LED, a light-emitting diode, is a two-lead semiconductor that has become a popular source of artificial light these days. In the simplest of terms, it glows when an electric current passes through it. Coming to LED Drivers, they are an electrical device capable of regulating the power to an LED. Why do we need to regulate the power, you might ask? This is because an LED might get damaged as the forward voltage (Vf) of an LED changes with temperature.
Choosing the right LED Driver
LED drivers should be chosen based on attributes and applications i.e. by Supply Voltage (-0.3 to +20 V, 2.7 to 5.5 V, 3 to 5.5 V), Output Voltage (up to 198 V) and Maximum Switching Frequency (from 200 Hz to 200 GHz). They should also be chosen based on the desired function i.e. constant current LED driver, high power LED driver, RGB LED driver, 24v LED driver, dimmable LED driver, as an LED Driver Board or LED Driver Integrated circuit and for any circuits that may require LED driver chips.
Power Source Considerations
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LED is similar to a diode and the current is exponential to voltage. It is based on Shockley’s diode equation i.e. any minor change in voltage can make a huge difference in current. Chances are high that while designing an LED driver if the voltage is set too high it might overheat or destroy the LED(s). Resistors in series can be a simple way of passively stabilizing the current, but energy might get wasted in the resistors. An active constant current driver is generally used to power and to regulate the light output to increase the life of batteries.
LDO Linear regulators, Switching Regulators, and µModule Regulators are few of the most used regulators.
Constant Current or Constant Voltage
The LEDs can be connected to a PCB in series or parallel circuits. While connecting the LEDs to ensure the same current- series circuits should be prioritized. In a parallel circuit, the same voltage is applied to each LED.
Theoretically, the same current would pass through each LED if they do not have any production tolerances and if a constant temperature of all LEDs is guaranteed. Since this is very difficult to achieve, it may happen that some LEDs succumb to a higher current and will, therefore, be destroyed.
LED Driver for Dimming, Blinking and Color Features
For Dimming, Blinking and Color regulation, including other special features in an LED grid, you will require an LED Driver. Drivers can be utilized for sequencing lights in a grid, lowering down the light intensity or combining a set of colored LEDs by limiting the current by using a set of one or more resistors in series or parallel.
Drivers can support color sequencing/changing in an LED lighting system by interfacing with a color sequencer. This can be achieved by an LED driver with a specific voltage output that transforms into a three-channel output (the usual red, blue, and green) to produce a wide array of combinations.
Applications of LED Drivers
Applications can vary from industrial, commercial, residential lighting to use in day-to-day products, which includes, automotive industry, electronic gadgets – television, smartphones, smart refrigerators, music players, gym equipment, etc. Due to the ultra-low running cost, usage and application of LED Drivers are increasing day-by-day.