USB Host Ground Pattern Area for Device Startup Stability
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Solution Overview
Problem
USB devices requiring current values exceeding the USB 2.0 specification before connection may experience unstable operations due to insufficient power supply, leading to initialization failures and startup issues.
Innovation Solution
An electronic unit with a USB host and device connected via a USB cable, featuring an additional GND pattern with an area of 2000 mm2 or more, which reduces the potential difference between GNDs and improves startup success rates, allowing stable operation for devices needing higher currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a USB device requires current exceeding USB 2.0 specification (100 mA before connection permission) to operate stably, then the device can function properly, but the operation becomes unstable due to insufficient current supply before connection is permitted
Solution Approach 1:
The patent applies preliminary action by providing an additional GND pattern before the USB connection permission is granted. This additional ground pattern is prepared in advance to reduce potential difference between GNDs, enabling the USB device to receive sufficient current (exceeding the standard 100 mA limit) during the initialization phase before formal connection permission, thereby ensuring stable operation from startup.
Solution Approach 2:
The patent changes the physical parameter of the ground connection by adding an additional GND pattern with specific area requirements. This modifies the electrical characteristics of the ground path, reducing potential difference between GNDs and enabling higher current flow than the standard USB 2.0 specification allows, thus resolving the contradiction between operation stability and current supply limits.
2Use of energy by moving object
If an external power supply is used to provide sufficient current to the USB device before connection permission, then current supply is improved, but operation stability is not guaranteed due to potential difference between GNDs
Solution Approach 1:
The patent introduces an intermediary element - the additional GND pattern - between the external power supply and the USB device. This additional ground pattern acts as a mediator to reduce the potential difference between GNDs, allowing the external power supply to effectively deliver sufficient current to the USB device during initialization, thereby ensuring both adequate current supply and operation stability.
3Reliability
If the area of the additional GND pattern is increased to reduce potential difference between GNDs, then startup success rate is improved, but manufacturing complexity increases
Solution Approach 1:
The patent specifies a quantitative parameter threshold for the additional GND pattern area (2000 mm² or more) to achieve the desired effect of reducing potential difference between GNDs and improving startup success rate to about 80%. This clear parameter specification provides a straightforward manufacturing guideline, balancing the need for improved reliability with ease of manufacture by defining a specific area threshold rather than requiring complex design optimizations.
Data Source
AI summary
An electronic unit includes a USB host and a USB device. After the USB host and the USB device are connected to each other by a USB cable, a signal requesting for a connection permission is transmitted from the USB device to the USB host, and the USB host determines whether to permit a connection based on the signal. The electronic unit further includes a power supply configured to supply power to the USB device, and an additional GND pattern different from a GND pattern of the USB cable is electrically connected to a GND of the USB port of at least one of the USB host and the USB device. An area of the additional GND pattern is 2000 mm2 or more.