Constant Current LED Lighting Premature Failure


“I have state of the art LEDs and a constant current driver, why are they burning out?”

LEDs are much more sensitive than other types of lighting -especially when incorrectly used on constant current systems which may lead to premature failure. Make sure the heat sink and any cooling system is working properly, correct wiring configuration and making sure it is operating within rated specifications.

Constant current systems can provide longer life of LEDs if properly used, because constant current disposes of thermal runaway issues. When an LED is on for extended periods, or operating in warm environments the forward voltage drop will decrease and would normally pull more current than the LED is rated for. This is the main problem for diodes (LEDs) when they are “the load” as found in lighting systems. Constant current drivers will not allow excess current, and since the voltage output will adjust to the lower forward voltage drop of the heated LED, would not have to worry about the constant current driver providing damaging excess voltage.

Below are a few pointers to help you out and give your lighting system extra longevity when dealing with constant current systems:

Replace Damaged LEDs Immediately
The constant current driver will keep the same current running through the remaining amount of “good” LEDs causing them to burn out -or burn out prematurely. When an LED burns out or gets damaged, turn the power off and fix any damaged LEDs before turning the power back on. Constant voltage drivers do not have this issue, as they always keep the same voltage.

Wire Lighting to Output BEFORE Applying Power to Input
Make sure your LED lighting is wired to your constant current driver output BEFORE applying the input power to the driver. If wiring the output after applying input power, the output voltage is unknown and may be sitting higher than the rated LED voltage and cause premature failure or instantly burn them out. Constant voltage drivers do not have this problem because their output voltage is fixed.

Constant Current Driver Troubleshooting
Depending on the constant current driver being used, the voltage output in its “open-load” state may give you readings that are fluctuating up and down the full range of the voltage output window as it may try to pump the fixed current. Sometimes a typical DC multi-meter will have a hard time reading this because it would appear as an AC voltage instead of a DC voltage. The output may also be sitting at min or max of the voltage output window. In most cases, you will need to have a load on the output to fit in the voltage output range and also the current output rating of the driver.

Choosing the correct LED and LED Driver

The “in closing” section seems to negate the entire rest of the article.


@SiliconChip Looks like it was updated to clear this up.
Thank you