Power

2W LED Driver Addresses High-Power Backlighting Applications

6th June 2007
ES Admin
Catalyst Semiconductor has announced a 2W LED driver to address high-power backlighting applications. The CAT4240 boost converter provides a high switch current up to 750mA and high voltage up to 38V, making it ideal for driving a wide range of backlighting applications ranging from 1W LEDs in series to multiple strings of lower-power LEDs.
The CAT4240 LED driver provides 2 watts of output power from a 3V to 5V supply and up to 6 watts when configured with a higher voltage, split supply of 9V to 12V. Additionally, the device is designed with a low-noise, high-frequency switching scheme and contains fully integrated features, which eliminates the need for external components associated with soft-start and over-voltage protection, reducing noise and saving board space.



Many high-voltage boost converters typically use a simple variable-frequency switching scheme. This approach results in a wide range of unwanted harmonics, which are not easy to filter or eliminate. The CAT4240 uses a fixed frequency (1MHz) switching architecture making it ideal for low noise applications. A high voltage CMOS output stage in the device allows large LED strings (up to 38V) to be accurately biased and regulated from a low voltage input supply while still delivering efficiency levels of up to 87%.



To eliminate excessive “in-rush” currents which can occur during initial power-up, the CAT4240 offers an integrated soft-start control. In the event of an open-LED fault condition, an internal over-voltage protection circuit will place the device into a low-power operating mode restricting the output voltage to safe levels without the need for external circuitry. Both of these features are fully integrated, eliminating the need for external components and the associated cost and board space overhead.



Designers have a choice of controlling LED dimming in the CAT4240 using a DC voltage, logic signal, or pulse width modulation (PWM) signal.



Product Features

* Drives high voltage LED strings up to 38V

* Switch current limit 750mA

* 1MHz fixed-frequency, low-noise operation

* Fully protected

* Packaging: 5-lead SOT23 (1mm max height)



The CAT4240 LED driver is priced at $0.84 each in 10,000 piece quantities. Samples are available now. Projected lead-time for production quantities is currently 6 to 8 weeks ARO.

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