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WLED drivers for cameras feature built-in LDOs

Posted: 12 Apr 2007 ?? ?Print Version ?Bookmark and Share

Keywords:WLED drivers? white LED? camera supply?

Maxim Integrated Products has introduced the MAX8645X/MAX8645Y, said to be the smallest white-LED (WLED) drivers with two built-in LDOs for camera supply. These charge pumps reduce total required area by 40 percent by integrating in a single IC the WLED backlight drivers, camera-flash drivers and camera power supplies. These new devices are suitable for flip-, folder- and slide-style cellphones and smartphones in which the LCD and camera module are located in the upper half of the phone, and space is at a premium.

Programmable 200mA LDOs
The MAX8645X/MAX8645Y integrate two programmable 200mA LDOs for powering the camera module. These LDOs feature low-noise (40?Vrms) performance to ensure a clean and stable power source during image acquisition. This is particularly important for minimizing picture noise with the high-resolution cameras used in current and next-generation cellphones. Two control pins allow for the selection of nine different output-voltage combinations, which simplifies ordering and stocking requirements.

The use of a charge-pump regulator enables thin designs, as no inductor is required. Additionally, use of an adaptive 1x/1.5x/2x charge pump and low-dropout current regulators enable 85-percent efficiency. The drivers provide 1MHz fixed-frequency switching, which allows for tiny external components and further reduces total solution size.

Six WLEDs, two flash LEDs
These devices drive six WLEDs at up to 30mA/LED with 5bit dimming resolution and 0.2 percent current matching; they also drive two flash LEDs at up to 200mA/LED with 5bit resolution. Dimming control can be accomplished using either a simple 2bit logic interface, or, for finer resolution, the logic pins can be connected together and used as a serial-pulse interface. Other features include soft-start to reduce in-rush current and a thermal-derating function, which protects the LEDs by scaling back the drive current at high operating temperatures.

The drivers are available in 4-by-4-by-0.8mm TDFN packages and are specified over the extended temperature range from -40C to 85C. Prices start at $2.81 (1000-up, FOB USA).




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