Anyone worked with either of these drivers from Lightmalls?

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bibihang
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wight wrote:

I think everything else on the market in 17mm is pretty low current (as if we didn’t already consider 2A low).


I don’t expect these drivers come with high current draw ability, but can they be modded (resistor) and handle current at about 5A?
wight
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bibihang wrote:
wight wrote:

I think everything else on the market in 17mm is pretty low current (as if we didn’t already consider 2A low).


I don’t expect these drivers come with high current draw ability, but can they be modded (resistor) and handle current at about 5A?
Definitely not 5A from either driver. The AX2002 won’t get close. I’m not sure what can be done with the SF driver, but I doubt that more than 3A is a good idea for the small inductor.

Still fine, still on a break. One day I’ll catch up with you folks! previous wight catchup Wink
list of my drivers & variants (A17DD, FET+1 stuff, WIP stuff, etc)

ohaya
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Well, it looks like one of the two I had (the one pictured in http://budgetlightforum.com/node/32575?page=2#comment-625661) just went up in a blaze of glory :)….

I had put that one driver into a C3 awhile ago, and was messing with it today, and was trying to get a picture take of measured tailcap current:

That was tailcap current with 2×14500 Efest batteries in series, so I guess about 48 watts?

We took too long getting that picture, mucking around with the phone camera, and then it got dimmer. After that, it was only one mode, and bright, but not super bright.

So, I took the light apart to do a post mortem, and found that the area around the one of the legs of one of the AOEC/A0EC chips had burnt.

I tried to see if I could desolder that chip off to replace it, since I have the new FETs, but ended up pulling the LED22A, the stacked resistors, and both of the AOEC/A0EC chips off, and it looks like the trace that was under the AOEC/A0EC that burnt was delaminated (pulled off of the board).

I’m still a little disappointed and surprised (I guess that some others won’t be) that this happened, because I’ve had the driver in the C3 for awhile now and have been using it on-and-off, not for any length of time, but in short spurts, and it seemed to be ok.

wight
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Even with the voltage sag under load, that sounds terrible (assuming you were driving an XM-L or XM-L2). 48W turns into what? 24W at the LED? 50% efficiency? A linear driver would have done just as well.

I’d say the entire PCB was probably saturated with heat since there must have been large losses in most/all power components. That specific trace may have been sinking heat from the FET, so it delaminated a little early due to being a little hotter than the rest of the PCB. Once it didn’t have the PCB to sink heat into it burned up once it was run for long enough in a single stretch.

Potting may or may not have saved it, but assuming what I said in the first paragraph is correct about efficiency this is just not the driver for the job. I’m just pulling a number out of a hat here, but I certainly wouldn’t want to push a buck driver below 70% efficiency.

Still fine, still on a break. One day I’ll catch up with you folks! previous wight catchup Wink
list of my drivers & variants (A17DD, FET+1 stuff, WIP stuff, etc)

bibihang
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Thank you all for the information. Looks like we still cannot find good buck driver at this size yet. Sad

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