LED driver, a vital component of the LED system, usually gets less attention. However, it is essential for the manufacturers of LED lighting systems to have good knowledge about LED drivers as well.
The new generation sophisticated LED drivers makes it easier for the designers to design LED luminaires more easily. Today, LED drivers are more innovative and intelligent, and hence, enable LED lighting systems more flexible.
Why LED drivers are vital
LED drivers convert any given voltage into a constant current that makes LEDs light up in the desired brightness and color. LED drivers respond to the changing input voltage while maintaining a constant amount of current supply to the LED. They are commonly used for blinking, dimming and color mixing of LEDs in various applications.
As LEDs are available with different power ratings, drivers must produce different constant currents to operate them. Single-watt LEDs require a constant current of 350mA, while 2W LEDs need 700mA. The maximum output voltage of a driver, thus, determines the number of LEDs that can be operated in series. When the voltage is high enough to supply the desired number of LEDs, buck drivers are used. But when the voltage is too low, boost drivers are required. However, in some cases, a combined driver type is needed.
How LED drivers have advanced
The constant pressure to reduce chip sizes and increase lumens per watt has forced manufacturers to come up with modified drivers equipped with the latest technologies, which could further enhance the efficiency of LED lighting and make it more cost effective. They are now coming up with automated features and water proofing/moisture protection and a lot more.
With the recent technological advances, LED drivers have become more innovative, and offer increased flexibility for LED lighting solutions.
Innovative buck/boost driver: An innovative buck/boost driver automatically switches to the correct mode based on the available voltage. When the battery voltage drops below a minimum level of 22V or 23V, the driver automatically switches to boost mode so that the entire battery charge can be used to operate the LEDs. The hybrid LED driver can be connected to an input voltage of between 8V and 36V DC, and provides 2V to 40V DC and a constant current of 350mA or 500mA at the output. Its efficiency is around 92 per cent.
High voltage drivers: Until recently, drivers reached their limit at 40V, so it was not possible to include more than 11 or 12 LEDs in a string. Today, the high voltage drivers can supply up to 17 LEDs in series with constant currents between 350mA and 1200mA. A powerful model comes in a metal casing and provides up to 70W. All drivers of this family can be dimmed in analogue and digital mode. The built-in reference source allows dimming by means of a potentiometer, and also supplies external sensors or controllers for advanced control functions.
Flicker-free TRIAC dimmer: TRIAC dimmers provide a phase-cut sine wave that deteriorates to current pulse if the device is dimmed too much. The two circuits interfere with each other. As there are many TRIAC dimmers installed in homes and offices, and nobody wants to spend a lot of money replacing them when shifting over to LED lighting, engineers have solved this problem by developing a driver that is tailor-made for installation in existing lighting control systems. With such a driver, it is now possible to dim LEDs continuously and without flickering to zero.