Abstract: A method of configuring a signal for controlling a voice coil motor (VCM) is disclosed. A voltage at an error amplifier of a VCM driver is accessed. A target value at the error amplifier is accessed. A difference value between the target value and the voltage is determined. An impedance value of the variable compensation coupled with the error amplifier is adjusted, based on the difference value.

Abstract: A method of configuring a signal for controlling a voice coil motor (VCM) is disclosed. A voltage at an error amplifier of a VCM driver is accessed. A target value at the error amplifier is accessed. A difference value between the target value and the voltage is determined. An impedance value of the variable compensation coupled with the error amplifier is adjusted, based on the difference value.

Abstract: A method for compensating for a disturbance in power from a power supply, wherein the disturbance without the compensating would otherwise affect a positioning apparatus coupled to the power supply. The method comprises receiving the disturbance in power from the power supply, deriving a compensation for the disturbance in the power, and transmitting the compensation to a control system for the positioning apparatus.

Abstract: Circuitry in a hard disk drive (HDD) senses the supply voltage, normally at power-on, and applies appropriate DC-to-DC conversion (pass-through, step-down, or boost regulation) according to the design requirements of the HDD.

Abstract: During normal operation of a hard disk drive, control logic controls a plurality of switching elements to provide electrical power to a spindle motor and head motor of the disk drive from a voltage source coupled to first and second voltage supply nodes (e.g., Vcc and ground), the spindle motor has a set of motor windings to which the electric power is applied to rotate the spindle motor, and the control logic is configured to enter a regenerative braking state during normal operation where the switching elements are controlled to isolate the spindle motor from the first voltage supply node and cause regenerative braking of the spindle motor so that kinetic energy due to rotation of the spindle motor is converted to electrical power that is supplied to the head motor by virtue of inductance of one or more motor windings in the set.

Abstract: A modem generally comprising an analog front end circuit, a hybrid circuit, and a variable impedance element. The hybrid circuit may be configured to couple the analog front end circuit to a transmission line. The variable impedance may be disposed within the analog front end circuit and connected to the hybrid circuit to trim an echo cancelling function of the hybrid circuit.

Abstract: A system and method for determining the velocity and/or position of a coil driven actuator arm without the aid of servo signals. A sample-hold unit is used to measure no-motion coil voltage in the voice motor coil while applying a predetermined coil current. Then, while the same magnitude (opposite direction) current is applied to move the actuator arm, the coil voltage is measured. The coil voltage is reduced by the measured no-motion coil voltage, producing a measurement of back-emf. The back-emf may be amplified by a predetermined factor to yield an estimation of velocity, and this amount may be integrated to provide a gauge of relative actuator arm position.

Abstract: A system and method for determining the velocity and/or position of a coil driven actuator arm without the aid of servo signals. A sample-hold unit is used to measure no-motion coil voltage in the voice motor coil while applying a predetermined coil current. Then, while the same magnitude (opposite direction) current is applied to move the actuator arm, the coil voltage is measured. The coil voltage is reduced by the measured no-motion coil voltage, producing a measurement of back-emf. The back-emf may be amplified by a predetermined factor to yield an estimation of velocity, and this amount may be integrated to provide a gauge of relative actuator arm position.