Catalyst boost converter drives up to 10 LEDs

Content Dam Leds En Ugc 2006 06 Catalyst Boost Converter Drives Up To 10 Leds Leftcolumn Article Thumbnailimage File
12688 0 main Date Announced: 20 Jun 2006

Boost Converter from Catalyst Semiconductor Drives Up to 10 LEDs with Low Noise and Reduced Board Space

CAT4238 LED driver operates at fixed 1MHz frequency, provides on-chip over-voltage protection and soft-start functions

SUNNYVALE, Calif., June 20, 2006 -- Catalyst Semiconductor, Inc. (NASDAQ:CATS) a supplier of analog, mixed-signal and non-volatile memory semiconductors, today announced 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.

CAT4238 Product Features
• Drives up to 10 LEDs (up to 38V)
• Drives high voltage LED strings
• Power efficiency up to 87%
• Low quiescent ground current 0.6mA
• Adjustable output current
• Fixed-frequency (1MHz) low-noise operation
• Soft-start “in-rush” current limiting
• Shutdown current less than 1µA
• Open LED over-voltage protection (OVP)
• Automatic shutdown at 1.9V (UVLO)
• Thermal overload protection
• Thin SOT23 (1mm max height) 5-lead package
• 100% RoHS-compliant Green Package

Price and Green Package Availability
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.

About Catalyst Semiconductor
Founded in 1985, Catalyst Semiconductor, Inc. is headquartered in Sunnyvale, California. The Company produces analog and mixed signal products in addition to an extensive range of nonvolatile memories. The analog and mixed-signal product lines include Digitally Programmable Potentiometers [DPP(tm)], Microcontroller Supervisory circuits, White and Color LED Drivers and DC/DC converters. The memory product lines consist of Serial and Parallel EEPROMs, Flash and NVRAM. Catalyst devices are used in telecommunications, networking systems, computation, automotive, industrial and consumer markets. Typical applications include LCD displays, automotive instrumentation, optical networks, modems, wireless LANs, network cards, DIMM modules, cellular telephones, digital satellite box receivers, set-top boxes and Internet routers. Catalyst's Quality Management System is ISO 9001:2000 certified. All Catalyst products are available in “green” lead- and halogen-free versions with full RoHS compliance.

Catalyst Semiconductor, Inc. Sherry Hill Telephone: 408-542-1080 Fax: 408-542-1200


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