What type of voltage regulators to use for IoT

[Farukh Khan]

Hello Guys,

I am trying to run bunch of relays, two arduino megas and one raspberry pi for one of my IoT home automation project. Not really sure what type of voltage regulators or any other voltage source I should use. For the main system I have a 24V 30A Power Supply. Now I want to use specific voltages for different components in the system. For raspberrypi 5V, for some sensors 3.3V, for two arduinos, 9V-11V each and for the relays power a 12V. I am kinda confused whether or not I should build linear voltage regulators for each of these use cases or use individual buck convertors for each use case or a buck/boost?. Or should I go for a zener diode voltage regulator solution? There's also a battery in the system which will provide power to all those sensitive components during a power outage which is very common in my country. I want to provide electricity(voltage and current) as clean as possible to my various sensors and the SoC and microcontrollers. Also efficiency will be very important in this case, because I have a battery in play. What you guys think would be the best approach?

As far as I know, for the linear voltage regulators the efficiency is a crap. Then I also have to do heat management. But the advantage is the linear voltage supply with almost negligible voltage ripples.

On the other hand buck convertors or even buck-boost convertors are very efficient but they have higher ripple voltages which I don't really want in my sensitive system.

And zener diodes might be crap if used as the sole voltage regulator. But what about clipping and clamping the linear or buck-boost convertors with some zener circuitry? for clean and stable voltages and currents?

My requirements for particular cases:
1. 5V3A - for raspberry pi 3 B+ with display.
2. [email protected] - for each arduino mega.
3. [email protected] - for the sensitive sensors and also lora modules at place.
4. [email protected] - for the 12V OMRON Relays
5. [email protected]~5A - for 50W Amplifier circuitry for voice control and feedback.

Also, there might be two battery chargers that I need to use for the two gel cell battery pack I am planning to put for system backup. The two batteries might be 12V 5AH each connected in parallel to provide a total of 10AH backup. I am also not sure what circuitry or which type of charger I should use to safely charge these gel cell batteries for longest lifespan. Please do suggest if you guys have any idea on this too.

Thanks.

 

[kellys_eye]

Buck converters would work in all applications. There are techniques to minimise ripple where this is a potential issue.

 

[Farukh Khan]

@kellys_eye can you please elaborate? What techniques I might use in a buck convertor to reduce the ripple as low as linear convertors? within the µV range?

Also, should I use only buck convertors? or a buck-boost convertor?

And any suggestion for the charging circuitry that might be used in this case?

 

[kellys_eye]

Ask 'why' you need to reduce ripple to μV range and consider 'should you'?

Unless you're going down the scientific/medical route there is (probably) no requirement to be so specific with such factors.

You're talking 'home automation' and tens of thousands of people do it using the methods you propose and we don't hear/discuss 'μV ripple' requirements! You'd get more 'ripple' from the NOISE on the power lines and would require screened cans and cables everywhere to cut it down to those levels.

 

[WHONOES]

The noise on a switching supply can be reduced by either out a few turns of both output leads on a suitable ferrite ring core or by passing them through a cylindrical core that is designed to go round a cable. These can be very effective.

 

[Farukh Khan]

@kellys_eye I have plans for an implementation of some sort of medical sensors on the system. So, I want to keep the overall electricity(voltage and current) as clean as possible with good efficiency. Also, I will be mounting high resolution gyro and vibration sensor, so that I can monitor the overall vibration of the building because the area I live in is affected by earth quakes often. So, I don't want any false alarm or even no alarm due to any ripples in the system voltage for these kind of critical situations.

What if I use a platinum grade computer power supply instead of any buck convertors or any commercial switching power supplies? Will the computer power supply be more reliable and provide overall cleaner electricity under load? As the whole system will run 24/7/365.

@WHONOES Please can you provide a real world example of what you mentioned?


Thank You.

 

[kellys_eye]

If you have specific details for the medical device (or whatever) you want to use then of course a separate PSU can be used to suit its needs but overall your need for supplies with μV ripple is 'ridiculously' over-rated.

Find the specifications for the active devices being (or planned to be) used and they will state the power supply requirements IF they are specialised in any way. The only supply I can see (in your list) that might require attention is those in item 3 - a total consumption of 4 watts.........................

Find a 3.3V 'high grade' power supply if this is the case.

 

[Farukh Khan]

@kellys_eye what kind of high grade power supply you are talking about? Can you provide any examples?

What do you think about the idea of using a full platinum grade computer PSU for this whole system? Those PSU also have all the necessary outputs that I might need starting from 3.3V to 12V. So, I can also get away without using any buck convertors. Will I get the same level of reliability, efficiency and clean electricity using those high grade computer PSU? or the buck convertor approach is the best one you think for the items 1,2,4,5?

 

[kellys_eye]

How does a 'platinum high grade psu' differ from any other typical computer PSU? Will all your devices be located in a place to take advantage of he PSU? Without using long leads?

You're overthinking the potential problems - best thing would be to proceed in a conventional manner and address any PSU isses as they arise - which I doubt you will come across anyway.

 

[Farukh Khan]

@kellys_eye actually almost all the devices will be located in a single box without the relays. The relays will be on the specific power outlets and points, but I have custom made relays with a 330uF caps on each of the module to keep the voltage stable throughout the transmission. Platinum grade 80 plus rating PSU are just more efficient on input to output ratio. As they say, its 93 percent efficient.

And yeah maybe I am overthinking it. I would proceed with conventional method and see what happens afterwards.