Low-Power USB Enumeration for Depleted Battery Charging
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Solution Overview
Problem
Portable USB devices often fail to enumerate with a USB host when their battery is depleted, preventing charging at higher power levels until the battery is sufficiently charged, which prolongs charging times and is not compliant with USB specifications.
Innovation Solution
A system and method that allows USB devices to enumerate using low power provided by a host device before full enumeration, enabling charging to begin even when the battery is low, and switching to normal enumeration when sufficiently charged, utilizing low-power enumeration circuitry to manage power levels and initiate charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the USB device waits for sufficient battery charge before enumeration, then USB specification compliance is maintained, but charging time is prolonged
Solution Approach 1:
The patent segments the enumeration process into two distinct phases: a low-power preliminary enumeration phase that can proceed with depleted battery, and a subsequent full enumeration phase. This segmentation allows the device to begin charging immediately while maintaining USB specification compliance by using only permitted low-power modes during the initial phase.
Solution Approach 2:
The patent performs preliminary enumeration actions before the battery is fully charged. The device initiates the enumeration process in advance using low-power communication protocols, allowing the host to recognize and begin charging the device before sufficient power is available for full device operation.
2Productivity
If power is supplied in excess of USB specification levels, then charging speed is improved, but host device compatibility is lost
Solution Approach 1:
The patent implements dynamic power management where the device adapts its power consumption based on enumeration status. During the preliminary low-power enumeration phase, the device dynamically constrains its power draw to USB specification levels to ensure host compatibility. After successful enumeration, the device can then utilize higher power levels for faster charging.
Data Source
AI summary
System and method for enumerating and/or enumerating a device. The device may be a USB portable device which adheres to a first standard, e.g., the USB specification, and may engage in enumeration with respect to a USB hub/USB host device. Where a battery included in the device is sufficiently low, the device may engage in low power enumeration, e.g., to begin charging the device using enumerated power. Low power enumeration may allow the device to enumerate even when the device is incapable of powering on. Additionally, or alternatively, the device may determine whether the hub/host device is capable of providing high power charging. If it is, the device may begin charging the battery of the device using power provided by the hub/host device at a high power level.