What is the difference between constant current and constant voltage LED drivers?

Understanding the difference between constant current and constant voltage LED drivers is essential when working with LED lighting.  This is because using the wrong type of driver can lead to poor performance or even damage your lighting system.

Constant Current

A constant current LED driver supplies a fixed electrical current.  Current is measured in milliamps.  Two examples that you might see would be 350mA or 700mA.  The constant current driver will automatically adjust the voltage to suit the LED load.  These drivers can be found in high-power or integrated LED fittings.  This includes fittings such as downlights, LED panels, and commercial luminaires.  The main advantage of constant current drivers is that they provide precise control over the electrical current flowing through the LED.  This helps to maintain consistent brightness and prevent overheating.

Constant Voltage

A constant voltage LED driver provides a fixed output voltage, converting it from mains voltage to the required voltage for your lights.  This will likely be 12V or 24V.  It allows the current to vary depending on the connected load.  These drivers are used for LED strip lights, LED tape, signage, and other modular lighting systems.  Because the voltage is fixed, it is believed that these systems are easier to design and install.   

What are the main differences?

The key difference between these two types lies in how they regulate power.  Constant current drivers control the current and ensure that it remains stable regardless of voltage fluctuations.  Constant voltage drivers on the other hand maintain a steady voltage whilst allowing the current to adjust based on demand.

Choosing the correct type of driver is crucial as they have two different functions.  If you connect a constant voltage LED to a constant current driver it may receive too much current and become damaged.  Using a constant current LED with a constant voltage driver may result in insufficient power meaning that it will not function as intended.

Dimming capabilities can also differ between these two types of LED drivers.  Both types are capable of supporting dimming but the method will depend on the driver's design.  It’s important to ensure compatibility between the driver, dimmer switch, and LED fitting.  This can be done by establishing the dimming type for all of these components which can be found in the manufacturer specifications.