Magnetic disk device, control method of magnetic disk device, and program

Abstract

To provide a magnetic disk device, a control method of the magnetic disk device, and a program to maintain normal operations as much as possible when a PLP function is executed and improve the PLP function.SOLUTION: A magnetic disk device according to the embodiment operates by receiving power from a first power source that supplies power having a first voltage and a second power source having a second voltage higher than the first voltage. The magnetic disk device includes: a power supply determination unit that detects whether a power interruption occurs in either the first power source or the second power source; and a control unit that when a power interruption occurs in one of the power sources, supplies power from the other power source to an unneeded circuit until a power supply interruption process is completed in the unneeded circuit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a magnetic disk device, a control method for a magnetic disk device, and a program. [Background technology]

[0002] Conventionally, hard disk drive devices as magnetic disk devices have been provided with a PLP (Power Loss Protection) function as a measure to protect data in the event of an unexpected power outage. This PLP function uses the back electromotive force (PLP power supply) generated in the motor that drives the disk when the disk stops to write data stored in DRAM to FROM.

[0003] Previously, when a 5V / 12V external power supply was interrupted, the SoC (System on Chip) would detect the input of a fault signal from the SVC (Servo Controller), unconditionally cut off the power supply from the external power supply, and switch to the PLP function, which uses the back electromotive force (PLP power supply) generated in the motor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 10,996,740 [Patent Document 2] U.S. Patent No. 08924641 [Patent Document 3] US Patent Application Publication No. 2019 / 0065081 Summary of the Invention [Problem to be solved by the invention]

[0005] The problem to be solved by the present invention is to provide a magnetic disk device and a method for controlling a magnetic disk that can maintain normal operation as much as possible when the PLP function is being executed and can improve the PLP function. [Means for solving the problem]

[0006] The magnetic disk device of the embodiment is a magnetic disk device that operates by receiving power from a first power source that supplies power having a first voltage and a second power source that has a second voltage higher than the first voltage, and is equipped with a power supply determination unit that detects whether a power interruption has occurred in either the first power source or the second power source, and a control unit that, when a power interruption has occurred in either one of the power sources, causes power to be supplied from the other power source to the non-essential circuit to which power supply should be stopped until power supply interruption processing is completed in the non-essential circuit. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a block diagram showing the outline of the main part of a magnetic disk device according to an embodiment. [Figure 2] FIG. 2 is a timing chart showing what happens when the 5V external power supply is cut off. [Figure 3] FIG. 3 is a process flowchart during PLP operation in the embodiment. [Figure 4] FIG. 4 is a timing chart showing the case where the 12V external power supply is interrupted. [Figure 5] FIG. 5 is a timing chart when there is no data for PLP operation. [Figure 6] FIG. 6 is a timing chart of a reference example for explaining the effect of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Next, the embodiments will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing the outline of the main part of a magnetic disk device according to an embodiment. The magnetic disk device of the embodiment is configured as a hard disk drive device (HDD device).

[0009] The magnetic disk device 10 includes a servo controller (SVC) 11, a disk motor 12, a disk 13, a power switcher 14, a voltage conversion unit 15, an SoC (System on a Chip) 16, a DRAM 17, and a FROM 18. Furthermore, the magnetic disk device 10 is connected to an external power supply system 20 that includes a 12V external power supply 21 and a 5V external power supply 22 .

[0010] A servo controller (SVC) 11 receives 12V power PS12 from a 12V external power supply 21 of an external power supply system 20, and controls the disk motor 12 to perform servo control. In this case, the servo controller 11 includes a voltage regulator 11A and a power supply monitor 11B.

[0011] In this case, the voltage regulator 11A performs power conversion for servo control, and also performs voltage conversion of the 12V power PS12, and outputs the 5V power PS52 to the power switcher .

[0012] In addition, the power supply monitoring unit 11B monitors the voltage of the 12V power PS12 supplied from the 12V external power supply and the voltage of the 5V power PS51 supplied from the 5V external power supply 22, and outputs a fault signal (described later) to the SoC16 if a voltage abnormality such as a power cutoff is detected in either power supply.

[0013] The disk motor 12 rotates a (magnetic) disk 13 under the control of a servo controller 11 .

[0014] The disk 13 magnetically records various data. The power switcher 14 receives 5V power PS51 from the 5V external power supply 22 of the external power supply system 20 and 5V power PS52 from the voltage regulator 11A of the servo controller 11, and outputs either one to the voltage conversion unit 15.

[0015] The voltage conversion unit 15 supplies power to each part of the magnetic disk device 10 (SoC 16, DRAM 17, and FROM 18 in the example of FIG. 1) based on either the 5V power PS51 or the 5V power PS52 input from the power switcher 14.

[0016] The SoC 16 functions as a controller (control unit) that controls the entire magnetic disk device 10, and also performs control to realize a PLP function that backs up data from the DRAM 17 to the FROM 18. The DRAM 17 is a volatile memory that stores data before it is written to the disk 13 .

[0017] The FROM 18 is a non-volatile memory that stores the data stored in the DRAM 17 for backup purposes when the PLP function is being executed.

[0018] First, before describing the embodiments in detail, the principles of the embodiments will be described. In a magnetic disk device that operates by receiving power from a 12V external power supply 21 (= second power supply) and a 5V external power supply 22 (= first power supply), it is rare for both the 12V external power supply 21 and the 5V external power supply 22 to be cut off at the same time.

[0019] Therefore, in this embodiment, when either the 12V external power supply 21 or the 5V external power supply 22 is cut off and the power supply is cut off, the other power supply that is still capable of supplying power is effectively utilized to supply power to circuits that do not need to operate in PLP operation, and the unnecessary circuits are stopped reliably before PLP operation is performed using the back electromotive force of the disk motor 12, thereby avoiding the various problems described above.

[0020] From a fail-safe perspective, this uses a power supply that remains uninterrupted until power-down of unnecessary circuits is complete, which occurs in microseconds, before both power supplies are finally shut off in milliseconds.

[0021] In this way, by using the uninterrupted power supply until the unnecessary circuits are powered down, the power supply can be stabilized before the unnecessary circuits are powered down, and the risk of malfunction due to a drop in the PLP power supply can be avoided.

[0022] Next, the operation of this embodiment will be described in detail. In this embodiment, there are two external power supplies, a 12V external power supply 21 and a 5V external power supply 22. There are two ways to use one of the 12V external power supply 21 and the 5V external power supply 22, as follows.

[0023] The first mode is a mode when the 5V external power supply 22 is cut off, and in this first mode, power converted from 12V to 5V by the voltage regulator 11A of the servo controller 11 is used. The second mode is a mode when the 12V external power supply 21 is interrupted. In this second mode, the power output from the 5V external power supply 22 is used as is.

[0024] First, the operation in the first mode in which the 5V external power supply 22 is shut off will be described. FIG. 2 is a timing chart showing what happens when the 5V external power supply is cut off. FIG. 2A shows the signal level of the Ready signal that is set to "H" level by the SoC 16 when the magnetic disk device 10 is in normal operation.

[0025] Figure 2(B) shows the signal level of the Fault signal that is set to "L" level when the power supply monitoring unit 11B of the servo controller 11 detects an abnormality in at least one of the 12V external power supply 21 and the 5V external power supply 22.

[0026] 2(C) shows a signal output by the power-down timer 16A of the SoC 16 that counts up the time required for the shutdown process (power-down process) of all unnecessary circuits to be reliably performed when the Fault signal becomes "L" level, and becomes "H" level during the count-up period. Therefore, when the count-up is completed and the output of the power-down timer 16A, which once became "H" level, becomes "L" level again, all unnecessary circuits have been reliably shut down.

[0027] FIG. 2D shows a signal that goes to "H" level when the 12V external power supply 21, which is an external power supply, is in a power supply enabled state in the SoC 16, and goes to "L" level when the power supply is cut off.

[0028] FIG. 2(E) shows a signal that goes to "H" level when the 5V external power supply 22, which is an external power supply, is in a power supply enabled state in the SoC 16, and goes to "L" level when the power supply is cut off.

[0029] Figure 2(F) shows the state of PLP power supply from an external power source instead of the PLP power supply by back electromotive force. In Figure 2(F), the solid line shows the actual power supply state, and the dashed line shows the state where power can be supplied.

[0030] Figure 2(G) shows the supply state of a PLP power supply using back electromotive force. In Figure 2(G), the solid line shows the actual power supply state, and the dashed line shows the power supply possible state.

[0031] FIG. 3 is a process flowchart during PLP operation in the embodiment. Hereinafter, the operation in the first mode in which the 5V external power supply 22 is shut off will be described in detail with reference to the timing chart of FIG. 2 and the processing flowchart of FIG.

[0032] At time t1 in FIG. 2, when the 5V external power supply 22 is cut off as shown in FIG. 2(E), the power supply monitoring unit 11B of the servo controller (SVC) 11 sets the Fault signal to the “L” level as shown in FIG. 2(B). As a result, the SoC 16 sets the Ready signal to the "L" level, as shown in FIG. 2(A).

[0033] Next, SoC16 starts the processing during PLP operation shown in Figure 3, and to realize the PLP function, at time t1, as shown in Figure 2(C), starts counting (initiates) the power-down timer 16A of the unnecessary circuit, which is a circuit not used in PLP processing (step S11).

[0034] Next, the SoC 16 determines whether the 12V external power supply has been shut off (turned off) (step S12).

[0035] 2(D), the power supply monitor 11B detects the output of the 12V external power supply 21, and the servo controller 11 determines that the 12V external power supply 21 is not shut off (step S12; No). Therefore, the voltage regulator 11A of the servo controller 11 performs voltage conversion of the 12V power PS12 and outputs the 5V power PS52 to the power switcher 14. As a result, SoC16 sets this 5V power PS52 as the power supply for the PLP circuit and supplies power to the PLP circuit as shown at time t1 in Figure 2, and also supplies 5V power PS52 converted by the voltage regulator 11A of the servo controller 11 to the unnecessary circuits (step S25).

[0036] Therefore, unlike the conventional technology, the PLP power supply using back electromotive force does not need to supply power to unnecessary circuits, and therefore no drop in the power supply voltage of the PLP circuit occurs due to the power supply.

[0037] Then, to proceed to data backup, the SoC 16 determines whether or not there is unprocessed data in the DRAM 17 (step S14). In this case, the reason for determining whether there is pre-processed data in DRAM 17 is to avoid performing PLP operations, since performing PLP operations when there is no data to back up may actually cause problems, as will be described later.

[0038] In the determination at step S14, if unprocessed data exists in the DRAM 17 (step S14; Yes), a PLP operation needs to be performed, and therefore unnecessary circuits not required for the PLP operation are powered down (step S15).

[0039] Then, SoC16 determines whether the count-up ends at time t2, which is a time after the time when the power-down of unnecessary circuits has been reliably implemented and completed, and whether the count-up of power-down timer 16A has stopped (step S16).

[0040] In the determination at step S16, if the count-up of the power-down timer 16A has not yet stopped (step S16; No), the system enters a standby state.

[0041] In the determination of step S16, if the count-up of the power-down timer 16A has stopped (stopped) at time t2 in Figure 2 (step S16; Yes), it is no longer necessary to supply power to the non-essential circuits, and so as shown in Figure 2(G), the back electromotive force of the disk motor is used as the PLP power source (step S17), as in the conventional case. At the same time, as shown in Figure 2(F), the 12V external power supply 21 stops supplying power to the PLP circuit via the voltage regulator 11A of the servo controller (SVC) 11. Then, from a fail-safe perspective, at time t3, the 12V external power supply 21 is stopped.

[0042] Therefore, since the PLP operation can be performed by powering down unnecessary circuits using a stable power supply, the PLP operation can be completed reliably, and the reliability of the magnetic disk device 10 can be improved.

[0043] As a result, power continues to be supplied to the DRAM 17 that is the target of the PLP. Then, the SoC 16 performs a PLP operation to transfer the data to be backed up that is stored in the DRAM 17 to the FROM 18 and back it up (step S18).

[0044] Next, the SoC 16 determines whether the PLP operation is completed (step S19). If it is determined in step S19 that the PLP operation has not yet been completed, the process goes into a standby state. If it is determined in step S19 that the PLP operation has been completed, as shown at time t4 in FIG. 2, the SoC 16 turns off the power supply to the magnetic disk device 10 in order to restart the magnetic disk device 10 (step S20).

[0045] Furthermore, after turning off the power to the magnetic disk device 10, at time t5 when it can be reliably estimated that the magnetic disk device 10 has returned to its initial state, the SoC 16 turns on the power to the magnetic disk device 10 and restarts the magnetic disk device 10 (step S21).

[0046] Next, the SoC 16 determines whether or not the PLP operation was performed last time (step S22).

[0047] That is, in step S18, the SoC 16 determines whether or not the PLP operation of transferring the data to be backed up that is stored in the DRAM 17 to the FROM 18 has been performed. In the determination at step S22, if the PLP operation is not being performed (step S22; No), the process proceeds to step S24.

[0048] If it is determined in step S22 that the PLP operation has been performed (step S22; Yes), the SoC 16 reads the data to be backed up from the FROM 18 and restores the data to the disk 13 (step S23). As a result, the magnetic disk device 10 performs startup processing and returns to the ready state, which is the normal state, at time t6.

[0049] Next, the operation in the second mode in which the 12V external power supply 21 is shut off will be described. FIG. 4 is a timing chart showing the case where the 12V external power supply is interrupted. 4(A) to 4(G) are similar to FIGS. 2(A) to 2(G), and therefore the detailed description thereof is incorporated herein.

[0050] Figure 4 differs from Figure 2 in that the 12V external power supply 21 is in a cut-off state as shown in Figure 4(D) and the 5V external power supply 22 is in a power supplyable state as shown in Figure 4(E), and therefore the PLP power supply shown in Figure 4(F) is power from the 5V external power supply 22.

[0051] Hereinafter, the operation in the second mode in which the 12V external power supply 21 is interrupted will be described in detail with reference to the timing chart of FIG. 4 and the processing flowchart of FIG.

[0052] At time t1 in FIG. 4, when the 12V external power supply 21 is cut off as shown in FIG. 4(E), the power supply monitoring unit 11B of the servo controller (SVC) 11 sets the Fault signal to the “L” level as shown in FIG. 4(B). As a result, the SoC 16 sets the Ready signal to the "L" level, as shown in FIG. 4(A).

[0053] Next, SoC16 starts the processing during PLP operation shown in Figure 3, and in order to realize the PLP function, at time t1, as shown in Figure 4(C), starts counting (initiates) the power-down timer 16A of the unnecessary circuit, which is a circuit not used in PLP processing (step S11).

[0054] Next, the SoC 16 determines whether the 12V external power supply has been shut off (turned off) (step S12). In this case, as shown in FIG. 4(D), the power supply monitoring unit 11B does not detect the output of the 12V external power supply 21, so the servo controller 11 determines that the 12V external power supply 21 is cut off (off) (step S12; Yes).

[0055] As a result, SoC16 sets 5V power PS51 from 5V external power supply 22 as the power supply for the PLP circuit, and supplies power to the PLP circuit as shown at time t1 in Figure 4, and also supplies 5V power PS51 to unneeded circuits (step S13).

[0056] Therefore, in this case, unlike the conventional case, there is no need to supply power from the PLP power supply due to back electromotive force to unnecessary circuits, and 5V power PS51 is supplied from the stable 5V external power supply 22, so there is no drop in the power supply voltage of the PLP circuit.

[0057] Then, to proceed to data backup, the SoC 16 determines whether or not there is unprocessed data in the DRAM 17 (step S14).

[0058] In the determination at step S14, if unprocessed data exists in the DRAM 17 (step S14; Yes), a PLP operation needs to be performed, and therefore unnecessary circuits not required for the PLP operation are powered down (step S15).

[0059] Then, SoC16 determines whether the count-up ends at time t2, which is a time after the time when the power-down of unnecessary circuits has been reliably implemented and completed, and whether the count-up of power-down timer 16A has stopped (step S16).

[0060] In the determination at step S16, if the count-up of the power-down timer 16A has not yet stopped (step S16; No), the system enters a standby state.

[0061] In the determination of step S16, if the count-up of the power-down timer 16A has stopped (stopped) at time t2 in Fig. 4 (step S16; Yes), it is no longer necessary to supply power to the non-essential circuits, and so as shown in Fig. 4(G), the back electromotive force of the disk motor is used as the PLP power supply as in the conventional case (step S17). At the same time, as shown in Fig. 4(F), the 5V external power supply 22 stops supplying power to the PLP circuit. Then, from a fail-safe perspective, at time t3, the 5V external power supply 22 is stopped.

[0062] Therefore, since the PLP operation can be performed by powering down unnecessary circuits using a stable power supply, the PLP operation can be completed reliably, and the reliability of the magnetic disk device 10 can be improved.

[0063] As a result, power continues to be supplied to the DRAM 17 that is the target of the PLP. Then, the SoC 16 performs a PLP operation to transfer the data to be backed up that is stored in the DRAM 17 to the FROM 18 and back it up (step S18).

[0064] Next, the SoC 16 determines whether the PLP operation is completed (step S19). If it is determined in step S19 that the PLP operation has not yet been completed, the process goes into a standby state. If it is determined in step S19 that the PLP operation has been completed, the SoC 16 turns off the power supply to the magnetic disk device 10 in order to restart the magnetic disk device 10, as shown at time t4 in FIG. 4 (step S20).

[0065] Furthermore, after turning off the power to the magnetic disk device 10, at time t5 when it can be reliably estimated that the magnetic disk device 10 has returned to its initial state, the SoC 16 turns on the power to the magnetic disk device 10 and restarts the magnetic disk device 10 (step S21). Next, the SoC 16 determines whether the PLP operation has been performed (step S22).

[0066] That is, in step S18, the SoC 16 determines whether or not the PLP operation of transferring the data to be backed up that is stored in the DRAM 17 to the FROM 18 has been performed.

[0067] If it is determined in step S22 that the PLP operation has been performed (step S22; Yes), the SoC 16 reads the data to be backed up from the FROM 18 and restores the data to the disk 13 (step S23). As a result, the magnetic disk device 10 performs startup processing and returns to the ready state, which is the normal state, at time t6.

[0068] The above explanation has been about the operation when data to be backed up exists, but as mentioned above, performing a PLP operation when data to be backed up does not exist may actually cause problems. Therefore, the operation when there is no data to be backed up will be described below with reference to the timing chart of FIG. 5 and the processing flowchart of FIG.

[0069] FIG. 5 is a timing chart when there is no data for PLP operation.

[0070] Figures 5(A), 5(B), 5(D) to 4(G) are similar to Figures 2(A), 2(B), 2(D) to 2(G), and therefore the detailed explanations therefor are incorporated herein.

[0071] 5 differs from FIG. 2 in that there is no need to perform a PLP operation, and therefore the process immediately shifts to restarting the magnetic disk drive at time t2 without powering down unnecessary circuits. Note that, as in FIG. 2, FIG. 5 shows a timing chart for when the 5V external power supply 22 is interrupted, but the same applies when the 12V external power supply 21 is interrupted.

[0072] Hereinafter, the operation when there is no data for PLP operation will be described with reference to the timing chart of FIG. 5 and the flowchart of FIG. At time t1, as shown in FIG. 5(D), when the 5V external power supply 22 is cut off, the Ready signal and Fault signal go to the "L" level as shown in FIGS. 5(A) and 5(B).

[0073] As a result, the SoC 16 starts counting the power-down timers of unnecessary circuits that are not used in the IPLP process in order to realize the PLP function (step S11). Next, the SoC 16 determines whether the 12V external power supply has been shut off (turned off) (step S12).

[0074] 5(D), the power supply monitor 11B detects the output of the 12V external power supply 21, and the servo controller 11 determines that the 12V external power supply 21 is not shut off (step S12; No). Therefore, the voltage regulator 11A of the servo controller 11 performs voltage conversion of the 12V power PS12 and outputs the 5V power PS52 to the power switcher 14.

[0075] As a result, SoC16 sets this 5V power PS52 as the power supply for the PLP circuit and supplies power to the PLP circuit as shown at time t1 in Figure 2, and also supplies 5V power PS52 converted by the voltage regulator 11A of the servo controller 11 to the unnecessary circuits (step S25).

[0076] Therefore, in this case too, the PLP power supply using back electromotive force does not need to supply power to unnecessary circuits, so there is no drop in the power supply voltage of the PLP circuit due to power supply.

[0077] Then, to proceed to data backup, the SoC 16 determines whether or not there is unprocessed data in the DRAM 17 (step S14). In this case, there is no pre-processed data in DRAM 17 (step S14; No), and there is no need to perform PLP operation, so SoC 16 immediately turns off the power to magnetic disk device 10 (step S20), as shown at time t2 in Figure 5, in order to restart magnetic disk device 10.

[0078] Furthermore, after turning off the power to the magnetic disk device 10, at time t3 when it can be reliably estimated that the magnetic disk device 10 has returned to its initial state, the SoC 16 turns on the power to the magnetic disk device 10 and restarts the magnetic disk device 10 as shown at time t3 in Figure 5 (step S21).

[0079] Next, SoC16 determines whether or not a PLP operation needs to be performed (step S22), but since no data to be backed up is stored in FROM, it determines that a PLP operation does not need to be performed, and the magnetic disk device 10 performs startup processing and returns to the ready state, which is the normal state, at time t4 in Figure 5.

[0080] Therefore, compared to when the PLP operation described in Figures 2 and 4 is performed, there is no need to perform power-down processing of unnecessary circuits, data backup processing, and processing of writing back backup data to disk 13, which reduces the risk of malfunctions associated with PLP operation and shortens the restart time of the magnetic disk device.

[0081] Next, the effects of the embodiment will be described in comparison with a reference example. In the following, for ease of understanding, the explanation will be given with reference to FIG. FIG. 6 is a timing chart of a reference example for explaining the effect of the embodiment. In the reference example, when the 5V external power supply or 12V external power supply is interrupted, the SoC detects the fault signal (low active in the example in Figure 3) from the servo controller and unconditionally switches to the PLP function.

[0082] More specifically, if the 5V external power supply 22 is cut off at time t11, the Ready signal and the Fault signal go to the "L" level, as shown in FIGS. 6(A) and 6(B).

[0083] As a result, in order to realize the PLP function, the SoC 16 starts counting the power-down timers of unnecessary circuits that are not used in the PLP processing, as shown in FIG. 6(C) (step S11). Furthermore, from the viewpoint of fail-safe, the SoC 16 stops the 12V external power supply 21 and the 5V external power supply 22 as shown in FIGS. 6(D) and 6(E).

[0084] As a result, before the power-down of unnecessary circuits that prevent the drop in the 5VPLP power supply is completed, the disk motor back electromotive force is switched to the PLP power supply as shown in FIG. 6(F). That is, since the unnecessary circuits have not yet been powered down, there is a risk of a malfunction in the PLP function due to a drop in the PLP power supply caused by the operation of the unnecessary circuits.

[0085] Furthermore, even if backup data is not present in the DRAM, such as when the power is cut off during data read, the system is forced to switch to PLP processing. This means that unnecessary PLP switching can lead to a risk of malfunction due to PLP processing and longer restart times.

[0086] However, when an external power supply interruption occurs, it is rare for both the 12V external power supply 21 and the 5V external power supply 22 to be interrupted simultaneously. According to the magnetic disk device of the embodiment, if either the 12V external power supply 21 or the 5V external power supply 22 is interrupted for some reason, the power supply that is not interrupted is used up to powering down unnecessary circuits not required for PLP operation, so that it is possible to suppress the occurrence of problems such as a voltage drop in the PLP power supply.

[0087] Furthermore, since it is determined whether or not the PLP operation is actually necessary, and if it is not necessary, the PLP operation is not performed, the processing procedure is simplified. Therefore, according to the embodiment, it is possible to improve functionality and reduce startup time by stabilizing the power supply before powering down unnecessary circuits and eliminating unnecessary PLP switching.

[0088] The program executed by the magnetic disk device of this embodiment is provided in a state that it is pre-installed in a ROM or the like. The program executed by the magnetic disk device of this embodiment may be configured to be provided by being recorded in an installable or executable file format on a computer-readable recording medium such as a USB memory, a semiconductor memory device such as an SSD (Solid State Drive), or a DVD (Digital Versatile Disk).

[0089] Furthermore, the program executed by the magnetic disk device of this embodiment may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. Also, the program executed by the magnetic disk device of this embodiment may be provided or distributed via a network such as the Internet.

[0090] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0091] 10 Magnetic disk device 11 Servo Controller 11A voltage regulator 11B Power supply monitoring section 12 disc motor 13 discs 14 Power Switcher 15 Voltage conversion unit 16 SoC 16A Power Down Timer 17 DRAM 18 FROM 20 External Power System 21 12V external power supply (second power supply) 22 5V external power supply (1st power supply)

Claims

1. 1. A magnetic disk drive that operates by receiving power from a first power source that supplies power having a first voltage and a second power source that has a second voltage higher than the first voltage, a power supply determination unit that detects whether a power interruption has occurred in either one of the first power supply and the second power supply; a control unit that, when a power interruption occurs in one of the power supplies, causes power to be supplied from the other power supply to the non-essential circuit until a process for power supply interruption is completed in the non-essential circuit to which power supply should be stopped; A magnetic disk device comprising:

2. the control unit supplies power for a PLP operation from the other power source to a PLP circuit when power is supplied to the unnecessary circuit.

2. The magnetic disk drive according to claim 1.

3. a PLP power supply for supplying power for PLP operation to the PLP circuit; when the power supply stop processing is completed in the unnecessary circuit, the control unit stops the power supply from the other power source to the PLP circuit and starts the power supply from the PLP power source to the PLP circuit.

3. The magnetic disk drive according to claim 2, comprising:

4. The control unit starts supplying power from the PLP power source to the PLP circuit, and then cuts off the other power source.

4. The magnetic disk drive according to claim 3.

5. a voltage conversion unit that converts a voltage of the power supplied from the second power source into the first voltage when a power interruption occurs in the first power source; The control unit supplies the power supplied from the second power source to the unnecessary circuit via the voltage conversion unit.

2. The magnetic disk drive according to claim 1.

6. A PLP circuit is provided for performing a PLP operation, The control unit determines whether the PLP operation is necessary when a power interruption occurs in one of the power sources, When the PLP operation is not necessary, the PLP circuit is not caused to perform the PLP operation, and the power supply to the magnetic disk device is cut off to perform a restart operation.

2. The magnetic disk drive according to claim 1.

7. 1. A method for controlling a magnetic disk drive that operates by receiving power from a first power source that supplies power having a first voltage and a second power source that has a second voltage higher than the first voltage, comprising: detecting whether a power interruption occurs in one of the first power source and the second power source; When a power interruption occurs in one of the power supplies, supplying power from the other power supply to the non-essential circuit to which power supply should be stopped until a process for power supply interruption is completed in the non-essential circuit; A method for controlling a magnetic disk device comprising the steps of:

8. 1. A program for controlling a magnetic disk drive by a computer, the magnetic disk drive being operated by receiving power from a first power source which supplies power having a first voltage and a second power source which has a second voltage higher than the first voltage, comprising: The computer, a means for detecting whether a power interruption has occurred in either one of the first power source and the second power source; a means for supplying power from the other power supply to an unneeded circuit to which power supply should be stopped until a process for stopping power supply is completed when a power cut occurs in one of the power supplies; A program that makes it work.

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