Intersil released two Endura pulse-width modulation (PWM) linear power system controllers. The devices provide power control and protection for DC/DC converters that are specifically designed and optimized to regulate power to the central processing unit (CPU) in Intel^® Pentium^® III-based, voltage regulation module (VRM) 8.5-compliant desktop PCs.

These circuits are the first to integrate power sequencing functions required by VRM 8.5, thus reducing converter bill-of-materials (BOM) cost compared to competing solutions requiring extensive external components to perform this function. The Endura ISL6523 is a dual PWM and dual linear controller and the ISL6524 is a single PWM, triple linear controller. Both highly integrated devices provide power control and protection for four output voltages in voltage regulation module (VRM) 8.5-compliant, high-performance microprocessor and computer applications. VRM 8.5 is an Intel specification for the latest Pentium III processors. The specification governs the regulation of power delivered to the processor.

"As power requirements for PCs and information appliances grow in complexity, systems designers are required to carefully consider voltage requirements and power efficiency," said Rick Furtney, vice president and general manager of Intersil’s Power Management product line. Intersil’s latest Endura power system controllers provide four regulated voltages, one each to the microprocessor core, AGTL+Bis, AGP Bus Power and the north/south bridge core. They control the power up sequencing of these voltages in accordance with VRM 8.5 requirements. The devices’ linear regulator drives are compatible with both MOSFET and bipolar series pass transistors. Fast PWM converter transient response delivers a high-bandwidth error amplifier and a full zero percent to one hundred percent duty ratio.

Intersil Corporation, 7585 Irvine Center Drive, Suite 100, Irvine, CA 92618. Phone: 949-341-7000, or 888-INTERSIL (468-3774) extension 8015; Fax: 949-341-7100 or

Intersil Corporation, 2401 Palm Bay Rd., Palm Bay, FL 32905. Phone: 321-724-7000; Fax: 321-724-7240

Intersil introduced two linear power system controllers that are sure to be dead-on for designers because they integrate power sequencing functions. It means that you don't need to add parts for the power control and protection on DC converters. The ISL6523 offers power control and protection for four output voltages in microprocessor and computer applications with 3.3 V, 5 V, and 12 V bias input. The IC has 2 pulse width modulators (PWM) and two linear controllers. One PWM controller regulates the microprocessor core voltage with a synchronous-rectified buck converter. The second PWM controller supplies the computer system’s +1.2 V bus power with a standard buck converter. The linear controllers regulate power for the 1.5 V AGP bus and the 1.8 V power for the chip set core voltage and/or cache memory circuits.

The ISL6523 includes an Intel voltage regulation module 8.5 compatible, TTL 5-input digital-to-analog converter that adjusts the microprocessor core-targeted PWM output voltage from 1.050V to 1.825 V in 25 mV steps. The reference and voltage-mode control provide ý1% static regulation. The second PWM controller’s output provides a voltage level of 1.2V with ý3% accuracy.

The linear regulators use external N-channel MOSFETs or bipolar NPN pass transistors to provide fixed output voltages of 1.5 V ý3% and 1.8 V ý3%. The ISL6523 monitors all the output voltages. Additional built-in overvoltage protection for the core output uses the lower MOSFET to prevent output voltages above 115% of the DAC setting. The need for a current sensing resistor is eliminated with an over-current function that monitors the output current by using the voltage drop across the upper MOSFET. The main criteria for selection of pass transistors for the linear regulators is package selection for efficient removal of heat.

The ISL6524 provides the power control and protection for four output voltages in high-performance microprocessor and computer applications. The IC integrates one PWM controller and three linear controllers, as well as the monitoring and protection functions into a 28-pin SOIC package. The PWM controller regulates the microprocessor core voltage with a synchronous-rectified buck converter. One linear controller supplies the computer system’s 1.2 V bus power. The other two linear controllers regulate power for the 1.5 V AGP bus and the 1.8 V power for the chip set core voltage and/or cache memory circuits. For more information you can find an application note for both chips at: http://www.intersil.com/data/AN/AN9/AN9925/AN9925.pdf

The ISL6523 and ISL6524 are both currently available in a 28-lead small outline SOIC package. Both devices are priced at $2.64 in 1,000 piece quantities or $2.09 in 10,000 piece quantities.

Data sheet ISL6523: http://www.intersil.com/data/FN/FN9/FN9024/FN9024.pdf

Data sheet ISL6524: http://www.intersil.com/data/FN/FN9/FN9015/FN9015.pdf