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Thread: Does a bare emitter need to be electrically isolated?

  1. #1

    Default Does a bare emitter need to be electrically isolated?

    If I want to use a bare Cree emitter (the 3.45mm square, not on a star), does the thermal pad on the bottom in the middle need to be electrically isolated? Or can it be electrically shorted to ground or to + (not to both at the same time of course ).

  2. #2

    Default Re: Does a bare emitter need to be electrically isolated?

    most of cree leds have isolated thermalpad, which one are you talking about?

  3. #3

    Default Re: Does a bare emitter need to be electrically isolated?

    Mainly XP-E, XP-G, and XP-C. But I'm also curious about XR-E and XM-L.

    By "isolated thermalpad", you mean it's OK to short it to ground or NOT OK to short it to ground?

  4. #4
    Flashaholic* AnAppleSnail's Avatar
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    Default Re: Does a bare emitter need to be electrically isolated?

    Quote Originally Posted by tylernt View Post
    Mainly XP-E, XP-G, and XP-C. But I'm also curious about XR-E and XM-L.

    By "isolated thermalpad", you mean it's OK to short it to ground or NOT OK to short it to ground?
    The datasheet will tell you if the thermal contact is electrically isolated. If so, then the thermal pad can touch the heatsink with no ill effects.

    WARNING. Cree LEDs have electrical contacts on the bottom, too. Either grind them away carefully or use a spacer, or your +/- contacts will be shorted.
    My biggest light-hog is my camera.

  5. #5

    Default Re: Does a bare emitter need to be electrically isolated?

    Quote Originally Posted by tylernt View Post
    Mainly XP-E, XP-G, and XP-C. But I'm also curious about XR-E and XM-L.

    By "isolated thermalpad", you mean it's OK to short it to ground or NOT OK to short it to ground?
    you can short it to either,

  6. #6

    Default Re: Does a bare emitter need to be electrically isolated?

    double
    Last edited by alpg88; 02-23-2012 at 11:11 AM.

  7. #7

    Default Re: Does a bare emitter need to be electrically isolated?

    Ok, cool -- isolating + is not a problem. Shorting - and the thermal pad together makes things much easier.

    Thanks guys!

  8. #8

    Default Re: Does a bare emitter need to be electrically isolated?

    I'd get dyslexic about it after all the explaining, couldn't you just double check it as many times and ways as you needed to with the circuit continuity tester function of a multimeter?
    The brighter the light, the darker the shadow.

  9. #9

    Default Re: Does a bare emitter need to be electrically isolated?

    I haven't bought the bare emitters yet -- wanted a sanity check before spending the $$$.

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