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3 watt Luxeon driver circuit

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by bryan1, Sep 24, 2005.

  1. williB

    williB New Member

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    Bryan , couldnt you also use your pic pwm output to drive pin 5 ?
     
  2. Oznog

    Oznog Active Member

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    Pin 5 is an ENABLE/PWM DIMMING pin. If you don't want to dim it with PWM you tie it to Vdd and LD as per pg 3 of the spec sheet. "Vdd" is a poor choice of name for that pin, it is not a power input but rather the output of the internal 7.5v reg. The power in is connected to Vin.

    The 300nS RC filter is:
    1. Replace the wire between R10 and CS (pin 2) with a resistor.
    2. Add a capacitor from pin 2 to ground.

    Resistance times capacitance must be greater than 300 x 10^-9. For example, 91pF and 3.3K. It can be a bit greater than 300x10^-9 but don't make it wildly greater. The resistor you choose should not be really high, stay under 50k, maybe even 30k. A cheap ceramic disk cap will do fine.

    I got that recommendation on the RC from Supertex directly. It's an obvious problem with the principle of the circuit and fixed all my probs. I love their part but find their negligence in documenting this fundamental requirement rather unfortunate!
     
  3. Master scientist

    Master scientist New Member

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    why not just try the STARPOWER, high efficiency luxeon driver by siliconchip,

    it can be used for 1w, 3w and 5w luxeon leds with just replacing 2 components to vary the current needed to run the leds at their highest intensity.

    IMHO
     

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