Shared Signal Line for USB Power Enable and Overcurrent Detection
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Solution Overview
Problem
In electronic devices, the increasing number of lines connecting control units for power and data communication poses a challenge as devices shrink in size, necessitating a reduction in wiring space.
Innovation Solution
The implementation of a connection circuit using a shared signal line for both enabling the sub-control unit and detecting defects, where the main control unit outputs a high voltage signal to enable the sub-control unit and detects defects by monitoring the voltage level, allowing the same line to be used for both functions, reducing the overall number of lines required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple separate lines are used for enable signal transmission and defect notification between control units, then reliable detection and clear signal transmission are achieved, but the number of lines and wiring space increase
Solution Approach 1:
The patent combines the enable signal transmission function and defect notification function into a single shared signal line. The sub-control unit uses the voltage level on this shared line to indicate both its operational status (enable signal) and defect status (overcurrent notification), thereby reducing the number of lines while maintaining detection reliability through voltage level interpretation
Solution Approach 2:
The shared signal line serves multiple functions: it transmits the enable signal from the main control unit to the sub-control unit, and simultaneously serves as a notification line for the sub-control unit to report defect conditions (such as overcurrent) back to the main control unit by changing its voltage level. This multi-functionality reduces wiring complexity while maintaining system reliability
2Device complexity
If a shared signal line is used for enable signal and defect notification, then the number of lines is reduced, but voltage level stability and accurate defect detection become challenging
Solution Approach 1:
The patent introduces a resistor as an intermediary element connected between the shared signal line and ground. This resistor acts as a mediator that helps stabilize the voltage level on the shared signal line when the sub-control unit detects a defect condition. The resistor ensures that the voltage level change is sufficient and stable for the main control unit to accurately detect the defect notification without misinterpretation
Solution Approach 2:
The patent utilizes voltage level parameter changes to encode different states: a high voltage level on the shared signal line indicates the enable signal is active and no defect is present, while a low voltage level indicates a defect condition (such as overcurrent). This parameter change approach allows the shared line to convey multiple pieces of information reliably through simple voltage level transitions that are easy to detect and interpret
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively reduces the number of lines needed for connecting control units, enabling reliable overcurrent detection and power supply management while maintaining efficient communication, even when control units are on separate substrates.
Implementation Method 1
the connection circuit is configured so that, when the predetermined voltage is outputted to the power line, the voltage level of the predetermined signal line is changed to the high voltage level by the predetermined voltage and, when output of the predetermined voltage to the power line is stopped, the voltage level of the predetermined signal line is changed to the low level
Data Source
AI summary
A CPU outputs a high level ENB signal to a USB-IC via an ENB line and monitors, after outputting the ENB signal, whether or not there is an overcurrent in the USB-IC on the basis of the voltage level of the ENB line. The USB-IC outputs, when it receives the ENB signal, a 5 V voltage to a VBUS line and stops, when an overcurrent occurs, output of the 5 V voltage to the VBUS line. A connector changes the voltage level of the ENB line to a high voltage level using the 5 V voltage of the VBUS line and changes, when output of the 5 V voltage is stopped, the voltage level of the ENB line to a low level. Thus, the ENB line may be shared for outputting the ENB signal from the CPU and for providing notification of an overcurrent from the USB-IC.