UV LED System Lifetime

Light Emitting Diodes (LEDs) are solid-state devices that produce light when an electrical current is allowed to flow from the positive (anode) side to the negative (cathode) side. Like other solid-state devices, they have a very long lifetime if used properly.

UV LEDs are one small, though important, part of a UV light source, but the rest of the system must also be taken into account when discussing the lifetime. This includes the internal control circuitry plus the cooling system to ensure the LEDs remain within their operating specifications, as well as the housing to protect the LEDs from environmental factors. Phoseon’s systems use patented and proprietary thermal management, sealing techniques, optical enhancements, and control circuitry to maximize performance without sacrificing lifetime.

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Factors Affecting LED Lifetime

Two major factors that affect the lifetime of LEDs are temperature and current. As LEDs convert electricity into light, heat is created within the p-n junction, known as the junction temperature. For a diode to achieve maximum life expectancy, the junction temperature has to remain in a safe operating zone. The UV Power output of a diode increases with input current but decreases with junction temperature. At any fixed input current, the cooler the junction temperature remains, the more UV output the diode will provide.

LED End of Life Characteristics

The normal ‘failure mode’ of an LED is gradual degradation of the light output. Many commercial LED lighting systems define failure at 70% of the original operating output, also known as L70. Phoseon light sources are designed to ensure an L80 lifetime (80% of original output) of at least 20,000 hours, but have shown to provide L80 at as much as 70,000 hours. Figure is actual data gathered by Phoseon Technology of a continuously operated light source.