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Charge pump LED drivers offer up to 95% efficiency

Posted: 08 Nov 2007 ?? ?Print Version ?Bookmark and Share

Keywords:charge pump LED driver? PWM interface? mobile backlighting?

Leadis Technology Inc. has unveiled a new family of charge pump-based LED drivers featuring up to 95 percent efficiency using its PowerLite Current Regulator.

Designed for mobile backlighting applications, the devicesLDS8866, LDS8865 and LDS8864include on-chip non-volatile memory that allows users to pre-set the maximum current of each of three LED banks, eliminating the need for external resistors. The drivers also feature a designer-friendly PWM interface, which controls the dimming of LED currents and supports up to six LEDs with a maximum current of 32mA per channel.

The new family of charge pump LED drivers offers multiple advantages for designers of portable applications. For longer battery life, the efficiency is increased up to 95 percent from the inclusion of both the PowerLite Current Regulator and a 1.33x-enabled charge pump. The low voltage dropout PowerLite Current Regulator provides a typical transition threshold of only 50mV, allowing the device to stay in the highest-efficiency mode longer. The maximum LED current is factory preset and can be programmed in the range from 0.5mA to 32mA in 0.5mA steps. In addition, the multi-fractional charge pump supports a wide range of input voltages from 2.7V to 5.5V.

"As portable applications continue to include more features needing an active display, such as internet, video, and games, Leadis LED Drivers continue to improve on the most important feature: longer battery life," said Donato Montanari, VP and general manager of LED drivers at Leadis. "Our PowerLite Current Regulator solves one of the most significant problems associated with Charge-Pump based LED Drivers, namely the transition between the high-efficiency state (1x-mode) and the lower efficiency states. By lowering the drop out voltage of the driver to only 50mV, we can extend battery life by up to 20 percent."

The devices are available in 16-lead TQFN 3mm x 3mm package with a maximum height of 0.8mm.

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