I need to make an 11 volt voltage regulator. I would really like this to be step-down, not a linear voltage regulator because I am going to be drawing between 1-2 amps at 11 volts, and if I was using a linear voltage regulator it would get very warm. The input voltage that I am using is going to be about 12.8 volts.
I know a linear regulator under these circumstances would have 86% efficiency, but they are not reliable when working with voltages close together.
The last option I can think of (which is still linear…) would be to use resistors to lower the voltage, but I don't think that that would be any cheaper than using a step down converter. Because the resistors would have to "handle" 3.6watts.
There are regulators like this on eBay (which I am bidding on, but only up to $2), should I just buy something like that? Or would it be cheaper to make it myself?
Even if it is cheaper, I don't know how, and that's why I'm here 🙂
Best Answer
That eBay thing is a switching regulator, aka a "switcher", aka SMPS (Switch-Mode Power Supply). These things can indeed reach efficiencies of 95 %, exceptionally 96 %. Lot of it depends on input and output voltage, and the highest efficiency is with parts that are designed for a specific input and output voltage. So the eBay thing won't always be as efficient, especially not at low output voltage or high input/output voltage ratio.
You can make them yourself; as you can see they only require a few parts, but designing a high efficiency switcher requires some experience to choose the right parts and make the right PCB layout. So I would suggest you buy one. I guess a component cost for the eBay module will be around 6 or 7 dollar, so 2 dollar would really be a bargain.
edit
You can't use the series resistor to regulate to 11 V. At 2 A and 12.8 V in you would need a 0.9 Ω resistor, but when the current drops to 1 A that resistor's voltage drop will be reduced to 0.9 V, and the output will rise to 11.9 V.