Electronic Switch Protection Circuit Using Pseudo-Random ADC Sampling
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Solution Overview
Problem
Existing electronic switching and protection circuits fail to effectively manage load currents in a way that prevents wire damage or overheating, particularly in long wires used in vehicles, where current fluctuations can lead to overheating and damage if not properly managed.
Innovation Solution
An electronic circuit with an electronic switch and a control circuit that includes a first protection circuit generating a protection signal based on the current-time characteristic of the load current, using an analog-to-digital converter to sample the load current pseudo-randomly and drive the switch accordingly, thereby preventing overload scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the electronic switch is used to manage load current, then the switching capability and control flexibility are improved, but the risk of wire overheating and damage increases if current fluctuations are not properly managed
Solution Approach 1:
The protection circuit continuously monitors the load current through the ADC and compares it against safe operating thresholds. When the current exceeds the maximum rated current or remains above the rated current for too long, the feedback mechanism triggers the electronic switch to open, preventing wire overheating while maintaining normal operation during acceptable current fluctuations
Solution Approach 2:
The protection circuit acts as an intermediary between the power source and the load, inserting monitoring and control functionality into the current path. The ADC and control logic mediate between the electronic switch and the load, ensuring that switching operations do not cause harmful current fluctuations that could overheat the wire
2Device complexity
If the ADC samples the load current at fixed intervals, then the measurement simplicity is improved, but the ability to detect current fluctuations and prevent overheating deteriorates
Solution Approach 1:
The sampling interval is made dynamic rather than fixed. The ADC automatically adjusts the sampling frequency based on the magnitude and rate of change of the load current. During periods of high or rapidly changing current, sampling occurs more frequently to detect potential overheating conditions, while during stable low-current operation, sampling intervals increase to reduce processing load
Solution Approach 2:
The sampling parameters (frequency, resolution, threshold values) are changed based on the operating conditions. The system transitions between different sampling modes depending on whether the current is near rated levels, exceeding maximum limits, or showing signs of rapid increase, allowing the monitoring system to adapt its behavior to the actual thermal risk
Data Source
AI summary
An embodiment electronic circuit includes an electronic switch comprising a load path, a first protection circuit configured to generate a first protection signal based on a current-time-characteristic of a load current through the load path of the electronic switch, and a drive circuit configured to drive the electronic switch based on the first protection signal. The first protection circuit includes an analog-to-digital converter (ADC) configured to receive an ADC input signal representing the load current, to sample the ADC input signal once in each of a plurality of successive sampling periods, and to output an ADC output signal that includes a sequence of values such that each of the values represents a respective sample of the ADC input signal. The ADC is configured to pseudo-randomly select a sample time in each sampling period.