LED light bulb with the power switch to achieve stepless dimming

However, the embossing technology (O2Micro) FAE Director and Director of Product Development Guoqing Quan said: "We should see three issues: first, TRIAC dimmer has one drawback, namely, power consumption, especially in light load , only about 10% efficiency, but will have much better PWM dimming, brightness down to 50%, there are about 80% efficiency. Second, any support dimming of the LED lighting TRIAC driver can not support programs the market all the TRIAC dimmer. Third, the largest LED lighting application markets (ie, global office lighting market) now widely used fluorescent lamps, their infrastructure does not TRIAC dimmer, and this market leader in LED lighting family market launch. "


In order to overcome these three problems, O2Micro invented a unique three-segment LED bulb / lamp dimming technology, the use of the patent application is among the analog dimming technology, it does not need TRIAC dimmer, simply use a wall switch to three sections of dimming can be achieved (100%, 50%, 20%), no RF remote control circuit, so do not just lower costs can be dimming, but also to remove the remote control.


The three sections of dimming technology, efficiency and even better than the PWM dimming method. Guoqing Quan said: "OZ8022A and OZ9992 support 100%, 60% and 20% of the three sections of simulated dimming function, the output LED string in 26V/300mA and 85-265VAC wide input voltage range of cases, the efficiency of the three segments were more than 86 %, 82% and 77%. "


OZ8022A and O2Micro OZ9992 is to support the successful development of three sections of two analog dimming of the LED controller, OZ8022A is the latest generation of products, the use of SOT-23-6 package, OZ9992 the previous generation, the use of SOP-8 package. OZ9995 controller also supports the three sections of dimming, however, it uses a PWM dimming.


Guoqing Quan said: "OZ8022A is OZ9992 improved version of its application is much simpler to achieve than OZ9992, so a lower BOM cost. Currently, the Japanese electrical appliance maker Orion has achieved commercial market launch of three sections based on OZ9995 LED dimming light bulbs, power range 5W to 8W, working life of up to 40,000 hours, Orion next generation of 4W, 6W and 9W LED lamp will be used OZ8022A. now there are several Japanese electronics manufacturers are evaluated OZ8022A and OZ9992.


Whether a home user or office user, three sections of dimming LED bulbs or tubes can be effective in helping users save energy costs. However, in actual use, due to different output power LED light bulbs or tubes in 60% and 20% brightness at issue is different, so many users want to dimming the brightness of the three sections to adjust the proportion, in order to satisfy all The different requirements of customers, O2Micro concentrated development in recent years without dimming technology, it also without using TRIAC dimmer, just use the wall power switch to adjust the brightness can be arbitrary.

Guoqing Quan said: "This no-class analog dimming technology is now developed, we may even have made the sample, if there is the right time, we will be officially announced. Now we focus on promoting or three sections of dimming LED driver OZ9992, OZ9995 and OZ8022A, but in the long term, we will focus on the promotion of non-dimming LED driver. "


Supplementary Content: How to remove the LED drive power input and output of electrolytic capacitors?


LED lighting drive power today have a structure and secondary structure of the points, a structure that is directly from the 220/110V AC power rectified step-down output driver to generate a constant current LED, secondary structure refers to the start of 220 / 110V AC power rectifier produces an intermediate step-down DC voltage (eg 48V), and then through a DC / DC conversion stage produces constant current output driver LED.


An architecture has the advantage of simple structure, fewer components required, BOM is relatively low, the disadvantage is a larger output ripple, usually requires a larger output of electrolytic capacitors (220uF). Secondary structure has the advantage of the output ripple is small, so you can remove the large electrolytic output capacitors, and replaced by smaller-capacity ceramic capacitors or film capacitors. However, the efficiency of the secondary structure at the expense of the general overall efficiency can be above 80%, while a structure is usually more than 90% can be achieved. In addition, the secondary structure of the cost will increase.


Bump Technology (O2Micro) FAE Director and Director of Product Development Guoqing Quan said: "If the use of two architectures to implement LED lighting drive power (such as the isolated flyback buck PFC stage + grade), then the output electrolytic capacitor can be ceramic capacitors or film capacitors. As for the AC input side, as safety considerations, in general, the input LC filter is essential. "


LED general lighting market currently required in Europe and America isolated power supply, because of their safety and EMC requirements more stringent. Isolated power supply efficiency is usually between 85-88%. Japan, Korea, China LED lighting power of contrast, did not specifically require electrical isolation, it is often non-isolated power supply, its efficiency can be 92-93%.


OZ9992 and OZ9995 is a non-isolated LED lighting for the development of the LED drive power drive, but they can also be used to develop the secondary structure of isolated LED driver power supply. Guoqing Quan said: "If achieved by the secondary structure (such as isolated flyback buck PFC stage + grade), in the first stage uses the PSR controller OZ8021, OZ9992, or in the second stage is used OZ9995, then the output of electrolytic capacitors can also replaced by ceramic capacitors. "


Of course, this is not absolute. Guoqing Quan said, the use of Boost PFC + Flyback isolated two-level structure of the program, Boost level output capacitor can be relatively small, but this will cause the input voltage Flyback part of the greater volatility. If Flyback loop bandwidth is wide, there is the opportunity to low-power (eg 10W) ​​ceramic capacitor used in applications as the output capacitor instead of a flicker.