Semiconductor Temperature Sensing Circuit with Series Regulator
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Solution Overview
Problem
Conventional semiconductor devices cannot continuously monitor the temperature of IGBTs in power conversion circuits due to binary temperature signals that become unreliable when the temperature exceeds a predetermined value.
Innovation Solution
A semiconductor device with a temperature sensing diode, a current source, an overheat protection circuit, and a series regulator that delivers the forward voltage drop to an external output terminal for continuous temperature detection, enabling accurate temperature monitoring by amplifying the voltage across the diode to several volts for improved noise immunity and detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a binary temperature signal is used for overheat protection, then the circuit construction is simple, but the temperature monitoring becomes unreliable when temperature exceeds a predetermined value
Solution Approach 1:
The temperature monitoring function is segmented into two independent pathways: a binary overheat protection signal for immediate safety shutdown, and a continuous analog temperature signal for ongoing monitoring. This segmentation allows each pathway to optimize for its specific function without compromise.
Solution Approach 2:
A series regulator circuit is introduced as an intermediary component that receives the forward voltage drop from the temperature sensing diode and converts it into a stabilized output signal delivered to an external terminal. This intermediary enables continuous temperature information extraction without interfering with the binary protection function.
2Measurement precision
If the forward voltage drop of the temperature sensing diode is used directly, then the circuit is simple, but the detection accuracy is insufficient due to noise and small signal magnitude
Solution Approach 1:
The weak electrical signal from the temperature sensing diode is substituted with a strengthened version through the series regulator circuit. The regulator amplifies and stabilizes the signal, replacing the inadequate direct voltage drop with a robust output suitable for accurate temperature detection.
Solution Approach 2:
The series regulator circuit changes the voltage parameter by converting the small forward voltage drop (typically less than 1 volt) into a larger, stabilized output voltage (several volts). This parameter transformation improves signal-to-noise ratio and detection accuracy while maintaining circuit simplicity.
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
Enables continuous and accurate temperature monitoring of semiconductor switches, enhancing operational safety and reliability by providing a precise temperature signal that is not affected by noise, even during normal operation.
Implementation Method 1
A temperature sensing diode 103 performs a characteristic of a forward voltage drop versus temperature, as disclosed in Patent Document 2, that the forward voltage drop decreases with increase in temperature
Data Source
AI summary
A semiconductor device of the present invention determines an overheat state by comparing a forward voltage drop of a temperature sensing diode with a reference voltage, and in addition includes a series regulator circuit composed of an amplifier and resistors, that receives the forward voltage drop of a temperature sensing diode and delivers an output voltage as temperature information to an external output terminal for temperature detection of the semiconductor device. Such a device can continuously detect the temperature of the semiconductor chip.