Analog Devices Releases White-LED Flash Driver For Cell Phone CamerasJune 29, 2009 by Jeff Shepard
Analog Devices, Inc. (ADI) introduced a dual white-LED (light-emitting diode) flash driver that maximizes the limited current available in battery-operated digital cameras to increase flash brightness to over 200 Lumens and improve picture quality.
The ADP1655 inductor-based flash driver is said to improve the reliability of high-resolution camera operation in cell phones, digital still cameras, camcorders, PDAs and other camera-equipped portable devices, particularly in dark environments. In a cell phone application, the new driver’s proprietary transmit masking function allows the camera flash to run at a higher LED current while simultaneously operating the phone’s RF transceiver to monitor the cellular base station for incoming signals.
The ADP1655 integrates a 2-MHz synchronous boost converter, a 500 mA (milli amp) programmable current source, and an I²C interface, which enables timers and currents to be easily programmed and data to be read back relative to system operation and safety controls. With 5% flash-current accuracy, the ADP1655 also improves flash brightness by allowing the camera to increase current to the LED without crossing safety thresholds that would trigger the phone to shut down.
The new driver additionally includes a high-side current source that allows the flash LED string to be connected to the camera’s ground plane, eliminating the need to route the LEDs back to the IC. This allows designers to simplify printed-circuit board routing, which reduces circuit trace length and thermal dissipation and allows the camera to be designed using a more compact layout.
The units are priced (each, 1000 pieces) at $0.95.