Current sensing circuit and hard disk drive including same
AssigneeSTMicroelectronics S.r.l.
InventorEzio Galbiati
Life of this patent
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Abstract
A circuit includes a set of input nodes configured to be coupled to respective ones of the windings of a spindle motor in a hard disk drive to sense the voltages applied to the windings. A set of output nodes is configured to provide output signals indicative of direction of flow of the currents through the windings. Level shifters are coupled to respective input nodes in the set of input nodes and have level-shifted output nodes configured to provide down-shifted replicas of the voltages at the respective input nodes in the set of input nodes. Flip-flops have inputs coupled to respective ones of the level-shifted output nodes of the level shifters and outputs configured to provide the output signals coupled to respective output nodes.
Claims20
A circuit, comprising:
- a first level shifter having a first input configured to be coupled to a first winding of a motor and a second input configured to be coupled to a motor voltage node;
- a second level shifter having a first input configured to be coupled to a second winding of the motor and a second input configured to be coupled to the motor voltage node;
- a third level shifter having a first input configured to be coupled to a third winding of the motor and a second input configured to be coupled to the motor voltage node;
- a first flip-flop having an input coupled to an output of the first level shifter, the first flip-flop also having an output configured to carry a signal indicative of a direction current flow through the first winding;
- a second flip-flop having an input coupled to an output of the second level shifter, the second flip-flop also having an output configured to carry a signal indicative of a direction current flow through the second winding;
- and
- a third flip-flop having an input coupled to an output of the third level shifter, the third flip-flop also having an output configured to carry a signal indicative of a direction current flow through the third winding.
A circuit, comprising:
- a set of input nodes configured to be coupled to respective ones of windings of a spindle motor in a hard disk drive to sense voltages applied to the windings;
- a set of output nodes configured to provide output signals indicative of direction of flow of currents through the windings;
- a plurality of level shifters coupled to respective input nodes in the set of input nodes and having level-shifted output nodes configured to provide down-shifted replicas of voltages at the respective input nodes in the set of input nodes;
- and
- a plurality of flip-flops having inputs coupled to respective ones of the level-shifted output nodes of the level shifters and outputs configured to provide the output signals coupled to respective output nodes.
A method of operating a hard disk drive that includes a spindle motor, the method comprising:
- driving the spindle motor in a brake phase, wherein the spindle motor is short-circuited and a spindle back electromotive force (BEMF) forces currents through windings of the spindle motor;
- driving the spindle motor in a tristate phase after the brake phase, wherein the tristate phase comprises detecting a direction of flow of currents through the windings by generating down-shifted replicas of voltages at the windings and latching a signal indicative of the direction of current flow;
- and
- driving the spindle motor in an active step-up phase after the tristate phase, wherein the currents through the windings of the spindle motor are recirculated based on the signal indicative of the direction of current flow.
Dependencies are inferred from the claim text.