Dual-Threshold Overcurrent Circuit for Instantaneous Load Current
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Solution Overview
Problem
Conventional overcurrent protection circuits struggle to balance instantaneous current requirements and overcurrent protection for loads with varying current demands, particularly in in-vehicle ICs that need to comply with ISO26262 standards, where a single overcurrent set value is insufficient.
Innovation Solution
An overcurrent protection circuit with a threshold generator that switches between two set values, a reference value generator, and a threshold controller to dynamically adjust the overcurrent detection threshold based on monitored current conditions, ensuring both instantaneous current security and overcurrent protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single overcurrent set value is used, then overcurrent protection is provided, but instantaneous current requirements cannot be met
Solution Approach 1:
The patent applies dynamics by making the overcurrent detection threshold adjustable rather than fixed. The threshold generator switches between a first threshold (higher) and a second threshold (lower) based on operational conditions, allowing the protection circuit to adapt to both instantaneous current requirements and sustained overcurrent protection needs.
Solution Approach 2:
The patent changes the parameter of the detection threshold by providing two distinct threshold values. The first threshold allows higher instantaneous currents during normal operation, while the second threshold provides stricter protection during abnormal conditions, resolving the contradiction between protection and adaptability.
2Reliability
If a lower overcurrent set value is used, then overcurrent protection is improved, but instantaneous current flow is restricted
Solution Approach 1:
The system dynamically switches between two threshold levels based on operational state. During normal operation, the higher first threshold is used to allow sufficient instantaneous current. When overcurrent conditions are detected, the system switches to the lower second threshold to provide enhanced protection, thus balancing productivity and reliability.
Solution Approach 2:
The overcurrent protection is segmented into two distinct modes with different threshold levels. The first mode uses a higher threshold for normal operation, and the second mode uses a lower threshold for protection, allowing the system to optimize both current flow and protection independently in different operational contexts.
3Adaptability or versatility
If dual threshold values are implemented, then both instantaneous current and overcurrent protection are achieved, but device complexity increases
Solution Approach 1:
The threshold generator is designed to perform multiple functions: it generates both the first and second thresholds, monitors current conditions, and switches between thresholds as needed. This multi-functionality reduces the need for separate dedicated circuits for each threshold level, thereby limiting the increase in device complexity while achieving dual threshold capability.
Solution Approach 2:
The patent merges the threshold generation and switching functionality into a single integrated threshold generator block. By combining these functions, the circuit avoids the complexity of having separate threshold setting circuits and switching mechanisms, achieving dual threshold operation with minimal additional complexity.
Data Source
AI summary
In order both to accommodate instantaneous current as well as overcurrent protection in accordance with the load, an overcurrent protection circuit has: a threshold value generation unit that, in accordance with a threshold value control signal, switches between setting an overcurrent detection threshold value to a first set value (∝ Iref) and a second set value (∝ Iset) lower than the first set value; an overcurrent detection unit that compares a sense signal in accordance with the current being monitored and the overcurrent detection value and generates an overcurrent protection signal; a reference value generation unit that generates a reference value (∝ Iset) in accordance with the seconds set value; a comparison unit that compares the sense signal and the reference value, and generates a comparison signal; and a threshold value control unit that monitors the comparison signal, and generates a threshold value control signal.