USB Hub Power Switch Current Limiting Logic
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Solution Overview
Problem
Conventional USB power switches face challenges in providing cost-effective over-current protection that balances the benefits of gang mode power switching with the reduced stress on USB connectors and individualized protection offered by individual mode power switching, especially as current limits increase and many USB connectors are designed for lower current levels.
Innovation Solution
A power switch embodiment that uses a single power switch and current sensing unit to monitor and control multiple USB ports, allowing for individualized current limit settings and over-current protection, thereby minimizing stress on connectors while maintaining cost efficiency by using a power port control logic unit to sum current measurements and compare them against stored limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If gang mode power switching is used to reduce cost, then the number of power switches and current sensing components is reduced, but USB connectors are exposed to current levels that exceed their ratings, causing stress and potential failures
Solution Approach 1:
The patent segments USB ports into different groups (first group and second group) with different current limit settings. The first group of ports has current limits set according to the lower current ratings of USB connectors, while the second group can support higher current limits. This segmentation allows the system to use a single power switch for cost efficiency while protecting connectors in the first group from excessive current stress.
2Reliability
If individual mode power switching is used to provide individualized protection, then each USB port has dedicated protection, but the cost increases due to requiring separate power switches and current sensing components for every port
Solution Approach 1:
The patent makes a single power switch and current sensing unit serve multiple USB ports with different current limit requirements. The power port control logic unit enables this single component to provide customized over-current protection for different groups of ports by dynamically configuring current limits based on connector ratings and device requirements, thus achieving individualized protection without the cost of dedicated components for each port.
3Power
If current limits are increased to support higher power USB charging ports, then more power can be delivered to devices, but USB connectors designed for lower current levels experience increased stress and potential failures
Solution Approach 1:
The patent applies different current limit settings to different groups of USB ports based on their specific connector characteristics. The first group of ports uses lower current limits matched to the ratings of USB connectors designed for lower current levels, while the second group of ports can utilize higher current limits if their connectors are rated for higher currents. This local quality approach ensures each port operates within safe current limits for its specific hardware while maximizing overall power delivery capability.
Data Source
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AI summary
A system, method and device for providing over-current protection to USB ports comprised in a USB hub, whereby a single switch is used to control the power supply to one or more groups of U SB ports based on determinations whether the current drawn by a group of USB ports has exceeded a predefined current limit. Embodiments provide the cost savings associated with gang mode power port switching and the reduced stress on USB components and individualized protection of USB ports associated with individual mode power switching. Embodiments utilize a plurality of current measurement units to measure the current drawn by each group of USB ports supported by a switch and further utilize a power port control logic unit to control the switch based on whether the current measurements have exceeded a current limit.