7 x Cree XM-L module

  • Hello!!

    Sorry !! i don't speak German very well so i contact you in English

    I purchased a 7XCree XML Module ( LED-TECH) , with 20V ( Desktop power Supply) it works fine.

    In my application, i have to use power with a 14.7V - 2600mAh Li-Ion Battery , so i have connected a XL6009 Boost voltage regulator

    in order to increase output voltage around 21Volts. The boost voltage is able to switch current to 4A.

    But during the test, while the output voltage remains stable, the output LED current increases! ( and battery output current too!!) from 0.8A to 2.4A in 60minutes!

    I fixed the 7X Cree module on a heatsink and measured a temperature around 51°C.

    Is it an heating problem with Cree Leds?

    Coul you help me? my goal is to power the module with an output current around 700mA.


  • Hi, you need to drive LEDs with constant current and not with constant voltage.

    This is normal behaviour with every LED. Forward voltage drops with increasing temperature.

    You need a "step up" or "boost" constant current supply to ensure stable 700mA current to your LEDs.

    Or if you are realy cheap, you could build a low dropout constant current supply behind your voltage regulator, that functions as a resistor.

    If you want best efficiency i would recomend you https://www.ledtreiber.de/shop…80%A2-2-6V~18V-p164952213 also available at ebay https://www.ebay.de/itm/Led-Se…elle-dimmbar/142381657320

    or something like a "Meanwell LDB-600L" or maby a bit overkill a "Meanwell LDH-45A-700".

    Somewhere out there, there are more, of these cheap boost voltage regulators just like yours, but with constant current control. I dont know them so i cant realy recommend them, or so maby someone else here can recommend one from ebay or some other china supplier...

    One think i must warn you tho, if you drive LEDs with constant current, you should never switch them on/off (open the current circuit) behind the current source, or the LEDs could get too much voltage delivered.

  • Are you sure, that you know, what you do? :/

    The Cree module needs constant current - you drive it with constant voltage?

    At second, a boost converter isn't a perpetuum mobile ;)

    The current flow in LED circuit is a different, like the current in battery circuit. The power will ever be the same. P = U * I

    LED have a higher voltage, as the battery, so will be te current from batttery be higher. If the voltage raise down, the current will be higher!

    Take a look, to the XL6006, please.


    That's you need :)

    The chinese will sell a cheap ready to use board 8)