Power Adaptor ESD Protection via Non-Linear Resistor
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Solution Overview
Problem
Electronic products are vulnerable to damage from electrostatic discharge (ESD) due to the lack of effective discharge paths in power adaptors, which can lead to malfunctions or permanent damage during ESD tests and real-world usage.
Innovation Solution
A power adaptor design that includes a protection circuit with a non-linear resistor and inductive components to form an electrostatic discharge path for electrostatic currents, providing a bypass for high-impedance protection during normal conditions and a discharge path during ESD events, enhancing ESD tolerance and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a power adaptor is designed with traditional protection circuits, then normal electrical protection is provided, but electrostatic discharge protection is insufficient
Solution Approach 1:
The patent applies parameter changes by using a non-linear resistor whose resistance value dynamically changes based on voltage conditions. During normal operation, the resistor maintains high resistance to minimize power loss, while during ESD events, it switches to low resistance to provide an effective discharge path. This dynamic parameter change resolves the contradiction by achieving ESD protection without requiring additional complex circuitry.
Solution Approach 2:
The non-linear resistor acts as an intermediary element between the primary and secondary circuits. It provides a controlled discharge path for electrostatic current while isolating the main circuit from direct ESD exposure. This intermediary approach enables ESD protection while maintaining the simplicity of the overall circuit design, as the resistor integrates seamlessly into the existing power adaptor architecture.
2Reliability
If a discharge path is provided for electrostatic current, then ESD protection is improved, but power loss increases during normal operation
Solution Approach 1:
The non-linear resistor dynamically changes its resistance parameter based on operating conditions. Under normal voltage conditions, it maintains high resistance (low power loss), and under ESD conditions, it switches to low resistance (high current discharge capability). This parameter transformation resolves the contradiction by ensuring minimal power loss during normal operation while providing effective ESD protection when needed.
Solution Approach 2:
The protection mechanism transitions from a static resistance value to a dynamic one that adapts to different operating conditions. The non-linear resistor automatically adjusts its electrical characteristics in response to voltage changes, being passive during normal operation and active during ESD events. This dynamic behavior eliminates the need for continuous power dissipation while maintaining protection capability.
3Loss of energy
If high impedance protection is used during normal conditions, then power loss is reduced, but ESD discharge capability is insufficient
Solution Approach 1:
The non-linear resistor exploits parameter changes to switch between high impedance (low power loss) and low impedance (high discharge capability) states. The resistance value is a function of the applied voltage, automatically providing the appropriate impedance level for the current operating condition. This resolves the contradiction by making the impedance adaptive rather than fixed.
Solution Approach 2:
The non-linear resistor is a self-regulating component that automatically adjusts its resistance based on the voltage across it without requiring external control circuits. During normal operation, it self-limits current to minimize power loss; during ESD events, it self-activates to provide a low-impedance discharge path. This self-service capability eliminates the need for additional control mechanisms while achieving both low power loss and high ESD discharge capability.
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
The solution effectively protects electronic components from electrostatic discharge by providing a suitable discharge path, improving the ESD tolerance and safety of electronic products during both testing and usage scenarios.
Implementation Method 1
a first non-linear resistor coupled to the return terminal of the primary side circuit and the negative output terminal of the secondary side circuit forming an electrostatic discharge path for an electrostatic current generated by the load
Data Source
AI summary
A power adaptor for converting an alternating voltage into a direct voltage to a load is disclosed. The power adaptor includes a primary side circuit including a hot line, a neutral line for receiving the alternating voltage, and a return terminal, a secondary side circuit including a positive output terminal and a negative output terminal for outputting the direct voltage, and a protection circuit including a first non-linear resistor coupled to the return terminal of the primary side circuit and the negative output terminal of the secondary side circuit forming an electrostatic discharge path for an electrostatic current generated by the load.