USB Source Device Power Limiting for Sink Protection
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Solution Overview
Problem
USB Type-C connectors compliant with the USB Power Delivery standard may provide unsuitable power to electronic sink devices if their firmware is not optimized, potentially causing damage due to exceeding the device's working voltage or failing to recognize the power source, leading to errors in charging procedures.
Innovation Solution
A USB charging method that detects the configuration channel pin of a USB Type-C connector, determines if the sink device is in a protect list, and generates an adjusted power option list by limiting voltage/current combinations to the sink device's best working voltage, preventing the selection of power levels that could damage the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the firmware of the electronic sink device inherently requests the largest power provided by the electronic source device, then the charging speed is improved, but the electronic sink device may be damaged due to exceeding its best working voltage
Solution Approach 1:
The source device performs preliminary identification of the sink device using VID/PID before power transmission begins. It proactively determines the sink device's best working voltage and pre-adjusts the power option list to exclude voltages exceeding this limit. This preliminary action prevents the harmful effect of excessive voltage before it can occur, while still allowing the sink device to request high power within safe limits.
Solution Approach 2:
The source device dynamically changes the voltage parameter in the power option list based on the identified sink device characteristics. It adjusts the available voltage options to match the sink device's best working voltage, ensuring that even when the sink device requests maximum power, the voltage remains within safe operational limits. This parameter adjustment resolves the contradiction between high charging speed and voltage safety.
2Device complexity
If the firmware of the electronic sink device is not optimized to recognize the power source type, then the device complexity is reduced, but charging errors occur due to unsuitable power requests
Solution Approach 1:
The source device acts as an intermediary that bridges the gap between different power source types (power supply or battery) and the sink device. It receives the power requirement ACK, identifies the power source type, and adjusts the power option list accordingly. This intermediary function allows the sink device to use simple, unoptimized firmware while the source device handles the complex logic of matching power parameters, thereby maintaining charging reliability without increasing sink device complexity.
3Power
If the USB Type-C connector outputs maximum power of 100W, then the power transmission capability is improved, but devices with lower power tolerance may be damaged
Solution Approach 1:
The source device applies local quality by providing different power levels to different sink devices based on their specific characteristics. Instead of a uniform maximum power output, it identifies each sink device's best working voltage and tailors the power option list accordingly. This allows the USB Type-C connector to maintain its 100W capability when needed while automatically reducing to appropriate lower power levels for devices with lower power tolerance, preventing damage.
Data Source
AI summary
A USB charging method adopted by an electronic source device and an electronic sink device electrically connected thereto through USB interface is present. The method comprises following steps: receiving a Discover Identity ACK from the sink device after connection; determining if the sink device is recorded in a protect list according to the Discover Identity ACK; adjusting voltage/current combinations which is to provide to the sink device according to a best working voltage of the sink device if the sink device is recorded in the protect list; transmitting the adjusted voltage/current combinations to the sink device.