Overheat Protection Circuit With Current-Adaptive Trip Temperature
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Solution Overview
Problem
Existing overheat protection circuits for semiconductor integrated circuits and modules operate based on fixed temperatures, failing to account for varying external environments and use conditions, which can lead to inadequate protection and potential damage.
Innovation Solution
An overheat protection circuit that includes a reference voltage generation circuit, constant current sources, a second voltage generation circuit, an output current detection circuit, and a blocking controller, which dynamically adjust the overheat detection temperature based on the output current, hastening detection and protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed temperature threshold is used for overheat detection, then the protection circuit is simple to implement, but it cannot adapt to varying external environments and use conditions
Solution Approach 1:
The patent implements dynamic overheat detection by making the temperature threshold variable based on output current. The comparison reference voltage, which determines the detection temperature, is dynamically adjusted according to the magnitude of output current through voltage generation circuits connected to current sources. This allows the protection circuit to adapt to different operating conditions without requiring multiple fixed-threshold circuits.
Solution Approach 2:
The patent changes the parameter of detection temperature threshold dynamically. By varying the comparison reference voltage based on output current magnitude, the detection temperature threshold transitions from a fixed value to a variable parameter. This enables the same circuit to provide appropriate protection across different operating conditions by changing the threshold parameter rather than requiring different circuit configurations.
2Measurement precision
If a fixed temperature threshold is used for overheat detection, then the circuit structure is simple, but the detection speed and protection accuracy decrease under varying load conditions
Solution Approach 1:
The patent implements feedback control where the output current detection result is fed back to adjust the comparison reference voltage. The voltage generation circuits receive the output current signal and generate an appropriate voltage offset that is fed back to the comparison circuit, creating a closed-loop system that continuously adjusts the detection threshold based on actual operating conditions, thereby improving detection accuracy.
Solution Approach 2:
The patent introduces voltage generation circuits as intermediary elements between the output current detection and the temperature comparison. These intermediary circuits transform the current magnitude information into appropriate voltage offsets that modulate the comparison reference voltage, enabling indirect but accurate adjustment of the detection threshold without direct complex control logic.
3Speed
If the overheat detection temperature is lowered for high current operations, then protection speed increases, but the risk of false detection increases
Solution Approach 1:
The patent dynamically adjusts the detection threshold based on output current magnitude. During high current operations, the comparison reference voltage is automatically lowered, which reduces the detection temperature threshold and enables faster protection response when needed. During low current operations, the threshold remains higher, preventing false detections. This dynamic adjustment ensures both fast protection speed and high reliability across different operating conditions.
Data Source
AI summary
According to an embodiment, an overheat protection circuit includes a reference voltage generation circuit, a constant current source, a second voltage generation circuitry, an output current detection circuit, and a blocking controller. The output current detection circuit generates a third current by subtracting the second current from the first current, and decreases the second current based on the third current as an output current generated by an output circuitry increases, the third current being proportional to the output current. The blocking controller compares the first and second voltages with each other, and generates a blocking control signal to block generation of the output current when the first voltage is higher than the second voltage. An overheat detection temperature drops as the second voltage drops, and detection of the overheat detection temperature is hastened as the output current increases.