Semiconductors

AnalogicTech – Highly integrated LED display drivers deliver many features

Dec 4 2006 - Semiconductors [More Semiconductors Articles]

By combining a high-performance charge pump, with backlight, flash and RGB drivers into a single 4mm x 4mm IC, controllable by a serial interface, AnalogicTech’s AAT2830/31 reduces parts count and system footprint, offering handset and portable system designers an exceptionally high level of integration and configurability, says the company.

The AAT2830/31, is a highly-integrated total display solution for handsets and other portable systems operating off a single-cell Li-ion battery. Built around a high-efficiency, tri-mode charge pump, the device delivers up to 600mA of current for the growing array of lighting applications in today’s portable systems including main and sub-display backlighting, camera flash, and RGB or auxiliary status lighting. Individual driving circuits for each function are controlled by patented, single wire AS2Cwire (Advanced Simple Serial Control) serial digital interface.

As handset and portable system designers expand their use of lighting functions to include main and sub-panel backlights, camera flash with movie-mode capability, RGB status and keypad backlighting, any discrete implementation of these subsystems conflicts directly with the need to minimise system footprint – the AAT2830/31 helps designers overcome many of these problems.

The device drives up to six outputs programmable up to a maximum of 30mA each, settable via an external resistor, for LED backlight applications. Individual control of each channel allows designers to drive four LEDs for a main display and two for a sub panel, or all six for a single display. LED intensity can be set to any of 16 levels using the AS2Cwire serial interface.

For camera flash functions, the AAT2830/31 supplies up to 600mA of current through four individual channels programmable up to 150mA each. In addition, the AAT2830/31 supports both flashlight and movie-mode operations. Three auxiliary outputs can be adjusted to handle up to 60mA for colour RGB, keypad, or status lighting applications. The AAT2830/31′s high efficiency tri-mode charge pump provides enough power to operate all three types of LED functions – backlight, flash and RGB – simultaneously.

All settings for backlight, flash and RGB lighting are programmable via AnalogicTech’s AS2Cwire interface. Colour RGB drivers on the AAT2830 can be programmed into up to 4096 colour / keypad intensity settings. For portable devices using smaller-scale displays, the AAT2831 offers RGB drivers programmable to 64-colour / keypad intensity combinations.

To protect the LEDs from thermal damage, the AAT2830/31 also features an integrated flash timer, which limits the maximum amount of time the LEDs can be illuminated. This unique feature also helps minimize battery drain during flash operations.

Specified over the -40C to +85C temperature range, the AAT2830/31 will be sampling in December 2006 and will be available in a Pb-free, thermally-enhanced, 24-pin QFN44 package, says the company.

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