Host Device Voltage Adjustment for USB Terminal Power Stability
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Solution Overview
Problem
In USB systems, the power supply from a host device to a terminal device can become insufficient due to increased resistance in the USB cable or connectors, leading to operational issues even when the USB 3.0 standard's higher current requirements are not met, and existing solutions like USB power supply boosters or adaptive voltage adjustment do not adequately address these issues.
Innovation Solution
A communication system that includes a host device with a power supply unit, current measurement, and a control unit that adjusts the voltage based on real-time current measurements and resistance calculations to ensure the voltage at the terminal device remains within a proper operational range, using a measurement unit and notification system to communicate resistance and voltage values between the host and terminal devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the USB cable length or connector contact resistance increases, then the voltage at the terminal device drops below the operational range, but increasing the power supply voltage at the host exceeds the USB standard specifications
Solution Approach 1:
The terminal device measures the actual voltage at its power supply input and feeds back this information to the host device. The host device uses this feedback to dynamically adjust its power supply voltage, ensuring the terminal device receives adequate voltage even when cable resistance is high, without exceeding USB standards under normal conditions.
Solution Approach 2:
The system dynamically changes the power supply voltage parameter based on measured conditions. The host device adjusts its output voltage from the standard 5V upward when needed, controlled by the feedback mechanism, to compensate for voltage drops caused by cable resistance or connector contact resistance.
2Reliability
If USB power supply boosters are added to compensate for voltage drop, then voltage stability improves, but device complexity and cost increase
Solution Approach 1:
The terminal device performs self-diagnosis by measuring its own power supply voltage and determining whether it is adequate for operation. Based on this self-assessment, the terminal device requests appropriate power supply adjustments from the host, eliminating the need for external booster devices.
Solution Approach 2:
The USB communication interface is used for multiple purposes: data communication and power supply negotiation. The existing communication channels are utilized to transmit power supply status information and control signals, avoiding the need for additional dedicated hardware components.
3Power
If the host device increases power supply current to compensate for resistance losses, then power delivery improves, but heat generation and energy loss increase
Solution Approach 1:
The host device applies partial compensation by increasing power supply voltage only to the extent necessary to maintain adequate voltage at the terminal device. The system avoids excessive power increase by using feedback control to apply only the minimum necessary compensation, reducing unnecessary energy loss and heat generation.
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 solution reliably maintains the power supply voltage within the operational range for the terminal device, ensuring proper operation even with varying cable resistances and current consumption, without the need for additional external boosters or devices, thus addressing the insufficiency issues in existing USB systems.
Implementation Method 1
The power supply unit applies a first voltage and outputs the first voltage to a host-side power supply line
Implementation Method 2
a first current measurement unit that measures a first current that flows through the host-side power supply line
Data Source
AI summary
A host-side control unit 120 receives a terminal-device-side notification value INFD indicating a second voltage V2 that is a voltage at a reference point P2 on a terminal-device-side power supply line 134 from a terminal device 130, calculates a first resistance value R1 indicating a resistance from a power supply unit 112 to the reference point P2 based on the terminal-device-side notification value INFD, a first voltage V1 output by the power supply unit 112, and a first current A1 measured by a first current measurement unit 116, and supplies the calculated first resistance value R1 to the power supply unit 112. The power supply unit 112 adjusts the first voltage V1 according to the first resistance value R1 and the first current value A1 measured by the first current measurement unit 116 at that moment so that the second voltage V2 falls within a predetermined first reference range.