Western Digital Corporation

Western Digital (Sea), Pte., Ltd.

Donald George Stupeck

Raffi Codilian

George J Bennett

Charles Royston Patton, Iii

A self-contained disk drive actuator velocity controller for, independently of the disk drive microprocessor, placing the actuator into a velocity mode to slew the actuator to a pre-programmed velocity during parking, unparking, power interruption or microprocessor malfunction. The velocity controller may place the actuator into the velocity mode in response to a timeout signal that is generated in the event the microprocessor fails to update the current demand DAC within a predetermined timeout interval. The velocity controller may also place the actuator into the velocity mode in response to a supply power loss. In addition, the velocity controller may be triggered in response to a command from the microprocessor to park or unpark the actuator. The velocity controller monitors the BEMF generated by the actuator motor coil and adjusts the gain of the actuator motor driver accordingly until BEMF reaches a value that corresponds to the target velocity. The velocity controller measures the BEMF very accurately because it includes a nulling or calibration circuit that operates during tracking mode to nullify the effects of parasitic actuator coil resistance.

Hardware velocity limit control system

A disk drive has a microprocessor, a digital controller chip, and an analog power chip, and a multi-winding spindle motor. The power chip operates under gross and fine control to connect and disconnect, during ON and OFF phases, a supply voltage to each winding on a PWM basis. The magnitude of the supply voltage and the temperature of the power chip vary. The microprocessor sends a digital control signal to the controller chip for gross control. The controller chip sends a PWM signal to the power chip for fine control. The power chip has pins for receiving the supply voltage, for sending a modulated signal to the controller chip; and for receiving the PWM signal from the controller chip. Circuitry in the power chip responds to the supply voltage to generate a first signal carrying analog information representing the magnitude of the power supply voltage, responds to the temperature of the power chip to generate a second signal carrying binary information corresponding to a thermal condition within the power chip, and responds to the first and second signals to generate a modulated signal which has a first characteristic carrying the analog information and a second characteristic carrying the binary information. Circuitry in the controller chip responds to the modulated signal to adjust the PWM signal to cause its ON phase to be substantially independent of the magnitude of the supply voltage, and demodulates the modulated signal to produce a warning signal and to send the warning signal to the microprocessor.

Method and apparatus for providing thermal feedback between an analog

A disk drive system for use in limited power applications is disclosed. The disk drive includes a spindle motor having two or more windings, along with a spindle motor driver which can drive the spindle motor in any of a unipolar, bipolar or tripolar mode. The bipolar or tripolar mode is used to start the disk drive and then the unipolar mode is used to operate the disk drive while data is being retrieved. By combining the three drive modes a large start current reduction and higher rotation velocities are achieved. Current consumption is further minimized by adaptively transitioning from bipolar to unipolar modes of operation. The disclosure also includes a general methodology for optimal motor K.sub.E and K.sub.M parameter selection.

Growing community of inventors

Laguna Hills, CA, United States of America

Donald George Stupeck