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LED Driver Stability Question

Nate Oborny
Prodigy 20 points

Hello,

I'm attempting to build an LED driver for a fluorescence detection system. The detection system works by exciting a fluorescent chemical using an LED as the light source, as that chemical moves through a fluid channel. Once excited, the chemical emits light at a different wavelength which is picked up by my detector. The system works well with a laser but stability issues arise when using an LED due to the fact that fluctuating intensity of the LED can look like a signal to the detector (optical filters aren't perfect so some of the background excitation light does leak through giving me a background level of light. If this background is not stable, it can be confusing).

I have been using an LED driver evaluation kit for testing but it's output is limited to 200mA and I need to move to another LED/wavelength that will require higher output current.  My question is: Given all of the variations in current drivers, how should I begin designing one for the maximum amount of stability? What parameters should I focus on?

Any pointers or suggested hardware would be appreciated.

Thanks,

Nate Oborny

  • 0
    TI__Expert 5130 points

    Hello Nate,

    I think some divers that can deliver flat output current (constant current with few ripples) may be suitable for your application as you said the fluctuating intensity of LED can look like a signal to the detector.

    When you are searching for solutions,  you'd better try dual-stage structure which has low output current ripple (or no ripple).  For other parameters, I think you can check if there is any protections and how to avoid thermal issue. Those are the parameters that affect the stability.

    Regards,

    Victor