A Brief Analysis of Cost Control Technology of LED Drivers

Currently, countries and regions around the world have begun to ban the use of incandescent lamps. Driven by policies and the long life effect of LED lamps, LED lighting entered a boom year in 2013. However, the boom will inevitably be followed by a gradual decline in the market. According to the lighting market share report of market research organization HIS, the sales volume of lamp sources has been declining year by year since 2015.

　　Countries and regions around the world have begun to ban the use of incandescent lamps (see Table 1 for details)

　　Table 1: Global Incandescent Lamp Ban Plan

　　Driven by policies and the long life of LED lamps, LED lighting entered a boom year in 2013. However, the boom will be followed by a gradual decline in the market. According to the lighting market share report of HIS Research, a market research organization, the sales volume of lamp sources has been declining year by year since 2015. (See Table 2 for details)

　　Table 2: IHS Lighting Market Share Report

　　According to a report released by IMS Research in April 2012, the price of LED lamps has been declining from US$30 in 2009, and will break through the US$5 mark around 2017. The popularity of LED lamps depends on the speed of price decline, and 40% of the cost of LED lamps is spent on the drive control circuit, so it is crucial to reduce the cost of control circuits including LED driver ICs. Correspondingly, the cost of drive control circuits is expected to decrease by 36% between 2013 and 2015.

　　Although LED driver power has made some breakthroughs in technology, the cost has remained at around 200 yuan. If the sales price is less than 400 yuan, it is basically a loss. However, the lowest sales price of foreign manufacturers such as Philips can be around 180 yuan. With the increase in labor costs, rent, marketing and office costs, it is very difficult to reduce the price of LED driver power. Many companies have to make up for the cost pressure from technology and design.

　　Simplified topology

　　To reduce the price, it is necessary to optimize the structural design while continuously upgrading the technology, and minimize the number of IC components used. At the 9th LED General Lighting Driver Technology Seminar held on November 25, Guo Chunming from PI pointed out that to reduce the cost of LED bulbs, it is necessary to change the LED driver technology. In the report, Guo Chunming pointed out that with the advancement of LED driver technology, the conversion from bipolar driver to single-stage driver technology can reduce the cost demand of the driver, and in the choice of topology available for the currently available LED driver, more tend to use non-isolated drivers. He also mentioned that the use of buck converters in the topology is small in size, uses low drain-source voltage stress, and uses the least number of filter components, so it has the advantages of high efficiency and can achieve the best EMI performance. Compared with the flyback and unipolar PFC combined with constant current flyback topology, it has the lowest cost.

　　Guo Chunming also listed the requirements for the lowest cost bulb driver, such as using the smallest possible heat sink to achieve high efficiency, meeting the EU Commission's environmental protection directive and Energy Star's consumer lighting requirements when inputting high and low voltage, using buck and buck-boost topologies and the simplest possible EMI filter circuit to achieve the minimum number of components, using the minimum number of LEDs to meet the minimum brightness standard, and reducing the temperature stress of the heat sink to ensure constant output current during the production process. Reducing the cost of LED drivers through topology is only an optimization in design for enterprises, and strictly controlling the specifications is the key factor to ensure product quality.

　　A high-efficiency driver can be achieved through simple settings. The specifications of the settings need to be accurately grasped. Excessive specification design will lead to an increase in product costs. In terms of saving assembly costs, functions can be integrated as much as possible to reduce circuit board space. Using the best design can meet consumer needs with the smallest safety margin.

　　High voltage linear constant current technology

　　The high-voltage linear constant current power supply has no magnetic devices such as transformers, and no electrolytic capacitors, which can save one-third of the cost of general switching constant current power supplies. Due to the simple structure of the system, it only requires a few peripheral components and is suitable for systems with volume and cost requirements. With the emergence of HVLED lamp bead technology, non-isolated high-voltage linear constant current LED driver power supply technology has become a new hot spot for LED light source drivers. Professor Yan Chongguang of the Shanghai Institute of Microelectronics of Peking University also demonstrated an integrated photoelectric engine of HVLEDs+high-voltage linear constant current drive at the LED General Lighting Driver Technology Seminar: placing the driver power chip and LEDs lamp beads on the same side of the copper-clad aluminum substrate facilitates the automated production of SMT. The power supply has no transformer, no electrolytic capacitor, and has a low production cost. In the high-voltage linear constant current solution displayed on site, there are no magnetic components, no EMI filtering, and a built-in high-voltage power tube, which can be used to design and produce an integrated photoelectric engine. However, this technology also has its limitations, and has not yet been able to solve the problems of flicker, PF, and voltage regulation rate, which need to be improved and solved.