Picture of DC-to-DC Converter
I built this DC-to-DC converter for my 48V electric bike because I wanted to be able to plug-in some common 12V accessories, e.g. my cell-phone charger, or a GPS unit.

Step 1: Schematic

Picture of Schematic
Here's the schematic. The cap values are somewhat flexible depending on how much ripple you can tolerate. Be sure to observe the correct polarity for the electrolytic caps. I do not have a list of Digikey part numbers because I found many of the parts I needed at a local electronics surplus store. But all these parts (or something close) are available from Digikey.
olee51 month ago
Hi, thank you for a nice instructable.
I need your help plz. I need to use this converter with my diy 18650 li-ion battery pack and is about 57.6v 70A discharge(max). I checked the datasheet of the regulator ic but still wondering if I can apply it to my battery pack because of the ampare . Can you give me an advice plz?
olee5 olee51 month ago
Actually I'm using 50A Bms so the max current would be 50A
scd (author)  olee51 month ago
What are you planning to connect to the output of the converter?
What is the expected load current from the output of the converter?
olee5 scd1 month ago
Actually I'm planning to connect Arduino and IRS2104 using this kind of converter. I checked Digikey yesterday and found out LTC3637 would be great dor me. The datasheet even showed me a application ex for 12v output and I think input current is not that important for this chip(I'm not sure). Oh and one mistake I asked yesterday is, if I use the BMS, the 'continuous' discharge current would be 50A and it would be the input of the buck converter.
olee5 olee51 month ago
How do you think about using LTC3637?
scd (author)  olee51 month ago

The LTC3637 is only rated for 1A load current. Is this enough for your Arduino and IRS2104?

olee5 scd1 month ago
Yes. I searched yesterday and I concluded it would be fine :)
scd (author)  olee51 month ago

The 50A spec is a maximum rating for your BMS. The buck converter will only use a small fraction of this as its input current.

scd (author)  olee51 month ago

The LM2576HV-12 buck converter chip is rated at 60V, so yes, I think it should work, although 57.6V is pushing it a bit. It can handle up to 3A@12V (36W), but you may need some extra heat sinking if you plan to source that much current over a long period of time.

You can do a search on the Digikey site to find other buck converters that can handle higher voltages and higher currents. The circuit for any buck converter will look very similar to this one.
olee5 scd1 month ago
Really thank you for the help!!!
RickyD43 months ago

Your parts list includes a ferrite bead but the part number you have listed is a 10 microH inductor. What is the correct part number for the ferrite bead that would be similar to what you used?

scd (author)  RickyD43 months ago
Thanks for finding the error. I will fix the parts list.
You could try this one: 240-2296-ND
WaqarA28 months ago

Sir what, if we want to make 48V to 5V DC converter , changes we have to in this circuit.?? we need 5V to power controller in E-bike kit

scd (author)  WaqarA28 months ago

You could substitute an LM2576HV-5 for the LM2576HV-12

There are also many other buck converter chips available from other manufacturers that you could compare to decide which one would be best for your application.

Regards and Best of luck with your project :)
imark771 year ago
so this is such an interesting thing to run across as I am pondering something similar in voltage but different in requirements. I'm looking at something that has 48V in and 12V out, and looking at an output of approximately 500mA. the input current on the other hand is the tight spot as it varies and is vague and unclear as to what the maximum device draw capability is. and the rated output, is well never listed and varies between products.

so here's the idea.
wireless microphone receiver, requires 12V at Roughly 500mA (+/- 200mA).
XLR Cable
Mixer XLR microphone input, with 48V phantom power.

The Peace of mind of never having to dig out that darned power brick! = priceless!.
( On top of never having to find an outlet! ).
I call it a "phantom powered wireless microphone receiver" adapter ( But that's not what Google thinks! ).

More info on phantom power, what little there is.
Mikerwr1 year ago
How about 25v dc 200 amp to 16v dc 200amp any ideas?
scd (author)  Mikerwr1 year ago
That would take a custom designed DC-to-DC buck converter. I don't think it would be that difficult to design .. but the devil is in the details. What is the application?
cam11284 years ago
How would you make a 90V to 50V converter (with low amp levels)?
frank_w125 years ago
is there a way to go from 15 to 12
scd (author)  frank_w125 years ago
That's probably easiest to accomplish with a simple linear regulator such as a  7812 .. I found a 7812 datasheet here:

fatboyslim5 years ago
Is there a way of having in input of between 9-15 volts and achieving a ouput of 48-60volts?
scd (author)  fatboyslim5 years ago
Yes, but not with this circuit.  What you are looking for is called a boost converter.
kentdream6 years ago
LM2576HVT - 12 should do the job, however 2576HVT-12 only provide 3A output.

thz author SCD. I was also searching for a 48dc to 12dc for my electric bike.

maybe we can share more ideas about e-bike =)
BobS6 years ago
Not visible, no components list. This way it cannot be built. How about formulas to calculate different in and outputs; or make it variable/ adjustable? How about current?
Agreed, I would love to find out how to build this and step it down for a 24v system (Military Vehicles)
scd (author)  atombomb19456 years ago
This would work as-is with a 24V input voltage.
mykelpogi scd6 years ago
can you pls give more specific details on materials like voltage on capacitor , what kind of diode is shottky,inductor.. plss plss. can i use LM2575 instead of LM27576 more details pls.. because i real like to try ur work many thanks
scd (author)  BobS6 years ago
This particular switcher is not adjustable. It is 12V only. There are other similar switching regulators that do provide adjustability. The components are listed on the schematic and the output current capability is 3A (listed as a note in step 3)
can you give us a list of the electronics components please?
scd (author)  silencekilla6 years ago
Since I found many of the parts I needed locally, I don't have Digikey part numbers for everything, but I have updated the Instructable with a parts list including Digikey part numbers or substitutes where possible.
kelseymh6 years ago
Very nice idea! To make it easier to reproduce by others (not everyone is familiar with building circuits or wiring connectors), could you consider showing some additional steps or details?

  • Provide a list of the necessary components, and sources (e.g., RS part numbers) if possible.
  • How are the Molex (? hard to tell from the pix) connectors pinned out?
  • What does the back of the perf board look like?
  • Use image notes to call out each component (on both sides of the board)
  • How did you make the car-lighter dongle?
  • It looks like you had to drill a clearance hole in the case for one of the caps.
  • You're using nylon standoffs because the case won't close?
scd (author)  kelseymh6 years ago
The car-lighter dongle came from my local auto-parts store. The connectors are one-off types from my local electronics surplus store but almost any 2-pin connector would work. Yes I had to drill a clearance hole for the larger cap. Yes, the nylon standoffs were needed because the case wouldn't close but I see that as a feature because it allows for airflow to the regulator :-) I will try to improve the Instructable with more info. Thanks, Scott
NachoMahma scd6 years ago
. kelseymh makes some excellent points on how to make your iBle better, but, if one assumes that the reader has just a little bit of experience, it gives all the info needed. As is, I'd rate it 2½-3; with his suggestions incorporated and a few more details on assembly (eg, how the components are connected), possibly a 4. More info on theory of operation and how to adapt for other uses will give it a slight boost. . If the unit will be used for anything close to the rated 3A, a heatsink would be a good idea. Probably not an issue for cell phones and GPSs (?½A max?).