USB-C Power Management via CC Pin Voltage Feedback
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Solution Overview
Problem
USB cables with high resistance can lead to inefficient power delivery to rechargeable devices, causing over-low charging voltage and potential hazardous fires due to power conversion into heat, necessitating effective monitoring and management of power quality.
Innovation Solution
Implementing a power management system using USB type-C cables and controllers that estimate voltage drops across the ground line, allowing for load compensation and protective actions such as adjusting target voltages or disconnecting power to prevent hazards, by detecting voltage differences and current through communication pins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high current output is delivered through a USB cable with high resistance, then the charging power to the sink device increases, but the voltage drop across the cable increases causing the sink device to receive over-low charging voltage
Solution Approach 1:
The source device detects the voltage at the CC pin and uses this feedback information to estimate the cable resistance and calculate the voltage drop. Based on this feedback, the source device adjusts the output voltage to compensate for the cable resistance, ensuring the sink device receives adequate charging voltage even when using high-resistance cables.
Solution Approach 2:
The source device changes the output voltage parameter dynamically based on the detected CC pin voltage. By adjusting the output voltage according to the measured voltage drop across the cable, the system maintains reliable charging performance across different cable resistance levels.
2Power
If high current output is delivered through a USB cable with high resistance, then the charging power increases, but most power is converted into heat causing hazardous fires
Solution Approach 1:
The source device uses the CC pin voltage detection as feedback to estimate cable resistance and calculate voltage drop. This feedback mechanism allows the source device to identify high-resistance cables that cause excessive heat generation and take protective actions accordingly.
Solution Approach 2:
The patent converts the harmful voltage drop and heat generation into useful information by using the CC pin voltage measurement to detect cable resistance. This detected information is then used to compensate for voltage drops and prevent hazardous conditions, turning the harmful effect into a diagnostic signal.
3Length of stationary object
If USB cable resistance is high, then the cable can be longer or have higher gauge, but the output voltage is mostly consumed by the cable leaving the sink device with over-low charging voltage
Solution Approach 1:
The source device dynamically adjusts the output voltage parameter based on the detected cable resistance. By increasing the output voltage to compensate for the voltage drop in longer or higher-gauge cables, the system maintains reliable charging voltage at the sink device regardless of cable characteristics.
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
Ensures reliable and safe power delivery to devices by compensating for voltage drops and preventing overheating or fires by adjusting power levels and disconnecting power when cable quality is poor, thereby maintaining efficient charging and safety.
Implementation Method 1
detecting voltage differences and current through communication pins
Implementation Method 2
the resistance of the USB cable might convert most of the power output from the source device into heat, probably causing hazardous fire
Data Source
AI summary
A connector controller controls a connector with a power pin, a communication pin, and a ground pin. The connector detects the voltage at the communication pin at least twice to generate first and second voltages respectively. A bus power is supplied at the power pin. The first voltage is detected when a bus current to/from the bus power is about zero. The connector controller controls the bus power in response to a difference between the first and second voltage.