Power Switch Circuit Reverse Connection Protection
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Solution Overview
Problem
Existing power switch circuits lack effective protection against reverse connection, leading to potential damage when the power supply voltage is applied in the opposite direction, particularly during voltage fluctuations with significant temporal changes (large dV/dt), which can erroneously turn on high-voltage MOSFETs and cause malfunction or damage to the power supply destination circuit.
Innovation Solution
A power switch circuit design incorporating a switch (p-type MOSFET transistor) that connects and disconnects nodes to prevent voltage differences from exceeding transistor threshold voltages, combined with a control logic and gate drivers to manage the switching of transistors, ensuring the transistors remain off during reverse connection and voltage spikes, and utilizing a current mirror circuit to reduce power consumption and unnecessary power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a power switch circuit is provided without reverse connection protection, then the circuit structure is simple, but the circuit is vulnerable to damage when power supply voltage is applied in the opposite direction
Solution Approach 1:
The patent applies preliminary anti-action by incorporating a protection circuit that proactively prevents reverse connection damage before it can occur. The circuit includes a first switch and second switch arranged to block reverse voltage flow, along with a control circuit that detects reverse connection conditions and activates the protection mechanism in advance, thereby preventing damage to the power supply destination circuit without requiring complex post-failure recovery systems
Solution Approach 2:
The patent uses an intermediary approach by introducing a control circuit as a mediator between the power supply and the power supply destination circuit. This control circuit includes detection circuits that monitor voltage polarity and control circuits that manage the switching elements, acting as an intermediate layer that intelligently prevents reverse connection damage while maintaining normal power transmission, thus balancing protection needs with circuit simplicity
2Reliability
If conventional protection circuits are used, then reverse connection protection is provided, but voltage spikes with large dV/dt can still erroneously turn on MOSFETs and cause malfunction
Solution Approach 1:
The patent applies preliminary action by having the control circuit detect reverse connection conditions before voltage spikes can erroneously trigger the MOSFETs. The detection circuit monitors the voltage state and activates the protection switches in advance, ensuring that when voltage fluctuations with large dV/dt occur, the protection mechanism is already in place to prevent erroneous turn-on of the power switches
Solution Approach 2:
The patent implements feedback by using detection circuits that continuously monitor the voltage state and provide feedback to the control circuit. When reverse connection or abnormal voltage conditions are detected, the feedback signal triggers the control circuit to activate the protection switches, creating a closed-loop system that dynamically responds to voltage conditions and prevents both reverse connection damage and erroneous turn-on from voltage spikes
Data Source
AI summary
A semiconductor device according to one embodiment comprises a first transistor, a second transistor, a switch, and a first control circuit. The first transistor including, one end of a current path connected to a first node, another end of the current path connected to a second node, and a gate connected to a third node. The second transistor including, one end of a current path connected to the second node, another end of the current path connected to a fourth node, and a gate connected to the third node. The switch configured to connect the second node and the third node. The first control circuit configured to control the switch.