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Good morning/afternoon/night to everybody.
I have been asked to repair an LG L65 which had a shattered front glass (whose replacement was easy and super cheap). This phone had, however, also developed an intermittent fault with the camera LED flash. Upon disassembly I noticed that the LED would light up only if a very small pressure was applied to it, classic symptom of a damaged solder joint or more likely a broken bond wire. In fact, as soon as I tried to wiggle the package to check, the entire phosphor-loaded epoxy dome came fairly cleanly off.
Does anyone recognize this kind of package? On the top there are, for size comparison, what I believe are 0201 resistor footprints. The package is probably 2x3mm (I don't have a digital caliper) and roughly a couple of mm tall as well (much taller than the typical SMD LED packages).
I am a bit puzzled about the black square that can be seen in the package; I don't understand whether it is an integrated driver or something else (I can only see one bond pad on top of it, which combined with the back side maybe contacting the metallic substrate are still not enough for it to be a transistor, unless I am missing more connections on the other side).
If anyone knows what kind of package this is, or maybe the correct part number, please let me know.
The LED was a typical smartphone camera flash, probably 0.5W or more and >6000K (fairly cool white).
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No idea, but that's an interesting LED.
It looks like an array of individual dies, and judging by the multiple pins, may be an XY array, or several strings... variable output at correct colour temperature?
No wonder they can get flash-like brightness in the right circumstances.
Interesting. -
Actually it was all phosphor coated with a very cool white phosphor. I think it's just a plain high power blue die and the unknown black thing. This phone is very basic and has no "dual tone" flash or anything like that.
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Problem solved.
I was able to find a full schematic for the phone, and the unknown LED is an ELCH07-5565JJ6J7294010-N8(LM) LED flash produced by EVERLIGHT ELECTRONICS CO., LTD capable of 1.5A pulse current. The unknown black die is an integrated back-to back zener diode. The driver IC is an RT8542 underneath a can, that's why I couldn't see it.
Now I have to find a way to source this part which appear to be very hard to get. However, it looks pin compatible with an EHP-C04 which is a lower rated device. I guess that if I won't be able to source the right part I will stick with the lower rated one, since having an LED that works at half the brightness is better than having an LED that doesn't work at all. -
Just buy a few of them. The lower rated part will probably work well as a flash, providing you use it like a regular phone and not as a studio portrait camera.
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Alright, I can confirm that the EHP-C04 is a drop-in replacement and works perfectly fine. Comparing the repaired phone and a factory-condition one side by side it is possible to notice a difference in light temperature and a slight reduction in output, but it's perfectly usable anyway.
The only problem is that I bought 20 and thus I will have to find a creative way to use the other 19 that I am left with.