SOFT START WITH ACTIVE RESET

• US 20110179292A1
• Filed: 01/21/2010
• Published: 07/21/2011
• Est. Priority Date: 01/21/2010
• Status: Active Grant

• Current Assignee: Dell Products LP (Dell Technologies Inc.)
• Original Assignee: Dell Products LP (Dell Technologies Inc.)
• Inventors: Clegg, Joseph Alexander, Hijazi, Mohammed K., Wood, Merle J. III
• Granted Patent: US 8,327,165 B2
• Time in Patent Office: Days
• US Class Current: 713/300
• CPC Class Codes: G06F 1/26 Power supply means, e.g. regulation thereof for memories G11C

Abstract

A power supply input circuit includes an input node configured to removeably couple to an electrical source. A solid state switch is coupled between the input node and a capacitive load. An RC soft start circuit is coupled to the input node and the switch. The soft start circuit has a capacitor that causes the switch to increasingly pass electrical power from the source to the load as the capacitor charges from the source. An active reset circuit is coupled to the soft start circuit. The reset circuit is configured to detect when the source is removed from the input node and in response to the source being removed from the input node, the reset circuit discharges the capacitor to reset the soft start circuit.

Claims

1. A power supply input circuit comprising:

an input node configured to removeably couple to an electrical source;

a solid state switch coupled between the input node and a capacitive load;

an RC soft start circuit coupled to the input node and the switch, the soft start circuit having a capacitor that causes the switch to increasingly pass electrical power from the source to the load as the capacitor charges from the source; and

an active reset circuit coupled to the soft start circuit, the reset circuit configured to detect when the source is removed from the input node and in response to the source being removed from the input node, discharges the capacitor to reset the soft start circuit.

2. The power supply input circuit of claim 1, wherein the capacitive load has an input capacitance value of approximately 10,000 micro Farads.

3. The power supply input circuit of claim 2, wherein the electrical source provides electrical power wirelessly to the input circuit.

4. The power supply input circuit of claim 1, wherein the capacitor is discharged in less than 30 milliseconds.

5. The power supply input circuit of claim 1, wherein the reset circuit includes a transistor that passes charge from the capacitor to discharge the capacitor.

6. The power supply input circuit of claim 5, wherein a comparator device drives the transistor.

7. The power supply input circuit of claim 1, wherein the switch is a MOSFET switch.

8. An information handling system (IHS) comprising:

a processor;

a memory device coupled to the processor; and

a power supply input circuit, the power supply input circuit comprising;

an input node configured to removeably couple to an electrical source;

a solid state switch coupled between the input node and a capacitive load;

an RC soft start circuit coupled to the input node and the switch, the soft start circuit having a capacitor that causes the switch to increasingly pass electrical power from the source to the load as the capacitor charges from the source; and

an active reset circuit coupled to the soft start circuit, the reset circuit configured to detect when the source is removed from the input node and in response to the source being removed from the input node, discharges the capacitor to reset the soft start circuit.

9. The IHS of claim 8, wherein the capacitive load has an input capacitance value of approximately 10,000 micro Farads.

10. The IHS of claim 9, wherein the electrical source provides electrical power wirelessly to the input circuit.

11. The IHS of claim 8, wherein the capacitor is discharged in less than 30 milliseconds.

12. The IHS of claim 8, wherein the reset circuit includes a transistor that passes charge from the capacitor to discharge the capacitor.

13. The IHS of claim 12, wherein a comparator device drives the transistor.

14. The IHS of claim 8, wherein the switch is a MOSFET switch.

15. A method comprising:

coupling a solid state switch between an input node and a capacitive load;

causing the switch to increasingly pass electrical power from an electrical source to the load as a capacitor, which is coupled to the input node and the switch, charges from the source;

detecting when the source is removed from the input node and in response to the source being removed from the input node; and

actively discharging the capacitor to reset the soft start circuit.

16. The method of claim 15, further comprising:

providing the capacitive load having a capacitance value of approximately 10,000 micro Farads.

17. The method of claim 16, further comprising:

providing electrical power wirelessly from the source to the input circuit.

18. The method of claim 15, wherein the actively discharging the capacitor is performed in less than 30 milliseconds.

19. The method of claim 15, further comprising:

passing the charge from the capacitor to discharge the capacitor using a transistor.

20. The method of claim 19, further comprising:

driving the transistor using a comparator device.