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LED driver suits wireless handsets

Posted: 22 Apr 2005 ?? ?Print Version ?Bookmark and Share

Keywords:california micro devices? cmd? photonic? integrated led driver? cm4600?

California Micro Devices (CMD) has unveiled PhotonIC CM4600, the first member of its new PhotonIC family of highly integrated LED drivers, that is capable of driving all the LEDs in a wireless handset.

As mobile phones integrate higher levels of multimedia capabilities, primary and secondary display resolutions are increasing and their brightness is a key selection criterion for consumers, explained CMD. Color LEDs are also increasingly being used to support features such as "funlights" or color alerts. As a result, the company said, handset and display module designers are facing new challenges in terms of form factor, power consumption and solution cost.

As a response, CMD developed the PhotonIC CM4600, which features 7 outputs driving 25mA each to support the backlight requirements of the primary and secondary displays, 3 outputs driving 25mA each to support RGB "funlights," and one output capable of driving up to 250mA for the white LED camera flash. These outputs are all constant current and matched to within one percent. The maximum current can be set with a single resistor. Programmability provided through the I?C interface enables designers to incorporate features such as blinking, dimming, linear dimming and various other sequences.

The new LED driver uses a charge pump architecture that provides high drive capability for the camera flash function with system operating efficiencies up to 95 percent resulting in extended battery life. Another key feature of the PhotonIC CM4600 is that the LED drive power returns via ground facilitating board layout and minimizing noise.

CMD added that the high level of integration featured by the PhotonIC CM4600 results in significant part count and space savings since the single chip is housed in a small 4-by-4mm TQFN 24 lead package. By using the CM4600, handset and display module designers can achieve space savings of up to 50 percent, and reduce cost up to 40 percent compared to alternative solutions consisting of two or three chips, the company said.

The PhotonIC CM4600 is already sampling, with production scheduled in Q3 2005. Pricing for this new product starts at $2.20 each in 1,000 units. A comprehensive reference design kit is also available for evaluation.

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