USB Power Supply Adaptive Reference Voltage Control
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Solution Overview
Problem
USB power supply apparatuses face challenges in maintaining bus voltage output due to significant voltage drops across the switch and bus line, particularly at higher current levels, which can fail to meet specifications like USB-PD and Type-C standards.
Innovation Solution
A USB power supply apparatus with a controller that adaptively adjusts a reference voltage based on bus voltage detection, using a bus voltage detection unit to compare with threshold voltages and generate signals to correct voltage drops, ensuring the bus voltage remains within specified limits by dynamically adjusting the reference voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a switch and bus line are used to supply power at high current levels, then power delivery capability is improved, but voltage drop increases causing bus voltage to fall below specification limits
Solution Approach 1:
The controller preliminarily adjusts the reference voltage upward before the voltage drop occurs at high current levels. By detecting the current level and proactively modifying the reference voltage, the system compensates for the expected voltage drop in advance, ensuring the bus voltage remains within specification limits even when delivering high power.
Solution Approach 2:
The system implements feedback control by continuously monitoring the bus voltage and comparing it against specification limits. When voltage drop is detected or anticipated, the controller adjusts the reference voltage to compensate, creating a closed-loop control system that maintains bus voltage compliance while enabling high current power delivery.
2Reliability
If the reference voltage is increased to compensate for voltage drop, then bus voltage regulation is improved, but power supply circuit output requirements increase
Solution Approach 1:
The reference voltage is made dynamic rather than fixed. The controller adaptively adjusts the reference voltage level based on real-time operating conditions, specifically the current level and detected voltage drop. This dynamic adjustment allows the system to compensate for voltage drop only when necessary, rather than continuously operating at elevated voltage levels, thus reducing unnecessary power supply circuit output requirements while maintaining bus voltage regulation.
3Device complexity
If a simple voltage regulation approach is used, then device complexity is reduced, but load regulation performance deteriorates at varying current levels
Solution Approach 1:
The system implements self-service load regulation where the controller automatically detects voltage drop conditions and adjusts the reference voltage without external intervention. The bus voltage detection unit and controller work together to autonomously compensate for voltage drop across varying current levels, providing adaptive load regulation performance without requiring complex external control circuits or manual adjustment mechanisms.
Data Source
AI summary
A USB power supply apparatus supplies electric power to a USB power reception apparatus. A bus line connects the output of the power supply circuit and the USB power reception apparatus. A switch is provided on a path of the bus line. A feedback circuit feedback controls the power supply circuit such that the output voltage VOUT of the power supply circuit approaches a reference voltage VREF. A controller adaptively controls the reference voltage VREF based on an electrical state of the USB power supply apparatus.