Cardiac Pacemakers, Inc.

Seagate Technology Incorporated

Control Data Corporation

William A Palm

Jean-Cheui Hsung

Lloyd A Van Hofwegen

Keith R Maile

William J Linder

David W Kelly

Michael W Dooley

Richard J Wessels

Jeffrey Laackmann

Duane A Young

A power management system for an implantable device is disclosed. One application is an implantable cardioverter/defibrillator. Charging circuits for implantable cardioverter/defibrillators require relatively large currents from the power supply. The present power management system provides extended device operation and reduced charge cycle time. The present system monitors both current and voltage drawn from the power supply to prevent a loss of system voltage. Elective replacement indication is performed using charging information provided by the present power management system.

Power management system for an implantable device

A device for braking a rotating magnetic disk in a magnetic storage system senses a back EMF generated by a drive spindle motor. By electrically shorting the coils in the drive spindle motor the rotation of the magnetic disk is stopped. The back EMF is compared with a reference voltage. The reference voltage is selected so that the rate of rotation of the magnetic disk is large enough that a magnetic head 'flies' over the surface of the disk, but small enough so that surge currents in the drive spindle motor will not damage the motor coils. Field effect transistors are used to electrically short the coils. A holding capacitor holds a voltage on the gates of the FETs upon loss of power to the magnetic storage system. A reset circuit draws charge from the holding capacitor upon power-up of the storage system.

Motor brake circuit for magnetic disk drive system

A transistor amplifier circuit operating in matrix interconnection for selectively amplifying signals received on a magnetic recording media by a low impedance head is disclosed which uses a common base preamplifier circuit for signal selection with a common collector amplifier and a common emitter feed-back network.

Matrix selection amplifier circuit for low impedance heads in a magnetic

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Minnetonka, MN, United States of America

William A Palm