LED lighting market development and LED driver solution selection

The global light bulb market has an appetite of 20 billion pieces. After the ban on the production and sale of incandescent lamps in 2012, although the penetration rate of energy-saving fluorescent lamps (CFL) still prevails, with the global environmental awareness rising, light-emitting diodes ( LED ) have become a policy promoted by various countries, among which LED bulbs will be one of the priority products introduced in the lighting plans promoted by many countries. Market research institutions estimate that the penetration rate of LED bulbs will be 3% in 2011, and the shipment volume will reach 600 million pieces, with an output value of 8 billion US dollars. By 2013, with the replacement of 40-watt and 60-watt traditional bulbs, the overall market size will increase dramatically to 2.5 billion pieces.

The massive market for LED lighting is ready for activation

The economic benefits of LEDs are mainly reflected in their better power saving effect and the advantages of illumination efficiency. In addition, due to the ultra-long life of LEDs, their replacement cost is significantly better than other light sources. The global market for light bulbs has an appetite of 20 billion pieces. After the ban on the production and sale of incandescent lamps in 2012, although the penetration rate of energy-saving fluorescent lamps (CFL) still prevails, with the global environmental awareness rising, light-emitting diodes (LED) have become a policy promoted by various countries, and LED bulbs will be one of the priority products introduced in the lighting plans promoted by many countries. Market research institutions estimate that the penetration rate of LED bulbs will be 3% in 2011, and the shipment volume will reach 600 million pieces, with an output value of 8 billion US dollars. By 2013, with the replacement of 40-watt and 60-watt traditional bulbs, the overall market size will increase dramatically to 2.5 billion pieces. Countries such as Japan, South Korea and North America have implemented subsidy policies for green products such as LED lighting. Currently, places including stores, shops and factories are also willing to replace them with LED lighting. It is estimated that the global LED lighting penetration rate will exceed 10% in 2011, attracting major manufacturers such as Nichia , Philips , Osram and Cree to compete for business opportunities. As more and more countries begin to allocate budgets to replace LED street lights , and the annual price drop of LED lighting reaches more than 30%, it is estimated that the penetration rate will increase to nearly 20% in 2013, and the market prospects are promising. (Data source: New Electronic Technology Magazine)

Governments of various countries - LED lighting development plans

Japan… 21st Century Lighting Project

Next Generation Lighting Program

Taiwan… White Light Source Project

South Korea…GaN semiconductor Development plan

Europe… Rainbow Project

China… Country Semiconductor lighting Engineering

Due to the light source characteristics of LED, special product design and high-efficiency drive circuit, and in terms of optical design, LED is a unidirectional point light source, which can be very well designed optically, which is conducive to making light reach the designated area and reduce reflection. These can improve the illumination effect, so the illumination cost should be the key indicator for evaluating the take-off of LED applications.

From the perspective of LED production capacity, technology and availability, the Chinese government is promoting the self-sufficiency of LED in the mainland through the Metal Organic Chemical Vapor Deposition incentive program. The program is expected to spend $1.6 billion on MOCVD equipment between 2010 and 2012 , and also provide subsidies of up to $1.8 million for each equipment. Local governments have also proposed preferential measures such as lowering tax rates, accelerating the replacement of old equipment with new ones, and free land use. Therefore, the program is equivalent to encouraging existing Chinese LED manufacturers to expand production capacity, and has also led to the emergence of many new entrants. Manufacturers from Taiwan and South Korea have also entered China in the form of joint ventures. They have all become factors in promoting the increase of China's production capacity.

Because of this, we believe that the massive market for LED lighting is ready for activation.

The lighting market will first activate outdoor large-angle lighting, such as street lamps, billboard lights, etc. The first indoor lighting to be activated will be long-term lighting applications, including tunnels, cold storage, garages, supermarkets, factories, shopping malls (cold white light), and office buildings. It is expected that most commercial lighting will be activated by the end of 2011, while home lighting will mainly be activated by high-end customers.

However, the LED lighting market also faces many challenges. In addition to price, improving luminous efficiency , reducing glare, and improving light configuration and uniformity are all key points, especially in the field of replacing fluorescent lamps.

High-efficiency LEDs have the disadvantage of having a higher color temperature and tending to be cooler. Due to differences in usage habits, some application environments (such as clothing stores) or some countries (such as most Asian countries) require warm white light with a lower color temperature, which will lose up to 30% of the light source efficiency. For this reason, the activation threshold of warm white light is higher than that of cold white light. We estimate that when the cost of LEDs can be reduced by about 40%, warm white light will have the economic efficiency of current cold white light, which is expected to be around the end of 2011.

The life of LED lamps has always been controversial. Although the life of LED chips may be greater than 100,000 hours, the packaging and driving links may cause the life of the entire lamp to decrease. The current standards for LED street lamps stipulate that the life must reach 30,000 hours, and most of the standards for indoor lighting stipulate that the life must reach 20,000 hours, which is also the general level of the industry.

Currently, most LED lifespans are estimated using data models after a certain period of testing . Due to the long lifespan of LEDs, it is difficult for customers to judge the lifespan of LED lamps based on experience, and previous non-standard LED products have affected the public's expectations of LED lifespans.

LED lighting Power supply and driver selection

In LED lighting design, there are generally two types of drive schemes: linear drive and switch type drive.

Linear drive application is the simplest and most direct drive application method. In lighting-level white light LED applications, although there are problems such as low efficiency and poor regulation, it can meet more specific applications due to its simple circuit and small size.

The switch type driver can obtain good current control accuracy and high overall efficiency, and its application methods are mainly divided into two categories: buck type and boost type. Buck switch driver is used for applications where the power supply voltage is higher than the terminal voltage of the LED or multiple LEDs are driven in parallel. Boost switch driver is used for applications where the power supply voltage is lower than the terminal voltage of the LED or multiple LEDs are driven in series.

It is generally believed that isolated drives are safe but less efficient, while non-isolated drives are more efficient and should be selected according to actual usage requirements.

Designing a basic LED driver for a typical lighting application is relatively simple, but if additional features such as phase-controlled dimming and power factor correction (PFC) are required, the design becomes complicated. Non-dimming LED drivers without power factor correction typically include an offline switching power supply that regulates the output at a constant current.

The back-end architecture of an LED driver includes a current regulation circuit with short-circuit protection. This can be achieved using a linear regulation circuit, however this approach is inherently inefficient and therefore suitable for low output currents and is not typically applied to multi-stage architectures. An alternative approach is to use a simple buck regulator circuit with current feedback to limit the output current to exceed the desired LED drive current. This offsets the variation of the total LED forward voltage with temperature and device tolerances, and also limits the current in the event of a short circuit or other fault condition, thereby protecting the driver from damage.

E27 3.5W LED Bulb Driver Solution Recommendation

Working principle diagram

Main chip of the solution: STMicroelectronics (STMicro) type ALTAIR03TR (SO16 chip package), quasi-resonant working mode chip, high integration and high reliability.

The main parameters are as follows

& mid dot;Input voltage: AC90~264V,50/60Hz

Power factor: > 0.5

Average efficiency: > 75%

Output constant voltage/constant current: DC10.2V, 350mA +/-5%

LED combination: 1W x 3 in series

Solution features: Built-in 700V MOSFET, very few components, high cost performance