Abstract: Embodiments of the present disclosure include multiple DC-DC converters configured to generate multiple voltages based on one or more voltage sources. The DC-DC converters are configured to produce a first voltage and second voltage when a first power source is active, when a second power source is active, or when both the first and second power sources are active. In example embodiments, one voltage is used by a network device to power internal circuitry, and another voltage is coupled to tethered devices.

Abstract: In some implementations, a method is provided. The method may allow a powered device to determine the maximum power available from power supply equipment. The method includes determining the length of a cable connecting the powered device to the power supply equipment based on the resistance of the cable. The method further includes determining the maximum power available to the powered device based on the length of the cable. The powered device may then be operated based on the maximum power available.

Abstract: In some implementations, a method is provided. The method may allow a powered device to determine the maximum power available from power supply equipment. The method includes determining the length of a cable connecting the powered device to the power supply equipment based on the resistance of the cable. The method further includes determining the maximum power available to the powered device based on the length of the cable. The powered device may then be operated based on the maximum power available.

Abstract: A method and apparatus to regulate voltage used to power an ASIC comprising an ASIC having a signal source and a modulator. The modulator establishes a characteristic of a signal created by the signal source to indicate a voltage level to be used to power the ASIC. The signal is communicated to a voltage regulator to apply an optimal voltage to the ASIC.

Abstract: A method and apparatus to regulate voltage used to power an ASIC comprising an ASIC having a signal source and a modulator. The modulator establishes a characteristic of a signal created by the signal source to indicate a voltage level to be used to power the ASIC. The signal is communicated to a voltage regulator to apply an optimal voltage to the ASIC.

Abstract: An apparatus for parking a read/write head during power interruptions and methods of operating the same result in a hard disk drive apparatus that reduces the time to steady state the operating hard disk drive. The apparatus for reducing the time to steady state the operating disk drive having an actuator arm coupled to a voice coil for latching the actuator arm when power is interrupted comprises a Y-winding spindle motor having a first winding, a second winding, and a third-winding, and a spindle motor controller coupled to the Y-winding spindle motor configured to dynamically short the first winding and the second windings to produce a retarding force against the Y-winding motor and to direct power produced by the third winding in series with the first two windings in parallel to the voice coil for moving the actuator arm to a latched position and to maintain sufficient power to the spindle motor to provide greater operating range (headroom).

Abstract: A common mode termination includes a shielded connector, a receive section and a transmit section, each section comprising an isolation transformer, a common mode transformer, a reference autotransformer, and an AC shield return. Each transmit section reference autotransformer and receive section reference autotransformer has a center tap for the application of a bias voltage and a bias voltage return. The bias voltage is fed through a common mode transformer, and the resultant common mode termination reduces the conduction of EMI from the serdes coupled to the common mode termination to cables connected to the connector. This common mode termination also provides a reference termination for the copper twisted pair cable and reduces resonances on the cable. Finally, this termination also provides filtering on the DC power source wires and improves noise immunity from transients coupled onto the twisted pair cable into the system.

Abstract: An apparatus for parking a read/write head during power interruptions and methods of operating the same result in a hard disk drive apparatus that reduces the time to steady state the operating hard disk drive. The apparatus for reducing the time to steady state the operating disk drive having an actuator arm coupled to a voice coil for latching the actuator arm when power is interrupted comprises a Y-winding spindle motor having a first winding, a second winding, and a third-winding, and a spindle motor controller coupled to the Y-winding spindle motor configured to dynamically short the first winding and the second windings to produce a retarding force against the Y-winding motor and to direct power produced by the third winding in series with the first two windings in parallel to the voice coil for moving the actuator arm to a latched position and to maintain sufficient power to the spindle motor to provide greater operating range (headroom).

Abstract: a An apparatus for preventing damage to components of a hard disk drive having a microprocessor when the microprocessor fails. The hard disk drive further includes at least one read/write head and a data storage disk having a designated parking zone. The apparatus includes a microprocessor monitoring circuit configured to be coupled to the microprocessor. The microprocessor monitoring circuit is configured for detecting a microprocessor failure condition in the microprocessor. The apparatus further includes a head park circuit coupled to the microprocessor monitoring circuit. The head park circuit is configured to receive a park command from the microprocessor monitoring circuit when the microprocessor failure condition is detected by the microprocessor monitoring circuit.

Abstract: A voice coil motor (VCM) driver has four field effect transistors connected to a motor coil as an H-bridge. A sense resistor in series with the coil and the H-bridge senses coil current. A feedback amplifier provides a feedback signal from a voltage developed across the sense resistor. A summing junction sums current command signals with the feedback signal. A transconductance loop compensation amplifier has an inverting input connected to the summing junction, has a non-inverting input connected to a reference level, and has an output control signal node. The control level is connected to control linear transconductance differential driver amplifiers including the four field effect transistors during a linear drive mode.

Abstract: A voltage boost circuit within a hard disk drive is realized by switching a center tap node of a three phase spindle motor to ground during a power down sequence, thereby employing inductance of the spindle motor as a voltage boost inductor. The boosted voltage is rectified and stored in a capacitor for use, e.g. to control a source transistor of an actuator driver during an actuator retract operation.