NE556 Datasheet | Next Electromics

NE556 Dual Timer Technical Summary

Overview

The NE556 and NE556-1 are highly stable dual monolithic timing circuits designed for accurate time delay generation and oscillation. These devices integrate two independent 555 timers in a single package, sharing only the V_CC and ground connections. Each timer is controlled by external resistors and capacitors, allowing for flexible timing configurations. The NE556 series is widely used in applications requiring precision timing, pulse generation, and sequential control.

Features

Dual Timer Configuration: Replaces two 555 timers, saving board space and simplifying design.
High-Speed Operation: Turn-off time less than 2µs (NE556-1) and maximum operating frequency exceeding 500kHz (NE556-1).
Wide Timing Range: Capable of timing intervals from microseconds to hours.
Flexible Modes: Operates in both astable (oscillator) and monostable (one-shot) modes.
High Output Current: Outputs can sink or source up to 200mA, suitable for driving relays, LEDs, and other loads.
Adjustable Duty Cycle: Allows precise control of output pulse characteristics.
TTL Compatibility: Ensures seamless integration with digital logic circuits.
Temperature Stability: Excellent performance with a temperature coefficient of 0.005%/°C.
MIL-STD Compliance: SE556-1 variant meets military standards for rugged applications.

Applications

The NE556 is versatile and finds use in a broad range of timing and pulse generation applications, including:

Precision Timing: Accurate time delays and intervals in industrial and consumer electronics.
Sequential Timing: Coordinated timing for multi-stage processes.
Pulse Shaping: Generation of clean, well-defined pulses for signal processing.
Pulse Generators: Custom waveform generation for testing and control systems.
Missing Pulse Detectors: Monitoring systems for detecting skipped pulses in repetitive signals.
Tone Burst Generators: Audio applications requiring controlled bursts of tones.
Pulse Width Modulation (PWM): Control of motor speed, LED brightness, and power delivery.
Time Delay Generators: Delayed activation of circuits or processes.
Frequency Division: Clock division for digital systems.
Touch-Tone Encoders: Telecommunication applications for DTMF signal generation.
Industrial Controls: Automation and process control timing.
Appliance Timing: Household and commercial appliance timing functions.
Traffic Light Control: Timing sequences for traffic signal systems.

Electrical Characteristics

Absolute Maximum Ratings

Supply Voltage (V_CC): NE/SA556, NE556-1: +16V; SE556: +18V
Maximum Power Dissipation (P_D): 800mW

Operating Conditions

Temperature Range:
- NE556D/F/N: 0°C to +70°C
- SA556N: -40°C to +85°C
- SE556F/N: -55°C to +125°C

Package Information

The NE556 is available in multiple package options to suit different application requirements:

14-Pin Plastic Small Outline (SO) Package (NE556D): Compact surface-mount option for space-constrained designs.
14-Pin Ceramic Dual In-Line Package (CERDIP) (NE556F, NE556-1F, SE556F): Robust ceramic package for high-reliability applications.
14-Pin Plastic Dual In-Line Package (DIP) (NE556N, NE556-1N, SA556N, SE556N): Standard through-hole package for prototyping and general use.

Pin Configuration

The NE556 features a 14-pin configuration with the following pinout:

Pin 1: Discharge (Timer 1)
Pin 2: Threshold (Timer 1)
Pin 3: Control Voltage (Timer 1)
Pin 4: Reset (Timer 1)
Pin 5: Output (Timer 1)
Pin 6: Trigger (Timer 1)
Pin 7: Ground (Shared)
Pin 8: Trigger (Timer 2)
Pin 9: Output (Timer 2)
Pin 10: Reset (Timer 2)
Pin 11: Control Voltage (Timer 2)
Pin 12: Threshold (Timer 2)
Pin 13: Discharge (Timer 2)
Pin 14: V_CC (Shared)

Functional Description

The NE556 consists of two independent 555 timers, each featuring a comparator, flip-flop, and discharge transistor. The timing interval for each timer is determined by an external resistor-capacitor (RC) network. The device can be triggered and reset via falling-edge signals, providing flexibility in system design. The output stage is capable of sinking or sourcing significant current, making it suitable for driving a variety of loads directly.