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What will happen if light is shown on IR LED (emitter) when it's in reverse bias condition?

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    \$\begingroup\$ Please clarify your question. So far, I want to answer 'nothing,' but to be sure I'd need to know exactly what you're anticipating (or wanting) to happen. \$\endgroup\$ Jun 14, 2016 at 9:04
  • \$\begingroup\$ when connect on revers bias its working as photo diode. what will the IR LED (emitter) life by using it in Continues revers bias? \$\endgroup\$ Jun 15, 2016 at 3:34

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It works like a photo diode. I.e. if photon energy is high enough (wavelength is short enough) to create electron-hole-pairs you get a photo current proportional to the light flux.

It might be not very efficient though for that purpose because it was not designed (optimized) for that purpose.
E.g. the sensitive area is probably much smaller than that of an ordinary photodiode.

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  • \$\begingroup\$ yea.It working like a Photo diode. but what will the IR LED (emitter) Reliability by making it to Continues revers bias?..and Why cant we use the IR LED for the both purpose(TX & RX)? \$\endgroup\$ Jun 15, 2016 at 3:32
  • \$\begingroup\$ As long as max. reverse voltage and current is not violated I assume it doesn't harm the diode at all (affect the reliability); but as said: a LED is not designed for that purpose so efficiency (current per radiative flux) won't be very good (compared to an ordinary photo diode) and maybe other parameters (e.g. rise/fall times?) may be not very good either. \$\endgroup\$
    – Curd
    Jun 15, 2016 at 6:31

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