astable mode
Output can source or sink up to 200mA
Timing from microseconds to hours
1% initial timing accuracy
Temperature-stable: 50ppm/°C
Reset pin overrides all other inputs
Compatible with CMOS logic at 5V supply

Applications

Precision timing and time delay generation
Pulse generation and waveform shaping
LED flashers and tone generators
PWM motor speed control
Power-up delay and watchdog timers

Product Introduction:NE555P Product Introduction

The NE555P is the industry-standard precision timer from Texas Instruments that has been in production for over 50 years. It can be configured as either a monostable (one-shot) multivibrator producing time delays, or as an astable (free-running) multivibrator generating square wave oscillation. The timing is controlled by external resistors and capacitors, providing flexibility from microseconds to hours. The output can source or sink up to 200mA, directly driving relays, LEDs, and small speakers. The 1% initial timing accuracy and 50ppm/°C temperature drift ensure reliable operation across varying conditions. The 8-pin PDIP package is universally recognized and ideal for prototyping.

Working Principle:NE555P Working Principle

The NE555P contains two comparators, a flip-flop, a discharge transistor, and a resistive voltage divider consisting of three 5kΩ resistors (giving the device its name). The voltage divider sets the upper comparator threshold at 2/3 VCC and the lower comparator threshold at 1/3 VCC. In monostable mode, a negative-going trigger pulse on pin 2 (below 1/3 VCC) sets the flip-flop, driving the output high and turning off the discharge transistor. The external timing capacitor charges through the timing resistor toward VCC. When the capacitor voltage reaches 2/3 VCC, the upper comparator resets the flip-flop, driving the output low and turning on the discharge transistor to rapidly discharge the capacitor. The output pulse width is T = 1.1 × R × C. In astable mode, the capacitor charges through R1+R2 and discharges through R2 only. The charge time (output high) is 0.693 × (R1+R2) × C, and the discharge time (output low) is 0.693 × R2 × C, giving a free-running oscillation frequency of 1.44 / ((R1+2×R2) × C). The duty cycle is always greater than 50% in the basic configuration because R1+R2 > R2. The reset pin (pin 4) overrides all other inputs, forcing the output low and discharging the timing capacitor.

Pin Description:NE555P Pin Definition and Functions

Pin	Name	Type	Description
1	GND	Power	Ground
2	TRIG	Input	Trigger (active below 1/3 VCC, starts timing)
3	OUT	Output	Output (source/sink up to 200mA)
4	RESET	Input	Reset (active low, overrides all inputs)
5	CTRL	Analog	Control voltage (2/3 VCC, bypass with 0.01µF)
6	THRESH	Input	Threshold (ends timing at 2/3 VCC)
7	DISCH	Output	Discharge (open collector, discharges timing capacitor)
8	VCC	Power	Supply voltage (4.5V-16V)

Application Scenarios:In which products and applications isNE555P used

Time Delays: Monostable mode produces precise delays from 10µs to hours for power-up sequencing and debounce
LED Flashers: Astable mode with R and C values sets flash rate; 200mA output directly drives multiple LEDs
PWM Motor Control: Astable oscillator with control voltage modulation on pin 5 varies duty cycle for motor speed control
Tone Generation: Audio-frequency oscillation with speaker coupling produces alarm tones and beeps
Watchdog Timers: Monostable retriggered by MCU; timeout triggers system reset for safety-critical applications

Alternative Models:What chips are recommended as replacements for NE555P

Model	Manufacturer	Key Difference	Package	Specs
LM555CN	TI	Direct equivalent with identical timing characteristics and wider -40 to +85C temperature range	DIP-8	4.5-16V/200mA
TLC555CP	TI	CMOS version with 2-15V supply, 1µA typical supply current for battery-powered timers	DIP-8	2-15V/100mA CMOS
SA555P	TI	Automotive-grade -40 to +125C version for under-hood timer and control applications	DIP-8	4.5-16V/-40-125C
NA555P	TI	Wide-temperature -40 to +125C version with military-grade screening for reliability	DIP-8	4.5-16V/-40-125C
NE556N	TI	Dual timer version with two independent 555 timers in a single DIP-14 package	DIP-14	4.5-16V/dual
LMC555CN	TI	CMOS low-power version with 1.5V minimum supply and 2MHz astable frequency capability	DIP-8	1.5-15V/100mA

NE555 is the industry-standard precision timer generating accurate time delays from microseconds to hours. It operates in both astable (oscillator) and monostable (one-shot) modes. CMOS versions (TLC555, LMC555) offer 2-15V supply and 1µA standby for battery applications. The NE556 provides dual timers in DIP-14. SA555 extends temperature range to 125C for automotive use.