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WLED driver enables large LCDs in portable apps

Posted: 01 Feb 2008 ?? ?Print Version ?Bookmark and Share

Keywords:WLED drivers? large LCD? portable applications?

Advanced Analogic Technologies Inc. has introduced the AAT1239-1, a high-frequency, high-efficiency constant-current boost converter capable of driving up to 10 white LEDs (WLEDs) connected in series. By driving up to 10 WLEDs in a serial string, the device simplifies the use of larger LCD panels in battery-powered portable devices, said the company.

Designed for backlight applications in PNDs, eDictionaries, electronic photo frames and cellular handsets, the white LED driver uses AnalogicTech's proprietary Simple Serial Control (S2CWire) single-wire interface to significantly reduce the display flicker that occurs with commonly-used low-frequency PWM control schemes. The single-wire S2CWire interface controls WLEDs across 26 discrete current steps, and requires no additional circuitry.

The AAT1239-1 also features a true load disconnect function that isolates the load from the power source while in the OFF or disabled state. By guaranteeing <1?A shutdown current, this feature extends battery life by eliminating leakage current in power-limited portable applications, said AnalogicTech.

Operating off a 2.7V to 5.5V input range, the AAT1239-1 delivers a maximum continuous output of 40V at 30mA and a constant LED current for up to 10 WLEDs in series. An integrated soft-start function eliminates output voltage overshoot across the full input voltage range. The WLED driver IC offers efficiency levels up to 82 percent. A high 2MHz switching frequency provides very fast response and helps reduce end product footprint by allowing the use of very small external inductors and capacitors.

The AAT1239-1 also offers shortcircuit, overvoltage and overtemperature protection. Qualified across the -40C to 85C temperature range, the AAT1239-1 is available in a Pb-free, 12-pin TSOPJW package.

Pricing is $1.08 in quantities of 1,000.

- Gina Roos

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