Abstract: The present invention achieves technical advantages as an improved Parallel Damping scheme suitable for very-low-supply preamp operation. The improved Parallel Damping Scheme accurately generates a programmable Iw flowing through the write head while compensating for a leakage current path through a Parallel Damping resistor.

Abstract: A demagnetizer for an inductive load having a driver circuit including at least one transistor and a ramp-down voltage source switchably connected to the driver circuit, so that when the ramp-down voltage source is connected to the transistor, it drives the voltage of the transistor below its threshold voltage.

Abstract: An amplifying circuit and method are disclosed for amplifying electrical signals, such as electrical signals generated by the read head of a disk drive. The circuit includes a pair of cross-coupled differential amplifier circuits. Each differential amplifier circuit is asymmetric, including two input transistors of different transistor types. For instance, a first of the two input transistors of each differential amplifier circuit may be a bipolar transistor and a second of the two input transistors may be a field effect transistor. By utilizing asymmetric differential amplifier circuits, a relatively wider operating frequency range is obtained.

Abstract: A method and apparatus for controlling a write current capable of improving an adjacent track erasure (ATE) property of a hard disk drive. The method for controlling the write current in a hard disk drive includes applying overshoot current and write current to a head to write data on a disk, waiting for a predetermined time to pass, with the predetermined time being determined according to a thermal pole tip protrusion (TPTP) property of the head, and reducing the overshoot current and the write current upon passing of the predetermined time. Accordingly, since the overshoot current and the write current are decreased at the time of the TPTP being saturated, it is possible to effectively improve an ATE property of the hard disk drive.

Abstract: To reconstruct data transmitted over a transmission path, for example a cable, the corresponding signal received by the receiver is firstly amplified and subsequently made discrete by means of an A/D-converter (6), in order to obtain a suitable digital signal, whereby the signal amplified for this purpose is scanned with a relatively low sampling rate, which can frequently lie in the Nyquist range or can be even less than the Nyquist frequency. Subsequently the signal made discrete in this way is filtered by means of a digital high pass filter (8) and equalized by means of a digital cable approximation filter (9) to compensate any distortion occurring during the transmission over the transmission path. By means of a phase locked loop (14, 18) a regenerated clock (CLK) and synchronous with this clock the originally transmitted data (DATA) is recovered from the digital signal processed in this way.

Abstract: A disk drive is disclosed for optimizing write current settings relative to drive operating characteristics and an ambient temperature reading. Test data is written to and read from the disk using different write current settings to generate a plurality of corresponding quality metrics. The quality metrics are evaluated to generate an optimized write current setting for the ambient temperature reading. In one embodiment, the first write current setting is selected relative to a previously optimized write current setting that corresponds to the ambient temperature reading. This embodiment expedites the optimization process by testing write current settings surrounding a previous write current setting rather than testing the entire range of write current settings.

Abstract: A recording system records sector information on a recording medium, such as a hard disc drive, using a write gate signal. Timing of the write gate signal enables writing a servo data patterns over the servo wedge fields of the disc and, if the hard disc drive contains prior recorded data, writing null data over selected sector segments of the hard disc.

Abstract: An asymmetry-reducing circuit adapted to process an input signal having positive and negative pulses of different amplitudes and generate a corresponding balanced signal having positive and negative pulses of substantially uniform amplitudes. The asymmetry-reducing circuit balances the input signal by providing signal contributions corresponding to the second and third orders of the input signal. In a representative embodiment, the asymmetry-reducing circuit includes a differential amplifier and a plurality of arrayed MOS transistors connected to its inputs and outputs such that source-to-drain conductance of the transistors provides input and feedback resistances to the amplifier. A switch set selectively couples the fingers (gates) of the transistors to the input signal to modulate the source-to-drain conductance with said signal such that the input and feedback resistances change in a complementary manner.

Abstract: A disk drive is disclosed which demagnetizes the head after a write operation. Write circuitry applies a write signal to the head in order to write data to a selected data sector during a write operation, wherein the write signal comprises a predetermined write current amplitude. Control circuitry demagnetizes the head at the end of the write operation by maintaining the write current amplitude while increasing a frequency of an AC write signal applied to the head over a predetermined demagnetization interval, wherein increasing the frequency of the AC write signal decreases an amplitude of the AC write signal when observed at the head.

Abstract: A method of enhancing the thermal stability of gray codes is disclosed. The gray code block in a servo area is recorded with a combination of two different magnetization directions. When the two different magnetization directions are expressed as “+” and “?”, the information “1” is recorded as “++??” or “??++” with the information “0” recorded as “+?+?” or “?+?+”. Since the filter for gray code demodulation is provided with a perpendicular recording mode, the servo area does not use long-wavelength signals that are susceptible to thermal demagnetization. As a result, thermal stability is enhanced.

Abstract: Method and apparatus for removing residual magnetization in a data transducer, such as a recording head used to write data to a recording medium in a data storage device. A residual magnetization sense circuit senses a residual magnetization of a pole of the data transducer as a result of the application of a data transmission current to the transducer. A demagnetization current generator removes the residual magnetization by supplying the transducer with a demagnetizing current that decreases to a final magnitude in accordance with a selected profile. The demagnetization current preferably comprises a bi-directional, time varying current of selected frequency to the transducer that tapers linearly, exponentially or in a step-wise fashion to the final magnitude. The demagnetization profile is preferably continuously adapted during operation.

Abstract: The present invention provides a disk storage system with a low error rate, which is suitable for reduction in size. The other end of the signal line, which is connected with a read head at one end, is connected with a head bias circuit to apply a sense current to the read head and a pair of first and second capacitance elements for allowing the read signal element formed by the read head to pass, a loop is provided for amplifying the read signal obtained through the first and second capacitance elements by supplying the read signal to an input terminal of a differential amplifying circuit and for converting the amplified signal into the current by transconductance and providing a positive feedback of the amplified signal to the input terminal of the differential amplifying circuit.

Abstract: Techniques for detecting data, such as servo data, from input or incoming data read from a transmission medium, such as magnetic recording medium, in the presence or absence of radial incoherence. In one illustrative recording medium-based aspect of the invention, such a technique for detecting data from input data stored on a recording medium comprises the following steps. First, one or more samples are interpolated from one or more samples which have been generated from the input data at a given symbol rate. The one or more interpolated samples have one or more phases associated therewith which differ from a phase associated with the one or more samples generated at the given symbol rate. Then, an optimum or best phase is selected from the symbol rate phase and the one or more interpolated phases such that at least a portion of the one or more samples associated with the optimum phase are identified as representative of detected data.

Abstract: A data storage system includes a set of disks where each disk is operable in a plurality of discrete angular velocity levels. A disk controller controls the angular velocity of each active disk. The controller replicates a first portion of data on a plurality of the disks stores a second class of data in the set of disks without replication. The disk controller routes data requests to one of the active disks based, at least in part, on the current loading of the active disks to maintain balanced loading on the active disks. The disk controller alters the angular velocity of at least one of the active disks upon detecting that the latency of one or more of the data requests differs from a specified threshold. In this manner, the disk controller maintains the angular velocity of the active disks at approximately the same minimum angular velocity needed to attain acceptable performance. The disk controller may replicate the first portion of data on each of the disks in the set of disks.

Abstract: Asymmetry correction for an MR read head in a magnetic recording channel employs an exponential function to correct MR read head asymmetry. The asymmetry correction function has the form ƒASC(y)=y?q(eay+e?ay?2), wherein a is a parameter that can be adjusted for optimal channel performance, and q is an asymmetry correction coefficient.

Abstract: A system and method for measuring in real-time the current of a current mode driver circuit for writing data through a write head in tape or disk drive storage devices, the current mode driver circuit including one or more current mirror circuits for providing a current output in proportion to current through the write head during a write operation, the system comprising: device for converting the current mirror circuit current output into a first voltage; device for generating a second voltage representing a reference current; and, a device for comparing the first voltage value to the second voltage and generating an output signal indicating a ratio of the first and second voltages, the ratio being a measure of the current output of the current mirror circuit.

Abstract: A recording system, such as a magnetic or optical recording system, sets input attenuation level setting and variable gain amplifier (VGA) operating region during zero gain start (ZGS) by sharing the ZGS adjustment between attenuator settings and VGS gain setting. Further adjustment is made to attenuator settings and VGS gain setting for each subsequent servo or read sector event. The input attenuation level setting and variable gain amplifier (VGA) operating region are set so as to minimize effects of gain error due to incorrect attenuator setting, and subsequently operate the VGA near the center of its range where the non-linear effects are minimal.

Abstract: A write driver produces balanced voltages across head by using the input write data drive transistors of a slower transistor type (typically PNP) on one half of an H-bridge configuration, while transistors of a faster transistor type (typically NPN) in the other half of the H-bridge configuration are driven indirectly by transistors of the slower type, with a trans-resistance in series with transistors of the faster type. Accordingly, the voltage nodes on either side of the write head are pulled to Vcc and Vee symmetrically. A trans-resistance block (40) uses current sources to pull current from capacitive nodes for faster switching.

Abstract: A read amplifier system for connection through interconnects to a magnetoresistive (MR) head includes two input transistors, two bias transistors connected to the two input transistors by common source connections, a bias voltage control circuit connected to base terminals of the two bias transistors, a common mode voltage control circuit connected between first and base terminals of the input transistors to provide feedback from the first terminals to the base terminals, and a compensating circuit connected between the outputs of the amplifier system and the base terminals of the input transistors for providing a feedback from the outputs to the base terminals. The two base terminals of the input transistors are respectively connected to the interconnects of the MR head. The bias voltage control circuit applies a bias voltage to base terminals of the two bias transistors, and through the common sources to the base terminals of the input transistors, and thereby across the MR head.

Abstract: A method for providing data to determine an optimal track per inch (“TPI”) density for a head of a hard disk drive. The method utilizes a VGA control signal that is used in an automatic gain control loop of the disk drive. First VGA values are stored during a routine where a head reads the disk at different offset positions across an N track. The head is then moved to an offset position of an adjacent track N+1 and then erases at least a portion of the N+1 track. Second VGA values are then stored as the head again reads the N track at different offset positions of the track. This process is repeated for a plurality of different TPI values. The effective head width is determined from the second VGA values are plotted relative to different TPI values. An optimum TPI value can be determined from this plot.

Abstract: A read head for use with an interconnect transmission line having a characteristic impedance of Z0 includes a tunnel valve device and a shunt resistor RS that is connected in parallel across the tunnel valve device. The tunnel valve device has a device resistance RT corresponding to a predetermined resistance-area (RA) product. The value of the shunt resistance is based on the parallel combination of RT and RS substantially equaling the characteristic impedance Z0 of the interconnect transmission line. The predetermined resistance-area (RA) product is about equal to at least about 10 Ohms-?m2. Alternatively, the predetermined resistance-area (RA) product is about equal to a “corner” value of RAc for the tunnel valve device.

Abstract: The present invention provides a data recording method a data recording and/or reproducing apparatus for recording data transmitted from a computer to a magnetic tape. In case a recording head fails to write data (data ID=582) of fragment ID=5 to a track (track 7), then, the data is rewritten to the first fragment (ID=0) of a next track (track 8). Thus, the data can be rewritten not on the track basis but on the fragment basis, which can reduce loss of tape capacity significantly.

Abstract: The present invention comprises a pair of circuits (171, 172) within the first stage (100) of an AC signal pre-amplifier. The present invention reduces the current mismatch at the base of the first stage transistors (141, 142, 143, 144) resulting in faster switching times by reducing input stage offset and, hence improving input dynamic range.

Abstract: A data storage device, data write method, and program to avoid extra power consumption and suppress a write error that may result from voltage variations. To write data onto a magnetic disk, a write circuit generates a write current that is to be supplied to a write head. The write circuit operates on a positive power supply voltage provided by a host computer, and on a negative power supply voltage generated by a programmable DC—DC converter mounted on a hard disk drive's card. The magnitude of the negative power supply voltage generated by the programmable DC—DC converter is varied in accordance with the temperature surrounding the magnetic disk. Further, the magnitude of the negative power supply voltage generated by the programmable DC—DC converter is varied in accordance with the magnitude of the positive power supply voltage supplied from the host computer.

Abstract: The present invention covers circuits to achieve high data rate writing.

Abstract: A write driver driving a write current through a head connected to the write head by an interconnect. The write driver includes a circuit matching output resistance to the odd characteristic impedance of the interconnect and a voltage boosting circuit. The voltage boosting circuit in connected between a high voltage reference or supply voltage and a low voltage reference, and includes a current source, such as a MOS transistor, connected to the input node of a capacitor. During the overshoot duration, the current source operates at saturation to generate a pulsed current with an amplitude of half the load current. The circuit includes another transistor in series with the current generator between the capacitor and the driver output. A forward bias diode is connected between the capacitor output node and high voltage reference and enters reverse bias during overshoot duration swinging the driver output voltage above supply voltage.

Abstract: An information recording/reading apparatus employs a preamble to reproduce a clock used when recording information in a recording medium and reads the information out of the recording medium at a timing synchronized with a read signal. The preamble is split and recorded by replacing a middle portion of the preamble with data and a sync byte. While a first buffer is employed to delay signal data read out of the recording medium, a frequency offset detector detects a frequency offset using the split preamble.

Abstract: A tape head assembly comprises a transducer head having plural arrays of transducing elements, the transducing elements comprising at least one of write elements and read elements. The tape head assembly further comprises a set of conditioning elements, the conditioning elements comprising at least one of write drivers and read amplifiers. Multiplexing circuitry selectively couples the conditioning elements to one of the plural arrays of transducing elements.

Abstract: The probability of occurrence of post-recording erasure phenomena in which recorded data is erased is reduced by adding at the end of a sector block a repetition pattern 56 of a minimum bit length for that sector block.

Abstract: In a Maximum A posteriori Probability decoding (MAP decoding), a correlation and a deviation of noises for past and future states which depend on input signal patterns in past N bits and future Q bits are calculated by training by a noise correlation arithmetic operating unit 84 and they are stored. Upon reproduction, in a white noise arithmetic operating unit 91, white noise values for the past and future states in which colored noises are converted into white noises are obtained by using the stored correlation and deviation of the noises. In an input signal arithmetic operating unit 92, an input signal (channel information) ?c(yk|Smk) of the MAP decoding is calculated from the white noise values and the deviation for the past and future states. A likelihood in the MAP decoding is obtained from the input signal.

Abstract: A slider having leading and trailing edges is configured to fly on an airbearing above a data storage disk rotating from the leading edge to the trailing edge. Read and write heads are mounted on the slider proximate the trailing edge. An auxiliary thermal sensor is mounted on the slider, but preferably nearer the leading edge. Forward placement of the sensor allows it to sense mechanical defects before they reach the heads, thereby permitting a write inhibit operation, for example. The sensor may also be used to detect airbearing modulation. Appropriate action may be taken when unacceptable airbearing modulation is detected, such as notifying the user and/or scrubbing the slider. The sensor is preferably wider than the heads. This allows, for example, an in-situ glide test to be performed faster using the sensor. An arm electronics module is preferably configured to permit concurrent operation of the sensor and heads.

Abstract: An apparatus for providing head amplitude characterization using gain loops is disclosed. A variable gain amplifier (VGA) receiving input signals and generates a VGA output signal. A digital-to-analog converter (DAC) circuit provides a desired input signal to the VGA and a gain control loop drives the VGA to gain lock the VGA to the provided desired input signal. An analog-to-digital converter (ADC) provides a digital output representing an ADC code spread in response to the VGA output. A controller drives the DAC to provide the desired input signal to the VGA and generates control signals for controlling the ADC, the controller further determines read head channel amplitude based upon the signal provided to the DAC, the ADC code spread received from the ADC and gain code provided by the gain control loops.

Abstract: In order to account for the misplacement of a write element during a servowriting process, the width of the information being written can be varied. In a self-servowriting disk drive, for example, the write current supplied to a read/write head can be adjusted to vary the width of information, such as servo bursts, written by the head. By calibrating the head and determining the misplacement of the head while writing, an edge of a servo burst can be placed in the desired position regardless of the misplacement of the head simply by adjusting the width of the written burst. This description is not intended to be a complete description of, or limit the scope of, the invention. Other features, aspects, and objects of the invention can be obtained from a review of the specification, the figures, and the claims.

Abstract: An apparatus for providing head amplitude characterization is disclosed. A DAC is used to apply known signals to a variable gain amplifier in the front end of a read channel. The signal is processed through the read channel and at the output of an ADC, the signal is read and used to determine the input channel amplitude. Knowing the amplitude of the two input signals, the ADC code spread and the two VGA gain codes, an equation is generated for determining the amplitude of a head.

Abstract: Disclosed is a rotatable media storage device (RMSD) connectable to a host. The RMSD include a movable head to perform track following, a disk, and a synch mark detection circuit. The disk includes a circumferential track that has a plurality of embedded servo wedges utilized in track following. The synch mark detection circuit has a first detection mode and a second detection mode. In the first detection mode, the synch mark detection circuit detects a servo synchronization signal based on the head reading a SSM of a servo header of an embedded servo wedge. In the second detection mode, the synch mark detection circuit detects a servo synchronization signal based on the head reading a SSM and a wedge identifier of a servo header of an embedded servo wedge. The wedge ID is utilized in conjunction with the SSM to validate the servo synchronization signal.

Abstract: In a magnetic disk drive, a writing element and its surrounding area thermally expand due to the heat generated by a write head coil. The transient phenomenon of such thermal expansion may invoke the transient phenomenon of inadequate writing capacity, thereby causing a writing error at an early stage of a write operation. Control is provided which increases/decreases either or both the write current to be applied to a write head and the amount of its overshoot on an individual sector basis during a writing sequence.

Abstract: Provided in a disk drive of a perpendicular magnetic recording system is a data channel to execute signal processing suited to the characteristics of either servo data signals or user data signals read from a disk. This data channel decodes data by executing PRML signal processing of positive coefficient PR equalization for data signals of vertical rectangular waveform in the read signals read by a read head from the disk. The data channel converts servo signals of vertical rectangular waveform into differentiated waveform signals, and reproduces servo data from the differentiated waveform signals.

Abstract: A recording/reproducing apparatus capable of switching over among a plurality of heads with high precision, wherein the apparatus is provided with: a recording/reproducing unit for recording/reproducing signals onto/from a recording medium with a plurality of heads; a generating unit for generating control data for controlling the recording/reproducing unit; and a transmitting unit for transmitting control data generated by the generating unit to the recording/reproducing unit, wherein priority is given in transmission to data for controlling the switching of the plurality of heads over other data.

Abstract: A method and system are disclosed for providing a variable speed digital read channel. The read channel includes an analog portion and a digital portion. The read channel includes an analog-to-digital converter (ADC) for converting an analog read signal into a sampled read signal. The ADC is synchronized to a sample clock. The sample clock has a variable clock rate. The digital portion includes a digital filter for reducing noise. The digital filter can be implemented as a low pass filter (LPF), a high pass filter (HPF), or a bandpass filter (BPF). The filter receives the sampled read signal from the ADC. The digital filter is synchronized to the sample clock. The digital filter's cutoff frequencies adjust automatically as the variable clock rate is changed, and does not require reprogramming. The digital portion may also include a digital automatic gain control device.

Abstract: A pre-amplifier, a Thevenin writer and a disk drive employing transistors having a breakdown voltage below a circuitry operating voltage. In one embodiment, the pre-amplifier includes an emitter-follower transistor pair couplable to a power supply and a differential transistor pair, having a collector-emitter breakdown voltage below a voltage of the power supply, that receives current from, and controlled by, the emitter-follower transistor pair.

Abstract: The present invention uses Electronic Lapping Guides (ELG's), which are patterned on every tape head, as servo format verifiers. This is implemented by specifically placing the ELG's at the appropriate locations to match the servo signal track locations and thus be usable to verify the servo format patterns on the formatted tape. According to another aspect of the present invention, tape head components which have faulty read sensors, servo sensors, or write elements which have valid ELG's may be used for the servo format verification purpose.

Abstract: A sampled amplitude read channel is disclosed for magnetic disk storage systems comprising an adaptive non-linear correction circuit for correcting non-linear distortions in the read signal, such as asymmetry caused by the non-linear response of a magneto-resistive (MR) read head. The analog read signal is sampled and the discrete time sample values equalized into a desired partial response prior to sequence detection. The non-linear correction circuit is inserted into the read path prior to the sequence detector and adaptively tuned by a least-mean-square (LMS) adaptation circuit. In one embodiment, the non-linear correction circuit is a discrete-time Volterra filter comprising a linear response for implementing an equalizing filter, and a non-linear response for attenuating non-linear distortions in the read signal. The filter coefficients of both the linear and non-linear sections of the Volterra filter are adaptively adjusted by the LMS adaptation circuit.

Abstract: A method and apparatus to control changes in a flying height between a write head and a disk caused by a write current or an overshoot value of a write current are provided. The method comprises: changing a write current or an overshoot value of the write current in relation to a temperature; determining whether the head and the disk surface of a hard disk drive are in contact in relation to changes of the write current or the overshoot value of the write current; and setting the write current and the overshoot value of the write current as a threshold when the head and disk surface are in contact. Accordingly, the magnitude of a write current and the threshold of an overshoot value can be accurately set, and a write current equal to or less than the threshold can be provided when a write operation is performed, thereby providing a reliable write operation.

Abstract: A write driver 100, 200, 300 is implemented to provide near-ground common mode output voltages to produce a more symmetrical head voltage swing (i.e. ±0.4V from ground to ±5V supply voltages). These features help to reduce the effects of common mode impedance associated with the interconnection to the disk drive head to improve overall performance. Lower jitter at high data rates can be achieved when compared to prior art techniques for implementing current mode write drivers. Further, the matched impedance between the write driver 100 and the interconnection 106 eliminates unwanted reflections. ECL level voltage swings (200–500 mV) have replaced more conventional CMOS level voltage swings (5V) to further reduce overall power dissipation associated with the write driver. The small ECL level switching further maintains constant power dissipation with changes in operating frequency and results in less NTLS effects due to quieter supplies.

Abstract: A driver circuit drives a write element for magnetic recording, and permits high speed recording while preventing noise from entering an adjacent read element. An H bridge circuit, which causes a write current to flow, in accordance with a write drive signal, in a write coil of the write element, is provided with an overshoot circuit, in which positive and negative power sources are of the same potential. It makes a flyback voltage vertically symmetrical. Further, a feedback circuit is provided which monitors the voltages at both ends of the write coil, and prevents a variation in the common potential of the write coil. Terminal resistors are further provided to prevent the effects of reflection in a transmission line, and to prevent a change in the write waveform.

Abstract: In recovering data originally written on a carrier of magnetic media after a catastrophic failure, data may be read without prior knowledge of the write channel by which the data was originally written and in the presence of intersymbol interference of the readback signal. This is accomplished by forming an image of the spatial response function of the magnetoresistive transducer used to recover the data and by forming an image of the raw data read from the carrier of magnetic media by the magnetoresistive transducer for which the response function has been characterized. An image of the distribution of virtual magnetic charge on the carrier of magnetic media is obtained through deconvolution of the image of the response function of the magnetoresistive transducer and the raw readback signal. The readback signal corresponding to the data originally written on the carrier of magnetic media is then recovered by spatial differentiation of the image of virtual magnetic charge.

Abstract: A repeatable run-out (RRO) detector employs one or more digital interpolators to interpolate asynchronous sample values representing an RRO address mark (AM) and RRO data, and an asynchronous maximum-likelihood (AML) detector to detect the RRO AM. The AML detector selects one of either the asynchronous or interpolated sample sequences that are closest in distance to the ideal RRO AM sample sequence. In addition, a gain value is generated for each of the asynchronous and interpolated sample sequences. Once the RRO AM is detected, the AML detector provides a RRO AM found signal. Gain estimate values for either the selected asynchronous or selected interpolated sample sequences corresponding to the RRO AM found signal are averaged over a predefined number of detection events to generate a best gain error metric (BGEM). The BGEM is employed to adjust the gain of the asynchronous sample sequence.

Abstract: A smart retry operation, or set of retry procedures to be performed in sequence, that optimizes itself for a data storage device's individual characteristics, including variations across the data storage media and variations introduced as the device degrades over time, is disclosed. The data storage media (e.g. a disc in a disc drive) is divided into a number of zones and a separate smart retry operation is maintained for each zone. The data storage media is then tested to find errors correctable by the retry procedures. A statistical likelihood for each retry procedure is developed. The sequential order of the retry procedures in each zone's operation is then optimized based on the statistics. A single read/write retry sequences or separate read and write retry sequences may be maintained. The retry operations may be constantly re-optimized over the lifetime of the data storage device.

Abstract: A method of measuring the degree of thermal pole tip protrusion (TPTP) of a magnetic head and controlling a recording current in consideration of the degree of TPTP, in relation to a hard disk drive includes measuring the rate of errors contained in data by performing writing and reading operations while changing the level of an overshoot current (OSC), detecting a minimum error rate and a maximum error rate while changing a range of the OSC, and determining the degree of TPTP by measuring the difference between the minimum error rate and the error rate at the maximum OSC.

Abstract: A disk drive is disclosed for optimizing write current settings relative to drive operating characteristics and a plurality of ambient temperature readings. Test data is written to and read from the disk to generate quality metrics that are evaluated to generate an optimized write current setting for each ambient temperature reading. In one embodiment, the optimized write current settings are derived during manufacturing and used in-the-field during normal operation. In another embodiment, the optimized write current settings are re-optimized in-the-field to compensate for changes in the drive operating characteristics that occur over time (e.g., environmental changes and electrical and mechanical changes).