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How to glow 16 IR LED together constantly (without using individual resistors) using just LED drivers (no microcontroller)?

Shubham Anand
Prodigy 10 points
Other Parts Discussed in Thread: LM317, TPS61165

I want to glow an array of 4X4 IR LED  [TIL 38 IR LED] constantly using LED driver only but not using any microcontrollers. How can it be done? Thanks in advance.

  • 0
    Prodigy 30 points

    I'm not a 100% sure since I am just learning myself. But from what I've looked at on some of the driver sheets. If you just wire up the driver to provide the proper current per channel. Then you should only have to provide a voltage to the enable pin or what ever pin would turn it on. (I'm not sure if they are always called one thing or another) The only catch being that you have to select a driver with either enough channels or a high enough output voltage to power all the led's that you have in series. Depending on the driver you will also have to make sure you input voltage is high enough to supply the output voltage. If I'm correct a buck always needs an equal or higher input voltage then the required output where a boost could use a lower input to provide the higher output. Some are obviously capable of doing both. You could also use something like a LM317 linear regulator configured as a current controlling circuit. It would be simple enough and you would just need a switch to turn the whole thing on and off.

    I'm hoping I'm helping a bit and not confusing you but since no one else posted I thought I would try.

    Rich

  • 0
    Prodigy 60 points

    Hi Shubham, you do not state what power supply you have but I can offer a solution.

    I am currently driving a series array of 18 White LED's from a supply as low as 5V. This array would appear to be too high a voltage for the output switch, but there are ways to overcome this.

    The TPS61165 is an excellent boost regulator that will allow you to generate the 32V you would need to drive a series string of 16 IR leds. Current limit is a simple sense resistor connected in series with the LED string connected to the feedback input of the regulator.

    This is a high frequency switch mode regulator so capacitor and inductor values are small, as is their physical size. Open LED protection is included in the design and the tiny SOT-23 package allows it to fit almost anywhere.

    If you need further assistance, please do not hesitate to contact me via this forum. It is here for all of us to learn from.

    Regards, Dave Neale

     

    Download the datasheet and have a look.