Electronic – Does (and when how) the lifetime of a LED depend on the PWM frequency


Let's assume two options for driving a standard LED at its rated current.

  1. PWM set to 50% duty cycle at 10 kHz
  2. PWM set to 50% duty cycle at 50 kHz

Technically both LEDs would produce the same amount of light and the 'blinking' won't be visible to the human eye or a camera (except maybe for a high speed camera…)

Best Answer

Let me open my trusty MIL-HDBK-217F and see what it says about LEDs and their longevity: -

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The main factor affecting the failure rate per million hours is temperature.

Of interest, if I read the next section about laser diodes they do take into account duty cycle pulsing but their conclusion (on page 6-21) is that at 50:50 duty cycle the failure rate for laser diodes is about 25% of that when continually driven.

They also conclude (on page 6-22) that if you operate a laser diode at a light output power of 50% of its rating it will last ten times longer than operating it at 95% of it's rated output power.