The demand for dimming can be roughly divided into three categories: one is the need for functional light adjustment, such as the entrance to the door, the meeting room, etc .; the second is the embodiment of comfort and lifestyle in home life, such as the combination of light and dark, color temperature Heating and cooling can be adjusted according to the needs of the environment and can also play a role in the atmosphere; the third is the need for environmental protection and energy saving, such as the energy saving needs of public places. Such as parking lot lighting, shopping mall lighting, road lighting, etc.
At present, according to the dimming method, we can also be roughly divided into: thyristor dimming, remote control dimmer wall switch and some commercial lighting dimming systems, such as 0-10V, Dali and so on.
How to provide a cost-effective LED product to consumers in accordance with dimming requirements and appropriate dimming methods will be the key to testing the industry.
As a product born to meet people's demand for dimming halogen lamps, thyristor dimmers do not need to change wiring, the device cost is lower, and the popularity of European and American households is higher. Therefore, thyristor dimming technology will be an existing dimming method in the replacement market. But it is undeniable that SCR dimmers also have great shortcomings. include:
. The power factor will be worse, the shorter the conduction angle, the worse the power factor. When adjusted to 1/4 light, the power factor will be lower than 0.25.
. In the dimming state, the electromagnetic compatibility will be very poor.
. The efficiency is poor, because when dimming, insufficient load will cause the thyristor to shut down early, causing the LED lamp to fail to work stably, and the problem of flickering occurs. To solve the flicker problem, it is usually necessary to install a bleeder or dummy load to maintain the normal operation of the thyristor by consuming power on the bleeder. In this way, there is a waste of energy, which is contrary to the original intention of dimming and energy saving. At light loads, the efficiency of the thyristor dimmer system is only about 10%.
At the same time, the matching problem is also a very serious problem. It is very difficult to develop a thyristor dimmer compatible with dozens of brands on the market and to ensure compatible dimmable LED lamps.
Therefore, SCR dimming will be based on the market as a transitional product that can only be used as a replacement market. At the same time, thyristor dimmers are not popular in China, and the penetration rate is less than 1 in 10,000, so it is impossible to become a mainstream dimming method. It is foreseeable that the wall switch mode, remote control mode and commercial dimming control system will become the mainstream of the Chinese dimming market.
The inherent low cost and convenience of the wall switch method make it a mainstream method with great advantages. This dimming method uses the switch on the wall to achieve the purpose of dimming. The advantage of this method is that there is no need for additional dimming components, no need to change wiring, no addition of any dimmer, according to the existing installation method, each lamp can achieve dimming, in addition, because the dimming state is completely controlled by the chip Internal control, within the full voltage range, regardless of the brightness, it can achieve high efficiency and high power factor, and meet the standards of electromagnetic compatibility.
O2Micro first realized the advantages of the wall switch dimming method, and developed the original "Free Dimming" technology based on the wall switch dimming method. "Free Dimming" technology is completely from the customer's point of view, to provide customers with easy-to-use, can be in any occasion, no additional cost dimming solution. At the same time, O2Micro has developed a series of dimming chips using this technology. For example, OZ8022T and OZ8027T with segmented dimming; OZ8024S with continuous dimming; OZ2082 with night light function, which is very suitable for ceiling lamps; OZ2082C with color temperature adjustment. This series of chips satisfies people's needs for functional light adjustment, comfort demands in home life, and environmental protection and energy saving. At the same time, it is worth emphasizing that these series of chips are all packaged in SOP-8, which integrates active power factor correction technology, and the peripheral parts are very streamlined; at the same time, it achieves constant current control of the full voltage range of 85-265V, LED open circuit, short circuit protection Features. This allows customers' products to face the global market. The cost of this series of dimming drive circuits is very similar to that of non-dimming drive circuits, which also satisfies customers' cost considerations.
The remote control dimming method and commercial dimming control system will also occupy a place in the future market. The remote control dimming method has the flexibility of dimming effect and the friendliness of the customer interface. A major advantage is that there is no need to change existing lines. In addition, the use of a remote controller can realize various functions such as dimming and color adjustment. But at the same time, the cost of using remote dimming control methods will be relatively expensive. Must use signal transmission module, and more complicated LED power driver. At present, the products of this type of dimming are mainly used to create indoor light environment and set off the atmosphere. Living room LED ceiling lights are more common on the market.
Commercial dimming systems have a place in the mid- to high-end commercial market. Its purpose is to control the lighting effect of the whole area in real time through a set of control systems. This system will glow in conference lighting, stage lighting and other places.
From the perspective of power supply driving, the difference between the remote control method and the commercial dimming control system is only the source of the dimming control signal. Remote control mode, using infrared signal, or wireless signal to provide PWM dimming control signal. The commercial dimming control system may provide 0-10V or PWM dimming control signals through the bus or another control line. The power supply driver is mostly a two-stage architecture: the front stage "AC / DC" provides constant voltage output, and the rear stage "DC / DC" provides LED constant current control and dimming function. Based on this architecture, O2Micro provides a one-stop solution for OZ8023 + OZ562. OZ8023 is a flyback control chip that integrates active power factor correction function and instant start function to complete the constant voltage output function. The post-stage OZ562 is a BUCK control chip that provides constant current control of 1-2 strings of LEDs. OZ562 also provides 10: 1 analog dimming interface and 100: 1 PWM dimming interface. It can provide constant current control with extremely high dimmability. At the same time, OZ562 integrates the functions of TLV431, simplifying the system design. And integrates the dynamic adjustment function of AC / DC output voltage. According to the LED output voltage level, it can dynamically adjust the AC / DC output voltage level of the previous stage OZ8023. The advantages of this technology are very obvious: first, it can greatly improve the current accuracy of LEDs under a wide range of output conditions, that is, greatly improve the load regulation rate; second, it can make the efficiency of DC / DC under light and heavy loads basically Consistently, greatly improve the system efficiency under light load.
In summary, facing the current LED lighting market, O2Micro has focused on the development of a series of control chips to meet the needs of Chinese consumers for LED dimming functions. At the same time, it provides a series of chip products that meet remote control dimming, wall switch dimming, 0-10V, Dali dimming, etc., providing a one-stop solution platform for Chinese lamp manufacturers.
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