Catalyst Semiconductor’s New Boost Converter Drives Up to 10 LEDs With Low Noise and Reduced Board Space
Catalyst Semiconductor, Inc. announced that it has expanded its family of LED drivers with the CAT4238, a high-voltage boost converter designed to drive up to 10 LEDs. The CAT4238 uses a low-noise, high-frequency switching scheme and contains fully integrated features, which eliminate the need for external components associated with soft-start and over-voltage protection. This helps designers reduce noise and save board space in mid- to large-size LCD panel backlighting applications.
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 CAT4238 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 up to 87%.
To eliminate excessive "in-rush" currents which can occur during initial power-up, the CAT4238 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.
The CAT4238 expands Catalyst's family of boost converter LED drivers by building on the Company's earlier, CAT4137 and CAT4237 devices, which drive five and eight LEDs respectively.
The CAT4238 is available in a low-profile (1mm max height), RoHS-compliant 5-lead thin SOT23 package. The ordering code is CAT4238TD-GT3 and pricing for 10,000 piece quantities is $0.78 each. Samples and evaluation kits are now available. Projected lead-times for production quantities are currently 6 to 8 weeks ARO.
