77. LED Circuit

Question.5

You are using a 3535 RGB LED emitter rated at 1 W per color channel (3 W total).
You mount it on a standard FR-4 PCB with no thermal vias or copper pour under the thermal pad.
After 5 minutes of full-white operation, the blue channel dims significantly, while red/green remain brighter.
What is the most likely cause?

Blue LED forward voltage rises over time with high power operation.
Overheating due to poor thermal dissipation from the package
Incorrect current limiting resistor on the blue channel
Data signal corruption affecting only the blue die

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