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Topic: Power Supply For Arduino Nano (Read 690 times) previous topic - next topic

Lucifer22334

Apr 18, 2019, 03:21 pm Last Edit: Apr 18, 2019, 03:22 pm by Lucifer22334
Hi all,


I want to know how many currents should be supplied to Arduino Nano for Perfect Working. I have to build a circuit which provides constant 3A and 5V. I am gonna use it to provide raspberry Pi and Arduino nano. So just wanted to know that this will not burn the Arduino Nano, right?

And How much current will be drawn from Arduino nano GPIO Pins and 3.3V and 5V Supply Pins?

herbschwarz

Hello Lucifer22334,
Let me answer your power supply questions.
I have seen this many times that people do not
understand power supply ratings.
There are, basically, two types of DC power supplies:
regulated and unregulated.
The unregulated type is the simplest kind:
 A rating of, let's say, 5 volts at 1 Amp means
 exactly that. You can expect that you will
 measure 5 volts at its output terminals when
 it is delivering 1 Amp to a load. However, if
 there is no load on that supply, there is no
 voltage drop in its wires, so the terminal
 voltage will be higher than 5 volts. That means
 that the output voltage will change according
 to how much current it is delivering to a load. How
 much 'extra' voltage there will be is dependent upon
 the quality of the unit.
The regulated type of 5 volt at 1 Amp supply is more
complicated:
 It has circuitry that works to keep the output voltage
 constant, and corrects that according to the load current.
 With no load, its output terminal voltage will be 5 volts.
 (That is the easy way to tell is the supply is regulated.)
 With a 1 Amp load, its terminal voltage will be very close
 to 5 volts. So, the output of a regulated supply remains
 quite constant while the load changes.
That having been stated, you can understand that a power
supply delivers a terminal voltage but the current it supplies
depends on what is connected to it as a load. A 1 Amp supply
can not deliver that current into a load that does not require
it. Ohm's law holds here, too, The output current is: terminal
voltage divided by the load resistance. No load, no current.
If you have another question, just ask it.
Herb

Paul__B

The Nano requires 5 V.  It will never in itself require more than about 250 mA.  You cannot "draw" current from the 5V pin, that is where you feed 5 V in, though you can alternatively use the USB connector.  You should simply forget about the "Raw" or "Vin" pin as the little regulator on board cannot provide significantly more than the bare requirements of the ATmega328 chip itself.

You should never attempt to draw more than 30 mA from any one GPIO pin, or about 100 mA in total.  I am being a bit conservative here, but that will be a good rule.

You should not attempt to draw significant current from the 3.3 V pin, if some other devices requires 3.3 V, it should have its own regulator.

Lucifer22334

The Nano requires 5 V.  It will never in itself require more than about 250 mA.  You cannot "draw" current from the 5V pin, that is where you feed 5 V in, though you can alternatively use the USB connector.  You should simply forget about the "Raw" or "Vin" pin as the little regulator on board cannot provide significantly more than the bare requirements of the ATmega328 chip itself.

You should never attempt to draw more than 30 mA from the anyone GPIO pin, or about 100 mA in total.  I am being a bit conservative here, but that will be a good rule.

You should not attempt to draw significant current from the 3.3 V pin, if some other devices requires 3.3 V, it should have its own regulator.
So I have to Provide Nano with 5V and 1A rather than 3A, right? Or will it be Fine? And I am Going to Connect an IR Transmitter LED Array with it. Like 7-14. So will it Work With it? I am Gonna use 940nm LED which draws max 100mA(100 mA continuous, 1000 mA pulse. Approx 1.6V forward voltage)

Paul__B

You must provide the Nano with 5 V.

The Nano itself uses very little current.  If you feed it with 5 V via the USB connector - such as from a "phone charger" - then it will pass that on to the "5V" terminal via a diode.  This is limited by the diode's current rating and you lose half a volt in the diode - which you probably do not want to do.

So the proper way is to connect the 5 V regulated power supply to the "5V" terminal as well as in parallel, the device you want to power with the 5 V.  That device may draw significant current, the Nano will not draw much.

As long as the power supply is rated for more than the current you propose to draw in total, it generally does not matter how much more it can supply; it will not be required to.

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