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. -- 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 1uA

--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. For additional information about Catalyst Semiconductor, visit our website at: www.catsemi.com.

Forward Looking Statements

Except for those statements that report the Company's historical results, the statements being made are forward-looking statements. Such forward-looking statements are subject to risks and uncertainties, including, but not limited to references to product availability and lead times. Factors that can affect product availability and lead times include manufacturing process interruptions at our own and our foundry and other vendors' production facilities, variable customer demand, and silicon cycles. More information about factors that could cause actual results to differ materially from those in the forward-looking statements is contained under the heading "Certain Factors That May Affect the Company's Future Results of Operations" described from time-to-time in Catalyst's SEC reports including, but not limited to, the report on the Form 10-K for the year ended April 30, 2005 and Forms 10-Q for the subsequent three fiscal quarters.

Editor Notes:

1. Trademark notices: DPP is a trademark of Catalyst Semiconductor, Inc.

2. Electronic images are available at: www.catsemi.com/editor.