Semiconductor Device Short-Circuit Protection Circuit
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Solution Overview
Problem
Existing intelligent power devices (IPDs) face significant losses when protecting against load short-circuits, as current interrupt functions do not work in partially short-circuited states and current limit functions only activate after a 1 millisecond timer elapses, leading to inefficiencies in both heavily and partially short-circuited conditions.
Innovation Solution
The semiconductor device incorporates a power control circuit that uses drain-source voltage and output current to determine the extent of short-circuiting, enabling immediate current interruption and limiting in both heavily and partially short-circuited states, without relying on timers, thereby reducing power losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current interrupt function is used to protect against heavily short-circuited loads, then device protection is achieved, but power loss increases due to delayed response
Solution Approach 1:
The patent implements dynamic response adjustment by detecting the degree of short-circuit and dynamically switching between current limit mode and current interrupt mode. The control circuit monitors output current and drain-source voltage to determine the short-circuit severity, then dynamically adjusts the protection strategy: using current limit for partial short-circuits and current interrupt for heavy short-circuits, optimizing both protection effectiveness and power loss reduction
Solution Approach 2:
The patent changes the operational parameters of the semiconductor device based on the detected short-circuit condition. By monitoring the drain-source voltage and output current, the system identifies the short-circuit state and changes parameters such as gate voltage to switch between limiting and interrupting current, thereby adapting the protection mechanism to the specific fault condition to minimize power loss while ensuring device safety
2Reliability
If current limit function is used for partially short-circuited loads, then device protection is achieved, but response time increases due to 1 millisecond timer delay
Solution Approach 1:
The patent implements preliminary detection of the short-circuit state by continuously monitoring output current and drain-source voltage before the fault fully develops. The control circuit is pre-configured to immediately recognize partial short-circuit conditions and switch to current limit mode without waiting for timer delays, enabling proactive protection that reduces response time while maintaining device safety
Solution Approach 2:
The system dynamically adjusts its response based on real-time detection of short-circuit severity. By continuously monitoring electrical parameters, the control circuit can immediately transition from normal operation to current limit mode when partial short-circuit is detected, eliminating the 1 millisecond timer delay and achieving faster protective response
3Device complexity
If traditional protection methods are used, then simple control logic is maintained, but protection effectiveness decreases in partially short-circuited states
Solution Approach 1:
The patent segments the protection function into two distinct modes: current limit mode for partial short-circuits and current interrupt mode for heavy short-circuits. The control circuit is divided into detection units that separately monitor output current and drain-source voltage, and control units that independently manage each protection mode. This segmentation allows the system to effectively handle different short-circuit scenarios while maintaining clear and manageable control logic
Solution Approach 2:
The control circuit is designed with multi-functionality to handle both current limit and current interrupt operations within a single integrated system. By incorporating detection units for both output current and drain-source voltage, and control units that can switch between limiting and interrupting modes, the system achieves universal protection capability across different fault conditions without requiring separate protection circuits, thereby improving protection effectiveness while keeping the overall structure unified
Data Source
AI summary
A first overcurrent detection unit detects whether a drain-source voltage of an output transistor is greater than or equal to a first reference value and outputs a first detection signal. A second overcurrent detection unit detects whether an output current passing through the output transistor is greater than or equal to a second reference value and outputs a second detection signal. When receiving the first detection signal indicating that the drain-source voltage is greater than or equal to the first reference value, a latch circuit latches the second detection signal; when receiving the first detection signal indicating that the drain-source voltage is smaller than the first reference value, the latch circuit outputs the second detection signal without latching it. Based on the output of the latch circuit, the drive circuit controls the output transistor to either turn it off or turn it on and off alternately.