New High-Voltage PWM Controller Services ISDN Power Supplies: Vishay IC In SOIC-14 Cuts Component Count, Simplifies Transformer Design

MALVERN, PENNSYLVANIA - January 24, 2000 - A new high-voltage PWM controller for ISDN power supplies that simplifies transformer design and reduces the need for external components was announced today by Vishay Intertechnology, Inc. The new Si9113DY provides multiple output dc-to-dc conversion for ISDN applications while meeting CCITT and ETR-080 requirements. Intended for systems requiring as much as 10 W of power, the new IC will be used in power supplies for feature phones, PBX systems, modems, NT1 and NT1+ equipment, subscriber line interface circuits, and dc-to-dc conversion modules.

Packaged in a 14-pin SOIC, the Si9113DY allows designers to implement a single-switch PWM circuit with a minimum of external parts. A wide input voltage range, from 23.5 V to 200 V, eliminates the need for an external start-up circuit. A dedicated internal comparator enables very accurate programmable start and stop input voltage thresholds, as required by various telecom standards. This eliminates the need for an external zener diode or high-end transformer. The programmable hysteresis avoids unintentional locking of the system during start-up, especially when the system is fed from long loops of telephone lines.

The Si9113DY's current mode control results in better load and transient response, which translates into less capacitance at the output. A 500-kHz internal oscillator provides a user-selectable 15-kHz to 250-kHz converter output frequency, further reducing capacitance requirements and allowing simpler, smaller magnetics designs.

"The Si9113DY offers high-efficiency operation across its entire input voltage range while giving designers a high level of functional integration," said Tony Armstrong, Product Marketing Director at Vishay Siliconix. "As such, it's the core of a total solution that is simple to implement and very affordable compared to the alternatives."

Additional components available from Vishay for ISDN power supplies include transformers, capacitors, resistors, and 200-V power MOSFETs, including new LITTLE FOOT devices in the TSOP-6 package.

Samples and production quantities of the Si9113DY are available now, with lead times of up to 10 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.