——Interview with Dr. Eric Yang, Vice President of Technology Marketing, MPS
What kind of application (PWM or constant current) is your company's LED drive system? What are the advantages of the product?
The WLED market application is mainly concentrated in LCD screen backlighting and lighting. As a new generation of green environmental protection light source, it has excellent performance in saving electricity, environmental protection, color and reliability. In the field of LCD screen backlighting, different LCD sizes have different LED driver requirements. As the production capacity of LED chips increases, applications continue to expand to large sizes. Currently in the notebook application, WLED has completely replaced CCFL. It is estimated that in 2010, more than 50% of monitors and more than 20% of TV sets will use WLED backlights. The Energy Star and CEC standards will also be a significant driving force for WLEDs in large-size backlight applications.
MPS has distinct features in a variety of specific applications. For example, in GPS and netbooks, the common dimming method is DC dimming. This is to avoid audio noise in the device, but the disadvantage is that the color temperature of the LED will change under different current conditions. The MP3304 series features "High Frequency True PWM Dimming" technology that allows the PWM dimming frequency to exceed the audio to 20kHz or more while maintaining a minimum dimming brightness of less than 5%.
In conventional cell phones and camera backlighting, an inefficient charge pump drive mode is typically employed. The MP3306, which is being developed, uses synchronous rectification technology and is compatible with buck-boost mode, which increases the average conversion efficiency from 70% to 90%, which significantly improves the battery life of handheld devices.
In the field of display backlighting, the MP3389 series offers the industry's 12-way scalable drive capability, excellent thermal performance, rich dimming and protection.
In the field of lighting, the current LED application market is concentrated in applications where power is too large and too small, and high power (>50W) such as street lights, landscape lighting and other applications. Low power (<5W) such as decorative spotlights, flashlights, entertainment equipment, etc. At the same time, indoor lighting applications in 5~20W are also booming. As with backlighting, the focus and solution are very different for each different application.
For example, in streetlight applications, a three-stage drive architecture is usually used, including a pre-stage power factor correction circuit, an intermediate-stage isolated DC-DC conversion circuit, and a constant current drive circuit for each LED lamp. In the harsh working environment, heat dissipation design, reliability, and longevity have become design difficulties. The increase in efficiency is critical to the temperature rise and longevity of the system. The MP2488 is an LED driver specifically designed for the street light field with 55V, 2A drive capability and up to 97% efficiency. It is the most efficient and integrated solution in the market.
It is worth mentioning that the MP2483's unique buck-boost mode provides a wide range of input and output characteristics, and the input voltage can be any value greater or less than the WLED load voltage. And the 55V input voltage range and rich dimming, protection features make it suitable for general lighting applications of 5 ~ 10W, such as decorative halogen replacement, household appliances lighting and so on.
What are the prospects for future LED drive technology and in what direction?
The development of LED drive technology has always been closely integrated with the front-end LED supply chain and back-end specific applications. What kind of application is used, what kind of LED is used; what kind of dimming and protection requirements determine the LED driving technology to achieve optimal design. The current trend in the market is mainly reflected in the fact that the integration of LED driver Solutions will become higher and higher, and the target market will be more and more subdivided; custom ICs and solutions will become common; LEDs are widely used in large-size LCD backlights. Applications are just around the corner; some high-end LEDs in the general lighting sector have emerged, but it will take time to replace the current CFL.
Which applications will drive the development of LEDs?
Large-size LCD backlighting and general-purpose lighting will greatly increase the demand for LED chips, and is also the main direction to promote the development of the LED industry. At present, there are not many technical obstacles in the application of large-size LCD backlights, and the development of major manufacturers is also in progress. LED TV has the technical advantages of ultra-thin, environmental protection and energy saving, high-definition picture quality, rich colors and high reliability. It can be expected to develop in the next 3 to 5 years.
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