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.
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.
| Description | Example 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
Sourcing Line Driver (UDN2981/MIC2981)
The UDN2918/MIC2981 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.
| Description | Example Value |
| GPIO voltage |
3.3 or 5 V |
| Coil supply voltage |
12 to 50 V |
| Number of channels |
8 |
| Output current (RCOIL) |
500mA per channel |
| Duty cycle |
0 - 100% |
One advantage of using Sourcing Line Drivers is you can also vary the duty cycle as they are on the high side, allowing for higher power PWM to e.g. Fade a 12v LED or vary the speed of a higher power motor.
Wiring Diagram
