There seem to be a lot of different kinds of DC-DC converters. More than just step-up, step-down and step-up/down.
What are all these different kinds called? What do I have to search for to find what I'm looking for?
Input | Output | Pot
5V | 12V | No
12V | 5V | No
(fixed input, fixed output)
--------------------
1-5V | 5V | No
12-24V| 5V | No
1-24V| 5V | No
(random input, fixed output)
--------------------
5V | 6-24V | Yes
12V | 1-5V | Yes
12V | 5-24V | Yes
(fixed input, variable output)
--------------------
1-6V | 8-24V | Yes
8-24V| 1-6V | Yes
1-24V| 1-24V | Yes
(random input, variable output)
--------------------
1-6V | 8-24V | No
8-24V| 1-6V | No
(random input, random output)
I'm not sure if all of these constallations exist. But I think I've seen most of them (not with the exact same voltages though).
All I know is that
[lower voltage] to [higher voltage] is called step-up or boost
[higher voltage] to [lower voltage] is called step-down or buck
a combination of both is called boost-buck or step-up/down
.
But what what are all the different kinds of random/fixed/variable input/output converters called?
Most are programmable to set the output voltage. Most modules do his with a pot so you can easily change it. The only difference with a fixed output version is that it uses a soldered on resistor. But to the dc-dc chip it is no difference. If you want to use a module with a fixed voltage you can remove to pot and replace it with the right resistor. Or just don't bother, set the right voltage and maybe fix the pot in place (nail polish does a great job).
And for the input, non I've seen has a fixed input. They all have a range. For a step down it's some minimum voltage above the output voltage and a max voltage. And for a step up it's some minimum voltage and some max voltage a little under the output voltage.
I found it to be extremely hard to find a step-up converter that takes 1-5V and converts that to a fixed 12V.
I remember using a step up converter that had a pot and I adjusted it to output 12V while the input was 5V, but as soon as the input voltage dropped, the output voltage dropped, too.
Then you probably just dropped under it's minimum supply voltage 1V is pretty low and most can't do that.
Also, 1V to 12V gives you a ratio of 12. The current on the input is 12 times higher then the input, not including the efficiency. Let's say that's 80% (just random, it's probably way lower) you already have a current that's 12 / 0,8 = 15 times higher then the output current... That's pretty extreme.
The other variable is the switching speed. Generally the faster the better but faster tends to limit the top current because of core saturation in the coil.
felic:
I found it to be extremely hard to find a step-up converter that takes 1-5V and converts that to a fixed 12V.
I remember using a step up converter that had a pot and I adjusted it to output 12V while the input was 5V, but as soon as the input voltage dropped, the output voltage dropped, too.
Ok, my input may not be as educated as others in here as I am (perhaps like you) still amateur in electric engineering world, but I recently did large study of voltage regulators that fit into my projects and did learn alot and started with exact questions you asking. I can probably add couple points too. I am not sure if you a looking to find completely assembled regulator or building one yourself, I assume you are looking to build one yourself.
I think other important thing is efficiency, different regulators have different efficiency curves, some can be very efficient at higher current and be terrible at lower currents, others vise-versa, you need to keep an eye on that.
Another thing, if you trying to build voltage regulator on a breadboard, if it is a switching regulator then chances are it won't perform well or not fire up at all, use good short wires, perhaps protoboard will work better.
There are also seems to be two sub-typed of chips: 1 - regulator, 2 - controller, speaking in "plane english" the difference is in the number of components you need to use controller have all switching elements (e.g.: diodes, transistors, mosfets) outside, regulator normally has that all built in.
If you building voltage regulator from scratch for your project, I think choosing the right one is simple do this:
go to digikey.com (or other supplier)
go to voltage regulators (or voltage controllers) department, narrow down large list by input and output voltages, then by MAX output current, then by package and price (as some of them are quite pricey, up to $7/chip). You will probably end up with list of few regulators that fit your need, then one by one study their datasheet, see how many external components required and which circuit is easier to build. choose couple , build prototypes , test them and in the end you will end up with one that is perfect for what you need.
PS: I think it will be very hard to find decent 12V regulator that can take input voltage as low as 1v, but who knows.
Take a look at the step up, or boost, regulators at www.pololu.com
They have some that work from single battery cells, and I think 12V was an output option. 3.3V and 5V for sure.
1V is pretty low and most can't do that.