How to Use a Line Driver IC


As you add more components to your projects, there are often ICs which can help to reduce both the complexity of wiring, as well as the footprint of your project.

Line Drivers are an integrated set of transistors, packaged in an IC, allowing for multiple higher power outputs to be driven from your low power Arduino project.


As they are simply sets of transistors they are either Sourcing or Sinking power, so bear this in mind when adding them to your projects.


Note IconNote

The power rating for these ICs is often stated per-channel, and if you require more current you can couple the channel outputs together to deliver more current.

            e.g. ULN2803A : has 500ma per-channel, so if 1A is required link 2 or 3 outputs together.

Why Use Them?

The reasons to use a Line Driver are the same as using a Transistor. 

These are often good replacements for relays, if the amperage consumed is generally low, and just like standard transistors allow for PWM to also be used.


Sinking Line Driver (ULN2803A)

The ULN2803A allows for 8 channels to be controlled from 8 low power inputs.  Our outputs can be up to 50V!

You can use an external PSU to supply your high power outputs, and this will also be connected to the IC, sharing GND with your board.

The full datasheet can be found here.

DescriptionExample Value
GPIO voltage 3.3 or 5 V
Coil supply voltage 12 to 50 V
Number of channels 8
Output current (RCOIL) 20 to 300 mA per channel
Duty cycle 100%


Wiring Diagram

ULN2803A Wiring Diagram

Video Overview


We will be updating this page with the Sourcing Line Driver shortly.... so check back for more details soon, or subscribe to our YouTube Channel to stay up to date.