Voltage Switch Circuit Control for USB Power Delivery
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Solution Overview
Problem
Existing voltage switch circuits face challenges in minimizing power losses and voltage drops during switching operations, especially in high-load and precision applications, due to diode voltage drops and transistor timing delays, which are not suitable for universal serial bus (USB) power delivery.
Innovation Solution
A control method for a voltage switch circuit using two channels with controlled switch operations, where the output voltage is managed to prevent backflow current by transitioning through a intermediate voltage, allowing seamless switching between input voltages with reduced voltage drops, employing two control loops to manage the transition of switch circuits from complete to incomplete conducting states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a diode is placed between input and output terminals to enable switching, then switching operation can be performed, but power losses increase due to diode voltage drop
Solution Approach 1:
The patent extracts and removes the diode from the circuit, replacing it with transistor-based switching. This eliminates the inherent diode voltage drop (typically 0.7V for silicon diodes) that causes power losses, while maintaining the switching functionality through active transistor control.
Solution Approach 2:
The patent substitutes the passive diode-based switching mechanism with an active transistor-based control system. This replacement allows for controlled switching without the fixed voltage drop characteristic of diodes, reducing power losses while enabling precise switching operation.
2Loss of energy
If transistor switching is used to reduce power losses, then power efficiency improves, but time delay occurs due to turn-off timing requirements
Solution Approach 1:
The patent implements preliminary action by controlling the first transistor to enter an incomplete conducting state before the second transistor is fully activated. This staged approach allows the output voltage to transition smoothly to the intermediate level, preventing backflow current and eliminating the need for lengthy dead time delays while maintaining power efficiency.
Solution Approach 2:
The patent employs dynamic control by transitioning the first transistor from a complete conducting state through an incomplete conducting state to a fully off state. This dynamic, multi-stage switching process optimizes both power efficiency and switching speed, avoiding the fixed time delays associated with traditional binary switching approaches.
3Loss of energy
If sequential transistor switching is implemented, then power losses are reduced, but output voltage drops below input voltage by diode voltage drop amount
Solution Approach 1:
The patent introduces an intermediate voltage state as a mediator in the switching process. By controlling the output voltage to transition through this intermediate level (rather than directly from one input voltage to another), the system achieves seamless switching without the voltage drops associated with diode-based approaches, thereby improving output voltage precision while maintaining power efficiency.
Solution Approach 2:
The patent utilizes parameter changes by dynamically adjusting the conduction state of transistors and the output voltage level during switching. This continuous parameter adjustment allows the output voltage to precisely track the desired value throughout the transition, eliminating the fixed voltage drop inherent in diode-based switching and achieving high precision in multi-voltage switching applications.
Data Source
AI summary
A method of controlling a voltage switch circuit can include: controlling an output voltage of the voltage switch circuit to be switched from a first voltage input to a first switch circuit to a second voltage input to a second switch circuit to be no larger than a smaller one of the first and second voltages before the second switch circuit starts conducting; switching the output voltage to the second voltage when the second switch circuit starts conducting, where outputs of the first and second switch circuits are coupled together to provide the output voltage; and controlling the first switch circuit to turn off after the second switch circuit conducts and when the output voltage is no larger than the smaller one of the first and second voltages.