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White-LED driver touts innovative brightness control

Posted: 30 Jun 2005 ?? ?Print Version ?Bookmark and Share

Keywords:white led? mic2297?

Micrel points to its MIC2297, a PWM boost regulator that's optimized for driving 10 white LEDs in series, for its innovative brightness control circuitry, which in addition to conserving power also helps to cut noise and EMI.

"Consumers continue to demand crisper resolution and brighter screens on their electronic and hand-held devices," said Ralf Muenster, director of marketing for Power Products. "The MIC2297 offers the highest levels of brightness and clarity possible with the lowest power consumption with 1 microamp shutdown current; an ideal combination for the market's most demanding electronic devices." Applications include PDAs, smart phones, digital cameras, and LED flashlights.

The MIC2297, delivering up to 40 volts from a 2.5- to 10-volt input, operates at 600 kHz in a constant frequency mode to save board space, reduce external component sizes, and minimize noise and the ripple normally injected into the battery source with variable frequency topologies. To optimize efficiency, the feedback voltage is set to 200 mV, which is designed to reduce the power dissipation in the current-set resistor and ensure minimal current draw from the battery. Features include better than 1 percent line regulation, over-temperature protection, and under-voltage lockout. The MIC2297 also provides output over-voltage protection in two chip versions (nominally 15 volts, adjustable with a resistor divider to 42 volts) to guard against open LED conditions.

The device's datasheet is available at

The chip, in a lead (Pb)-free, 2.5-by-2.5 mm MLF-10L package, is priced at $1.33 each in 1k quantities.

- Vincent Biancomano


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