Using 7 Pairs of 3V White LEDs on Arduino Nano

Hey Guys -

Working on a project where I am using an Arduino Nano to control 7 pairs of LEDs in a limited space. My draft build used some spare yellow LEDs which had a forward voltage of 1.8-2.2V each so obviously attached each pair to a pin with a resistor without issue. Wanting to use white LEDs for final build, I've found that they are 3.0V each where the supporting 5V cannot light a 6V pair.

Purchasing 5mm White LEDs which are 2.5V (or lower) would be an easy fix, but can't find any. Space is very limited so don't have space for 7 boost converters. I've considered using a 6V supply, but also need to power the other components including SSD1306 OLED, a servo, DHT22, rotary encoder, & piezo buzzer.

Any suggestions? Thanks!

Wire the pair of higher Vf LEDs in parallel with a current limit resistor each.

Follow CrossRoads suggestion just be careful about the current you are sucking out of the micro, it has both a maximum limit on each pin as well as a chip maximum. If this is a problem you could look at a discrete chip such as the 74HC540. In SOIC they will not use much space. There is also the possibility of using something like a Semtech SC620, no resistors are needed. It has a I2C interface with an enable pin. I hope this works for you as I have no idea of your skills or resources.

Awe man - I should have thought of parallel - was thinking too much into it. Thanks!

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