Load Driver Circuit for Distinguishing Load Open and Ground Faults
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Solution Overview
Problem
Existing intelligent power devices (IPDs) face challenges in reliably detecting abnormal conditions at their output terminals, particularly load open and ground faults, which are critical for meeting functional safety standards like ISO 26262.
Innovation Solution
A load driving device incorporating a semiconductor integrated circuit with an abnormality detection circuit that distinguishes between load open and ground fault by comparing output current with multiple threshold values using MOSFETs and comparators, generating distinct abnormality detection signals for each condition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If abnormality detection is implemented using conventional methods, then basic fault detection is achieved, but reliable distinction between load open and ground fault cannot be made
Solution Approach 1:
The abnormality detection function is segmented into two independent detection paths: one for detecting load open conditions and another for detecting ground faults. Each path uses dedicated comparison circuits with separate threshold values, allowing simultaneous and independent detection of both abnormality types without interference, thereby achieving both high measurement precision and functional safety reliability
Solution Approach 2:
Threshold values serve as intermediary reference parameters that mediate between the output current signal and the abnormality determination. By introducing first and second threshold values as intermediate comparison standards, the system can accurately distinguish between different abnormality conditions (load open vs. ground fault) based on where the output current falls relative to these intermediary thresholds
2Measurement precision
If multiple threshold comparisons are implemented to distinguish abnormality types, then detection accuracy improves, but device complexity increases
Solution Approach 1:
Multiple comparison operations are merged into a unified detection circuit architecture. The first and second comparison circuits are integrated to share common functional blocks such as the output current generation unit and threshold management, allowing multiple threshold comparisons to be performed simultaneously within a single cohesive circuit structure, thereby improving detection accuracy while controlling device complexity
Solution Approach 2:
The detection circuit is designed with multi-functional components that can perform multiple roles. For example, the output current generation circuit serves both normal operation and abnormality detection functions, and the comparison circuits can evaluate against multiple thresholds using the same hardware structure, enabling high measurement precision without proportionally increasing device complexity
Data Source
AI summary
The present disclosure provides a load driving device. The load driving device includes a load, a resistor configured to be connected in parallel to the load, and a switch device. The switch device includes an output terminal, a ground terminal, a first switch element and an abnormality detection circuit. The output terminal is configured to connect the load and the resistor. The ground terminal is configured to connect to a ground potential. The first switch element is configured to be connected between the output terminal and the ground terminal. The abnormality detection circuit is configured to distinguish between a load open at the output terminal and a ground fault at the output terminal based on a magnitude relationship between an output current flowing through the first switch element, a first threshold value and a second threshold value greater than the first threshold value.