LED driver is the core component of led lamp, so how much do you know about LED driver? The following article will give you a detailed answer.
What is an LED Driver?
An LED driver is a self contained power supply which regulates the power required for an LED flood lights or array of LEDs. The light emitting diodes are low energy, lighting devices with a long lifespan and low energy consumption, hence the requirement for specialized power supplies.
An LED driver performs a function similar to a ballast for discharge lamps. It controls the current flowing through the LED. Most LED drivers are designed to provide current to a specific device or array. Since LED packages and arrays are not presently standardized, it is very important that a driver is selected that is matched to the specific device or array to be illuminated.
Introduction of LED Driver
Due to increasing energy regulations, most people are familiar by now with the long life spans and energy savings associated with LEDs, or light-emitting diodes. However, many are not aware that these innovative light sources require specialized devices called LED drivers to operate. LED drivers (also known as LED power supplies) are similar to ballasts for fluorescent lamps or transformers for lowvoltage bulbs: they provide LEDs with the electricity they require to function and perform at their best.
LEDs require drivers for two purposes:
1. LEDs are designed to run on low voltage (12-24V), direct current electricity. However, most places supply higher voltage (120-277V), alternating current electricity. An LED driver rectifies higher voltage, alternating current to low voltage, direct current.
2. LED drivers also protect LEDs from voltage or current fluctuations. A change in voltage could cause a change in the current being supplied to the LEDs. LED light output is proportional to its current supply, and LEDs are rated to operate within a certain current range (measured in amps). Therefore, too much or too little current can cause light output to vary or degrade faster due to higher temperatures within the LED.
In summary, LED drivers convert higher voltage, alternating current to low voltage, direct current. They
also keep the voltage and current flowing through an LED circuit at its rated level.
How does an LED driver differ from a convectional power supply?
An LED light driver is somewhat like cruise control in a car, the power level required changes throughout the LED’s temperature increases and decreases. Without the correct LED light driver the LEDs would become too hot and unstable resulting in failure and bad performance. To ensure the LEDs function perfectly the self contained LED driver is required to supply a maintained constant amount of power to the LED.
The LEDs provide low voltage and protection for the LEDs.
Provides low voltage
Individual LED bulbs operate at voltages ranging from about 1.5 to 3.5 volts and currents of up to a maximum of 30mA. The domestic bulbs may consist of several bulbs, in series and parallel combinations and which requires a total voltage of between 12 and 24 V DC. The LED driver rectifies the AC and lowers the level to suit the requirements. This means converting the high AC mains voltage which ranges from 120 Volts to 277Volts, to the required low DC voltage.
Provides protection to the LED bulbs
The LED drivers provide protection to the LED bulbs against current and voltage fluctuations. The drivers ensure that the voltage and current to the LED bulbs remains within the operating range of the LEDs regardless of fluctuations in the mains supply. The protection avoids providing too much voltage and current that would degrade the LEDs or too low current that would reduce the light output.
Types of LED drivers
The LED drivers are either used externally on internally within the LED bulb assembly.
Internal LED drivers
These are commonly used in domestic LED bulbs to make it easy when replacing the bulbs; the internal drivers are usually housed in the same case as the LEDs.
Internal vs. External Drivers
For the aforementioned reasons, every LED light source requires a driver. However, some LEDs, particularly those designed for household use, contain internal drivers rather than separate, external drivers. Household bulbs usually include an internal driver because it makes replacing old incandescent
or CFL bulbs easier. These include LED bulbs with standard screw-in or plug-in bases (E26 / E27 or GU24/ GU10 – see images below) or those that specify a line-voltage (120 volts) input on their datasheet. LEDs that typically require an external driver include cove lights, downlights, and tape lights, as well ascertain fixtures, panels, and outdoor-rated lights. These bulbs are often used for commercial, outdoor,
or roadway lighting purposes. They typically require a separate driver because it’s simpler and cheaperto replace the driver than the LEDs. Sometimes, LEDs will come equipped with a separate driver. Other times, manufacturer datasheets will specify whether or not an LED requires a separate driver, along with the type of driver it requires if necessary.
A key piece of understanding how LED drivers work is knowing the different LED configurations. The two most common LED configurations are series and parallel.
In a series configuration, one LED’s anode (aka positively charged electrode) is connected to another’s cathode (aka negatively charged electrode). This enables a single, non-stop current to flow through all the LEDs in the series, usually called a string.
Important to note that in order to keep the entire string of LEDs running, you have to make sure you’re providing enough voltage for the sum of them all. So, for instance, if each LED needs 2V to illuminate and you have 10 LEDs, they will require 20V.
Another standard configuration for LEDs is a parallel configuration. Here we would connect multiple strings of LEDs in parallel — or side-by-side — to a driver. So, for instance, if you had 50 LEDs you could have five strings of 10 LEDs each running parallel, rather than all 50 in one string. A parallel configuration is for situations where you want to limit the voltage necessary to operate the strings of LEDs.
You can also configure parallel strings of LEDs in a matrix. This happens when sets of parallel strings of LEDs connect to each other in a series.
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