LED drivers, constant current or constant voltage?

XTAR Light

Apr 26, 2010
LED lights require a driver to provide and properly deliver the required output. And there are two main types of drivers, constant current and constant voltage. Both of them act as the power supply for an LED light source, but the delivery methods differ.

Constant Current LED Driver
This type of diver is designed for a range of output voltages and a fixed output current. It varies the voltage along an electronic circuit, which allows a constant electrical current through the device. Higher current ratings make the LED brighter, but if not regulated, the LED will draw more current than it is rated for, which may result in drastically lower LED life span and burning out due to increased temperature. A constant current driver is good to drive high power LEDs as it maintains a consistent brightness across all LEDs.

Constant Voltage LED Driver
It requires a fixed output voltage with a maximum output current. These LEDs require one stable voltage, usually 12V DC or 24V DC. An LED light rated for constant voltage usually specifies the amount of input voltage. The driver will maintain a constant voltage, no matter what kind of current load is put on it. More often, constant voltage drivers are implemented in under-cabinet lights, or LED flex strips.

As for applications, the constant voltage driver may be slightly less efficient, but it enables a full flexibility to allow a greater final load size. If the intended end-use is for illumination, the constant current driver can be a better choice. It provides better lighting consistency and brightness. The systems can be easily tuned to keep LEDs operating in their most efficient range.

In your opinions, what's other Pros and Cons in driving LEDs with constant current or constant voltage? Besides, are there suggestions for optimizing flashlights' design, to meet better light output, light quality and longevity targets?