Part of a circuit I'm designing needs to control servo motors rated for 5V. I've measured that they can draw over 1A when active.
The issue is that my circuit is powered by a 2-cell LiPo battery, which I've gathered has a 6V minimum, 8.4V maximum output.
Another part of the circuit uses 3.3V, so I used a switching regulator from 6-to-28V down to 3.3V, and it works perfectly. I thought that a similar component to regulate down to 5V would be about as expensive ($2-$3 ish), but I'm finding on DigiKey that I'm looking at at least $16 per regulator for even a 1A-output 5V regulator, and significantly more for a 2A output.
This is really way too expensive for me, especially since I will have 4+ servos to power. Is there a better way to power servos from a 2-cell LiPo? I would really like to power everything off of one battery, but it seems like I may just need to power the servos with a separate 5V battery (NiCd or other, not sure).
Edit: My search parameters earlier somehow caused me to miss the LM2596, for $2.5. Will this work how I want, if I adjust it to have a 5V output? It seems a little too cheap to be true. 🙂
Datasheet: http://www.onsemi.com/pub/Collateral/LM2596-D.PDF
Best Answer
The cost of the regulator seems about right, and is definitely not too good to be true. But what makes you think that the regulator is all you need? Look at the data sheet you linked to, and look closely at the applications section. You will need several more components, particularly including an inductor which cannot be just any old inductor. Even worse, you'll need a way to mount all your components, and you cannot just solder them together. Switching supplies are susceptible to layout errors, so a printed circuit board is a really, really good idea.
Between the components and the pcb, for small quantities of finished product (like, let's say 100) you'll almost certainly end up spending more than 16 bucks a unit.
So eBay is probably your best bet.