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DC-to-AC converter reduces audible noise in EL lamp apps

Sunnyvale, Calif. — Maxim Integrated Products has introduced a high-voltage, +/-15 kV ESD-protected, DC-to-AC converter designed for driving electroluminescent (EL) lamps. The MAX4990E uses an inductor-based boost converter to generate a high 250 Vp-p (max) voltage for maximum EL lamp brightness. A high-voltage, full-bridge output converts this high voltage to the AC waveform required to drive an EL lamp.

To maximize design flexibility, the MAX4990E provides resistor-adjustable slew-rate control for audible-noise reduction, capacitor-adjustable switching frequencies, and multiple options for controlling the output voltage. This device is suitable for MP3 players, PDAs, smartphones, and other applications that require bright and efficient backlighting.

The MAX4990E provides multiple customization features that enable designers to optimize the driver performance for specific EL lamps including the proprietary acoustic-noise-reduction circuit that controls the slew rate of the AC voltage. To allow the determination of optimal values for passive components, the boost-converter and lamp switching frequencies can be controlled by either an external source such as a PWM signal or capacitors. The MAX4990E implements EL lamp dimming control by allowing users to set the output voltage through a DC analog voltage, PWM signal, or resistor connected to GND.

Featuring a wide +2.4V to +5.5V supply-voltage range, the MAX4990E accepts a variety of voltage sources such as lithium-ion (Li+) batteries and battery chargers. It also features a low 100 nA shutdown current. Fully specified over the -40°C to 85° extended temperature range, the MAX4990E is available in a 3 x 3 mm, 14-pin TDFN package.

Pricing: Starts at $0.99 (1000-up, FOB USA).

Datasheet: MAX49903

Maxim Integrated Products , 1-800-998-8800, www.maxim-ic.com

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