Patent Application
20100053802
This invention relates to electronic circuits, and more specifically to a disk-drive motor driver.
Magnetic disk-drives, such as hard-drives, are implemented in almost all personal computers and enterprise-class server computers. Typical magnetic disk drives are operated by a spindle motor (SPM) that spins the magnetic disk and a voice control motor (VCM) that drives and positions the magnetic disk read and/or write head. As an example, the VCM can be a linearly operated servo motor that can operate in a seek mode and in a tracking mode. In the seek mode, the VCM is moved across the magnetic disk to seek a specific location to read data from or write data to the magnetic disk. In the tracking mode, the VCM remains stationary or moves very slowly to stay on-track of the disk while data is being read from or written to the magnetic disk.
One embodiment of the invention includes a disk-drive motor control system. The system comprises a seek mode power supply configured to provide a first voltage corresponding to a seek mode associated with a disk-drive voice control motor (VCM). The system also includes a track mode power supply configured to provide a second voltage corresponding to a tracking mode associated with the disk-drive VCM. The first voltage can be greater than the second voltage. The system further includes a disk-drive motor driver configured to provide a current to the disk-drive VCM at a first magnitude in the seek mode based on the first voltage, at a second magnitude in the tracking mode based on the second voltage, and at a third magnitude in a head-retraction mode.
Another embodiment of the invention includes a method for controlling a disk-drive. The method comprises switching a disk-drive voice control motor (VCM) to a seek mode power supply via a first H-bridge circuit upon the disk-drive entering a seek mode and providing a current at a first magnitude to the disk-drive VCM through the first H-bridge circuit during the seek mode. The method further includes switching the disk-drive VCM to a tracking mode power supply via a second H-bridge circuit upon the disk-drive entering a tracking mode, and providing the current at a second magnitude to the disk-drive VCM through the second H-bridge circuit during the tracking mode. The first magnitude can be greater than the second magnitude.
Another embodiment of in the invention includes a disk-drive motor control system. The system comprises means for providing a first voltage corresponding to a seek mode associated with a disk-drive voice control motor (VCM) and means for providing a second voltage corresponding to a tracking mode associated with the disk-drive VCM, the first voltage being greater than the second voltage. The system also comprises means for providing a third voltage corresponding to a head-retraction mode associated with the disk-drive VCM. The system further comprises means for providing a current to the disk-drive VCM at one of a first magnitude based on the first voltage in the seek mode, a second magnitude based on the second voltage in the tracking mode, and a third magnitude based on the third voltage in the head-retraction mode.
The invention relates to electronic circuits, and more specifically to a disk-drive motor driver. The disk-drive motor driver can include a voice control motor (VCM) output stage that controls a VCM and a spindle motor (SPM) output stage that controls an SPM. A seek mode power supply provides a seek mode voltage to the disk-drive motor driver that is provided to the SPM output stage and the VCM output stage. Thus, the seek mode voltage is provided to control the SPM and the VCM during a seek mode. A tracking mode power supply provides a tracking mode voltage to the VCM output stage, with the tracking mode voltage being less than the seek mode voltage. Thus, during a tracking mode, the VCM output stage switches to the tracking mode voltage to conserve power.
The VCM is controlled based on providing current through the VCM in one of two directions. As such, current that is provided in a first direction through the VCM moves the VCM in one direction, and current that is provided in the other direction through the VCM moves the VCM in the other direction. Thus, the VCM output stage can include an H-bridge circuit to provide the current through the VCM based on a pair of control signals. As one example, the VCM output stage can also include a set of switches that switch the H-bridge circuit to the seek mode voltage in the seek mode and to the tracking mode voltage during the tracking mode. As another example, the VCM output stage can include two H-bridge circuits, a first H-bridge circuit that is coupled to the seek mode voltage and a second H-bridge circuit that is coupled to the tracking mode voltage. Thus, in the seek mode, the VCM output stage can provide the current to the VCM using the first H-bridge circuit, and in the tracking mode, the VCM output stage can provide the current to the VCM using the second H-bridge circuit.
The disk-drive motor driver can also operate in a head-retraction mode. As an example, upon there being insufficient seek mode voltage to spin the SPM or to maintain adequate current through the VCM, the disk-drive motor driver can enter the head-retraction mode to generate a sufficient amount of current through the VCM to retract the magnetic disk read/write head to avoid damage to the magnetic disk. In the head-retraction mode, back-electromagnetic field voltage of the SPM can be rectified to generate a head-retraction voltage. The head-retraction voltage is thus implemented to provide the current through the VCM in a specific direction to retract it. As an example, the disk-drive motor driver can include a switch that provides a current path through the H-bridge circuit to provide current to the VCM to retract the read/write head regardless of the seek mode voltage or the tracking mode voltage. As another example, the disk-drive motor driver can provide the current through the first H-bridge circuit to the VCM to retract the read/write head.
The disk-drive motor control system 10 also includes a disk-drive motor driver 16 that is configured to provide currents to the SPM 12 and the VCM 14. Specifically, the disk-drive motor driver 16 includes an SPM output stage 18 and a VCM output stage 20. In the example of
The disk-drive motor control system 10 includes a motor controller 22 configured to provide command signals to the disk-drive motor driver 16 for operating the SPM 12 and the VCM 14. In the example of
The disk-drive motor control system 10 further includes a tracking mode power supply 24 that provides a voltage VTRACK and a seek mode power supply 26 that provides a voltage VSEEK. As an example, the tracking mode power supply 24 and the seek mode power supply 26 can each be configured as a linear power supply or a pulse-width modulated (PWM) power supply. To move the VCM 14 quickly across the magnetic disk can require substantially more power than to move the VCM 14 very slowly or to keep the VCM 14 substantially stationary. As an example, the voltage VSEEK can have a magnitude of approximately 5 volts, which can be greater than the magnitude of the voltage VTRACK (e.g., approximately 2-3 volts). As a result, the disk-drive motor driver 16 can switch between the voltage VSEEK and the voltage VTRACK in response to the mode signal MODE to generate the current IVCM via the VCM output stage 20. Accordingly, the disk-drive motor driver 16 can switch to the lesser magnitude voltage VTRACK during the tracking mode, thus conserving power during the tracking mode. In addition, power can be substantially conserved in the seek mode and/or the tracking mode as well based on the voltage VSEEK and/or the voltage VTRACK, respectively, being generated from a PWM power supply.
In addition, the SPM output stage 18 can be configured to include circuitry configured as an additional voltage source to control the VCM output stage 20. Specifically, the SPM output stage 18 can include a back-electromagnetic (EMF) rectifier that is configured to rectify back-EMF voltage associated with the SPM 12. The back-EMF voltage can thus be provided to generate the current IVCM to retract the magnetic disk read/write head via the VCM 14. As an example, the back-EMF voltage can be rectified to generate the current IVCM in the event of a power loss associated with one or both of the tracking mode power supply 24 and the seek mode power supply 26.
The disk-drive motor driver 50 includes an SPM output stage 52 and a VCM output stage 54. In the example of
The VCM output stage 54 includes an H-bridge circuit 56. The H-bridge circuit 56 includes four N-type field effect transistors (FETs) N1, N2, N3, and N4. The transistor N1 interconnects a power node 58 and a first output node 60, and has a gate that is coupled to a first control signal CTRL1. The transistor N2 interconnects the first output node 60 and a negative rail voltage, demonstrated in the example of
Based on the states of the control signals CTRL1 and CTRL2, the H-bridge circuit 56 can be configured to provide a current path for the current IVCM through the associated VCM (not shown). Specifically, the example of
As one example, the control signal CTRL1 can be asserted (i.e., logic high) while the control signal CTRL2 can be de-asserted (i.e., logic low). Therefore, the transistors N1 and N4 are activated. Accordingly, current flows from the power node 58 through the transistor N1, to the associated VCM as the current IVCM1, back from the associated VCM as the current IVCM2, and through the transistor N4 to ground. As another example, the control signal CTRL2 can be asserted while the control signal CTRL1 can be de-asserted. Therefore, the transistors N2 and N3 are activated. Accordingly, current flows from the power node 58 through the transistor N3, to the associated VCM as the current IVCM2, back from the associated VCM as the current IVCM1, and through the transistor N2 to ground.
The VCM output stage 54 also includes a second switch SW2, a third switch SW3, and a fourth switch SW4. As an example, the switches SW2, SW3, and SW4 can be configured as transistors, such as N-type FETs. The second switch SW2 is closed during the seek mode and the tracking mode to couple the third and fourth switches SW3 and SW4 to the power node 58. The third switch SW3 interconnects the power node 58 and the tracking mode voltage VTRACK, such as generated by the tracking mode power supply 24, and the fourth switch SW4 interconnects the power node 58 and the seek mode voltage VSEEK. The third switch SW3 is controlled by the mode signal MODE and the fourth switch SW4 is controlled by an inverted state of the mode signal MODE via an inverter 64. Therefore, the switches SW3 and SW4 are each activated to mutually exclusively to couple the respective one of the tracking mode voltage VTRACK and the seek mode voltage VSEEK to the power node 58 during the respective tracking mode and seek mode. Accordingly, the respective one of the tracking mode voltage VTRACK and the seek mode voltage VSEEK is provided as the voltage supply to the H-bridge circuit 56 in response to the mode signal MODE. As a result, during the tracking mode, the VCM output stage 54 can generate the current to the associated VCM based on the lower magnitude tracking mode voltage VTRACK to substantially reduce power consumption.
In addition, in the example of
It is to be understood that the disk-drive motor driver 50 is not intended to be limited to the example of
The disk-drive motor driver 100 includes an SPM output stage 102 and a VCM output stage 104. In the example of
The VCM output stage 104 includes a first H-bridge circuit 106 and a second H-bridge circuit 108. The first H-bridge circuit 106 includes four N-type FETs N6, N7, N8, and N9. The transistor N6 interconnects the seek mode voltage VSEEK and a first output node 110, and has a gate that is coupled to a first control signal CTRL1. The transistor N7 interconnects the first output node 110 and a negative rail voltage, demonstrated in the example of
The second H-bridge circuit 108 includes four N-type FETs N10, N11, N12, and N13. The transistor N10 interconnects the tracking mode voltage VTRACK and the first output node 110, and has a gate that is coupled to the first control signal CTRL1. The transistor N11 interconnects the first output node 110 and ground, and has a gate that is coupled to the second control signal CTRL2. The transistor N12 interconnects the tracking mode voltage VTRACK and the second output node 112, and has a gate that is coupled to the second control signal CTRL2. The transistor N13 interconnects the second output node 112 and ground, and has a gate that is coupled to the first control signal CTRL1.
Similar to as described above in the example of
The VCM output stage 104 also includes a first pair of switches SW6 and a second pair of switches SW7. As an example, the switches SW6 and SW7 can be configured as transistors, such as FETs. The first pair of switches SW6 interconnect the control signals CTRL1 and CTRL2 to the first H-bridge circuit 106 and the second pair of switches SW7 interconnect the control signals CTRL1 and CTRL2 to the second H-bridge circuit 108. The first pair of switches SW6 is controlled by the mode signal MODE and the second pair of switches SW7 is controlled by an inverted state of the mode signal MODE via an inverter 114. Therefore, at a first state of the mode signal MODE corresponding to the seek mode, the switches SW6 are activated, such that the control signals CTRL1 and CTRL2 control the first H-bridge circuit 106 to provide the currents IVCM1 and IVCM2 to the associated VCM at a greater magnitude based on the greater magnitude seek mode voltage VSEEK. Similarly, at a second state of the mode signal MODE corresponding to the tracking mode, the switches SW7 are activated, such that the control signals CTRL1 and CTRL2 control the second H-bridge circuit 108 to provide the currents IVCM1 and IVCM2 to the associated VCM at a lesser magnitude based on the lesser magnitude tracking mode voltage VTRACK. As a result, during the tracking mode, the VCM output stage 104 can generate the current to the associated VCM based on the lower magnitude tracking mode voltage VTRACK to substantially reduce power consumption.
In addition, in the example of
It is to be understood that the disk-drive motor driver 100 is not intended to be limited to the example of
In view of the foregoing structural and functional features described above, certain methods will be better appreciated with reference to
At 158, the disk-drive is switched to a tracking mode. The tracking mode can correspond to a VCM remaining substantially stationary or moving slowly across the magnetic disk to remain in a specific location while data is read from or written to the magnetic disk. At 160, the VCM output stage is switched to a tracking mode power supply. As an example, the VCM output stage can activate a switch to couple an H-bridge circuit to the tracking mode power supply. As another example, the VCM output stage can activate one or more switches to couple control signals corresponding to the VCM motion direction to the one of two H-bridges that is coupled to the tracking mode power supply. At 162, the current is provided at a second magnitude to the disk-drive VCM based on the tracking mode voltage. As an example, the tracking mode voltage can be approximately 2-3 volts, thus providing lesser current to the VCM. The current can be provided through an associated H-bridge in one of two directions based on the state of control signals that control transistors in the H-bridge. Therefore, in the tracking mode, the disk-drive can substantially conserve power.
What have been described above are examples of the invention. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the invention, but one of ordinary skill in the art will recognize that many further combinations and permutations of the invention are possible. Accordingly, the invention is intended to embrace all such alterations, modifications, and variations that fall within the scope of this application, including the appended claims.
