Four major trends in LED lighting in 2013

As 2012 is about to pass, this year is a mixed picture for LED manufacturers. Although many countries, including China, have already banned the sale of incandescent lamps, sales of LED lamps have not broken out as scheduled. Instead, there have been a series of chain storms in which lighting manufacturers have closed down. However, there are also manufacturers who are smiling and making full profits. Overall, this year's LED market is a year of normal adjustment. For the LED lighting market in 2013, LED light bulbs replacing 40-watt (W) incandescent bulbs will have the lowest retail sales. The price has reached the sweet spot of US$10, and the industrial circles are optimistic that the overall LED lighting market will get warmer next year. Therefore, what companies are now doing is to do a good job of technical reserves and program selection, and only wait for the market to fully invest. Here, we discuss the four trends of LED lighting solutions in 2013 in conjunction with new products released by several mainstream LED manufacturers such as Power Integrations.

Trend 1: Large upgrade of dimming technology is expected to become a lighting highlight

In LED lighting applications, the challenges of dimming technology are very large. Because LED lighting adopts current driving mode, and the existing dimmers are mostly voltage dimming, the challenges in compatibility are considerable, but this It is also a good tool to identify the advantages and disadvantages of the solution. In the previous LED dimming solutions, common problems include small dimming range, sudden brightening in dimming, and flickering when dimming is low, which seriously affects the user experience. With the introduction of proprietary solutions such as PI, LED dimming is expected to be resolved. With PI's newly released LYTSwitch IC, excellent dimming performance can already be achieved, and NEMA can be easily achieved even at low conduction angles. SSL6 standard, in addition to the start-up speed of the driver is very fast, usually less than 500 milliseconds, even if the 10% of the light output is turned on when the start speed is also very fast, in the actual program, the use of LYTSwitch IC design light bulb can be related to Nearly the same dimming angle is turned on when turned off, which virtually eliminates sudden brightening. In addition, the dead zone in TRIAC dimming is also eliminated because the LYTSwitch controller ensures that dimming is performed immediately when the dimmer begins to operate. In this regard, PI claims to have a patented circuit technology. From the dimming curve, PI's scheme has obvious advantages.

Another challenge of dimming technology is the compatibility issue. There is no one program that can achieve 100% compatible dimmers. Therefore, it can be achieved that 90% or more of the dimming technology is very good. Now it is Power that claims to be able to achieve this ratio. According to Integrations, PI does do a lot of work in dimming. With the gradual popularization of LED lamps, the upgrade of dimming technology can bring more and better experiences to users, and it will become a new selling point. You can look at this function when choosing a solution. In support of dimming mode, manufacturers generally support thyristor dimming and PWM dimming.

Trend 2: Single-level circuit architecture gradually dominates the mainstream

In the past, in order to obtain better dimming characteristics, many solutions adopt a two-stage architecture, namely, the architecture of “PFC (Power Factor Correction) + Isolated DC/DC Converter”. Such a design can effectively reduce the power profile. Wave, because designers think the ripple of single-stage PFC circuit is too big, fear that cause LED life span, luminous efficiency and color temperature problem, so, adopt two-stage circuit more, and now, with high switching frequency single-stage With the introduction of the solution, the advantages of a single-stage circuit are very obvious, because in terms of efficiency, it is difficult for a two-stage circuit to compete with a single-stage circuit. Currently, several vendors can achieve a single-stage solution with an efficiency of more than 92%. Two-stage circuits are usually used. Only about 85% efficiency.

Another advantage of a single-stage circuit is that the circuit is simple. As can be seen from the above figure, PI's solution can achieve 92% efficiency! Therefore, the future adoption of single-level circuits will dominate the mainstream. This is also the opinion of some industry experts.

Trend 3: Integrated PFC and MOSFET become standard

In previous schemes, especially for low- and medium-power lighting solutions, many manufacturers did not consider PFC circuits because the country did not have mandatory requirements on the one hand and increased the program costs on the other, but now integrated PFC in medium-low power drive solutions. Has become a standard, first of all, this is in line with the general trend of energy-saving emission reduction, and the other is the Chinese government in the bidding project to first explicitly put forward such requirements, so chip manufacturers have followed suit.

For example, PI's LYTSwitch IC integrates PFC and constant current (CC) into a single switching circuit, which can increase efficiency in typical applications to more than 90%, power factor greater than 0.95, and easily meet EN61000-3-2C Harmonic distortion (THD) requirements. THD can be less than 10% after the design has been optimized. The following figure shows the circuit efficiency for three typical applications.

According to McKinsey's market research report "Lighting the Way", LED bulb prices fell by around 9% per quarter. In order to make up for the loss in price, IC component manufacturers will adopt high integration strategies to enhance the functions of the driver ICs. At present, many manufacturers adopt the integrated MOSFET strategy to integrate 500V or 600V MOSFETs and provide a complete protection scheme, which can make LED solutions more compact Reliability has also improved. The current PI solution is to integrate high-voltage MOSFETs with 650V and 725V.

Trend 4: Electrolytic capacitor solutions mature

Since the LED lighting has gradually been heated up, the use of electrolytic capacitors in the lighting program has been controversial, and those who oppose think that electrolytic capacitors are the life-time killer of LED lamps, and think that electrolytic capacitors have seriously affected the lifespan of LED lamps, while those who support believe that The role of electrolytic capacitors in filtering out ripples can not be ignored, especially the low-frequency flicker caused by the high ripple current caused by the non-electrolytic capacitor has attracted more and more attention. Some researchers believe that the frequency lower than 165Hz Even though the human eye does not easily perceive it, it has caused physical discomfort to some people's eyes. A large-scale low-frequency ripple may also cause the bright and dark grid of the beats of some digital camera devices. It is recommended to use high-capacity electrolytic capacitors to solve this, but this increases the cost and size. Is there no solution yet?

Judging from the latest new products, the leading manufacturers unanimously believe that the electroless capacitor solution will be the mainstream of the future. Each solution to the problem of flicker and ripple is unique. For example, the trend adopted by PI is to increase the frequency of switching power supplies. At 132 KHz, the ripple is much smaller at such high frequencies. At the same time, the required transformer core can also be reduced, which in turn reduces the cost.

Of course, the high-integration single-stage solution is also needed to eliminate the effect of electrolytic capacitors. Using PI's LYTSwitch IC as an example, not only high-voltage and large-capacity electrolytic capacitors can be omitted, but also the number of external components can be reduced, thereby significantly extending the use of the driver. Lifetime, Andrew Smith, Senior Product Marketing Manager at Power Integrations, pointed out that such a solution can extend LED lamp life even at high ambient temperatures. In addition, the use of precise primary-side control allows the driver to achieve true tight constant-current performance. The constant current regulation rate under load, in a wider temperature range and under manufacturing variations is better than +/- 5%, which in itself helps to prolong the life of LED lamps.

In 2013, LED lighting will use more intelligent lighting controls, such as remote control via mobile phones or other devices. However, the ever-changing, low-cost and high-reliability lamps are users who are willing to pay for it. The 2012 harvest will be good. The manufacturer is in line with this principle.

Looking forward to 2013, the LED market will recover from the downturn. Lighting companies will choose your solution and welcome a new climax market!