A system for controlling slew rate in a motor control circuit for a motor comprises a high side switching device coupled to a coil of the motor, the high side switching device operable to control a voltage excitation signal applied at the coil. The system also comprises a high side slew rate control circuit operable to control a slew rate of the voltage excitation signal. The high side slew rate control circuit includes: an amplifier having an output coupled to an input of the high side switching device, a current sink coupling a first input of the amplifier to ground, a capacitor further coupling the first input of the amplifier to ground, and a feedback path from an output of the high side switching device to a second input of the amplifier.
CROSS REFERENCE TO RELATED APPLICATIONS
This application is related to pending U.S. patent application Ser. No. 9/231,513, (Attorney's Docket No. TI-23524) filed on Jan. 14, 1999, entitled "System and Method for Controlling Low Side Slew Rate in a Spindle Motor Driver."
This application claims benefit from provisional patent application Ser. No. 60/083,381, filed on Apr. 28, 1998, entitled "Apparatus and Method for Controlling Slew Rate."
A system and method for providing rotation control stability within a disk drive. In accordance with the system of the present invention, a disk storage medium on which information is recorded is driven to rotate by a multiphase-phase DC servomotor. An actuator is utilized for loading and unloading the head to and from the disk storage medium. A load/unload controller commands the actuator to load or unload said head. In order to effectively compensate for an abrupt change in load on the servomotor caused by loading the head onto the disk storage medium, a slew rate switching unit is utilized to alter a slew rate of current supplied to the three-phase DC servomotor, based on a loading start command issued by the load/unload controller.
An electrical circuit whose slow rate can be changed. Included in the circuit is an input node for applying a voltage signal, a first switch in series with the input node, and a resistance in series with and in-between the input node and first switch. The slew rate of the circuit is adjusted by changing the equivalent resistance between the input node and the first switch based upon a control signal.
Methods and systems for driving a motor are disclosed. A center tap voltage and a desired center tap voltage are used to generate a voltage feedback. A power amplifier receives a reference current and the voltage feedback. The power amplifier provides a phase current to a phase of a motor. The phase current is substantially centered about the desired center tap voltage as a consequence of the voltage feedback. Thus, high-side to low-side or state to state current variations are reduced thereby reducing the occurrence of problems such as torque ripple and back EMF.
