Why is a good quality driver important for led luminaire?

Do you know what is the most important part of a lamp?Today we are talking about the key components of luminaires at present, the driver.

Let's start a simple question: why do we need a driver? This brings us to the characteristics of LEDs. The volt-ampere characteristics of LEDs are shown in the figure below: please note that the horizontal axis represents voltage, and the vertical axis represents current in the diagram.

Due to such characteristics, a slight change in voltage can lead to a huge change in current, whereas a huge change in current only results in a slight change in voltage.

It is evident from the above diagram that all LED drivers should be of constant current type. Any other type of driver can cause significant damage to the lifespan of LEDs. Among them, the harm caused by the so-called ‘linear’ driver is particularly severe.

Historically, ‘linear’ drivers have had many names, which represent the development process of this type of driver.

It first appeared in 2007 or 2008 and was called AC-LED, with the aim of eliminating the rapid evaporation of electrolyte in electrolytic capacitors caused by abnormally high temperatures within the driver. The design concept of AC-LED is to do away with a driver at all. Its principle is shown in the diagram below.

I don't want to get into too much technical detail here. 1) It's just that this structure is inefficient for the use of LED chips. 2) The design of the entire structure does not consider fluctuations in external voltage, which can easily burn out the LEDs. 3) Additionally, luminaires made with this structure have severe flickering issues.

After 7 or 8 years, the improved structure of AC-LED emerged again under the name of ‘light engine’. I still don't want to get into too much technical detail here. Perhaps the first attempt to improve the AC-LED solution was made by the American company ExClara, which first released the EXC100 chip. ExCLara's solution combines AC-LED with constant current source, and segments the entire LED branch circuit to reduce the voltage on each LED branch circuit while increasing the flickering frequency.

However, this solution does not solve all the shortcomings of AC-LED, such as flickering and inefficient use of LEDs. Additionally, it introduces a new problem: uneven light emission within a single lighting cycle.

Since then, there have been no fundamental improvements to this solution. Due to its numerous shortcomings, this solution has completely become the ‘standard configuration’ for low-end luminaires in China.

Could it be any worse?

YES

Due to the stringent cost requirements of low-end luminaires, to save on driver housing and related wiring, a combination of "linear" drivers and DoB (Driver on Board) is used, with the drive integrated onto the light board. As a result, the driver, which needed to dissipate heat, was subjected to heat from the light board, which made the original unstable driver system even worse. Even more worse, to reduce severe flickering, the ‘linear’ driver was equipped with electrolytic capacitors. However, the high temperature working environment accelerated the shortened lifespan and decay of the electrolytic capacitors. In the end, the original goal of avoiding the use of electrolytic capacitors from the AC-LED solution was not achieved.

It's no exaggeration to say that if the LED determines the upper limit of a luminaire, then the driver determines its lower limit. Unfortunately, nowadays the lower limit of luminaires is very low.