Universal serial bus current limit

• US 20050269883A1
• Filed: 06/02/2004
• Published: 12/08/2005
• Est. Priority Date: 06/02/2004
• Status: Active Grant

• Current Assignee: Fundamental Innovation Systems International LLC (Fundamental Innovation Systems International Holdings LLC)
• Original Assignee: Blackberry Limited
• Inventors: Veselic, Dusan, Drader, Marc A., Mak-Fan, David James
• Granted Patent: US 8,378,527 B2
• Time in Patent Office: Days
• US Class Current: 307/131
• CPC Class Codes: G05F 3/08 wherein the variable is dc
• CPC Class Codes: G06F 1/26 Power supply means, e.g. regulation thereof for memories G11C

Abstract

A load device includes a power input having an interface to a power supply; a peripheral power bus including an internal capacitance, and an active switch coupled to the power input and the peripheral power bus for applying power from the power input to the peripheral power bus. The load device also includes a switch controller coupled to the active switch for regulating the in-rush current drawn by the internal capacitance through the active switch while the internal capacitance is being charged.

Claims

1. A load device comprising:

a power input having an interface to a power supply;

a peripheral power bus including an internal capacitance;

an active switch coupled to the power input and the peripheral power bus for applying power from the power input to the peripheral power bus; and

a switch controller coupled to the active switch, the switch controller being configured to regulate an in-rush current drawn by the internal capacitance through the active switch.

2. The load device according to claim 1, wherein the power input comprises a system power bus for the load device, the active switch is disposed electrically between the system power bus and the peripheral power bus, and the switch controller is configured to regulate the in-rush current by maintaining a voltage at the system bus above a predetermined lower limit.

3. The load device according to claim 2, wherein the switch controller is configured to maintain the system voltage by cyclically opening and closing the active switch until the internal capacitance has charged up to a predetermined level.

4. The load device according to claim 3, wherein the switch controller is configured to cyclically open and close the active switch by pulse-width modulating the active switch.

5. The load device according to any one of claims 1 to 4, wherein the load comprises a portable computing device, and the interface comprises a universal serial bus interface.

6. In a load comprising a power input for interfacing to a power supply, a peripheral power including an internal capacitance, and an active switch for applying power from the power input to the peripheral power bus, a method for powering the load from the power supply, comprising regulating an in-rush current drawn by the internal capacitance through the active switch.

7. The method according to claim 6, wherein the power input comprises a system power bus for the load, the active switch is disposed electrically between the system power bus and the peripheral power bus, and the regulating step comprises maintaining a voltage at the system bus above a predetermined lower limit.

8. The method according to claim 7, wherein the voltage maintaining step comprises cyclically opening and closing the active switch until the internal capacitance has charged up to a predetermined level.

9. The method according to claim 8, wherein the step of cyclically opening and closing the active switch comprises pulse-width modulating the active switch.

10. The method according to any one of claims 6 to 9, wherein the load comprises a portable computing device, and the interface comprises a universal serial bus interface,

11. A computer-readable medium including computer processing instructions for a processing unit of a portable computing device, the portable computing device comprising a system power bus having an interface to a power supply, a peripheral power bus including an internal capacitance, and an active switch coupled to the system power bus and the peripheral power bus for applying power from the system power bus to the peripheral power bus, the computer processing instructions when executed by the processing unit causing the portable computing device to regulate an in-rush current drawn by the internal capacitance through the active switch.