Power failure management in disk drives
View Patent ↗A disk drive is disclosed comprising a disk, a spindle motor operable to rotate the disk, a head actuated over the disk, an interface operable to receive a host supply voltage, and a capacitor. The host supply voltage is used to charge the capacitor to a capacitor voltage higher than the host supply voltage. During a power failure, the host supply voltage stops charging the capacitor, and a motor supply voltage is generated from the spindle motor. The capacitor voltage is used to operate control circuitry, and when the capacitor voltage decays below the motor supply voltage, the motor supply voltage charges the capacitor.
1. A disk drive comprising:
a disk;
a head configured to write data to the disk;
a microactuator configured to actuate the head;
an interface operable to receive a host supply voltage;
a power storage device configured to store a backup voltage;
a voltage booster configured to receive the host supply voltage at a voltage booster input and generate a boosted host supply voltage; and
control circuitry configured to, in response to a power failure event:
disconnect the voltage booster input from the host supply voltage and connect the voltage booster input to the backup voltage;
generate a boosted backup voltage using the voltage booster; and
power the microactuator using the boosted backup voltage.
2. The disk drive of claim 1 , wherein the control circuitry is further configured to power the microactuator using the boosted host supply voltage during normal operation.
3. The disk drive of claim 1 , wherein the microactuator is a piezoelectric microactuator.
4. The disk drive of claim 1 , wherein the control circuitry is further configured to charge the power storage device using the boosted host supply voltage during normal operation.
5. The disk drive of claim 4 , wherein the control circuitry is further configured to charge the power storage device to a voltage level greater than the host supply voltage.
6. The disk drive of claim 1 , further comprising a first switch configured to selectively connect the voltage booster input to the host supply voltage or the backup voltage, wherein the control circuitry is further configured to disconnect the voltage booster input from the host supply voltage and connect the voltage booster input to the backup voltage at least in part by operating the first switch.
7. The disk drive of claim 6 , further comprising a second switch configured to selectively connect the control circuitry to the host supply voltage or the backup voltage, wherein the control circuitry is further configured to, in response to the power failure event, disconnect the control circuitry from the host supply voltage and connect the control circuitry to the backup voltage by operating the second switch.
8. The disk drive of claim 1 , further comprising a diode connected between a motor supply voltage and the power storage device.
9. The disk drive of claim 8 , wherein the diode is configured to allow the motor supply voltage to charge the power storage device when the motor supply voltage is greater than a voltage level of the power storage device.
10. A device comprising:
control circuitry configured to:
provide a host supply voltage received via an interface to a voltage booster over an input of the voltage booster;
use the voltage booster to generate a boosted host supply voltage from the host supply voltage; and
during a power failure:
disconnect the voltage booster input from the host supply voltage and connect the voltage booster input to a power storage device storing a backup voltage;
use the voltage booster to generate a boosted backup voltage; and
power a microactuator using the boosted backup voltage, the microactuator being configured to actuate a head of a disk drive.
11. The device of claim 10 , wherein the control circuitry is further configured to use the host supply voltage to charge the power storage device to a voltage level higher than the host supply voltage.
12. The device of claim 10 , wherein the microactuator is a piezoelectric microactuator.
13. The device of claim 10 , wherein the control circuitry is further configured to charge the power storage device using the boosted host supply voltage during normal operation of the disk drive.
14. The device of claim 10 , wherein the control circuitry is further configured to disconnect the voltage booster input from the host supply voltage and connect the voltage booster input to the power storage device using a switch.
15. The device of claim 10 , wherein the control circuitry is further configured to compare a motor supply voltage to a voltage level of the power storage device and allow the motor supply voltage to power the power storage device when the motor supply voltage is greater than the voltage level of the power storage device.
16. The device of claim 15 , wherein the control circuitry is further configured to compare the motor supply voltage to the voltage level of the power storage device using a diode that is forward biased from the motor supply voltage to the power storage device.
17. The device of claim 10 , wherein the control circuitry is further configured to receive the backup voltage from a voltage regulator.
18. The device of claim 10 , wherein the control circuitry is further configured to use a motor supply voltage to power a voice coil motor (VCM) when a voltage level of the power storage device is greater than the motor supply voltage.