Power Supply Controller Turn-Off Circuit for MOSFET Ground Fault Protection
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Solution Overview
Problem
In high side driver power supply controllers, the MOSFET can erroneously turn on due to increased gate-source voltage when the ground terminal is not properly grounded, leading to malfunction.
Innovation Solution
A power supply controller with a turn-off circuit that forces the MOSFET into a turn-off state when the ground terminal potential is higher than the source potential, preventing erroneous activation by controlling the gate potential and using a turn-off circuit to manage the MOSFET's state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gate driving circuit controls the gate potential based on the ground terminal potential, then the MOSFET can be turned off reliably under normal conditions, but when the ground terminal is not properly grounded and its potential rises above the source potential, the MOSFET erroneously turns on due to increased gate-source voltage
Solution Approach 1:
The turn-off circuit applies a preliminary counter-action by detecting the ground terminal potential in advance and forcing the MOSFET into a turn-off state when the ground potential exceeds the source potential, preventing the erroneous turn-on before it can occur
Solution Approach 2:
The turn-off circuit acts as an intermediary between the gate driving circuit and the MOSFET, inserting an additional control mechanism that overrides the gate driving circuit when ground potential becomes abnormal, thereby isolating the MOSFET from harmful voltage conditions
2Device complexity
If the ground terminal potential is used as the reference for gate driving control, then the control circuit can operate with simple reference, but when grounding is improper, the reference potential itself becomes elevated causing false activation
Solution Approach 1:
The control function is segmented into two independent parts: the gate driving circuit that operates under normal conditions using ground terminal reference, and the turn-off circuit that activates only when ground potential becomes abnormal, allowing each part to optimize for its specific function without increasing overall complexity
Data Source
AI summary
A power supply controller including a MOSFET between a power source and a load, a ground terminal, a gate driving circuit structured to control a gate potential of the MOSFET to turn on power and control the gate potential of the MOSFET to turn off power based on a ground terminal potential, and a turn-off circuit structured to switch the MOSFET into a turn-off state regardless of control by the gate driving circuit when the ground terminal potential is at a higher value than a source potential of the MOSFET.