I have Arduino with DAC, LED, wireless, and other peripherals running on a single beefy scooter 12v battery and two step down voltage regulators.
One regulator is set at 8v and goes to Arduino internal regulator to guarantee that the voltage is consistent if battery starts draining.
The second regulator is powering rest of the peripherals and is set at 5.2v.
Question: is this an overkill? should I just power everything with a single regulator set at 5.2v (bypassing Arduino's internal regulator and directly powering Arduino using vin)?
P.S. The reason I am asking is that have some issues (long story for this post) and wasn't sure if having slightly different voltage on Arduino vs. the rest of the peripherials may lead to issues (I am using a shield and there could be a connection between Arduino vin and the regulator powering the peripherals.
mm.
depend on the amount of peripherals you have you can just feed 12V to arduino and draw 5V from it
If you only have, say, one 0.96 inch OLED, no problem. If you somehow have 5 7.4 inch tft LCDs you will need a external supply.
You can measure the current with a multimeter. I will say you can safely draw 500mA from the Arduino
What is that? Plenty of "Arduino" controllers out there.
Yes. No need for that. Go for the needed. Vcc, 5.0 volt and/or 3.3 volt.
What issues?
Post links to the datasheets of those peripherals. Some of them will work, like the DAC. Some might need extra power supply, like the wireless. The LED, if a LED strip, will need an separate power supply line.
I think it's a good idea. A lot of sophisticated designs use multiple regulators - to reduce the power demand of one regulator having to take all the excess power. Multiple regulators share the power so it's less demanding on a single regulator. I thought it was a good idea so much that I designed a PCB that has two regulated outputs, one fixed at 5 and the other variable from about 5-12 volts. I use this power board on almost any Arduino project now, and never had any issues after that.
I started using multiple regulators after I burned one up on an Arduino (I don't remember if it was an Uno or Leonardo or what). It's easy to push the Arduino regulator a little too far, and above about 300mA it will start burning up (depending on model, input voltage, and load you draw). Better safe than sorry I say.
I found it best to power most projects from Vin with about 7.5-8 volts keeping the Arduino's regulator cool. In some cases I will take a little of the 5V onboard, like for pots on the analog inputs, but whenever I need to power a lot of LEDs (like a LCD backlight), or motors or pretty much any circuit that demands higher power, I use a separate regulator. The other advantage is that any noise from the other circuits is less likely to travel through the power and glitch the microprocessor.
With other chips connected directly to the Arduino you should be careful about signal levels, but for powering things like motors, LEDs, relays, and most other higher current digital on/off or PWM things, a transistor is often used anyways, so wiring that to a different power bus is simple.
There is some art to engineering, and no single solution will be right for everything, but if you have the space and the extra pennies, multiple regulators are a valid design concept.
Powering through Vin or the power jack means that the Arduino and all peripherals that are on the 5V rail are powered by the onboard 5V regulator. The on board 5V regulator is not heat sinked so will supply limited current before it overheats and shuts down. The amount of current depends on the voltage input to Vin or the power jack. The higher the voltage the less current can by supplied. I would use a buck converter to drop the 12V to 5V and connect that to the 5V on the Arduino, bypassing the, weak, 5V regulator. Then the rated current of the DC DC converter is available on the 5V line.
That doesn't mean it's always necessary or even a good idea. And not every design needs to be sophisticated. In fact, a design is best kept as simple as possible in principle.
Nor does it mean that it is a bad idea. Principles and actual practical design often diverge. There isn't a very good case to never use the Vin and regulator on-board to power the microprocessor.
The regulator is there so the cost is zero. It can improve the regulation for the processor.
The problem is when using the 5 volt output (or 3.3) to power other stuff. As mvoltin explained, he is using two regulators, that isn't overkill. In this automotive-type design, a second pre-regulator to the on-board regulator may enhance reliability. I've done the same thing and it really does work and is quick and simple to implement.
And as mentioned by many forum users, what your original design is not "wrong", and will work pretty well. HOWEVER, due to the generally not-so-efficient nature of LDOs I will try to use as few of them as possible. Which include utilizing the one on the Arduino board.
You can feed your 12V from the barrel jack, or, (surprise!) from the Vin pin. It is electrically connected to the positive side of barrel jack, so you can do that.
