Low-voltage DC-DC converter 16-75 VDC in; 12VDC @ 3A out

nasukaren's picture

Here are some pics of the low-voltage converter that I created using the National Semiconductor LM2576HVT-12-ND buck-converter. The chip pretty much did everything for me -- all I had to do was to add two power-smoothing caps, a blocking diode, and a RF choke (which I mistaking undersized; promptly blew up and which I jerry rigged a loop of wire).

In the top left of the photo above, you will also note my premade, off the shelf 12VDC to 5VDC converter. This powers my LED headlights.

The following photo is the back side. Please note that I am a really lousy solderer. The LM2576HVT-12-ND will take any input from 16-75VDC and output a steady 12VDC @ 3A continuous but they mention that with active cooling it could do 5A continuous. That's 36-60 watts, plenty for me.

This is the wiring schematic that I used:

Top side again. The setup is small enough that my ESC and UBEC still fit in the project case with plenty of space for airflow -- and for another DC-DC converter to fit in there in case 3~5A is not enough.

The resulting low-voltage converter and ESC "mounted" on my bike with duct tape. This is an older photo, I've reduced some of the wiring and since changed the SB50 connector to a PowerPole 45.

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Comments

Looks great! Any idea as to how efficient it is?

nasukaren's picture

Thanks! The spec sheet from National Semiconductor says it's 88% efficient.

Karen

Working on a Piaggio Boxer (mo-ped) EV conversion: http://gpsy.com/ev

Personally, I was disappointed - I thought you building a "real" boxer like on your logo :) My favorite dog ,BTW

But I can use the other info so all is forgiven :)

nasukaren's picture

Shhhhh....... I am actually owned by a beagle, so don't let him know I'm working on a boxer!

Karen

Working on a Piaggio Boxer (mo-ped) EV conversion: http://gpsy.com/ev

nasukaren's picture

Darn it, my servo tester blew. I'm not sure why, it was working one day and not the other. It rained a little bit, but a little rain shouldn't hurt an IC.... :-( Anyway, my boxer is on hold while I wait for another servo tester.

:-(

Karen

Working on a Piaggio Boxer (mo-ped) EV conversion: http://gpsy.com/ev

Karen, you have the worst luck... or is it that what we(you) are trying to do won't work reliably (use R/C components in a ridable EV)

nasukaren's picture

I think I'm personally deadly towards integrated circuits plus I don't think all of these R/C components are all that "battle hardened."

I'll be sure to pot my next servo tester in some epoxy or silicone before it goes out in the field!!

Karen

Working on a Piaggio Boxer (mo-ped) EV conversion: http://gpsy.com/ev

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