There are a wide variety of LED drivers, both current-based and voltage-based, readily available on the market. When choosing a driver, the right kind of LED circuit topology should be considered, as should exigencies related to dimming and flicker. It’s difficult to choose an LED driver, and the developing nature of the market makes it hard to find a singly satisfactory option immediately, but the following tips will help buyers make the right selection.
CURRENT VOLTAGE OR CONSTANT CURRENT?
Whether or not current or constant voltage should be specified in driver choice is a big deal. Among LED arrays are two separate types: CV, or constant voltage, and CC, or constant current. CV arrays limit current when LEDs get hot by using internal components like constant current resistors (CCRs) or other regulators. A CC array connects LEDs serially.
There are two main reasons buyers choose CV: when they don’t know the way the LED lights/arrays/strings will be used, or how many of them will be used (this affects the need for current draw), or when the array is already of the CV kind and comes built with a range of fixed currents. It makes sense to ensure the selected driver has the correct voltage. \ If neither of these things are problems, a CC driver will likely be a better choice.
VOLTAGE RANGE MATTERS
When it’s clear what kind of current draw is required to properly align with light-level application requirements, CC arrays definitely make more sense as far as efficiency is concerned. Any LED that needs continuous current will necessarily require a CC LED driver. Such drivers only have a limited range of voltages that can be driven, often in the form of “minimum” and “maximum” permissible voltage. Before purchasing a CC array, buyers should ensure the LED arrangement doesn’t have voltage needs beyond such a range.
THE “FLICKER” CONTROVERSY
Once the buyer has determined whether CC or CV best fits their needs, they need to consider what has come to be known as the “flicker” controversy. There are flicker issues related to dimming, and the controversy revolves around how much is too much. Current industry recommendations stipulate the 120-Hz ripple which emanates from a driver should be below ten percent in office, task, and decorative areas. LED drivers that can be dimmed exist, but this affects flicker. Ultimately, how much is too much is up to the buyer, but professional options will keep it below the ten percent threshold mentioned earlier.