Abstract: Various embodiments of the present invention provide apparatuses, systems and methods for magnetic recording with a multi-level write current waveform. For example, an apparatus for magnetic recording with a multi-level write current waveform is disclosed that includes a pattern detection circuit operable to detect patterns in data to be written by the magnetic write head and to yield a pattern indicator signal, and a write driver operable to generate the multi-level write current waveform for the magnetic write head. At least one electrical characteristic of the multi-level write current waveform is based upon the patterns detected by the pattern detection circuit.

Abstract: Various embodiments of the present invention provide apparatuses, systems and methods for heat assisted magnetic recording. For example, an apparatus is disclosed that includes a signal generator operable to generate laser trigger pulses at the transition rate of the magnetic write data signal, a variable delay element operable to control an alignment between the laser pulse control signal and the magnetic write data signal, a phase difference detector operable to control the variable delay element, a triggerable pulse generator circuit operable to generate a laser pulse control signal based on the laser trigger pulses, a magnetic write head operable to record data to a magnetic storage medium under control of the magnetic write data signal, and a laser diode operable to heat the magnetic storage medium under control of the laser pulse control signal.

Abstract: An apparatus comprising a control circuit, a driver circuit and a write head. The control circuit may be configured to generate a plurality of control signals in response to a data input signal. The driver circuit may be configured to generate a differential write control signal in response to the plurality of control signals. The driver circuit may receive the plurality of control signals through a flexible bus. The driver circuit may be located remotely from the control circuit. The write head may be configured to write information by physically moving above one of a plurality of tracks on a disk in response to the write control signal. The driver circuit may be configured to move along with the write head.

Abstract: Various embodiments of the present invention provide systems and methods for data writing. As an example, a heat assisted loopback circuit is discussed that includes: a read circuit, a magnetic write circuit, a heat write circuit, and a loopback circuit. The read circuit is operable to sense data from a storage medium, and to provide the sensed data as a read output. The magnetic write circuit is operable to provide a write output corresponding to an excitation signal of a write head. The heat write circuit is operable to provide a heat output corresponding to an excitation signal of a heat source. The loopback circuit is operable to selectively couple a derivative of the heat output to the read output and to selectively couple a derivative of the write output to the read output.

Abstract: Various embodiments of the present invention provide systems and methods for data writing. As an example, a heat assisted data write circuit is discussed that includes a heat write output, a magnetic write output, and a variable phase shift circuit operable to modify a relative phase of the heat write output to the magnetic write output.

Abstract: An apparatus comprising a control circuit, a driver circuit and a write head. The control circuit may be configured to generate a plurality of control signals in response to a data input signal. The driver circuit may be configured to generate a differential write control signal in response to the plurality of control signals. The driver circuit may receive the plurality of control signals through a flexible bus. The driver circuit may be located remotely from the control circuit. The write head may be configured to write information by physically moving above one of a plurality of tracks on a disk in response to the write control signal. The driver circuit may be configured to move along with the write head.

Abstract: Various systems and methods for controlling DC motors are disclosed herein. For example, one method provides for controlling a polyphase, brushless DC motor. The method includes providing a DC motor that has a plurality of phases. Such a DC motor operates by inducing a current in the plurality of phases in accordance with a plurality of commutation states. In the example, six commutation states are discussed, but fewer than or more than six commutation states may exist. The method further includes initializing a count, inducing a current in the plurality of phases in accordance with a first commutation state, and incrementing the count until the current achieves a threshold in the first commutation state. Then, a current is induced in the plurality of phases in accordance with a second commutation state, and the count is decremented until the current achieves the threshold in the second commutation state.

Abstract: An apparatus and method for determining a head parameter value (e.g., head resistance) of a resistive head. A test head current is supplied to the head during a head parameter measurement interval using the same current sources that supply a bias current to the head during an operating (read operation) interval. The determined head parameter value is latched for use in setting the control loop gain for a control loop that controls the current sources during the operating interval.

Abstract: Various systems and methods for controlling DC motors are disclosed herein. For example, one method provides for controlling a polyphase, brushless DC motor. The method includes providing a DC motor that has a plurality of phases. Such a DC motor operates by inducing a current in the plurality of phases in accordance with a plurality of commutation states. In the example, six commutation states are discussed, but fewer than or more than six commutation states may exist. The method further includes initializing a count, inducing a current in the plurality of phases in accordance with a first commutation state, and incrementing the count until the current achieves a threshold in the first commutation state. Then, a current is induced in the plurality of phases in accordance with a second commutation state, and the count is decremented until the current achieves the threshold in the second commutation state.

Abstract: A (e.g., hard-disk drive (HD)) system supports reader standby mode and/or writer standby mode. For reader standby mode, reader circuitry in the system's preamplifier is transitioned to a low-power mode during write operations. To provide quick transition from write mode to read mode, the reader circuitry is transitioned to pre-read mode before the end of the write operation. For writer standby mode, the preamplifier's writer circuitry is transitioned to a low-power mode during read operations. To provide quick transition from read mode to write mode, the writer circuitry is transitioned to a pre-write mode before the end of the read operation. The availability of a reader standby mode during write operations and a writer standby mode during read operations reduces power consumption as compared to HD systems that leave the reader circuitry in pre-read mode throughout each write operation and the writer circuitry in pre-write mode throughout each read operation.

Abstract: A disc drive system, such as a magnetic or optical recording and/or playback system, for low-data rate applications implements one or more circuit operations, such as read signal detection and related servo functions, as software-based digital signal processing steps in a dedicated software-based processor. The drive system incorporates increased buffering, modified input sample processing techniques, multiplexing of processing functions, and modified automatic gain control techniques to allow circuit operations to be performed with software-based digital signal processing techniques.

Abstract: An apparatus and method for determining a head parameter value (e.g., head resistance) of a resistive head. A test head current is supplied to the head during a head parameter measurement interval using the same current sources that supply a bias current to the head during an operating (read operation) interval. The determined head parameter value is latched for use in setting the control loop gain for a control loop that controls the current sources during the operating interval.

Abstract: A (e.g., hard-disk drive (HD)) system supports reader standby mode and/or writer standby mode. For reader standby mode, reader circuitry in the system's preamplifier is transitioned to a low-power mode during write operations. To provide quick transition from write mode to read mode, the reader circuitry is transitioned to pre-read mode before the end of the write operation. For writer standby mode, the preamplifier's writer circuitry is transitioned to a low-power mode during read operations. To provide quick transition from read mode to write mode, the writer circuitry is transitioned to a pre-write mode before the end of the read operation. The availability of a reader standby mode during write operations and a writer standby mode during read operations reduces power consumption as compared to HD systems that leave the reader circuitry in pre-read mode throughout each write operation and the writer circuitry in pre-write mode throughout each read operation.

Abstract: A recording system stores recording cycle information identifying the parameters for recording user data on a particular data sector. During a subsequent operation, the recording system employs the recording cycle information to select a different set of parameters for recording new user data at the particular data sector. One of the parameters might identify a recorded pattern in a balance pad at the data sector, and another one of the parameters might identify a scrambler seed value. By employing a different set of recording parameters for each occurrence of recording user data at the particular sector, sample timing of, for example, a read channel might be based on an average of easy and hard transitions.

Abstract: For use with a servowriter that includes a writer core having a plurality of transistors that route servowriting current in response to a servo write signal, a write transition controller, a method of operating the same and a magnetic disk drive incorporating the controller or the method. In one embodiment, the controller includes: (1) logic circuitry, coupled to the writer core, that selectively blocks the servo write signal based on a state of a write current control signal and (2) current shunt circuitry, coupled to the writer core, that operates concurrently with the logic circuitry selectively to shunt current around the writer core based on the state.

Abstract: A disc drive system, such as a magnetic or optical recording and/or playback system, for low-data rate applications implements one or more circuit operations, such as read signal detection and related servo functions, as software-based digital signal processing steps in a dedicated software-based processor. The drive system incorporates increased buffering, modified input sample processing techniques, multiplexing of processing functions, and modified automatic gain control techniques to allow circuit operations to be performed with software-based digital signal processing techniques.

Abstract: For use with a servowriter that includes a writer core having a plurality of transistors that route servowriting current in response to a servo write signal, a write transition controller, a method of operating the same and a magnetic disk drive incorporating the controller or the method. In one embodiment, the controller includes: (1) logic circuitry, coupled to the writer core, that selectively blocks the servo write signal based on a state of a write current control signal and (2) current shunt circuitry, coupled to the writer core, that operates concurrently with the logic circuitry selectively to shunt current around the writer core based on the state.