Backlight controller shows its true colours

A colour controller integrates a colour photosensor for backlighting liquid crystal displays (LCDs) for a variety of portable display devices.

Avago Technologies has announced the industry's first colour controller with an integrated colour photosensor for backlighting liquid crystal displays (LCDs) for a variety of portable display devices.

Avago's new ADJD-J823 enables more accurate and consistent RGB LED backlighting, and richer colours than conventional technology.

This solution is ideal for use in digital cameras, cellphones, PDAs, portable DVD players and display screens measuring 7in diagonal or smaller.

The device has a small footprint and low profile that allows it to easily fit into portable LCD devices where board space is limited.

The 5 x 5 x 0.75mm integrated colour management (ICM) device operates at voltages as low as 2.5V.

"Avago is the only company that provides a complete off-the-shelf colour management solution for LCD backlighting, combining RGB sensors, colour controllers and high-brightness LEDs", said Lee Soo Ghee, Vice President and General Manager for Avago Technologies' Optoelectronic Products Division.

"By integrating the sensor and controller into one package, we are expanding the benefits of colour management to the growing array of applications using colour LCD screens in smaller consumer electronics".

In LCD TVs, the use of LED backlighting with Avago's award-winning illumination and colour management (ICM) control has been proven to offer 25% richer colours than conventional cold cathode fluorescent lamp (CCFL) backlighting.

In addition, LED backlighting totally eliminates the traces of mercury found in CCFLs to meet European Union reduction of hazardous substances (RoHS) mandates.

The ADJD-J823 is a CMOS mixed-signal IC with integrated RGB photosensors designed to be the closed loop optical feedback device of an RGB LED-based backlighting system.

This device also has a wide gain control and uses an algorithm to automatically select the optimum gain.

A typical system consists of an array of red, green and blue (RGB) LEDs, LED drivers and the ADJD-J823.

The device samples the light output from the RGB LED array, processes the colour information and adjusts the light output from the RGB LEDs until the target colour is achieved.

To do this, the device integrates an RGB photosensor array, an analogue-to-digital convertor front-end, a colour data processing logic core and a high-resolution 12bit pulsewidth modulation (PWM) output generator.

By employing a feedback system and the ADJD-J823, the light output produced by the LED array maintains its colour over time and temperature.

Samples and production quantities are available now through Avago's direct sales channel and worldwide distribution partners.

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