Semiconductor Module Overcurrent Detection Using Substrate Temperature Sensing
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Solution Overview
Problem
Existing semiconductor devices are susceptible to malfunctions due to current noise, which can lead to erroneous overcurrent detection and failure in protecting switching elements, especially in low on-resistance devices where the time to break due to overcurrent is shorter than the waiting time in conventional systems.
Innovation Solution
A semiconductor device with a temperature sense element independent from the switching element, utilizing a polysilicon pn diode to detect temperature changes on the semiconductor substrate, allowing for accurate overcurrent detection without relying on sense current monitoring, thus reducing noise-related malfunctions and providing effective protection without a waiting time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a waiting time (mask time) is introduced to filter noise in sense current detection, then false detection due to noise is reduced, but the response time to actual overcurrent increases, causing protection failure in low on-resistance devices
Solution Approach 1:
The patent extracts the temperature sensing function from the sense current detection system. A dedicated temperature sense element (polysilicon pn diode) is introduced to independently monitor temperature changes caused by overcurrent, separating this function from the noisy sense current path. This allows the waiting time to be reduced or eliminated while maintaining accurate overcurrent detection through temperature-based sensing.
Solution Approach 2:
The temperature sense element acts as an intermediary between the switching element and the protection circuit. Instead of directly monitoring sense current which is susceptible to noise, the temperature sense element indirectly detects overcurrent conditions through temperature changes, providing a noise-immune detection mechanism that responds rapidly without requiring mask time.
2Measurement precision
If sense current monitoring is used for overcurrent detection, then direct current measurement is achieved, but noise susceptibility increases causing erroneous detection
Solution Approach 1:
The patent substitutes electrical field-based sense current monitoring with thermally-based detection using a polysilicon pn diode. The temperature sense element converts thermal energy from overcurrent into detectable electrical signals through temperature-dependent voltage changes, replacing the direct electrical measurement approach that is vulnerable to noise with a thermal measurement approach that is inherently noise-immune.
Solution Approach 2:
Temperature serves as an intermediary parameter between overcurrent and detection. The temperature sense element monitors temperature changes that result from overcurrent heating, providing indirect but accurate detection that filters out high-frequency noise present in direct sense current measurements while maintaining detection precision.
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
The solution effectively reduces malfunctions caused by current noise and provides reliable overcurrent protection for semiconductor devices, including low on-resistance devices like SiC and GaN, by accurately detecting temperature changes and promptly turning off the switching element.
Implementation Method 1
a temperature sense element which is provided on the surface of the semiconductor substrate independently from the switching element and is dependent on a temperature
Data Source
AI summary
The semiconductor device of the present invention includes a semiconductor substrate, a switching element which is defined on the semiconductor substrate, and a temperature sense element which is provided on the surface of the semiconductor substrate independently from the switching element and characterized by being dependent on a temperature.