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How to use LP3950 LED driver with RGB LED light strip?

Wilson1
Intellectual 280 points
Other Parts Discussed in Thread: LP3950

I find LP3950 color LED driver, and there is example of the Typical Application:

I want to use it in color organ controller with 12V RGB LED light strip 5050. The LED light color changes need be synchronized to audio signal with both amplitude (beat) and frequency methods (4 channels). The audio input will be on-board electret microphone, and also 3.5mm audio input.
I know that I should use spectral decomposition of the signal by harmonics of the input signal. The input audio signal should be filtered into one of four categories by frequency: low, medium, medium-high, and high. Each frequency category is then assigned a specific pulse width modulated output that feeds to the color RGB SMD LED light strip. How to modify this schematic for my purpose?

  • 0
    TI__Intellectual 1985 points
    The audio synchronization feature is built into LP3950. You shouldn't need to deal with spectral decomposition of the audio signal. The audio signal can be feed directly into the device. However, you will not be able to have both amplitude and frequency mode at the same time. It is one or another.

    More importantly, the max voltage is around 5V; probably not able to drive the 12V RGB light strip.
  • 0 in reply to Hak-Leong Ng
    Intellectual 280 points

    What elements required to generate high voltage for LEDs and for protection the device pins from the over voltage?

  • 0 in reply to Wilson1
    TI__Intellectual 1985 points
    You have to generate the 12V power rail separately. LP3950 is not capable of generating that high voltage with its internal DC/DC converter.

    Can you share the spec and schematic of your 12V RGB LED light strip?
  • 0 in reply to Hak-Leong Ng
    Intellectual 280 points

    Hak-Leong Ng said:
    You have to generate the 12V power rail separately. LP3950 is not capable of generating that high voltage with its internal DC/DC converter.

    Can you share the spec and schematic of your 12V RGB LED light strip?

    I will use 12V 5A external Power Supply.  I need drive LP3950 and LED strip from this Power Supply.

    I need also protect all device pins from over voltage.

    12V 5050 Analog LED Strip spec:

    Total Power Consumption: < 72W (14.4W per meter), LED Power Consumption: 10.8W/m
    Total max current draw: < 6A (1.2A per meter)

    Additionaly, I want to make it work with separate 1W High Power LED's

    for 1W LED:

    LED working current:  350mA
    LED voltage drop for Red - 2.2V
    LED voltage drop for Green, Blue - 3.6V

    Rr = 8 Ohm
    Rg, Rb = 2 Ohm

    connection:

  • 0 in reply to Wilson1
    TI__Intellectual 1985 points
    Besides over voltage when LED is off, LP3950 will not be to handle that amount of current.
  • 0 in reply to Hak-Leong Ng
    Intellectual 280 points

    So what is workaround? What components capable of passing high current and what can protect from over voltage?