Industry's First 500-kHz Controller ICs With Two Integrated MOSFET Drivers Provide Up to 92% Efficiency in DC-to-DC Conversion Applications

SANTA CLARA, CALIFORNIA - April 25, 2003 - The industry's first 500-kHz PWM controller ICs to combine two integrated MOSFET drivers and integrated signal drivers for secondary synchronous rectification were announced today by Siliconix incorporated (NASDAQ: SILI), an 80.4%-owned subsidiary of Vishay Intertechnology, Inc. (NYSE: VSH).

Designed to provide a compact and efficient solution for fixed telecom applications requiring power supplies in the range of 50 W to 150 W, the new Vishay Siliconix half-bridge (Si9122, Si9123) and push/pull (Si9124) devices operate over a 12- to 72-V input voltage range, drive both primary side MOSFETs, and provide timing for the secondary synchronous rectifiers.

Each device incorporates a secondary-side FET drive signal for synchronous rectification and a direct primary MOS drive (1 A maximum) on the high and low side. A high-voltage start-up circuit is also integrated. Use of low-on-resistance MOSFETs as secondary synchronous rectifiers provides a significant increase in the converter efficiency - as high as 92%, even for low output voltages - when compared to using Schottky diodes.

The new ICs are compliant with the ETSI 300 132-2 standard, handling input voltages up to 100 V for 100 ms. Voltage-mode control with voltage feed-forward compensation provides for excellent line transient response. Programmable features include an input voltage detector, soft-start, a current-limit, and a programmable oscillator frequency from 200 to 600 kHz. All three devices also offer short-circuit protection, either through frequency foldback (Si9122) or hiccup mode (Si9123, Si9124), in addition to undervoltage lockout and thermal shutdown.

On-chip control of the necessary dead-time delays between the primary and secondary synchronous signals maintains high efficiency. An external resistor sets the switching frequency from 200 kHz to 600 kHz.

The Si9122, Si9123, and Si9124 controller ICs are suitable also for use in medium-power isolated power supplies from 20 W to 150 W, central office switching equipment, distributed power systems, compact power modules, networking, and the Internet infrastructure. The Si9122 is available in the TSSOP-20 or SO-20, and the Si9123 and Si9124 are available in the TSSOP-16 package. All are rated over the industrial temperature range of -40°C to +85°C.

Samples and production quantities of the Si9122, Si9123, and Si9124 are available now, with lead times of eight weeks for larger orders.

Vishay Intertechnology, Inc., a Fortune 1,000 Company listed on the NYSE (VSH), is one of the world's largest manufacturers of discrete semiconductors (diodes, rectifiers, transistors, and optoelectronics and selected ICs) and passive electronic components (resistors, capacitors, inductors, sensors, and transducers). These components are used in virtually all types of electronic devices and equipment, in the industrial, computing, automotive, consumer, telecommunications, military, aerospace, and medical markets. Its product innovations, successful acquisition strategy, and ability to provide "one-stop shop" service have made Vishay a global industry leader. Vishay can be found on the Internet at http://www.vishay.com.