Need a on board power supply

I have created a board that contains a ESP 32 microprocessor that requires 3.3v DC. I also have a device on the same board that requires 12v DC, As I have it right now, there are two power terminals, one for 3.3v and one for 12v. I’d like to put some sort of circuit on this board so I can power the whole thing with a single 12v connection. In other words, I need a circuit that will drop the 12v down to 3.3v. The 3.3v needs only 250ma of power but it should be pretty clean.



I found the below link of options.
Would these work for you?
Click here

Thank You!

Could it actually be that simple? One little thing? WOW! I had no idea something like this existed.

I selected 3986-S12HIS3.3-1WA2-ND Should I put a cap across the output? Or just place the 4 little pins?

I can’t seem to find the data sheet for this device though. Where should I look?


Hello bart,

Perhaps 811-2921-5-ND would be a better option, since it is in stock ready to ship, where 3986-S12HIS3.3-1WA2-ND is a marketplace product with a 30 day estimated lead time. This one also has a datasheet found here.

Regarding input fusing, below is a snippet from the datasheet:

Below is a document found from Texas Instruments addressing input/output capacitor calculation and selection:

Although it costs more than 2x as much, for a more hobbyist friendly system, I like this module.

The main reason I prefer it is the hobbyist friendly documentation.


At first glance, you just might be right. I’m going to look over the docs Ryan mentioned and make my decision. I won’t have a chance to do this until this weekend. So, I’m not ignoring you both. I will let you know what happens.

Thanks to both of you!


From what you’re describing, it doesn’t look like you need an isolated 3.3V supply. Because of that, I would lean toward something like the 945-R-78K3.3-0.5-ND

or the SVR05S3V3.

If you need a really quiet 3.3V supply (with very low ripple) then I would recommend that you go with a 5V switching regulator and then add a 3.3V low dropout (LDO) linear regulator to drop your voltage down to 3.3V. This will give you a very quiet 3.3V supply.

You may want to first test one of the above mentioned 3.3V switching regulators with some good capacitors, such as the A750EK476M1EAAE040 or the A768EB476M1ELAE042 aluminum polymer capacitors and see if the ripple is low enough without a linear regulator.