Out in Front: May 9, 1996
Pentium Pro power controller provides fast slewing
Micro Linear's single-chip power controller for the Pentium Pro provides as much as 13A of dc power via two external N-channel MOSFETs and offers greater than 90% efficiency. To meet Intel's power-management transition modes for the CPU, the ML4900 controller can slew its output current as fast as 30A/msec. To accomplish this task, the device uses two feedback loops. Its coarse loop triggers when the output voltage drops more than 3%, indicating sudden current demand, and initiates a current-pumping effect. As the output voltage comes back to within the 3% range, the ML4900's fine-tuning loop keeps the output within target.
The ML4900 monitors its 5 and 12 V inputs and its output voltage, signaling the CPU if voltage levels falls out of target ranges. In addition, the IC senses the 4-bit code from the Pentium Pro, which indicates to the controller what supply value—from 2.1 to 3.5V—the CPU requires. The ML4900 is available in a 16-lead SOIC package and costs $4.92 (1000).
—by Bill Schweber
Micro Linear Corp, San Jose, CA. (408) 433-5200,fax (408) 434-6441, info@ulinear.com.
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