Abstract: A voltage controller and method providing multiple modes of operation. Embodiments include pulse-width modulation (PWM), feed-forward (FF), pulse-frequency modulation (PFM) and skip operation (PWM-FF-PFM/SKIP). Controller embodiments have integrated MOSFET components, comparator hysteresis, oscillator feed-forward, fixed gain, and error amplifier (EA) limits thereby providing improved efficiency and noise immunity.

Abstract: A method according to one embodiment may include providing a redundant feedback circuit. The method of this embodiment may also include coupling the redundant feedback circuit to a feedback control loop and decoupling a feedback circuit from the feedback control loop. The method of this embodiment may also include calibrating the feedback circuit. The method of this embodiment may also include recoupling the feedback circuit to the feedback control loop and decoupling the redundant feedback circuit from the feedback control loop. Of course, many alternatives, variations, and modifications are possible without departing from this embodiment.

Abstract: A method according to one embodiment may include providing a redundant feedback circuit. The method of this embodiment may also include coupling the redundant feedback circuit to a feedback control loop and decoupling a feedback circuit from the feedback control loop. The method of this embodiment may also include calibrating the feedback circuit. The method of this embodiment may also include recoupling the feedback circuit to the feedback control loop and decoupling the redundant feedback circuit from the feedback control loop. Of course, many alternatives, variations, and modifications are possible without departing from this embodiment.

Abstract: A method and apparatus for a voltage reference is provided. The circuit may include one or more of the following features: cascode compensation with load balancing to increase the bandwidth of the amplifier for enhanced power supply rejection ratio; PMOS and NMOS in the input stage to expand common mode, having a high gain over voltage range; current mirror using active resistors; and a start-up circuit. The voltage reference comprises an amplifier having an output, the amplifier comprising a first amplifier stage and a second amplifier stage. The amplifier further includes a power-down circuit coupled to the second amplifier stage to float the amplifier output when a power-down signal is active. The voltage reference includes a source follower, the output of the amplifier coupled to the gate of the source follower, and a bandgap circuit for providing a bandgap voltage.

Abstract: A disk drive storage device employs two control subsystems, one for transducer position digital control and the other to control and precisely regulate spindle motor angular velocity in accordance with a crystal reference and a speed correction made at least once each revolution. A single servo sector on a data surface provides prerecorded track centering information. Overall electromechanical operations during track following activities are synchronized by the crystal controlled disk spindle motor subsystem which locates the position in time and space of the servo sector and which also interrupts program execution of the transducer position digital control subsystem and causes it to execute a subroutine for track centerline position correction. Direct digital commutation of the brushless DC spindle motor by a programmed digital microprocessor is an aspect of the present invention.