INDUSTRY COMPONENT

Watchdog Timer

A hardware or software timer that resets a microprocessor system if it fails to receive periodic signals, preventing system lockups.

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Component Specifications

Definition
A watchdog timer (WDT) is an electronic or software-based timing device used in microprocessor and logic solver systems to detect and recover from malfunctions. It operates by requiring the system to periodically reset the timer before it expires. If the system fails to do so (indicating a software hang, hardware fault, or abnormal operation), the watchdog timer triggers a system reset or generates an interrupt to restore normal operation, ensuring reliability in industrial applications.
Working Principle
The watchdog timer counts down from a preset value. The system software must regularly 'pet' or reset the timer before it reaches zero. If the timer expires due to lack of reset signals (caused by software errors, infinite loops, or hardware failures), it generates a reset signal to restart the microprocessor or trigger a fail-safe response, preventing prolonged system failure.
Materials
Typically consists of semiconductor materials (silicon for integrated circuits), ceramic or plastic packaging, and metal contacts. Common IC packages include DIP, SOIC, or QFN with operating temperature ranges of -40°C to +85°C or industrial-grade -40°C to +125°C.
Technical Parameters
  • Package SOT-23, SOIC-8, DFN
  • Output Type Active-low or active-high reset
  • Reset Timeout 1ms to 10s (configurable)
  • Supply Voltage 1.8V to 5.5V
  • Current Consumption 1µA to 10µA (typical)
  • Operating Temperature -40°C to +125°C
Standards
ISO 13849-1, IEC 61508, IEC 61131-2

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Watchdog Timer.

watchdog timer WDT microprocessor safety system reset industrial automation fail-safe hardware timer software watchdog IEC 61508 machine safety Watchdog Timer in Computer, Electronic and Optical Product Manufacturing

Parent Products

This component is used in the following industrial products

Microprocessor/Logic Solver

The core processing unit within a safety controller that executes safety-critical logic functions and monitors safety inputs.

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Engineering Analysis

Risks & Mitigation
  • Single point of failure if not redundant
  • Incorrect timeout setting causing unnecessary resets
  • Software bugs preventing proper timer reset
FMEA Triads
Trigger: Software hang or infinite loop
Failure: Watchdog timer expires, system resets
Mitigation: Implement robust software with periodic timer resets and error handling
Trigger: Hardware fault in timer circuit
Failure: Timer fails to reset or triggers falsely
Mitigation: Use redundant timers, select high-reliability components, and follow derating guidelines
Trigger: Power supply fluctuation
Failure: Unstable timer operation
Mitigation: Implement power monitoring and brown-out detection circuits

Industrial Ecosystem

Compatible With

Interchangeable Parts

Compliance & Inspection

Tolerance
±1% to ±10% timing accuracy depending on application criticality
Test Method
Functional testing via software simulation of failures, environmental stress testing (temperature, voltage), and compliance with IEC 61508 SIL levels

Buyer Feedback

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Frequently Asked Questions

What is the main purpose of a watchdog timer?

To detect and recover from system malfunctions by resetting the microprocessor if it fails to operate correctly within a specified time frame.

Can a watchdog timer be implemented in software?

Yes, software watchdogs exist but are less reliable than hardware timers as they depend on the same faulty system; hardware watchdogs are preferred for critical applications.

What happens when a watchdog timer expires?

It triggers a system reset, interrupt, or fail-safe action to restore normal operation and prevent unsafe conditions.

Can I contact factories directly?

Yes, each factory profile provides direct contact information.

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