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-   -   oops!! (http://www.diyaudio.com/forums/power-supplies/86674-oops.html)

Danko 17th September 2006 04:48 PM

oops!!
 
I was testing my 50V -> 5-15V synchronous buck regulator, when the 0.01R current sense resistor, series with the 50V DC bus exploded, and the PCB was burning in flames :)
The output current was about 60A. I think the mosfets cross-conducted, and they become a "short-circuit", and the 0.01R burned.
The MOSFETs were FDP3632, paralelled 2 on the upper side, and the lower side.

btw, the 1.5mm^2 wire in a bucket of water was a good dummy load :-)

Here was the resistor....

http://sziget.mine.nu/~danko/aramkor...t/dscn0466.jpg

Wear eye-protecting glasses, when you experiment with high power stuffs!!!!
Your safeti is the most important!
(I was wearing also)

ifrythings 19th September 2006 07:58 AM

Umm... what resistor??? all I see is masive pile of charcole...:D

Tell me about eye protection, had a chunk of mosfet almost hit my eye (about an inch away) now I always wear saftey glasses when first or testing time come :D

Eva 19th September 2006 11:53 AM

I can only see a pile of junk in that picture, how about showing the actual prototype?

poobah 19th September 2006 05:02 PM

You have cross-conduction... or, you ran out of inductor (saturation).

The joys of SMPS desing!

:D

Workhorse 19th September 2006 05:52 PM

Quote:

Originally posted by poobah

The joys of SMPS desing!

:D

Hi poobah,

It seems to me that you dont need to wear glasses to protect your eyes from the small wonders of smps designing!
;) :D ;)

JensRasmussen 19th September 2006 06:04 PM

Re: oops!!
 
Quote:

Originally posted by Danko
I was testing my 50V -> 5-15V synchronous buck regulator, when the 0.01R current sense resistor, series with the 50V DC bus exploded, and the PCB was burning in flames :)
The output current was about 60A. I think the mosfets cross-conducted, and they become a "short-circuit", and the 0.01R burned.
The MOSFETs were FDP3632, paralelled 2 on the upper side, and the lower side.

btw, the 1.5mm^2 wire in a bucket of water was a good dummy load :-)

Here was the resistor....

http://sziget.mine.nu/~danko/aramkor...t/dscn0466.jpg

Wear eye-protecting glasses, when you experiment with high power stuffs!!!!
Your safeti is the most important!
(I was wearing also)

Hi,

Cool pic :flame:

You might suffer from uneven power loss in the fets as you have two in parallel......

I always use one big fet rather than two..... much better solution IMHO.

\Jens

poobah 19th September 2006 06:41 PM

...ahem... DESIGN...

:(

Nordic 19th September 2006 08:45 PM

Actaly Poobah looked normal until the day wanted to see close-up what made a nest of tantalums smoke....

poobah 19th September 2006 09:22 PM

I have blown up up tantalums... how did you know?

Ever seen a wookiee on fire?

:D

subwo1 20th September 2006 09:45 PM

I found that using only one gate resistor per paralleled MOSFET set ended a problem with them failing.


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