USB-PD Power Supply Isolation Using LDO Threshold Control
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Solution Overview
Problem
Existing USB-C cables and connectors using USB-PD technology face issues with voltage regulation, where the power supply level negotiation can result in voltage exceeding target values, potentially damaging electronic devices due to lack of effective voltage isolation.
Innovation Solution
A device with a low-dropout linear voltage regulator and control circuit that compares input and output voltages, using a hysteresis comparator to control a switch and maintain the output voltage below a threshold, preventing damage by isolating the connector when the voltage exceeds the threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If voltage negotiation is performed in USB-PD technology, then power supply adaptability is improved, but voltage may exceed target values causing device damage
Solution Approach 1:
The patent introduces an intermediary device positioned between the power source and the electronic device. This intermediary monitors the voltage during negotiation and actively isolates the electronic device when voltage exceeds safe thresholds. The intermediary acts as a mediator that protects the device while allowing the negotiation process to continue, thus maintaining adaptability while preventing voltage surge damage.
2Reliability
If voltage isolation is implemented to prevent damage, then device protection is improved, but power supply efficiency deteriorates
Solution Approach 1:
The patent employs dynamic voltage isolation rather than static isolation. The isolation mechanism is activated only when voltage exceeds the target threshold during negotiation, and remains inactive during normal operation. This dynamic approach ensures device protection when needed while maintaining power supply efficiency during normal power delivery, thus resolving the contradiction between protection and efficiency.
3Measurement precision
If voltage threshold monitoring is added, then voltage control precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the voltage monitoring and threshold detection function into a separate, dedicated circuit within the intermediary device. This modular extraction allows for precise voltage threshold monitoring without significantly increasing the complexity of the main USB-PD negotiation system. The monitoring function is handled by specialized components designed for this specific purpose, keeping the overall system manageable while achieving high measurement precision.
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
Effectively protects electronic devices from voltage surges by ensuring the output voltage remains within safe limits, preventing damage and ensuring stable power delivery.
Implementation Method 1
a low-dropout (LDO) linear voltage regulator connected between the first and third terminals, the regulator being configured to provide the second voltage based on the first voltage
Implementation Method 2
the control circuit of the switch comprises a hysteresis comparator, a first input of which is coupled to the first terminal, a second input of which is connected to the third terminal
Data Source
AI summary
A first terminal receives a first DC voltage. A switch selectively couples the first terminal to a second terminal providing an output. A control circuit selectively actuates the switch in response to a comparison of the first DC voltage to a second DC voltage. A low-dropout (LDO) linear voltage regulator, connected between the first and third terminals, operates to provide the second DC voltage from the first DC voltage.