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OPT3101: OPT3101 multiple photodiodes

Ben Jansen
Prodigy 20 points
Part Number: OPT3101

Hello, would it be possible to use two/three SFA213 photodiodes in parallel to increase the sensitivity of the OPT3101? Probably more noise, capacitance etc but larger area instead of using optics like lens or reflector. Getting the proper small angle lens for a few prototypes seems near impossible.

Thank You.

Ben Jansen

  • 0
    TI__Intellectual 1070 points

    Hello Ben,

    Will you share what the expected range and field-of-view for the design is?  There is a capacitance max of 6pF, also there are considerations such as crosstalk with multiple photodiodes which will need to be shielded.

    Rahland Gordon

  • 0 in reply to Rahland Gordon
    Prodigy 20 points

    Hello Rahland,

    Yes, I saw in the datasheet the 6pF limit. Using the reference led,s would be out of the question it seems.

    expected maximum range will be 3 meters. Field of view about the same as reference design. My main challenge is that the reflection area is matte black rubber. A bit like the coarse rubber floor tiles. So reflection is low and I expect diffracted. I am testing with a third party sensor module the Benewake TF Luna which uses a OPT3101. Not clear which led and photodiode. This sensor works well. But it has two lenses in front of the diodes. I expect these are custom made and not readily available at low cost. And mechanically they need to be positioned quite well. This complicates the mechanical design considerably. I hope for a design which doesn't need the lenses. I have not tried the reference design with the single LED (might work) but before buying an evaluation module I try to see what our options are.  Increasing the led output (multiple leds) is difficult as we need battery operation for several hours.

    Ben

  • 0 in reply to Ben Jansen
    TI__Intellectual 1070 points

    Hello Ben,

    There are off-the-shelf diodes with lenses that can be used.  Our system estimator tool give a few options for this pre-loaded.  You can find this tool here.  Also, this will allow you to see what type of performance you may get with your desired configuration of LEDs and PDs, even being able to input the reflectivity percentage of your target.  This would be a good place to start to see what other options you may have.

    Your design considerations would change if you use multiple diodes such as crosstalk and others.  Though it could be supported.

    Rahland