How are LEDs powered?

Because of its current-​voltage characteristics, LEDs require an application of appropriate regulatory-​stabilizing equipment, power supply (AC), which aim at transformation of alternate voltage into the fixed voltage with indicated value, for example, 12V, 24V or 48V. Some solutions of power supplies (AC) are equipped with controlling systems allowing dimming effect or color change of matrix. Often controlling equipment constitutes the integral part of LED modules.

From the point of view of conditions for LED powering, two basic types of equipment are distinguished: with current stabilisation named “constant-​current” and with voltage stabilisation named “constant-​voltage”. It is recommended to use these first positively affecting on the value and stability of luminous flux. Modern power supplies (AC) have to be equipped with compensation system of environment temperature flow as well as the system preventing from AC overheating made on the basis of, for example, thermistors. In case of common powering aims of LED, ACs are used.

Chain voltage with the frequency 50Hz is rectified with the help of bridge rectifier. Later on, rectified voltage is being impulsed by semiconductor switch controlled by Pulse Width Modulation(PWM) generator with the row frequency of several dozen Hz.
High-​frequency transformer is used in order to adjust the values of voltage to the required value, which is later rectified and smoothed. Isolation (Opt) served for separating of galvanic controlling system and AC output circuit. Input filtr is aiming at limitation of damages generated to the chain through the power supply, mainly higher current harmonics. Fuse protect the power supply frin the damages of short-​circuti and overload. Modern high quality constructions of impulse power supplies have eve practically sinusoidal shape of input current curve.