High-Side PMOS Overcurrent Protection With Adaptive Thresholds
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Solution Overview
Problem
Existing overcurrent protection techniques in semiconductor integrated circuits face challenges in setting an effective threshold value for overcurrent protection, particularly when the minimum operation voltage is lowered or load impedance decreases, leading to potential failure in detecting short circuits and providing adequate protection.
Innovation Solution
A semiconductor integrated circuit design that includes a high-side PMOS transistor, a driving circuit, and a first overcurrent protection circuit which compares a current detection signal with a threshold value that has a positive correlation with the power supply voltage, ensuring effective overcurrent protection by maintaining the threshold value above the operation-guaranteed range even in voltage reduction states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the minimum operation voltage is lowered to extend operating range, then the operation-guaranteed range is extended, but the difference between maximum operation current and minimum protection current narrows, making it difficult to set the threshold value
Solution Approach 1:
The patent applies dynamics by making the threshold value adaptive rather than fixed. The overcurrent protection threshold is dynamically adjusted based on the actual operating conditions (voltage and load), allowing the system to maintain proper protection margins across different operating points. This resolves the contradiction by enabling the system to adapt to extended voltage ranges while maintaining precise threshold setting through real-time adjustment.
Solution Approach 2:
The patent changes the parameter of the threshold value from a static design-time constant to a dynamic parameter that varies with operating conditions. By adjusting the threshold value based on actual voltage and load conditions, the system can maintain adequate separation between operation and protection regions even when the minimum operation voltage is lowered, thus resolving the precision setting problem.
2Power
If the load impedance is lowered to increase power delivery, then the operation current increases, but the operation-guaranteed range shifts toward higher currents, making it difficult to set the threshold value
Solution Approach 1:
The patent makes the protection threshold dynamic by linking it to the actual operating current and voltage conditions. When load impedance decreases and operating current increases, the threshold automatically adjusts to maintain the proper protection margin. This resolves the contradiction by allowing high power delivery through low impedance loads while maintaining precise overcurrent protection through adaptive threshold adjustment.
Solution Approach 2:
The patent changes the threshold parameter from a fixed value to one that varies with operating conditions. By adjusting the threshold based on actual voltage and current levels, the system can accommodate lower load impedances and higher operating currents while maintaining precise distinction between normal operation and overcurrent protection regions.
3Device complexity
If a fixed threshold value is used for overcurrent protection, then the protection circuit is simple, but it may fail to detect short circuits in voltage reduction states or cause false triggering
Solution Approach 1:
The patent transitions from a static fixed threshold to a dynamic threshold that adapts to operating conditions. The protection threshold is adjusted based on real-time voltage and current measurements, ensuring reliable short-circuit detection across different operating states including voltage reduction states. This resolves the contradiction by maintaining detection reliability through adaptivity while keeping the circuit implementation feasible.
Solution Approach 2:
The patent implements feedback by continuously monitoring operating conditions (voltage and current) and using this information to adjust the protection threshold. This feedback mechanism ensures that the threshold remains appropriate for current operating conditions, preventing both false triggering and failure to detect actual overcurrent conditions, thus resolving the reliability issue.
Data Source
AI summary
An output OUT is coupled to a load. A high-side transistor MH is arranged such that its source is coupled to a power supply line, and such that its drain is coupled to an output terminal OUT. A first OCP circuit compares a first current detection signal ICS1 that corresponds to a current ISRC that flows through the high-side transistor MH with a first threshold value IOCP having a positive correlation with a power supply voltage VDD of a power supply line, and generates a first OCP signal SOCP that indicates the comparison result. A driving circuit latch-stops the driving operation of the high-side transistor MH according to the first OCP signal SOCP.