Compaq Computer Corporation, Inc.

Phillip M O'Hara

Ralph K Williamson

Michael J Dougherty

To improve the reliability and lower the cost of electronic control circuits for direct current (DC) motors, the need for external mechanical sensors is eliminated through the use of low cost, highly reliable voltage comparator circuits. A motor driver integrated circuit provides for electronic storage of data, automatic execution of computer programs, and input/output transfer of various electronic signals used in the control of the DC motor. The voltage comparator circuits sense the operating state of the DC motor by comparing the motor current sense voltage, which is proportional to the torque of the motor, to threshold fixed reference voltages to determine whether the DC motor is running normally or is stalled. The motor driver IC stops or reverses the DC motor when it is stalled, thereby preventing damage and providing for fully automatic operation without external sensors.

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Tomball, TX, United States of America

Phillip M O'Hara