Smart Semiconductor Switch Leakage Current Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Smart semiconductor switches in idle mode cannot effectively detect leakage currents due to limited diagnostic functions, which can lead to uncontrolled battery discharge in applications like automotive systems.
Innovation Solution
A method and circuit for a smart semiconductor switch that includes a transistor and a control circuit to perform a leakage current test by deactivating the transistor, measuring the time it takes for the output voltage to fall below a threshold, and then reactivating it, allowing for detection of excessive leakage currents even in idle mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the smart semiconductor switch is operated in idle mode with most internal circuits inactive to reduce power consumption, then power consumption is reduced, but the ability to detect leakage currents is lost
Solution Approach 1:
The control circuit performs a preliminary action by temporarily switching off the semiconductor switch before the idle mode is fully activated. This preliminary switching-off action enables the subsequent measurement of the discharge time constant, which reveals information about leakage currents in the load. By performing this measurement action before returning to idle mode, the system gains diagnostic capability without permanently leaving the low-power state.
Solution Approach 2:
The control circuit implements periodic action by repeatedly switching the semiconductor switch between on and off states at predetermined intervals. During these periodic off-states, the discharge time constant is measured to detect leakage currents. This periodic switching allows the system to maintain idle mode operation for power savings while periodically performing diagnostic measurements to ensure reliability.
2Measurement precision
If the semiconductor switch is switched off to measure leakage current by observing voltage decay, then leakage current detection becomes possible, but the switch cannot simultaneously provide power to the load
Solution Approach 1:
The control circuit applies partial action by switching off the semiconductor switch only for brief predetermined intervals sufficient to measure the discharge time constant, rather than keeping it off continuously. This partial switching-off duration is exactly what is needed to obtain measurement data about leakage currents, while minimizing the interruption of power delivery to the load. The measurement is performed with just enough action to gather necessary information.
Solution Approach 2:
The system uses self-service by utilizing the inherent discharge characteristics of the output capacitance when the switch is temporarily off. The natural voltage decay of the output capacitance through the load provides the measurement signal itself, without requiring external test equipment or additional power sources. The load's own electrical characteristics serve as the measurement probe.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the detection of leakage currents, preventing unnecessary battery discharge by identifying faults in loads or supply lines, ensuring reliable operation in automotive applications.
Implementation Method 1
an output capacitance (CL) which is connected between the output node and a reference potential
Implementation Method 2
a check is performed to ascertain whether the time that elapses until the output voltage falls below a first voltage level is less than a (time) threshold value
Data Source
AI summary
In accordance with an embodiment, a method includes activating a semiconductor switch coupled between a supply node and an output node to apply an output voltage to an electrical load coupled to the output node, wherein a supply voltage is provided to the supply node; and performing a leakage current test, comprising: deactivating the semiconductor switch to isolate the electrical load from the supply node; after deactivating the semiconductor switch, checking whether a time that elapses until the output voltage falls below a first voltage level is less than a threshold value; and activating the semiconductor switch after the checking.