Texas Instruments Corporation

Seagate Technology Incorporated

Edward N Jeffrey

William Robert Krenik

Hao Chen

Roy Clifton Jones, Iii

James E Chloupek

David R Cotton

Fredrick W Trafton

Shaibal Barua

John M Baker

Dennis V Hahn

Robert Whyte, Jr

A circuit ( ) for braking a polyphase dc motor ( ) includes a circuit ( ) for producing an output signal indicating that the motor has slowed at least to an actual rotational speed and a braking circuit ( ) to brake the motor ( ) when the output signal indicates that the motor has slowed at least to an actual rotational speed. The circuit ( ) for producing an output signal indicating that the motor ( ) has slowed at least to an actual rotational speed includes a first counter ( ) for counting pulses of a speed signal, which may be a standard tach signal. The first counter ( ) produces a first output when the first counter ( ) reaches a first predetermined pulse count. A second counter ( ) counts clock pulses from a clock generator ( ) to produce a second output when the second counter ( ) reaches a second predetermined pulse count. The first output is connected to restart the first ( ) and second ( ) counters, and the second output provides an indication when the frequency of the speed signal is lower than a desired ratio to the clock pulse frequency.

Method and apparatus for braking a polyphase DC motor

A circuit ( ) and method for applying drive voltages to a voice coil motor (VCM) ( ) of a mass data storage device ( ) has two driver sets, each having a high side driver (HSD) ( ) and a low side driver (LSD) ( ) connected to the VCM ( ). Each driver set has two SENSEFETs ( ), each having a power FET and a sense FET. A circuit ( ) is provided for sensing a sense current in the sense FET of the LSD, and a circuit ( ) is provided for increasing the bias on the gates of the SENSEFET ( ) in the LSD when the sense current falls below a predetermined level (VREF). Also, a circuit ( ) is provided for driving a predetermined current in the SENSEFET of the HSD when the sense current falls below the predetermined level. Thus, a current at the predetermined level always flows in the SENSEFETs ( ).

Low distortion audio range class-AB full H-bridge pre-driver amplifier

An apparatus and method for converting a pulse-width modulation (PWM) signal to an analog voltage signal. A current source is provided to supply electrical charge at a controllable rate to a ramp capacitor which, during successively occurring cycles of the PWM signal, alternatively receives electrical charge from the current source and discharges previously received electrical charge. A first sampling capacitor receives electrical charge from the ramp capacitor to output a feedback voltage to a feedback circuit to adjust the rate of electrical charge supplied by the current source, with the charge transferred to the first sampling capacitor determined in relation to the charge stored on the ramp capacitor over an entire PWM cycle. A second sampling capacitor receives electrical charge from the ramp capacitor to output the analog voltage, with the charge transferred to the second sampling capacitor determined in relation to the duty cycle of the PWM signal.

Converting a pulse-width modulation signal to an analog voltage

A system for driving hard disk drive spindle and actuator motors is disclosed. The system comprises a spindle motor control circuit (120), a spindle motor power circuit (210), an actuator motor control circuit (110), and an actuator motor power circuit (210). The spindle motor control circuit (120) and the actuator motor control circuit (110) are formed on a first substrate (100). The spindle motor power circuit (210) and the actuator motor power circuit (220) are formed on a second substrate (200). The system also includes at least one disk (22) attached to a rotatable spindle (21), a spindle motor (400) for receiving and being energized by the spindle motor power signals, and for controlling the rotation of the spindle (21), a plurality of disk read heads (12) adjacent to the disks (22), and an actuator motor (300) for receiving and being energized by the actuator motor power signals, and for controlling the position of the disk read heads (12).

Method and circuit for driving hard disk drive spindle and actuator

A method of driving an electric motor includes generating a periodic, driving voltage. The driving voltage comprises a sequence of first, second, and third waveforms. The first waveform in the sequence is a generally constant, high voltage. The second waveform in the sequence is a down hook voltage. The third waveform in the sequence is an up hook voltage. The method also includes applying the driving voltage to a coil of the motor to generate a generally sinusoidal current through the coil of the motor.

Method and system for driving a three-phase motor in a mass storage

A method and system for limiting current in a read/write head retract circuit is disclosed. The system includes a temperature sensor (75) for sensing a temperature of the disk drive read/write head retract circuit (53). The temperature sensor (75) generates an output signal indicating whether the temperature is above or below a threshold temperature. The system also includes a voltage regulator (100) which applies a voltage to an actuator motor (54). The voltage regulator (100) receives an input signal operatively associated with the output signal of the temperature sensor (75), and adjusts the voltage applied to the actuator motor (54) in response to the input signal. In one embodiment, the system includes a hysteresis circuit (88) which adjusts the threshold temperature of the temperature sensor (75) when the temperature sensor output changes. The hysteresis circuit (88) prevents the system from oscillating rapidly around the threshold temperature of the temperature sensor (75), and thereby avoids unnecessary wear of the system components.

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Garland, TX, United States of America

Edward N Jeffrey