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DC/AC converter maximizes EL lamp brightness

Posted: 25 Oct 2007 ?? ?Print Version ?Bookmark and Share

Keywords:DC-to-AC converter? EL lamp? maximum brightness?

Maxim Integrated Products has introduced the MAX4990E high-voltage, 15kV ESD-protected, DC/AC converter designed for driving electroluminescent (EL) lamps. This device uses an inductor-based boost converter to generate 250Vp-p (max) 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 ideal for MP3 players, PDAs, smart phones and other applications that require bright, efficient, even backlighting.

The MAX4990E provides multiple customization features that enable designers to optimize the driver performance of this converter for specific EL lamps. It features a proprietary, acoustic-noise-reduction circuit that controls the slew rate of the AC voltage, thus reducing audible noise from an EL lamp. 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. Additionally, the MAX4990E implements flexible EL lamp-dimming control by letting users 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 Li-ion batteries and battery chargers. It also features 15kV ESD protection on the EL lamp outputs and a low 100nA shutdown current. Fully specified over the -40C to 85C extended temperature range, the MAX4990E is available in a 3mm x 3mm, 14-pin TDFN package. Prices start at 99 cents (1,000-up, FOB USA).

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