Smart Semiconductor Switch With Adaptive Overcurrent Thresholds
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Solution Overview
Problem
Existing smart semiconductor switches are inflexible when handling capacitive loads, leading to undesirable permanent overcurrent tripping during capacitive load switching.
Innovation Solution
A smart semiconductor switch circuit that includes an overcurrent protective circuit with a configurable overcurrent threshold, a control circuit for switching modes, and a capacitive load switching mode detection circuit, which adjusts the overcurrent threshold and temporarily overrides or delays overcurrent detection to prevent permanent tripping during capacitive load switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the overcurrent protective circuit uses a fixed low threshold to protect against overload, then the switch is protected against excessive current, but the switch trips permanently during capacitive load switching due to high inrush currents
Solution Approach 1:
The overcurrent threshold is made dynamic rather than fixed. The control circuit adjusts the threshold based on operating conditions: a first (lower) threshold during normal operation for protection, and a second (higher) threshold during capacitive load switching mode to accommodate inrush currents. This resolves the contradiction by making the protection adaptive to different operational states.
Solution Approach 2:
The overcurrent threshold parameter is changed based on the detected switching mode. When capacitive load switching is detected, the threshold parameter is increased from the first threshold to the second threshold, allowing the system to tolerate higher inrush currents temporarily while maintaining protection during normal operation.
2Adaptability or versatility
If the overcurrent threshold is increased to allow capacitive load switching, then the switch can handle inrush currents, but the switch loses protection against actual overcurrent conditions during normal operation
Solution Approach 1:
The threshold dynamically switches between two values based on operational mode. During normal operation, the lower first threshold provides strict protection. During detected capacitive load switching, the higher second threshold is applied to accommodate inrush currents. This dynamic adjustment resolves the contradiction by providing context-appropriate threshold levels.
Solution Approach 2:
The control circuit detects the capacitive load switching mode in advance and preliminarily adjusts the overcurrent threshold to the higher second threshold before the inrush current occurs. This preliminary adjustment prevents false tripping while maintaining protection during normal operation when the lower first threshold is active.
3Device complexity
If the switch uses a simple fixed threshold for overcurrent protection, then the circuit is simple and reliable, but it cannot distinguish between normal inrush currents and dangerous overload conditions
Solution Approach 1:
The control circuit provides multi-functionality by detecting different operating modes (normal operation vs. capacitive load switching) and adjusting the overcurrent threshold accordingly. This single control circuit handles both protection and adaptive threshold adjustment, resolving the contradiction by adding intelligence without requiring separate complex protection circuits for different load types.
Data Source
AI summary
A circuit for a smart semiconductor switch includes an electronic switch electrically coupled between an output node and a supply node. An overcurrent protective circuit is configured to generate an overcurrent signal in response to a load current flowing through the electronic switch exceeding a first overcurrent threshold, and to cause the electronic switch to be tripped. A control circuit is configured to switch the electronic switch on and off based on an input signal in a first mode, and to drive a load connected to the output node by repeatedly switching the electronic switch on and off in a second mode, and to prevent the electronic switch from being permanently tripped by the overcurrent protective circuit.