CAP-XX Intros BriteFlash for LED Flash Camera Phones

CAP-XX Inc. has introduced its BriteFlash power architecture to provide LED flash camera phones with enough light to produce high-resolution images. CAP-XX's BriteFlash architecture provides enough flash power to eliminate both dark and blurry photos using high-capacitance (0.4 to 1 farad), low equivalent-series-resistance (less than 100 milliohms), thin (1 to 3 millimeters) prismatic supercapacitors to support a battery and deliver the pulse power to drive an LED to full light intensity.

"Greater than 2-megapixel camera phones require a high-intensity flash in medium to low light conditions to ensure good pictures," said Anthony Kongats, CEO of CAP-XX. "Some solutions are available but lack adequate power to produce quality photos in all light conditions. Our BriteFlash power architecture completes the equation with the power to drive today's LEDs."

The CAP-XX BriteFlash power architecture is similar to a Xenon flash solution used in digital cameras today, where a low-current charge pump (boost converter) charges the supercapacitor to 5.5 volts then the supercapacitor drives the LED at very high current for the flash pulse. CAP-XX's supercapacitor-based solution, however, delivers more light energy (flash power x flash duration) and has a much thinner form factor than the Xenon one. Designers are forced to choose thinner, hence reduced-capacitance 330-volt cylindrical electrolytic storage capacitors necessary in Xenon designs to fit them in space-constrained camera phones. These reduced-capacitance electrolytic capacitors, which are still bulky at 6 to 10 millimeters, reduce the light energy the flash can provide.

BriteFlash offers maximum power and supports a flash photo up to 3 meters, compared to 1 meter or less for camera phones without a supercapacitor in low lighting. A dual-cell supercapacitor such as a 0.55-farad, 50-milliohm CAP-XX GS206 delivers over 25 watts to the LEDs versus 2 to 4 watts without a supercapacitor. A supercapacitor also eliminates the need to shut down the rest of the phone because the battery isn't needed to supply any current during the flash, leaving it free to supply other power needs such as OLED display or RF transmission.

The battery only needs to provide a low-charging current of 250 mA to the supercapacitor to support a recovery time between flashes of approximately 2 seconds. This is less time than the LED needs for thermal recovery between flashes. The low-charging current allows designers to use lower-cost, smaller boost converters or charge pumps because the supercapacitor supplies the peak current. Without a supercapacitor, the boost converter has to be sized for peak flash current. The CAP-XX BriteFlash reference designs show how to optimize the power subsystem with a supercapacitor.

The total cost of the CAP-XX BriteFlash solution is US $4 to $5 including the LEDs, supercapacitors and circuitry. The supercapacitor alone costs $1.50 for the single-cell solution and $2.50 for the dual-cell one in quantities of 10,000 or more.