System and method for dynamic USB power source

• US 7,310,697 B2
• Filed: 11/01/2004
• Issued: 12/18/2007
• Est. Priority Date: 11/01/2004
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Pandit, Amol, Bohl, Robert, Byrne, Dan
• Primary Examiner(s): Rinehart; Mark H.
• Assistant Examiner(s): DALEY, CHRISTOPHER ANTHONY
• Application Number:
  US10/978,607
• Publication Number:
  US 20060095641A1
• Time in Patent Office: 1,142 Days
• Field of Search: 710/313, 710/1, 710/2, 710/310, 713/300, 713/310, 709/209, 455/572
• US Class Current: 710/313
• CPC Class Codes: G06F 1/266 Arrangements to supply power to external peripherals either directly from the computer or under computer control, e.g. supply of power through the communication port, computer controlled power-strips

Abstract

The dynamic VBUS power source provides a system and method for dynamically powering USB devices. Briefly described, one embodiment is a method comprising determining when the USB device is a master device or a slave device, powering the USB device over a USB connector using a power unit when the USB device is the slave device, and powering a second USB device over the USB connector using the USB device when the USB device is the master device.

Claims

1. A method for powering a universal serial bus (USB) device, comprising;

determining when the USB device is a master device or a slave device;

powering through a first switch the USB device over a USB connector using a power unit when the USB device is a slave device; and

powering through a second switch located between the USB device and a second USB device over the USB connector using the USB device when the USB device is the master device;

detecting a logical low on a USB identifier (ID) connector; and

detecting a logical high on a VBUS connector,

such that the USB device is powered over the USB ID connector using the power unit;

inverting the logical low on the USB ID connector to a second logical high; and

outputting a third logical high when the USB ID is inverted to the second logical high and when the logical high on the VBUS connector is detected; and

closing the first switch when the third logical high is output such that the USB device is powered from the power unit coupled to the first switch.

2. The method of claim 1, further comprising:

closing the first switch when the USB device is the slave device such that the USB device is powered from the power unit coupled to the first switch; and

opening the second switch when the USB device is the slave device such that the second USB device is isolated from the USB device.

3. The method of claim 1, further comprising:

opening the first switch when the USB device is the master device such that the power unit coupled to the first switch is isolated from the USB connector; and

closing the second switch when the USB device is the master device such that the second USB device is powered by the USB device.

4. The method of claim 1, further comprising detecting a logical high on a USB identifier (ID) connector such that the second USB device is powered by the USB device.

5. The method of claim 1, further comprising detecting a logical low on a VBUS connector such that the second USB device is powered by the USB device.

6. The method of claim 1, further comprising:

receiving alternating current (AC) power from an electric distribution system; and

converting the received AC power into direct current (DC) power suitable for the USB connector.

11. The method of claim 1, further comprising opening the second switch when the logical low on the USB ID connector is detected such that the second USB device is isolated from the power unit.

7. A system for powering a universal serial bus (USB) device, comprising:

means for determining when the USB device is a master device or a slave device;

means for receiving alternating current (AC) power from an electric distribution system and converting the received AC power into direct current (DC) power suitable for a USB connector;

means for powering the USB device over the USB connector using the means for receiving and converting power when the USB device is the slave device; and

means for powering a second USB device over the USB connector using the USB device when the USB device is the master device;

means for detecting a logical low on a USB identifier (ID) connector; and

means for detecting a logical high on a VBUS connector such that the USB device is powered over the USB connector using the means for receiving and converting power;

means for inverting the logical low on the USB ID connector to a second logical high;

means for outputting a third logical high when the USB ID is inverted to the second logical high and when the logical high on the VBUS connector is detected; and

means for closing a first switch when the third logical high is output such that the USB device is powered from the means for receiving and converting power coupled to the first switch.

8. The system of claim 7, further comprising;

means for closing a first switch when the USB device is the slave device such that the USB device is powered using the means for receiving and converting power, the means for receiving and converting power coupled to the first switch; and

means for opening a second switch when the USB device is the slave device such that the second USB device is isolated from a power unit.

9. The system of claim 7, further comprising:

means for opening a first switch when the USB device is the master device such that the means for receiving and converting power coupled to the first switch is isolated from the USB connector; and

means for closing a second switch when the USB device is the master device such that the second USB device is powered by the USB device.

10. The system of claim 7, further comprising means for opening a second switch when the logical low on the USB ID connector is detected such that the second USB device is isolated from the means for receiving and converting power.