LED driver is the source of power for LEDs. Whenever you are building an LED luminaire, you will always need a driver or possibly even multiple drivers. There are different types of LED drivers, as there are different types of LEDs.
LED drivers can be divided into two categories: constant current(CC) and constant voltage(CV) drivers. One thing is for sure, LED driver is usually AC/DC converter. In another words it converts AC voltage from main 220V, 230V or 240V power supply to DC supply suitable for the LED component.
As indicated by their name, constant current drivers always feed relatively constant current. Voltage range may vary, many times the output voltage range is related to the physical dimensions of the driver. This restriction may set some selection challenge if luminaire is compact and there is limited space for the driver.
The most important thing for a good constant current driver is, obviously, the ability to keep to current constant. Under heavy electric load, the current may not stay constant.
One key characteristic of constant current LED driver is its efficiency. Efficiency tells you how much of the input power the driver can actually use to power the LED. Efficiency is announced as percentage. The higher the percentage is, the better it is.
Another important characteristic for LED driver is the power factor. The maximum value for power factor is 1. The higher the power factor is, the better it is. Basically the power factor tells you how much load the driver puts on the electrical network.
Together with efficiency of the driver, these two facts can be crucial in defining which power supply to choose for our LED component or module.
As constant current driver keeps the current constant, a constant voltage driver keeps the voltage constant. The feeding current varies according to the load. The higher the load is, the bigger the current is.
Constant voltage drivers are usually used in applications where all LED components are in series. Constant voltage drivers with high powers can be used as electrical energy supplier for many smaller power constant current drivers. In larger lighting systems, they are storages that feed stabile current into the LED loads they have.
In some cases constant voltage drivers are the only suitable solution e.g. when replacing halogen lamps. Replacements require 12V or 24V voltage. If used in parallel mode, electrical load variation can result to brightness variation due to current variation.
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