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STMicroelectronics Develops 40W LED Flash for Smartphones

STMicroelectronics Develops 40W LED Flash for Smartphones

STMicroelectronics has developed a new chip to boost light output from LED-based flashes available in smartphone cameras.

Professional cameras use a xenon strobe light to produce a brief burst -- or flash -- of light, but the lighting on smartphone cameras is typically provided by an LED. The light output of a battery-powered LED is continuous, and much lower in intensity than a flash, leading to longer exposure times and darker, blurrier pictures.

But ST hopes to change that with its new STCF04 multifunction chip, which it says can control flash power up to 40W, compared to perhaps 2W for typical LED flashes today.

The key is the chip's ability to control the charging and discharging of a supercapacitor, which it uses to gradually store energy from the phone's battery and then deliver it to the LED in a short burst.

ST's chip, just 3 millimeters square, will add $2 or less to the cost of a cell phone, it said.

It contains a charger to store energy in a supercap, and a driver for an external transistor used to deliver 40 watts or more of peak power from the supercapacitor to a bank of LEDs. It also contains a temperature sensor to detect when the LEDs are in danger of overheating -- useful if they are being used as a torch rather than a flash; a light sensor for setting the exposure and flash intensity, and a driver for an auxiliary LED used either as a privacy indicator (you're on camera) or perhaps to help autofocus systems in low light.

At present, samples quantities of the chip are available, and ST said it will begin full production by the end of March.