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White LED driver features auto brightness adjustment

Posted: 16 Nov 2007 ?? ?Print Version ?Bookmark and Share

Keywords:white LED driver? LCD backlight? brightness control?


ROHM has begun sampling the BD6095GUL, touted to be first white backlight LED driver capable of automatic brightness adjustment of LCD backlights based on ambient brightness as well as the brightness of the image signal in real time, alleviating eyestrain, even during extended viewing.

The BD6085GUL is a simple compact version, and the BD6092GU controller, a multi-function type designed for illumination control that enables easy brightness adjustment when paired with an existing white LED driver.

The driver features a special sensor circuit for automatic fine tuning (256 steps) of drive current based on input from an illumination sensor IC, eliminating flicker while decreasing power consumption to 1/3 of conventional white LED drivers without a brightness adjustment function. In addition, the built-in charge pump circuit features a fourth step up ratio (x1.33) that is closer to the forward voltage of white LEDs, mitigating power loss, further reducing power consumption.

Added features of the device include superimposition of brightness adjustment via external PWM is possible, enabling backlight brightness control coordinated with the image signal. Also, the step-up voltage variation during PWM operation minimized, eliminating external capacitor noise. Gain control of the ambient light sensor IC BH1600FVC is automatically performed, allowing for a wide range of brightness measurements and an 8bit gradation backlight current adjustment (256 levels, 0.1mA steps) ensures flicker-free viewing.

The BD6095GUL is designed for all types of portable devices including mobile phones, PDAs, portable navigation devices, handheld gaming consoles, and portable audio players. The device is part of an expanding lineup that features real-time brightness control based on the image signal, x1.33 charge pump circuit and brightness adjustment based on ambient light.

Sample price is at $4.3 with mass production slated for February 2008.

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