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Why do LEDs require a constant current source and not a constant voltage source as power supplies?

I find that most of the devices use constant-voltage sources as power supplies. Why do LEDs need a constant current source?

LED Manufacturing
November 3, 2023

Jacob Jones

Bachelor's degrees in electronic engineering. Skilled in designing LED electronic components, products, and systems, developing and testing prototypes, troubleshooting, and debugging. 8+ years of extensive experience in the electrical and electronic manufacturing industry. Reach Me Now>>

Jacob Jones

The brightness of the LED is proportional to the current. So using a constant-current power supply can stabilize the brightness of the LED lamp. If a constant-voltage power supply is used, the current will fluctuate when the load changes, which will affect the brightness of the LED.

In addition, the relationship between the resistance and voltage of the LED is not linear. Thus a slight deviation from the constant voltage power supply may cause the current to change drastically, thereby burning out the LED lamp. Therefore, in the LED driving circuit, the use of a constant-current power supply can better protect the LED.

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