Current boost circuit

• US 9,240,742 B1
• Filed: 12/06/2013
• Issued: 01/19/2016
• Est. Priority Date: 12/06/2013
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Erickson, Dale H, Bucher, James D II
• Primary Examiner(s): Masih, Karen
• Application Number:
  US14/099,558
• Time in Patent Office: 774 Days
• US Class Current: 1/1
• CPC Class Codes: G11B 19/2081 emergency power-down
• CPC Class Codes: G11B 21/12 Raising and lowering; Back-spacing or forward-spacing along track; Returning to starting position otherwise than during transducing operation
• CPC Class Codes: H02P 25/034 Voice coil motors voice coil motors driven by DC power H02P7/025
• CPC Class Codes: H02P 29/025 the fault being a power interruption
• CPC Class Codes: H02P 29/032 Preventing damage to the motor, e.g. setting individual current limits for different drive conditions

Abstract

Systems and methods are disclosed for providing a current boost to support a voltage. In an embodiment, an apparatus comprises a voltage node; a switch coupled to the voltage node; a sensing circuit including an input coupled to the voltage node and an output for providing a corresponding voltage; and a voltage regulator coupled to receive the corresponding voltage and coupled to control the switch responsive to the received corresponding voltage. In an embodiment, a method comprises sensing a voltage; using a voltage regulator to turn on a switch responsive to the sensed voltage being less than a certain value; and providing additional current through the on switch to substantially maintain the voltage from being less than the certain value.

Claims

1. An apparatus comprising:

a back electromotive force (BEMF) supply for generating a BEMF voltage;

a current source;

a switch coupled to the current source and the BEMF supply to conduct current from the current source when the switch is on to maintain the BEMF voltage not less than a certain voltage;

a sensing circuit including an input coupled to the BEMF supply and an output for providing a voltage corresponding to the BEMF voltage; and

a voltage regulator coupled to receive the corresponding voltage and coupled to turn on the switch responsive to the received corresponding voltage being less than the certain voltage.

2. The apparatus of claim 1 further comprising an actuator assembly that is retracted using the BEMF voltage when the apparatus loses power.

3. The apparatus of claim 2 wherein the BEMF supply is a spindle motor.

4. The apparatus of claim 1 wherein the current source includes at least one capacitor.

5. The apparatus of claim 1 wherein the voltage regulator is low-quiescent current linear generator.

6. The apparatus of claim 1 wherein the switch is a power transistor.

7. The apparatus of claim 1 wherein the sensing circuit includes a voltage divider and another capacitor coupled to the BEMF supply in parallel.

8. The apparatus of claim 7 wherein the corresponding voltage is provided by the voltage divider.

9. The apparatus of claim 7 wherein a schottky diode is coupled between the BEMF supply and the parallel voltage divider and other capacitor.

10. An apparatus comprising:

a voltage node;

a switch coupled to the voltage node;

a sensing circuit including an input coupled to the voltage node and an output for providing a corresponding voltage; and

a voltage regulator coupled to receive the corresponding voltage and coupled to control the switch responsive to the received corresponding voltage.

11. The apparatus of claim 10 further comprising a current source coupled to the voltage node through the switch.

12. The apparatus of claim 11 wherein the current source includes at least one capacitor.

13. The apparatus of claim 11 wherein the voltage regulator and current source are coupled to a power supply.

14. The apparatus of claim 10 wherein the voltage regulator is low-quiescent current linear generator.

15. The apparatus of claim 10 wherein the switch is a power transistor.

16. The apparatus of claim 10 wherein the sensing circuit includes a voltage divider and another capacitor coupled to the voltage node in parallel.

17. The apparatus of claim 16 wherein the corresponding voltage is provided by the voltage divider.

18. The apparatus of claim 16 wherein a schottky diode is coupled between the voltage node and the parallel voltage divider and other capacitor.

19. The apparatus of claim 10 further comprising a back electromotive force (BEMF) supply coupled to the voltage node.

20. A method comprising:

sensing a voltage;

using a voltage regulator to turn on a switch responsive to the sensed voltage being less than a certain value; and

providing additional current through the on switch to substantially maintain the voltage from being less than the certain value.

21. The method of claim 20 further comprising providing the voltage from a BEMF supply.

22. The method of claim 21 further comprising retracting an actuator assembly using the voltage from the BEMF supply.