Led lighting fixtures are typically operated by a constant current and/or constant voltage driver. We are frequentlz being asked which of both power supplies is “better” and want to give an answer to this question in this article.

 

As the name suggests,  constant voltage LED driver delivers have a tightly regulated output voltage across all load conditions to the LED lights. Contrary to this, a constant current LED driver supplies a carefully controlled current that flows across a given range of output voltages. With other words, a cosntant current driver varies the output voltage to maintain the current at the prescribed value. 

 

 

Constant current drivers typically provide longer LED lifetime expectancy and better lighting consistency, especially when dimming is a requirement. LEDs are a non-linear device, which make them inconsistent. A small increase in the voltage can cause an exponential increase in current, and this can sometimes damage an LED if not properly regulated. As an increased current produces increased heat, constant currrent drivers are also better in the thermal management of a lighting system. Especially when it comes to high power lighting fixtures, the application of constant current drivers is indispensable. The main drawback of constant current drivers is their relatively high cost. 

 

Constant voltage drivers are more flexible, allowing more LEDs to be added until the maximum current capability of the constant-voltage LED is reached. Another advantage is their relatively low cost compared to constant voltage drivers. However, they do have an issue with thermal runaway and provide only inconsistend brightness For simple, small LED lighting applications, a constant voltage LED driver is probably all that is required. However, as the number of or the output power of the LEDs increases - mainly where long strings are involved - the need to more carefully manage the drive current warrants the use of a constant current LED driver.