Circuit and method for protecting emergency head-retract capacitor in a hard disk drive
AssigneeMarvell International Ltd.
InventorsSakti Rana, Yayue Zhang, Siew Yong Chui
Life of this patent
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Abstract
A protection circuit for a capacitor comprises a voltage pump that selectively charges the capacitor. A current source selectively charges the capacitor. A controller selectively activates the current source while deactivating the voltage pump when a charging voltage is less than a threshold charging voltage level and selectively deactivates the current source while activating the voltage pump when the charging voltage is greater than the threshold charging voltage level.
Claims37
A protection circuit for a capacitor, comprising:
- a voltage pump that selectively charges the capacitor;
- a current source that selectively charges the capacitor;
- and
- a controller that selectively activates the current source while deactivating the voltage pump when a charging voltage is less than a threshold charging voltage level and that selectively deactivates the current source while activating the voltage pump when the charging voltage is greater than the threshold charging voltage level.
A disk drive comprising:
- a platter;
- a moving head assembly that reads data from and writes data to the platter;
- a retraction circuit that communicates with a capacitor and that selectively retracts the head assembly;
- a voltage pump that selectively charges the capacitor;
- a current source that selectively charges the capacitor;
- and
- a controller that selectively activates the current source while deactivating the voltage pump when a charging voltage is less than a threshold charging voltage level and that selectively deactivates the current source while activating the voltage pump when the charging voltage is greater than the threshold charging voltage level.
A method for protecting a capacitor, comprising:
- selectively charging the capacitor using a voltage pump;
- selectively charging the capacitor using a current source;
- selectively activating the current source while deactivating the voltage pump when a charging voltage is less than a threshold charging voltage level;
- and
- selectively deactivating the current source while activating the voltage pump when the charging voltage is greater than the threshold charging voltage level.
A method for protecting a capacitor, comprising:
- (a) measuring a charging voltage in the capacitor;
- and
- (b) if the charging voltage is less than a threshold charging voltage, applying current to charge the capacitor;
- and
- (c) if the charging voltage is greater than the threshold charging voltage, pumping a voltage pump to charge the capacitor.
Dependencies are inferred from the claim text.