USB Port Power Control via D+ Line Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Portable electronic devices struggle to determine the maximum power they can safely draw from a USB port, leading to slow charging times and potential overloading or damage to the power source, as existing technologies lack a method to accurately assess the available power capacity.
Innovation Solution
A method that involves testing the D+ and D− data lines to determine the type of power source and adjust the current draw accordingly, using a combination of resistors, current, and voltage sources to identify the power-supplying capability, allowing the device to safely draw the maximum available current without overloading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the appliance draws maximum current from the USB port, then charging speed is improved, but the risk of overloading and damaging the power source increases
Solution Approach 1:
The appliance performs preliminary detection of the power source type through the D+ and D− data lines before initiating maximum current drawing. This preliminary action identifies whether the power source is a host computer or a dedicated charging supply, allowing the appliance to pre-determine the safe maximum current limit before charging begins, thus preventing overload while enabling optimal charging speed.
Solution Approach 2:
The appliance uses feedback from the D+ and D− data line states to continuously monitor and adjust the current draw. By detecting the electrical characteristics of the power source through these data lines, the appliance receives feedback about the power source's capacity and automatically adjusts its current consumption to match the safe maximum limit, ensuring both fast charging and power source protection.
2Power
If the appliance uses a dedicated charging power supply, then charging current is improved, but the complexity of determining safe current draw increases
Solution Approach 1:
The D+ and D− data lines serve multiple functions: they are used for both data communication and power source type detection. By utilizing these existing USB infrastructure components for dual purposes, the patent avoids adding separate detection hardware or complex assessment circuits, thereby enabling high-power charging capability identification without significantly increasing device complexity.
Solution Approach 2:
The D+ and D− data lines act as intermediaries between the appliance and the power source for communication. Through these intermediary data lines, the appliance indirectly detects the power source type and capacity without requiring direct power measurement circuits or complex interaction protocols, simplifying the overall detection mechanism while maintaining accuracy.
Data Source
AI summary
Methods of and apparatus for controlling power drawn by an appliance through a USB port. The method includes limiting any electrical current drawn by an appliance to one of seven levels according to whether the data lines receive a bias from a power line, the data lines are in electrical communication with each other, and the power source includes a host computing device, or according to logic and voltage levels of the data lines when any of the pull-down resistor and the current and voltage sources are connected or not connected to the D+ data line. The apparatus includes a controller programmed to selectively connect a pull-down resistor, a current source, and a voltage source to a D+ data line and to limit any electrical current drawn from a power source to one of the seven levels according to voltage levels on the D+ data line and a D− data line.