LED Wiring Configuration

I want to ask on how connect a parallel connection of 5 LED in a single Pin of an Arduino Nano.

I understand that the pin has a max of 40mA and an ideal 20mA and a 5v supply from the pin.
the only info I know about the LED I bought is that they are "3v" as per packaging. PS, the LED are 402 in size, and will be using a mix of Red White and Green LEDS.

Should I also consider the resistor used?
(from testing a single LED, the brightness of 1 LED using a 10k resistor is the perfect brightness, IDK if it is the same for 5 LEDs in parallel drawing power from a single pin of the Nano, or should I do something else)

Each LED needs its own resistor.

So if I were to attach a 10k resistor in series per LED, and connecting 5 LEDs(with a resistor in each LED) in parallel, it would work without any consequences?

I plan to power this setup with a 5V powerbank, if this affects anything.

The arduino nano runs off 5V. If you drive your LED from a pin you have
5V - (about 2V across the LED) - (about 0.5v drop on the pin) so about 2.5V remaining across your resisitor.
so a 10k resisitor gives you 0.25mA through the LED.

LEDs can be pretty dim below 1mA so I'd suggest a 2k2, 2k4 or 2k7 resistor for each.
Your 5 leds (with series resistrors) in parallel would then draw a total of about 5mA.

It would work fine but you may have to adjust the resistor values as green LEDs take a LOT more current to give the same brightness - I'd suggest a 1k or even down to 470 ohm for the green.

1 Like

If a 10k resistor gives adequate brightness, use one in series with each of 5 LEDs.

For 5 parallel LEDs, the minimum resistor value is 470 Ohm,

1 Like

Hanging multiple LEDs off one pin can become tricky design-wide.

How about using a small strip of WS2818 RGB LEDs. You can buy a small strip of these (anything from one LED to hundreds on a single strip).
There is a library to control these <FastLED.h>

The benefits of this are:-
A low-mess solution
Each LED can be controlled separately
Each LED is RGB so you can have just about as many colours as you want
Each LED is intensity-variable, so you can adjust the brightness of individual LEDs.

For connecting multiple LEDs off one pins - this is a terrific way to achieve that.

The WS2818 strip has 3 connections 5V and GND, and a control pin that you connect to the arduino pin via a 470R resistor (the R helps to suppress noise).

For this specific project, I have an IR Remote that has 8 buttons programmed with different LED for each button. There's even 1 button controls 5 LED in parallel which is the most, on most parts it is about 2 LED per button. So a LED strip is not the go to for this project.

Hi Paul, I dont know where you got that info.
By my calculations as follows:
a green LED drops 2V; the arduino output drops 0.5V on load
so a 5V supply leaves 2.5V.
2500mV/ 470ohm = 5mA approx
5 in parallel = 25mA.
so in principle you COULD go down to 330 ohm (8mA each) . However I agree it wouldnt be advisable.

Is it safe to say that using 5 LEDs in 1 output pin with a resistor of 1000ohm (or upwards) per LED is okay?


So you have 8 buttons that have control of each of their own LED, so the controller has an output for each of these LEDs?
Then you have a button that controls another output pin that has another 2LEDs and another button that controls another 5 LEDs?

How many LEDs do you have?

How many and what does EACH button control, "on most parts" is not very specific.

Tom... :grinning: :+1: :coffee: :australia:

It has a total of 21 LEDS.

I stand corrected, it has 9 buttons.

Button 1 3 LEDS
Button 2 2 LEDS
Button 3 3 LEDS
Button 4 5 LEDS
Button 5 2 LEDS
Button 6 2 LEDS
Button 7 1 LED
Button 8 1 LED
Button 9 3 LEDS

All LEDS are planned to be in Parallel per respective Button, and each single LED is with a series wired resistor.

Thanks, and its 22 LEDs.

If you put the LEDs in parallel that need one output, the brightness of those LEDS will be much lower than the others.
The difference between the LED controlled by Button 7 and the 5LEDs by Button 4 will be quite noticeable, if you pull the max current from each output.
Will there be a time when ALL 22 will be on.

You will have to check the maximum current that each output port can sink/source.

Tom... :grinning: :+1: :coffee: :australia:

This topic was automatically closed 120 days after the last reply. New replies are no longer allowed.