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Efficient LED TV backlight driving scheme

Posted: 29 Nov 2011 ?? ?Print Version ?Bookmark and Share

Keywords:ac-dc? power supply? backlight? TV?

LCD televisions designed with LED backlight continues to gain popularity compared to conventional TV architectures that use cold cathode fluorescent lamp (CCFL) bulbs because of the supreme feature set that these systems offer: greater brightness, higher contrast ratios, stylish thin designs, and significantly lower power consumption. To derive the full potential of the LED-based LCD backlight technology, however, it is important to achieve both good thermal design and precise backlight ON-OFF control for good picture quality by using the greater color gamut and higher contrast ratio of the LED, and suppressing LCD TV motion blur.

This application note presents novel power architectures with regard to the ac-dc total power supply for an LCD TV design, achieving higher power efficiencies and lower cost. The revolutionary iHVM mechanism enables intelligent LED bias control to minimize power loss. On the other hand, the fast LED drivers provide precise LED ON-OFF control. In this report, two reference designs are discussed. The PMP4298 is the basic topology reference design; this design consists of a primary ac-dc stage, a secondary boost dc-dc converter stage for the LED backlight, and a multichannel LED driver. The PMP4298A is proposed as a reference design that achieves a much higher efficiency and an overall lower cost by omitting the LED backlight dc-dc secondary stage. The LED driver is instead supplied directly from the ac-dc primary power-based LED backlight solution. Performance results are also presented.

View the PDF document for more information.

Originally published by Texas Instruments at as "High-Efficiency AC-DC TV Power Solutions: Proposing an Intelligent LED Backlight Driving Scheme".

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