AnalogicTech offers five new tri-mode charge pumps for white LEDs

Nov. 9, 2004
Date Announced: 09 Nov 2004 Advanced Analogic Technologies, Inc. (AnalogicTech), a developer of innovative power management solutions, today introduced five new tri-mode, high-efficiency charge pumps for white LED backlight and color LED applications. Complementing the company's extensive line of existing white LED drivers, the new AAT3151/2/3/6 family and AAT3129 devices allow AnalogicTech to offer a complete lighting solution for handsets, including drivers for white LED backlight, RGB LEDs, and camera flash solutions. The AAT3151/2/3/6 products represent AnalogicTech's first family of current sink LED drivers. Designed to meet the wiring requirements of second generation display modules, these new tri-mode devices combine a load switch (1X) and a high-efficiency (1.5X or 2X) charge pump with an internal sensing circuit that monitors the required voltage on each constant current sink input. The load switch and charge pump modes are set based on the input battery voltage and current sink input voltage. The AAT3151/2/3/6 devices can drive four or six individual LEDs with a maximum current of 30 mA per channel. To control current level for the LED channels, different devices in this product family feature AnalogicTech's proprietary S2Cwire(TM) (Simple Serial Control(TM)) or AS2Cwire(TM) (Advanced Simple Serial Control(TM)) interface. These unique interfaces simplify design and lower system cost by managing control and signaling over a single wire connection. For example, the AAT3153 utilizes S2Cwire single wire brightness control, while the AAT3156 adds the company's AS2Cwire interface which provides individual control of one bank of four LEDs and a second bank of two. "With these new devices, the designer can control four LEDs to backlight the main handset display and use the second group of two outputs to backlight a secondary display or drive a keypad backlight on a bar style phone," says Jan Nilsson, Vice President of Sales and Marketing for AnalogicTech. "Since the two groups of LEDs are controlled individually, the designer can use LEDs with dramatically different forward voltage characteristics on the sub-display without affecting current matching on the main display." All devices in the AAT3151/2/3/6 family require only four external components: two small 1uF ceramic capacitors for the charge pump flying capacitors, one 1 micro-F ceramic input capacitor, and one 0.33 micro-F to 1 micro-F ceramic charge pump output capacitor. RGB LED driver The second addition to the AnalogicTech product portfolio, the AAT3129, is targeted at RGB LED applications. This high-efficiency charge pump provides a single current source to deliver a regulated current to drive red, green, and blue LEDs via three internal switches. An on-chip AS2Cwire serial interface is used to enable, disable, and set the duty cycle of each internal MOSFET switch. Operating across a 2.7 V to 5.5 V input voltage range, the device requires only four small external ceramic capacitors. "Red, green, and blue LEDs have dramatically different forward voltage requirements, which creates significant problems for handset and portable device designers," said David Brown, Senior Manager of Applications Engineering for AnalogicTech. "By providing a single device to drive all three LEDs, the AAT3129 allows designers to easily control brightness and up to 4096 colors for fashion lighting, color backlighting, or camera flash applications and, in the process, reduce system component count and cost." Price and availability Rated over the -40 degrees C to 85 degrees C industrial temperature range, samples and production quantities of the AAT3151/2/3/6 and the AAT3129 are available now. AAT3151 and AAT3152 devices are available in a 12-pin 3x3mm DFN package and sell for $1.74 and $1.70, respectively; AAT3153 and AAT3156 parts are available in a 16-pin 4x4mm QFN package and sell for $1.86 and $1.90, respectively; and AAT3129 devices are offered in a compact 12-pin TSOPJW package and sell for $1.58 (all prices based on 1,000-unit quantities).

Advanced Analogic Technologies, Inc.

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