Charge Pump Powers Phone-Camera Flashes

Aug. 1, 2004
Intended to power the flash function in cellular phones, the AAT3112 is a dual charge-pump voltage doubler capable of delivering 500 mA of pulsed current to white and RGB LEDs that perform the flash function. The charge pump solution eliminates the

Intended to power the flash function in cellular phones, the AAT3112 is a dual charge-pump voltage doubler capable of delivering 500 mA of pulsed current to white and RGB LEDs that perform the flash function. The charge pump solution eliminates the need for dc/dc boost converters and expensive low-profile inductors that are required to meet the height limitations in flip phones. The device requires four small external capacitors for operation: two 1 µF ceramic types for the charge pump, one 10 µF ceramic for Cin and one 10 µF ceramic for Cout. The device operates over a 2.7V to 5.5V input range and can deliver a continuous current of 200 mA. Each charge pump can be independently enabled to extend battery life. A thermal management system protects the device during a short circuit condition by sensing the die temperature and causing thermal shutdown. Integrated soft-start circuitry prevents excessive inrush currents. A low-current shutdown utility reduces quiescent current to less than 1 µA. The device is packaged in a 16-pin QFN (3 mm x 3 mm) for operation over the -40°C to +85°C range. Price is $1.41 each/1,000. ADVANCED ANALOGIC TECHNOLOGIES INC., Sunnyvale, CA. (408) 737-4600.

Company: ADVANCED ANALOGIC TECHNOLOGIES INC.

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