What are the 5V and VIN pins for?
I believe I can supply the Arduino with power in three different ways:
- Use USB. The design trusts the 5V to be regulated, and does not regulate it in any way.
- Use a regulated power source, trusted to be 5V, and connect it to GND and 5V.
- Connect an unregulated power source, eg a battery, to GND and VIN. This should be above 6.2V (since the dropout voltage is 1.2V) and preferably between 9V and 12V. There is a built-in regulator that will supply the Arduino with exactly 5V.
But can I use any of those pins to power other components. E.g. if the Arduino is powered with USB, can I use the 5V pin to power a diode? I thought I could, but the voltage is 4.70V, while the USB is 5.07V. The VIN is 4.26V btw.
Are the 5V and VIN only for powering the Arduino?
where and when were you getting those voltages? It could be a drop from measuring with and without other current flowing from USB (if you measured initially without the arduino). There should be a small drop as the USB input power does go across a fuse (F1 on schematic) and a mosfet (T1) before reaching the 5v pin.
I put the Nano in a breadboard. And I measure the voltages with a multimeter, which I put in the breadboard right next to the pins from the Arduino. I understand that there can be a voltage drop when there is a load, ie when there is a current. But there is no other load in my setup, than what is inside the Arduino itself.
I measure the 5.07V, by putting the multimeter on the points where the USB connector is soldered to the Arduino.
No. You can draw power from the 5v and VIN pins on the arduino. VIN is the completely unaltered input power before the regulator (it will be useless if regulated 5v is supplied directly). Outputting power is what the 5v pin is intended to be used for, not as a power input.
From the arduino website:
5V. This pin outputs a regulated 5V from the regulator on the board. The board can be supplied with power either from the DC power jack (7 - 12V), the USB connector (5V), or the VIN pin of the board (7-12V). Supplying voltage via the 5V or 3.3V pins bypasses the regulator, and can damage your board. We don't advise it.
They can also be used to draw power from the barrel jack (Vin) or from USB or the on-board regulator (5V). The schematic of the board shows all exact power paths.
Ok, but then why does the 5V and VIN pins have lower voltages then? And wouldn't that be a problem for many applications? I imagine that if I used a LCD display rated at 5V, it could (potentially) be a problem that it only gets 4.70 or 4.26V?
Btw: I am not an electrical engineer, and I am not able to understand the schematics. Maybe one day :)
The MBR0520 Schotky Power Rectifier (Surface Mount Schottky Power Rectifier) is connected in the Series path of 5v pin present on Nano which can handle maximum of 12V reverse voltage and according to datasheet 20v typical valur thus we can power ON arduino NANO using 5v pin also provided you supply proper 5v through any type of DC-DC Converter to it. https://www.onsemi.com/pub/Collateral/MBR0520LT1-D.PDF http://malylubo.sk/wp-content/uploads/2013/01/Arduino_Nano_Schematic-1024x676.png
Usually I do is, after uploading the code to the barrel jack i give power to the barrel jack via vIn externally. that way u can power your other components directly from that source. you can go to higher voltage values too since the arduino allow up to 12v.