Device and method for adapting speed of a USB device based on available power

A USB device for coupling with a host, comprising:

• a module for selectively operating the device at a first or second operating speed depending on whether the host will permit the device to draw a requested power consumption level, the module initially operating the device at the first operating speed of full speed USB associated with a first power consumption level when the device is initially coupled with the host,
• wherein the module determines whether the host will permit the device to draw the requested power consumption level being higher than said first power consumption level, by reporting the device as having a descriptor set including a 100 to 500 mA descriptor, and the module determines if the host selects the descriptor set;
• wherein if the host selects the descriptor set, the module reconfigures the device, by simulating a disconnection to the host, to operate at a second operating speed of high speed USB associated with the requested power consumption level;
• and
• wherein if the host did not select the descriptor set, the module operates the device at the first operating speed of full speed USB associated with the first power consumption level.

A device for coupling with a host, comprising:

• a first mode of operation including a first operating speed of full speed USB and a first power consumption level;
• a second mode of operation including a second operating speed of high speed USB and a second power consumption level;
• and
• a module for selecting whether the device operates using the first mode or the second mode, the module selecting based in part on whether the host permits the device to operate at the second power consumption level;
• wherein the module initially operates the device at the first operating speed of full speed USB when the device is initially coupled with the host,
• wherein the module determines whether the host will permit the device to draw the requested power consumption level being higher than said first power consumption level, by reporting the device as having a descriptor set including a 100 to 500 mA descriptor, and the module determines if the host selects the descriptor set;
• wherein if the host selects the descriptor set, the module reconfigures the device, by simulating a disconnection to the host, to operate at a second operating speed of high speed USB associated with the requested power consumption level;
• and
• wherein if the host did not select the descriptor set, the module operates the device at the first operating speed of full speed USB associated with the first power consumption level.