Method of operating an electric motor, corresponding device and hard disk drive

A device, comprising:

• a set of driver circuits coupled to an electric motor in a hard disk drive, the set of driver circuits comprising high-side switches with high-side control terminals and high-side current flow paths, low-side switches with low-side control terminals and low-side current flow paths, switching nodes coupled to a winding of the electric motor, each driver circuit of the set of driver circuits comprising:
• a high-side switch of the high-side switches having a high-side control terminal of the high-side control terminals and a high-side current flow path of the high-side current flow paths therethrough, the high-side current flow path extending through the high-side switch between a supply node coupled to a supply voltage and a switching node of the switching nodes, high-side the control terminal being coupled to the switching node, and
• a low-side switch of the low-side switches having a low-side control terminal of the low-side control terminals and a low-side current flow path of the low-side current flow paths therethrough, the low-side current flow path extending through the low-side switch between the switching node and ground;
• control circuitry coupled to the set of driver circuits, the control circuitry configured to:
• generate respective conduction currents through the low-side current flow path of each of the low-side switches, in response to a command to reduce a motor speed of the electric motor, by coupling a drive voltage to the low-side control terminals of the low-side switches in the set of driver circuits;
• sense an intensity of at least one of the respective conduction currents flowing through the low-side current flow paths of the low-side switches in the set of driver circuits;
• and
• in response to the sensed current intensity exceeding a current intensity threshold, couple the control terminals of the low-side switches in the set of driver circuits to respective ones of the switching nodes.

A hard disk drive, comprising:

• an electric motor including a plurality of windings, the electric motor configured to move at a speed based on an intensity of at least one electric current flowing through the windings;
• a storage surface configured to store signals, the storage surface coupled to the electric motor;
• and
• a controller coupled to the electric motor via the windings and configured to drive movement of the storage surface, the controller comprising:
• a set of driver circuits coupled to the electric motor, the set of driver circuits comprising high-side switches with high-side control terminals and high-side current flow paths, low-side switches with low-side control terminals and low-side current flow paths, switching nodes coupled to a winding of the electric motor, each driver circuit of the set of driver circuits including:
• a high-side switch of the high-side switches having a high-side control terminal of the high-side control terminals and a high-side current flow path of the high-side current flow paths therethrough, the high-side current flow path extending through the high-side switch between a supply node coupled to a supply voltage and a switching node of the switching nodes, the high-side control terminal being coupled to the switching node, and
• a low-side switch of the low-side switches having a low-side control terminal of the low-side control terminals and a low-side current flow path of the low-side current flow paths therethrough, the low-side current flow path extending through the low-side switch between the switching node and ground;
• control circuitry coupled to the set of driver circuits, the control circuitry configured to:
• generate respective conduction currents through the low-side current flow path of each of the low-side switches, in response to a command to reduce the speed of the electric motor, by coupling a drive voltage to the low-side control terminals of the low-side switches in the set of driver circuits;
• sense an intensity of at least one of the respective conduction currents flowing through the low-side current flow paths of the low-side switches in the set of driver circuits;
• and
• in response to the sensed current intensity exceeding a current intensity threshold, couple the control terminals of the low-side switches in the set of driver circuits to respective ones of the switching nodes.