Convertor drives five white LEDs

The Semtech SC4509's built-in Schottky diode saves board space and reduces costs while still providing efficiencies of over 80%.

Semtech has released the SC4509 step-up convertor for white LED backlight applications with an integrated Schottky diode in a 2 x 2 x 0.8mm package.

The SC4509 can drive up to five white LEDs in series to provide a tiny solution for small LCD displays.

The device's built-in Schottky diode saves board space and reduces costs while still providing efficiencies of over 80%, which is better than most competing devices with integrated Schottky and similar to many that require an external Schottky.

To simplify control of the backlight, the device features a combination enable and PWM dimming pin that allows the user to turn the device on and off, or to apply a PWM dimming signal of up to 10kHz to control the output current level and dim the LEDs.

This pin can also provide a soft start capability to reduce in-rush current at start up.

The SC4509 features extensive protection capabilities including over-voltage protection, current limit, thermal shutdown and open LED protection.

The input voltage range for the SC4509 is 2.7V to 10V, and the device can output up to 20V at 30mA.

The device operates with a 1.2MHz constant switching frequency.

The SC4509 is available in either an MLPD-8 or SOT-23 package, both of which are RoHS compliant.

Both packages assure a small overall footprint and cost-effective solution.

"The SC4509 is one of the smallest LED boost convertors on the market, and it integrates the Schottky diode while still delivering the efficiency one usually associates with larger solutions", said Karl Volk, Director of Marketing for Handheld Power.

"In portables with small displays where size and battery life are priorities, the SC4509 offers a compact layout and simple interface to ease the design-in process".

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