Semiconductor Switch Overcurrent Protection Circuit
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Solution Overview
Problem
The increasing integration density of power MOSFETs leads to smaller semiconductor chips, which face heat management challenges due to higher energy conversion during turn-off processes, risking component damage from excessive heating.
Innovation Solution
A circuit arrangement with a semiconductor switch and a drive circuit that includes a current measuring arrangement to prevent the switch from turning off at high load currents, using a fuse connected in series to protect against destructive heat conversion, ensuring the switch remains on until the current drops below a predetermined threshold, and the fuse triggers if the current does not decrease within its triggering delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If power MOSFETs are designed with higher integration density to reduce size, then the volume of the semiconductor chip is reduced, but the heat dissipation capability deteriorates leading to excessive heating during turn-off processes
Solution Approach 1:
The drive circuit performs preliminary detection of load current before the turn-off process. When a high load current is detected, the drive circuit proactively prevents the turn-off command from being executed, thereby avoiding the generation of excessive heat in the semiconductor chip before it occurs.
Solution Approach 2:
The drive circuit acts as an intermediary between the control signal and the semiconductor switch. It intercepts and modifies the turn-off command based on real-time current detection, preventing the harmful interaction between high current and turn-off operation that would cause excessive heating.
2Reliability
If the semiconductor switch is prevented from turning off during high load current, then protection against heat damage is improved, but the load current cannot be interrupted leading to potential overload damage
Solution Approach 1:
The fuse connected in series with the load path acts as a safety intermediary. It remains inactive during normal high-current operation, allowing the semiconductor switch to remain on for protection. However, if the high current persists beyond a safe duration, the fuse triggers and interrupts the circuit, preventing overload damage to the load.
Solution Approach 2:
The fuse provides beforehand cushioning against potential overload damage. It is designed to trigger only when the current exceeds a threshold for a prolonged period, cushioning the system against the harmful effects of sustained overcurrent while allowing temporary high-current operation protected by the semiconductor switch.
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
This solution effectively prevents the semiconductor switch from being turned off at high currents, protecting it from heat-related damage and ensuring the connected load or voltage supply is protected by the fuse, allowing for safe energy conversion and preventing component destruction.
Implementation Method 1
a given electrical energy to be converted into heat leads to a greater heating of the semiconductor chip
Implementation Method 2
a fusible link can be connected in series with the load. Such a fuse triggers in accordance with a design-predetermined triggering characteristic curve
Data Source
AI summary
A circuit arrangement includes a semiconductor switch having a control terminal and a load path. A drive circuit is coupled to the control terminal of the semiconductor switch. The drive circuit has a current measuring arrangement for determining a load current flowing through the load path and is designed to prevent the semiconductor switch from being driven in the off state if the load current exceeds a predetermined load current threshold value. A fuse is coupled in series with the load path of the semiconductor switch triggers if a triggering condition dependent at least on the load current is present.