LED drivers are specified as either constant current or constant voltage, and using the wrong type for your fixture can damage the LEDs or cause uneven brightness.
Constant current drivers deliver a fixed amount of current (measured in milliamps, like 350mA or 700mA) while the voltage varies depending on the load. This is the standard for individual LED fixtures like downlights and spotlights, since LEDs are current-driven devices, their brightness and lifespan depend on stable current, not stable voltage.
Constant voltage drivers deliver a fixed voltage (commonly 12V or 24V) while the current varies. This is the standard for LED strips, where multiple LED segments are wired in parallel and each segment needs the same voltage across it.
Using a constant voltage driver on a single fixture built for constant current (or vice versa) can cause flickering, reduced lifespan, or in some cases, immediate LED failure.
FAQ
How do I know which type my fixture needs?
Check the fixture's spec label. Downlights and spotlights are almost always constant current. LED strips are almost always constant voltage.
Can one driver do both?
No, they're different circuit designs. You need the driver type that matches your fixture.