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I have some Deep UV LEDs that are about 100$ a piece. They are Very sensitive to voltage spikes, a nano-second spike could destroy one. I am building a USB powered Device with a battery, and I'm concerned that even plugging in the USB device, or turning on the battery could destroy the LEDs. I need to clamp the source current at 20ma.

What can I do to protect these LEDs?

This is the Part

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They are not all that sensitive to forward current - 1% duty cycle 200mA.

Reverse voltage is more of a problem with this kind of LED, as I understand it, so any kind of silicon diode across the LED will keep it within the -6V limit. You could use a 1N4148, for example.

The diode will not limit the LED current- to do that you would have to add a limiting circuit in series. It's possible to do this but probably not worthwhile, depending on what you are using to control the current. For example, if you are using a resistor it's unlikely to go short. If you are using a current regulator circuit you can add a series resistor so the current regulator is limited in the damage it can do.

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  • \$\begingroup\$ Im going to look at all the options I can, we cannot afford to blow any more 100$ LEDs. \$\endgroup\$ – j0h Nov 11 '16 at 18:10
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    \$\begingroup\$ "more"? Ouch. Be sure to use ESD precautions with UVLEDs. \$\endgroup\$ – Spehro Pefhany Nov 11 '16 at 19:05
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You can consider using a TVS (transient-voltage-suppression) diodes. TVS diodes are placed from the point that you want to protect to ground. Basically, when the voltage is high enough, and you should decide what is the voltage level that you want to protect, the diodes begin conducting, but most often in opposite direction, i.e. they are reversed polarized. That is why they don't conduct during normal operating conditions. For more information see Zener diode.

They are often used for sensitive ICs to protect against electrostatic discharge, and they're really cheap as well.

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  • \$\begingroup\$ Would I put one in parallel to the LED? I'll look into that! \$\endgroup\$ – j0h Nov 10 '16 at 19:13
  • \$\begingroup\$ I extended my answer with more detailed explanation. Basically, you put TVS diode from a point that you want to protect, to the ground. \$\endgroup\$ – Marko Nov 10 '16 at 19:19

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