what voltage regulator do i need?

Question

I have a motor that has voltage limit of 3V, but the LiPo battery supplies 7.4V power, what kind of voltage regulator do I need to protect the motor, a link to the page with voltage regulator will be helpful as well, thanks

Answer 1

It depends on two things:

(1) the current consumption of the motor, and

(2) whether you can accept 60% of your power being lost in the regulator.



For a small motor an ordinary series regulator will work. The LM317 is the cheapest and simplest, but it will require a couple of external components. See the datasheet for details. The downside of a series regulator is that you will lose most of your power heating up the regulator.



A better solution is a switching regulator. There are some 3 / 3.3V self-contained switching regulators on the market:

http://parts.digikey.com/1/parts/1591590-regulator-switch-3-3vdc-0-5a-sip-7803sr-c.html



If you need more current you will have to design your own switching regulator based on one of the many step-down switching regulator ICs that are available. The MAX652 is one such:

http://www.maxim-ic.com/datasheet/index.mvp/id/1139

Answer 2

You will waste more than half of the power if you use a regulator.



I'd need to know the current, but an LM338 will handle up to 5 amps with a good heat sink. Download the data sheet and study it. It has schematics on it.



.

Answer 3

The LM1086 ( 1.5 amps ) or LM1085 (3 amps) is a better choice

LT1084 and LT1083 are even more current

Good luck !