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FrozenGate by Avery

New Ultra-Low Drop-Out Constant Current Driver Design!






Wolfman29 said:
Unfortunately, diodes can fry from something called COD (catastrophic optical damage) which can occur nearly instantaneously from a huge overcurrent.
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Well darn.... that kinda sucks... I have hard time believing though that a diode can run straight DC at say 420mA but a 1A spike could kill it. I have yet to hear of this "COD" term...... very interesting. I doubt many people have done to much testing with that?
 
random person said:
Well darn.... that kinda sucks... I have hard time believing though that a diode can run straight DC at say 420mA but a 1A spike could kill it. I have yet to hear of this "COD" term...... very interesting. I doubt many people have done to much testing with that?
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1) No? I'll sell you a LOC. Try spiking it with 1A.

2) I would bet that nearly everyone on this board has had a few "experiments" that involved COD ;)
 
there is not testing for cod. it is fairly common here. i think they are also called zombie diodes. they can be used as dummy loads.

michael.
 
It's more commonly known as 'LEDing your diode' because when the coatings go poof, that's what your left with. An LED. And I have many LED'd laser diodes.. even 445's.

People forget laser diodes are still cavity devices. They have HR and OC coatings on the facets that forms the cavity.. and the power density in the cavity is going to be MUCH higher than what actually comes out of the diode as usable output. The coatings can only take so much power before they burn off.

Actually in most laser diodes, LOC's in particular, the coatings are the limiting factor, and not the current capacity of the PN junction.
 
COD is also known as LED-ing a diode. Basically, instead of discreet mirrors, the diode's ends are cleaved ultra flat and ultra polished to serve as the mirrors for the cavity. If too much light goes through these "mirrors," they burn up and don't reflect light back into the cavity to gain.

Where LEDs' damages occur due to overheating or obliterating the current spreaders or bond wires, laser diodes can die from too much light too, not necessarily too much heat. This is why some people have diodes that die from laser light reflecting back INTO the laser, focused back onto the front facet of the die by the same lens that focuses the output into a beam.
 
Verrry informative! Quite a pity though... was hoping I could test my laser out when its -40C outside and jack it with current and see how much power I could get. =( Hmm... will now make sure to put a cap on my drivers. Thanks :)
 
Don't you think if it had been possible, that you'd have seen 1W supercooled LOCs and 3W 445s posted by now?
 
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