367

While the B+ spikes may certainly be doing something bad to the LED, I’d say that other factors probably weigh in more heavily. Dale’s shown that things such as batteries, bypasses, clean lenses, etc can have big effects. With all that ruled out my vote is on the heavy currents put into the LED: the LED has thermal resistance between the die and the thermal pad and there’s no getting away from it. More heat will result in an elevated die temp which I suspect will degrade the LED much more quickly than at Cree’s maximum currents. That said, I certainly don’t know. I’d love to eliminate as much bad behavior as possible, including the voltage spike on B+.

This PCB (v030) is not compatible with Halo’s idea. Click through and take a close look at the first graph since it’s easier to read. Each division is 1 volt and zero is 1 division above the bottom (where the little yellow/orange tags are). In post #365 the MCU trace is aqua colored. Note that Halo’s idea is to determine MCU VCC, but as we can see MCU VCC is never similar to B+ voltage. Instead, VCC starts at ~4v and then bounces up to 5v and tapers back off.

I’m impressed with DEL’s results from post #648 here and plan to try out an RC snubber.