Hello!

I will use a bluetooth Ublox Nina-B112.
I need help making a circuit to add a volage regulator with input 15V-33V and output 0mA-30mA @ 3V3 stabilized (best case selectable 1.8V-3.6V) .

Someone could help me on this? Suggestions are welcome
Thanks!

 

Google LM317 power supply.

 

Hello dendad, thanks for your answer! I appreciate! But I have 24v in the circuit and I need to use a dc/dc converter to supply the Bluetooth with the specs that I talk before. Or with that voltage regulator is the best option?
I need some help doing the schematic to this.. Some suggestions are welcome

Thanks

 

An LM317 regulator will give you the ability to get an adjustable 1.8 to 3.6 V from 24V in. At that current, it will not get too hot but a heatsink is always a good idea.
You may want to use a switch mode regulator to drop the volts down to a lover voltage first to limit the heat. Then feed the LM317.

Do you need a variable supply, or is it you want both 1.8V and 3.6V at the same time?
A bit more clarity may help.

 

Going 33 to 3.3v is a big drop, you should consider a switching buck converter. You can get a module like one of these:

https://power.murata.com/products/dc-dc-converters/single-output-non-isolated.html

Or you can build your own, in which case i recommend installing the free TI switcher pro application. It will help you design a circuit and will choose a TI brand switching controller for you, which should be fine. Going the module route is advisable.

Edit --> After re-reading your post, and seeing that you only need 30mA, then I'm starting to agree with @dendad that a linear regulator may be ok. Your power dissipation will be the voltage change multiplied by the current, so for 30V input, 3.3V 30mA output the regulator would dissipate (as heat) ~0.8 watts. While this is wasteful and something to consider if you're running on battery power, you likely handle that heat with a heatsink and/or a ton of copper in that part of the board. The datasheet will tell you how much heat the package can dissipate for a given ambient temperature.

 

@dendad I will need a selectable supply with 1.8V-3.6V. Do you know some switch mode regulator and schematic to use in this case as you are talking?

I google and found LM2936 (LDO voltage regulator) you think it could be an option?

@MrSoftware thanks for your advise

 

I think an LM317 will work for you. Not the LM2936.
This is using standard resistor values. If the 3.7V is too high, try adding a higher value resistor across the 330R pot. For example, 6K8.



Here is a calculator.
https://circuitdigest.com/calculators/lm317-resistor-voltage-calculator

But the resistors have tolerances so the actual values will not be exactly as marked.
If you use the reg with the bolt down heat sink, make sure you insulate it from the case. Check the operation of the circuit before you put your load on it!

 

You said before is better make a switch mode regulator to drop the voltage down and then power the LM317.. Could you please make an example?
And I think is better add a current limiter 0.5mA-30mA.

Thanks for your help