LED Driver

Answer provided by Alfonso, Technical Engineering Manager for EYE Lighting with experience in Europe and Australasia in lighting, electrical systems, energy efficiency and renewable energy.

Basically constant current drivers operate supplying a constant value of output direct current to the LED module/s. This type of drivers is the most common and versatile.

Constant voltage drivers supply a fixed value of voltage, usually 12 or 24 Vdc. Are generally more efficient but on the other hand more sensitive to temperature changes.

All LED drivers should specify whether they are constant current or constant voltage and provide indications on the secondary side (DC output) ofVout value on constant voltage and Iout on constant current drivers.

LEDs (modules, arrays, chips, etc.) require a certain level of DC current and voltage to operate, referred to as forward current If and forward voltage Vf. Constant current drivers supply a fixed value of current, generally given in milliamps (mA) and the voltage Vf varies depending on the load connected i.e. the number of LED modules or chips connected. Connecting the LEDs in series ensures a uniform level of current flowing through all of them.

By contrast, constant voltage drivers supply always the same voltage (V) but If will be different depending on the load/LEDs connected at the output.

You may find in the market many different types of LED drivers but they are eventually either constant current or constant voltage. Some other LED drivers are programmable and offer multiple output values. They are generally constant current type and the fixed value of output current can be selected by means of a dip-switch selector or using an external resistor.

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