MOS Switch Fault Detection via Multi-Parameter Test Circuit
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Solution Overview
Problem
In safety-critical environments, such as automotive applications, existing technologies fail to accurately detect and differentiate between various fault states in MOS switch transistors, including faulty connections, short circuits, and shunt transistor faults, which is essential for ensuring functional safety.
Innovation Solution
A method and device that perform multiple test measurements, including determining gate capacitance, drain-source voltage, source voltage, shunt resistor testing, and voltage drop measurements, to evaluate the fault state of MOS switch transistors, using a test current generator, voltage measurement circuit, and evaluation circuit to determine fault states without disturbing normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple test measurements are performed to accurately detect fault states, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The test circuit is designed to perform multiple test measurements (gate capacitance, drain-source voltage, source voltage, shunt resistor testing, voltage drop measurements) using a unified architecture. The evaluation circuit processes different measurement types through a common interface, allowing one test circuit to accomplish multiple diagnostic functions rather than requiring separate dedicated circuits for each measurement type.
Solution Approach 2:
The test circuit utilizes a test current with magnitude selected essentially not to disturb normal operation of the switch device. By dynamically adjusting the test current parameter to be sufficiently small, the circuit achieves accurate measurements without affecting the operational state of the MOS transistor, thus maintaining measurement precision while avoiding the need for complex isolation circuits.
2Measurement precision
If test current is applied to measure fault states, then measurement precision is improved, but normal operation may be disturbed
Solution Approach 1:
The test current magnitude is specifically selected to be sufficiently small (essentially not to disturb normal operation) while still generating measurable voltage responses. This parameter optimization allows the test circuit to achieve adequate signal levels for accurate fault detection without injecting enough current to alter the switching state or operational characteristics of the MOS transistor.
Solution Approach 2:
The test current is applied as a partial action - just enough to generate measurable voltage signals for fault detection, but intentionally kept below the threshold that would cause significant disturbance to normal operation. This partial application of test current achieves the minimum necessary measurement capability without excessive intervention in the system's operational state.
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 precise detection and differentiation of fault states in MOS switch transistors, allowing for appropriate reactive measures to ensure system safety, such as bringing an automobile to a controlled stop in autonomous driving scenarios.
Implementation Method 1
applying a test current to a switch device comprising at least one switch transistor, the test current having a magnitude selected essentially not to disturb normal operation of the switch device, measuring a voltage in response to the test current
Implementation Method 2
measuring a voltage in response to the test current, and determining a fault state of the switch device based on the measured voltage
Data Source
AI summary
Methods and devices are discussed relating to testing of MOS switch transistors. For example, at least two different test measurements may be performed, and a fault state may be determined based on the at least two test measurements.