Embodiments disclosed herein generally relate to a method for monitoring optical power in a HAMR device. In one embodiment, the method includes enhancing a thermal sensor bandwidth through advanced electrical detection techniques. The advanced electrical detection techniques include obtaining calibration waveform data for a thermal sensor by calibrating the thermal sensor, obtaining real-time waveform data for the thermal sensor that may deviate from the calibration waveform data, updating the calibration waveform data to include the real-time waveform data, repeating obtaining real-time waveform data and updating the calibration waveform data during writing operations. By updating the calibration waveform data, the bandwidth of the thermal sensor is determined by a fixed sampling time interval, and the thermal sensor rise time to steady state would not be a limitation to its response time.

According to one embodiment, a magnetic disk drive selects in command evaluation in reordering processing, a command accessible in a shortest time. The device determines whether media bumps which influence a dynamic flying height (DFH) control exist in a seek section between completion of a previous command and start of a selected command or not, calculates a latency necessary for avoidance of the media bumps if it is determined by the determination that the media bumps which influence the DFH control exist, and selects the command accessible in the shortest time including the time obtained by summing the latency calculated by the calculation as the command to be next processed.

A data storage device is disclosed comprising a head actuated over a disk, wherein the head comprises a fly height actuator (FHA). An FHA control signal is applied to the FHA, wherein the FHA control signal comprises a rectangular wave having a duty cycle in the range of ten percent to thirty percent. While applying the FHA control signal to the FHA, the head touching down onto the disk is detected.

A sequence of symbols is generated to describe a set of write data, the symbols having a length of nT, where T is a channel clock rate and n is an integer over a predetermined range. Bi-directional write currents are applied to a write pole to record the sequence of symbols to a magnetic storage medium. The write pole has an effective footprint with a downtrack length of mT, where m is an integer. The write currents are switched between a first rail current and a second rail current for alternating symbols, the write currents further transitioning to an intermediate current value for at least one channel clock period for symbols longer than 1T. Write currents are applied to the write pole when recording symbols having a length longer than mT using the effective footprint of the write pole as an interval.

Embodiments disclosed herein generally relate to a method for monitoring optical power in a HAMR device. In one embodiment, the method includes enhancing a thermal sensor bandwidth through advanced electrical detection techniques. The advanced electrical detection techniques include obtaining calibration waveform data for a thermal sensor by calibrating the thermal sensor, obtaining real-time waveform data for the thermal sensor that may deviate from the calibration waveform data, updating the calibration waveform data to include the real-time waveform data, repeating obtaining real-time waveform data and updating the calibration waveform data during writing operations. By updating the calibration waveform data, the bandwidth of the thermal sensor is determined by a fixed sampling time interval, and the thermal sensor rise time to steady state would not be a limitation to its response time.

Embodiments provide a method of operating a voice coil motor via a transconductance loop. The method includes detecting an actual value of a supply voltage of the transconductance loop. An offset compensation signal of the transconductance loop is produced as a function of the detected actual value of the supply voltage based on a relationship between offset values and the supply voltage of the transconductance loop. The offset compensation signal is applied to a loop control signal of the transconductance loop. A drive current is applied to the voice coil motor. The drive current is related to a target drive current that is based on the loop control signal.

Systems and methods of laser bias calibration are presented. A preamplifier circuit may configure a laser current supplied to a laser emitter to be a first laser current of the plurality of laser currents during the writing of one or more first sectors. The preamplifier may further detect one or more gaps in a write power signal while the laser current of the laser emitter is configured to be the first laser current. In response to the detection of the one or more gaps in the write power signal, the preamplifier may configure the laser current supplied to the laser emitter to be a second laser current of the plurality of laser currents during the writing of one or more second sectors. The preamplifier circuit may be utilized in a heat assisted magnetic recording device.

A memory system, sensor circuit, and method of operating a memory system are provided. The disclosed memory system includes a first transducer configured to output a first electrical signal indicative of a first operating parameter of the memory system. The memory system is further disclosed to include a second transducer configured to output a second electrical signal indicative of a second operating parameter of the memory system where the second transducer shares a node with the first transducer. The memory system is further disclosed to include a sense amplifier that receives the first electrical signal and the second electrical signal and provide an output responsive to both the first electrical signal and the second electrical signal to a preamplifier Integrated Circuit (IC).

This disclosure is related to systems, devices, processes, and methods to optimize a laser power boost amplitude, a laser power boost duration, or both in a heat-assisted data recording device, such as in heat-assisted magnetic recording (HAMR). The amplitude and duration for the laser power boost may be determined for a specific portion of a write operation, such as a first sector of the write operation. During operation of a data storage device, the laser power boost may provide additional power to the laser for the specific portion. Once the laser power boost duration has elapsed, the data storage device may continue providing power to the laser at the normal power input range of the laser. The laser power boost settings may be determined on a per head per zone basis, per track basis, or another configuration.

A temperature compensation equation is generated during manufacture of a heat-assisted magnetic recording (HAMR) disk drive using initial total currents supplied to a laser diode of the disk drive at different initial operating temperatures. The total currents represent currents for recording data to or erasing data from the medium. The temperature compensation equation is stored in the disk drive, and updated, during field operation, using a subsequent total current associated with an operating temperature differing from the initial operating temperatures. The total current supplied to the laser diode for a subsequent write operation is adjusted using the updated temperature compensation equation in response to the operating temperature at the time of the subsequent write operation.