Portable Device Circuit for USB Charging Port Type Detection
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Solution Overview
Problem
Conventional methods for distinguishing between Dedicated Charging Ports (DCP) and Charging Downstream Ports (CDP) in USB systems often initiate data communication with the host, undermining the robustness of the USB system, as they attempt to determine the type of charging port, leading to incorrect current draw and potential data communication issues.
Innovation Solution
A method and system for a portable device circuit that selectively applies source voltages to data lines to differentiate between DCP and CDP without initiating data communication with the host, using a flowchart-based approach to determine the type of charging port without causing the host to detect the device, thereby preventing unnecessary data communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional detection methods are used to distinguish between DCP and CDP, then the portable device can determine the charging port type, but data communication is incorrectly initiated with the host
Solution Approach 1:
The patent segments the detection process into distinct phases: a first detection phase that applies voltage to data lines to determine port type, and a second communication phase that only begins after successful port type determination. This segmentation prevents premature data communication initiation that would occur in conventional single-phase detection methods.
Solution Approach 2:
The patent performs preliminary voltage application to data lines before initiating data communication. By applying voltage to the data lines in advance and detecting the port type first, the system ensures that communication is only established when appropriate, preventing incorrect communication initiation with hosts connected to DCP ports.
2Measurement precision
If voltage is applied to data lines for port type detection, then accurate differentiation between DCP and CDP is achieved, but data communication may be incorrectly initiated
Solution Approach 1:
The patent uses the data lines as an intermediary for port type detection without immediately using them for data communication. By applying voltage through the data lines to detect port type first, and only establishing communication after successful detection, the system avoids the harmful effect of unnecessary data communication while maintaining accurate port type differentiation.
Solution Approach 2:
The patent performs preliminary voltage application to data lines for detection purposes before initiating data communication. This preliminary action allows accurate port type differentiation to occur first, ensuring that data communication is only initiated when appropriate, thereby preventing the harmful effect of unnecessary communication.
3Adaptability or versatility
If conventional detection schemes are used, then the portable device can identify charging ports, but current draw may be incorrect
Solution Approach 1:
The patent segments the charging process into detection and operation phases. By first detecting port type through voltage application to data lines, and only after successful detection determining the appropriate current draw, the system ensures both charging port compatibility and accurate current draw, preventing the mismatch that occurs in conventional schemes.
Solution Approach 2:
The patent uses feedback from the voltage application detection process to determine subsequent current draw parameters. By monitoring the response of the data lines during the detection phase, the system gains information about the connected port type and adjusts the current draw accordingly, ensuring both compatibility and accuracy.
Data Source
AI summary
Disclosed is a method for use by a device to distinguish between a Charging Downstream Port (“CDP”) and a Dedicated Charging Port (“DCP”). The method comprises detecting that the device is attached to a charging port, and determining whether the charging port is the CDP or the DCP without causing a host coupled to the CDP to be able to detect the device if the charging port is the CDP.