Catalyst Semiconductor's CAT4240 boost converter delivers high switch current up to 750mA and high voltage up to 38V

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 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.