Seagate Technology Incorporated

John M Baker

Karl Louis Enarson

Andrew Robert Motzko

Hieu Van Nguyen

Garry Edward Korbel

David R Street

Timothy Ted Walker

Anish A Ukani

Edward N Jeffrey

Stuart Kevin Francis

Ronald D Metzner

Deanne Sue Grover

Robert Whyte, Jr

An apparatus and method for supplying bi-directional load current to a load device. Four current sensing metal oxide semiconductor field effect transistors are operably configured to form an H-bridge with the load device, each transistor having separately insulated gate, source and drain and sense terminals with a source to drain conductivity determined in relation to a voltage applied to the gate terminal and a sense current from the sense terminal determined in relation to a magnitude of source to drain current. Drive voltages are applied to the gate terminals of alternating pairs of the transistors to apply the load current to the load device. The sense currents are used to provide adaptive, closed-loop clamping of the drive voltages at levels sufficient to maintain the non-load current conducting transistors in a quiescent state.

Class AB H-bridge using current sensing MOSFETs

A method and apparatus are disclosed for optimizing operational performance of a disc drive. The disc drive is provided with an integrated temperature measurement circuit which provides a temperature measurement signal indicative of operational temperature of the disc drive. The integrated temperature measurement circuit is formed as part of an application specific integrated circuit (ASIC) housing additional circuitry used by the disc drive during operation. A parametric configuration circuit, operably coupled to the integrated temperature measurement circuit, identifies selected parameters for use by the disc drive to optimize disc drive performance, the parameters arranged as a plurality of parameter sets corresponding to a plurality of predefined operational temperature ranges. The parametric configuration circuit periodically measures the operational temperature of the disc drive through evaluation of the temperature measurement signal, identifies the operational temperature range in which the measured operational temperature falls, and implements the parameter set corresponding to the identified operational temperature range.

Integrated temperature sense circuit in a disc drive

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

An apparatus and method are disclosed for determining a maximum magnitude of bias current that can be safely applied to a head of a disc drive. The disc drive comprises a head disposed adjacent a rotatable disc having a recording surface on which data are magnetically stored, a preamplifier circuit which selectively applies bias currents to the head, and a head bias current selection circuit, operably coupled to the preamplifier circuit, which first determines the maximum magnitude of bias current that can be applied to the head in relation to a maximum power dissipation rating of the head and voltage measured across the head when at least one initial bias current of selected magnitude is applied to the head. Thereafter, a range of bias currents having different magnitudes less than or equal to the maximum magnitude are selected and evaluated to select an optimum magnitude for subsequent use by the drive.

Disc drive head bias current optimization

A motor control circuit controls a motor in a disc drive is provided. The motor control circuit includes a commutation circuit which provides commutation signals to the motor to commutate the motor at a commutation frequency. A frequency modulation circuit is operably coupled to the commutation circuit. The frequency modulation circuit provides a modulation signal which frequency modulates the commutation frequency according to a predetermined pattern.

Growing community of inventors

Tuttle, OK, United States of America

John M Baker