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I am making an autonomous bot where i need to power a few sensors (IR, PIR, sonic,etc) and an arduino. In total the sensors draw about 300 mA current(max).

My power supply is a LIPO of 12 V (11.1 V), 25C, 2200 mAh. I need this supply to control the motors and provide them enough power.

My sensors and microcontroller will essentially work on 5V, so I need to step down the voltage from my supply too.

Using 7805 is inefficient as its causing too much heat and as I need to run the bot continuously for a long time, I don't want to use a linear regulator. Should I use a buck switching regulator with a LM2596S? If yes, why and what other choices are available that i maybe missing out? Any help would be greatly appreciated.

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  • \$\begingroup\$ Sounds like a good plan. Is this lm2596S these chinese buck converter boards? I have never used them, but there could be some issues with noise. But that should be relative easy to take care of with some extra filtering if thats the case. You could also step the voltage down to 6-7V and then use an LDO from there. \$\endgroup\$ – Linkyyy Sep 27 '18 at 20:27
  • \$\begingroup\$ I also agree that a buck makes sense, of course. But another thing to put in your head is to drive as much as possible directly off of the main battery system's voltage and as little as possible off of the buck regulator. For example, if you need a relay then look for a 12 V relay (they usually can engage at 70%) rather than a 5 V relay. Just as an example. Either would work (with appropriate I/O circuitry.) But it may be better to pull as much load from the main system than from the down-regulated one. The fact your 5 V is already over-heating suggests you might have too much riding there. \$\endgroup\$ – jonk Sep 27 '18 at 21:50
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For a project like this you should use a self contained switching regulator.

The device you linked would be more accurately described as a switching controller. Unlike a 7805, it requires many external components with specific values to function correctly.

That's fine if you're going to build hundreds of something. But for one-offs it makes much more sense to use a self contained regulator that includes all the passives. Here're some examples that I've used in the past with good results:

DROK 1.5A Switching Buck Regulator, With Numeric Control

Same thing but with a pot instead of buttons

Adafruit 5v UBEC 3A

Dimension Engineering DE-SW050 (This is a very popular drop in replacement for the 7805)

And here's a picture of what I'm talking about for the future when all the links may be dead: Switching Regulator

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