LEDs 101 Miscellaneous

Thermal Runaway Explained

In our previous post: “Want help choosing the correct LED Driver?”, the term Thermal Runaway was referenced. Thermal Runaway leads to current crowding and the development of current filaments, which happens to be one of the primary causes of a semiconductor failure.

It all starts with the profile of silicon. The electrical resistance of silicon increases with temperature up to about 160 Celsius, then starts decreasing. When resistance decreases, it allows more current to enter through the overheated areas, in turn causing yet more compounding heat, eventually leading to total failure of the device and hence the term Thermal Runaway.

With adequate thermal management and the use of a constant current driver, an LED will not exceed its maximum operating temperature and will never approach Thermal Runaway.

About the author

Brooke Sault

Technology enthusiast working to enable the use of LED lighting - Living in the Green Mountain State of Vermont with my family and working with a company like LEDSupply, that is helping to provide energy saving LED products, is a great place and platform to accomplish my lifelong goal of making a positive impact on our world.


  • Sorry, this will probably seem rather snotty, but it’s rather hard to accurately put tone and emotion into text. I seek only to improve the professional quality of your website.
    LED’s are composed of *silicon*, (doped with various other elements for color) not *silicone*. Silicone, often a component of caulking, resembles a hydrocarbon, with silicon and oxygen substituted for the carbon. Silicone is a polymer, and more resembles a oil, rubber, or plastic than the metal or rock of silicon. It is also an excellent electrical insulator.
    This seems to be an unfortunate common misconception, probably due to the rise of spell-checkers, but using the correct term will set you above your competitors.

    • Thank you for the adding a valuable comment – I think we will go back and edit our post and be sure to note that spelling difference in the future. Thanks again for helping!

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