DC to DC converter - Step up and step down - for 12V battery

Thread Starter


Joined May 28, 2015

This may be obvious but haven't found much about it:

I would like to use a DC to DC controller as a charge controller to charge a 12V battery, limiting the output to 14V, so far so good.

Thing is I would like to change the input between sources, i.e. one being 9V (portable solar panel) and the other 19V (i.e. a laptop charger 4.7 amps, probably too much in amps but looking into other chargers), hence the need to step up AND step down. In addition I want it in a nice neat box for a very compact area ^^ (fireworks are optional :) )

So I found this:


Is this the right item or I am way off on how these things work?

Thank you! :D


Joined Jun 22, 2012
Your looking at two different concepts, voltage boosting or voltage dropping, so thats two different pieces of equipment.
You need to know what range of input voltage and what voltage and current you need outputting.


Joined Aug 27, 2013
Using the TI "Webbench" design tool a number of designs came up. I used: in: 8-20VDC, out: 14VDC at 1Amp. The charging circuit depends on the type of battery. E

Thread Starter


Joined May 28, 2015
Thanks. I understand in general they are 2 pieces of equipment but sometime designs include both (just not in a nice neat box...)

The converter I am looking into has the following input/output specs:
Input Voltage :5-32V
Output voltage: 12-35V (adjustable)
Output current range :0.5-5A (100W MAX)

So in theory I should be able to "plug in" a 9V or 19V input source and regulate to a 14V Max output to charge the 12V battery?

The part I doubt is: as it is advertised as boost, that would mean that even if we have the range I show above, I would only be able to go from 9V to 14V but not from 19V to 14V? (NOT at the same time of course) Or the wide range would allow me to do both?

Thanks again!


Joined Aug 1, 2013
The unit in your ebay link is boost only. It will boost 5V to 12V, but it will not buck 19V to 12V.

If you want to grow your own, Linear Technology has a line of buck-boost controller chips and excellent app notes. One of their demo boards will do what you want.