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Three-channel charge pump optimized for LED backlighting

Advanced Analogic Technologies Incorporated (AnalogicTech), a developer of innovative power management solutions, today announced the AAT3142, a new high efficiency, low noise, constant frequency charge pump for white LED applications. Integrating a 1X load switch, 1.5X fractional and 2X doubling charge pump, this tri-mode device is optimized for the unique backlight power requirements of high-volume consumer cell phones.

“Many of today's mass-market consumer cell phones employ small, efficient color displays,” observed Erik Ogren, Product Marketing Manager at AnalogicTech. “This three-channel, tri-mode charge pump provides the right balance of functionality and silicon overhead to meet the demanding cost/performance standards that these highly competitive consumer applications require.”

Tri-mode devices increase efficiency by stepping up voltage only when necessary. Since 80 percent of the discharge cycle of a lithium-ion/polymer battery is spent above the 3.5V threshold needed to drive white LEDs, constant use of a charge pump would waste energy. By integrating a 1X load switch, tri-mode devices like the AAT3142 allow the battery voltage to pass through to the output when sufficient voltage is available. The 1.5X and 2X charge pump modes are only activated when the battery power is low, allowing these devices to offer efficiency competitive to typical inductive boost converters.

The AAT3142 produces 32 constant current levels up to 30mA for each output from a 2.7V to 5.5V input. The device uses AnalogicTech's S2Cwireï (Simple Serial Control) serial digital input to enable, disable, and set current for each LED.

To reduce parts count and system footprint in compact portable devices, the AAT3142 uses a 1MHz switching frequency which enables the use of highly compact, 1F external capacitors: two charge pump flying capacitors, one input capacitor, and one charge pump output capacitor.

An integrated thermal management system protects the device if a short-circuit condition occurs at the output pin. Soft-start circuitry prevents excessive inrush current during startup. A low current shutdown feature reduces quiescent current to less than 1μA.

Specified over the -40 to +85 degrees centigrade temperature range, the AAT3142 is available immediately in a Pb-free, 12-pin TSOPJW package. The device sells for $0.92 in 1,000-piece quantities.

Advanced Analogic Technologies Incorporated (AnalogicTech) supplies power management semiconductors for mobile consumer electronic devices, such as wireless handsets, notebook and tablet computers, smartphones, digital cameras, and digital audio players. The company focuses its design and marketing efforts on the application-specific power management needs of consumer, communications, and computing applications in these rapidly evolving devices. AnalogicTech is headquartered in Sunnyvale, California, with offices in Beijing, Hong Kong, Japan, South Korea, Shanghai, Shenzhen, Sweden, and Taiwan, as well as a worldwide network of sales representatives and distributors.

For more information, please visit the AnalogicTech Tel: +1 408 737 4600; website: www.analogictech.com.

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