LED driver is the heart of the LED lighting system, LED driver defines the efficiency of the whole system, this in turn determines the reliability of the whole system.LED being driven from constant current source, needs a Constant Current Driver, hence LED drivers play a vital role in the system and should not be considered for its cost only.
LED driver is a general term given to the part of the LED lighting system which that provides the power to the LED module. General requirement of LED drivers is a constant current operation mode for brightness consistency, although there are also pockets of application that ask for constant voltage drivers.
We can classify the LED drivers to both internal and external. Internal LED drivers refers to the power source used for retrofit application, with design specifically to fit in confined spaces, low power and limited in functional features and made to match specific LED module parameters.
External LED drivers on the other hand is meant for more general application and designed to fit a diversified range of LED modules, comes with flexible and adaptive voltage range while holding a stable current level.
While internal LED drivers limits their application to power rating of 25W and less, external drivers stretch from power as low as 5W to as high as 200W or higher, with diverse application from signage, commercial lighting, industrial to street lamp. Due to its wide range of application and the need for end user contact, the design of external LED driver is more complex than internal drivers, with needs for safety and adaptive behaviour.
Addition to addressing the core requirement of LED drivers, a much larger form factor of the external LED drivers (compare to the internal LED drivers) provide allowance to expand into feature based product, with additive of intelligence enabling smart lighting function.
Let’s Discuss Market Growth and Key Drivers
Growth is spurred by ESSL tender and various government initiatives, better reliability & greater power saving are the key drivers for the growth of the LED Drivers. However, with the push for low cost solutions at the expense of quality, the initial growth will stagnate very quickly which will be followed by a more steady long term growth driven by demand for quality.
We will focus our topic to discuss external LED drivers.
The initial drive for external LED drivers began with signage application which saw the ease of system design to meet different signage size and shape, a much simpler choice of a LED driver with a single or more string of LED module, this compare to neon and fluorescent solution originally used.
A much higher efficiency of LED as well as its longer lifespan compare to its closest counterpart leads to governmental interest for public application, thus began the governmental initiative for conversion to LED lighting, propagating the growth of LED lighting segment and fast replacing other forms of lighting. To date, LED lighting is a common sight in the lighting arena with application stretch from street light, industrial, commercial to residential.
Home adaptation of LED lighting is the probably fastest growing segment today, followed by lighting for retail, industrial and street application. With serious price erosion in the retrofit segment due to high competition and its limitation to functional diversify leads to many manufacturers of both lamps and luminaire shift their production and use of retrofit in favour of LED drivers with more flexibility for their design. The increase in competition countered by barrier of entry such as regulatory requirement helps to maintain a steady yet moderate growth in the mid to high end LED drivers while we see erosion in price for the entry level LED drivers aiming for home and residential application, coincidentally with the largest market share.
So what might the game changer here?
Energy Starintends to revise program requirement for both lamps and luminaire by 2017, with regulatory standardization to formally include lighting product of LED nature. The regulation standard with have more detail coverage on LED lamps and luminaires in terms of safety and performance. While initiation is from USA, Europe and other part of the world may resonate with adoption of the regulatory standard for their region.
While the regulation introduced may not be as stringent as expected, we might see a paradigm shift in the product nature in the market. Products might shift from cost conscious to one with more focus on quality as manufacturers seek to remain in the market.
Another factor may be the ability to introduce feature set to LED lighting due to its DC operating nature. Unlike the need for sophisticated control needed for its competitor, it is easy to introduce digital control for LED lighting. While this is so, we must remain logical as to which segment of the market should we target for such features, while the need is similar, the approach is very different with sub-segment ranging between entry level dimming to the highly sophisticated smart building and city. The key balance is between the desired feature and affordability.
What are the Design Trends?
The LED driver design splits into 2 paths: Just light LED drivers versus intelligent LED drivers.
Just light drivers for no frill general lighting application equip only with basic power conversion function. Such product tends to be more cost centric due to the lack of additional feature requirement. Therefore design of such product focus more adhering to basic regulatory requirements, resulting in fulfilment of parameters such as power factor, harmonic components and isolation. On top of this, protection is another aspect which manufacturers very particular on due to diversification in application leading to variation in output requirement.
The other end of the spectrum is the intelligent LED driver, equip with dimming capability ranging from analogue (1-10V dimming) to digital (DALI, Zigbee). This is to address the need for smart building, smart city. Addition to what is needed in the just light product, there is a need for intelligent aspect to enable more features to lighting control such as LED behaviour compensation, output programmability, LED module thermal monitor and control. This group of product however is high end and applies to niche market.
In the midst of this, there is an emerging trend of LED driver with low end intelligence for brightness and colour temperature control, applicable more to residential lighting. Such drivers manipulate the LED output condition through detection of mains fluctuation, or mains switch. This is an emerging trend with the product seeks to meet market need for feature based product at a more affordable price.
Meeting Design Challenges
While LED driver design may look similar to that of a power supply, the requirements and needs are different and it certainly pose a challenge to designers. There are a few things that stand out.
The primary challenge for designers are the balance between cost and performance, and design will sway in different direction depending on power rating and area of application. In the lower power segment, designs are more tune to low system cost and output protection. As we move up in the power rating requirement, system cost is overcome by the need for adherence to regulatory standards, this is especially so for products with potential for government application. As a result, products of higher power range will need a much improved performance especially in power factor (PF), harmonic performance and efficiency.
This leads to manufacturers adopting a diversity in solutions to meet the shifting requirements of their users. It is not surprise that topologies uncommon to power supply design is used at all. For instance, single stage PFC flyback adaptation for up to 60 to 80W power range while 2-stage PFC LLC used in solution with as low power as 35W.
Unlike power supply, LED products are more than power conversion and also come with the need for output control. As a result, feature set is also another aspect which manufacturers need to take into consideration.
We are talking about building intelligence to LED drivers to enable output manipulation including dimming, digital & sensor interface and colour temperature adjustment. Moreover, the diversity in application leads to the need for highly flexible and adaptive products, as such the birth of programmable LED drivers with end user configurability and wireless communication.
So the challenge is to integrate digital control into power management system, which traditionally an analogue territory. In short we are merging two different worlds into one and experience will tell you the complexity need to achieve this.
Embrace New Lighting Trends with Infineon LED Drivers
If we are to discuss Infineon’s product feature, we first have to mention Infineon’s system approach to meet customer requirement where we focus on specific customer needs to achieve their design goals.
As a result, our product and solution design with criteria matching what our customer needs. We start with our legacy products, CoolMOSTM well known for its low RDS(ON) enabling improvements to system efficiency. It comes with a wide selection of electrical diversity and packages for our customers ease in finding a right fit product for their design. Our CE product is especially an attraction to manufacturers as its design aims at LED lighting application and it brings along performance value at an attractive price.
We also have an assortment of IC solutions for power function. For entry level LED drivers, the IRS2982 is an ideal choice for manufacturers looking for performance level solution for single stage LED driver, both isolated and non-isolated. The product comes with all necessary protection needed for an LED driver top with auto-burst mode for standby operation.
Moving higher is the configurable single stage PFC flyback LED driver solution using ICL8105, primary sensing constant current, thereby enabling single platform for diversified requirement. The solution also lead to a much lower component count, achieving the same effect with smaller form factor.
Addressing LED driver of higher power range, Infineon introduced ICL5101, a single chip 2-stage PFC LLC solution with capability for both constant current and constant voltage design. The added advantage of ICL5101 is an improvement with consistently high performance on power factor, lowiTHD and high efficiency, parameters valued by many manufacturers for mid to high power design.
On the secondary end of the design, we also made available a series of buck solution based on the ILD6xxx series and linear current regulator BCR series depending on our customers’ need. The implementation of these products and solution will help customers with a more stable output for a reliable LED driver design with effective output protection.
On top of providing performance level power conversion solutions to our customers, we also support our customers’ need on enabling 1-10V dimming function with our CDM10V which can work flawlessly with our LED driver solutions. Further diversification into feature base LED drivers can be achieved with our XMC range, ARM core Cortex microcontrollers and solutions we delivered with.
In short, we have products to help our customers to address their needs and realise their design. The most important thing is that we are not stopping here. With our focus on LED lighting segment, new products are in the pipeline to work even better and more fulfilling to the future needs for LED driver design and we will definitely up-date when it happens.
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