Charge pump with programmable flash timer

25th October 2006

Advanced Analogic Technologies Inc., Europe

ES Admin

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By combining a flash timer and high flash current drive with 32-step digital current control, AnalogicTech’s AAT3170 delivers unprecedented ability to optimise LED flash performance for a wide variety of next generation designs while providing complete flash LED protection. The AAT3170 is a high output, high efficiency current-output charge pump IC for white LED flash applications. The device combines a 600mA dual regulated current output flash driver and a safety timer. In addition, each LED output can be programmed in 32 steps by a single GPIO output through AnalogicTech’s AS2Cwire (Advanced Simple Serial Control) interface.

The AAT3170’s flash timer is programmable using an external capacitor. It can be used to either protect the LED from over dissipation in the event of a control logic failure, or to preset the flash duration. In addition, the tri-mode device maximises efficiency by combining a load switch (1x), fractional (1.5x) and doubling (2x) capability with an internal sensing circuit to match output to LED requirements. The 1x and 1.5x modes allow minimum current draw from the battery during lower LED current operations, such as torch or movie light modes, which run for a much longer period of time than the flash mode. Dual current sinks allow system designers to use single or dual (separate cathode) flash LED configurations.

The device’s 32-step single wire interface smoothes transitions and gives designers flexible control of brightness in flash or other lighting modes. The interface can also be programmed to provide a regulated voltage instead of current, for additional system loads.

The AAT3170 requires just five external components; two 1.0µF ceramic capacitors for the charge pump flying capacitors, one 1.0µF capacitor for CIN and one for COUT, and one additional capacitor to set the flash timer duration. The device also features a thermal management system and built-in soft-start circuitry.

The AAT3170 is immediately available in a Pb-free, thermally enhanced, 12-pin 3x3mm TDFN package.