26V Cap discharging through LED causes damage?

[eem2am]

If i connect a 1 Amp LED straight to a 18u8F ceramic cap thats charged to 26V...will the LED be damaged at all?

here is the LED datasheet...

here is the LED datasheet
**broken link removed**

 

[JStuffer]

It will most likely kill the diode. You say you use a ceramic cap. 18uF is a lot for a ceramic cap, it's likely a physically big cap, but whatever. Ceramic caps have somewhat low equivalent series resistance, so you'd be just dumping the whole charge through the diode, with current limited only by parasitistic resistances.

Use a resistor in series. It will shape the pulse.
For maximum transient current of 1A, you will need a 22.3 Ohm resistor, no smaller, preferably a 27 Ohm one.
For a longer pulse of Imax = 350mA, you will need a 64.8 Ohm resistor. You'll be able to find a 56 Ohm or a 68 Ohm one from E12 series.

JS

 

[smeezekitty]

Better use a 33 ohm resistor to not risk frying it.

 

[JStuffer]

That's right, if the supply is noisy, for example, it's better to be safe than sorry. Operating the diode on the edge of it's maximum ratings will shorten it's life too.
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