Load Switch Fault Detection With Diagnostic Terminal Feedback
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Solution Overview
Problem
Existing switch devices lack effective mechanisms to handle various abnormalities, such as overcurrent, temperature, and voltage fluctuations, which can lead to improper operation and potential damage in load drive systems.
Innovation Solution
The implementation of an abnormality detection circuit within each switch device that can detect and respond to overcurrent, temperature, and voltage abnormalities by controlling the output transistor and diagnostic signals, along with a control circuit to manage these abnormalities through off-latch, intermittent ON/OFF, and current restriction controls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an abnormality detection circuit and control circuit are added to detect and manage abnormalities, then reliability is improved, but device complexity increases
Solution Approach 1:
The switch device incorporates an abnormality detection circuit that automatically monitors itself for abnormalities such as overcurrent, overheating, and voltage fluctuations. The control circuit responds autonomously by generating appropriate control signals to maintain safe operation, enabling the device to self-diagnose and self-correct without external intervention, thereby improving reliability while keeping the added complexity minimal and integrated.
2Adaptability or versatility
If multiple control modes (off-latch, intermittent ON/OFF, current restriction) are implemented, then adaptability to different abnormality conditions is improved, but device complexity increases
Solution Approach 1:
The control circuit dynamically selects and switches between multiple control modes (off-latch control, intermittent ON/OFF control, and current restriction control) based on the type and severity of detected abnormalities. This dynamic adaptability allows the device to optimize its response to different fault conditions, improving versatility while managing complexity through a unified control architecture that automatically adjusts its behavior.
Solution Approach 2:
The control circuit changes operational parameters such as switching frequency, duty cycle, and current limits based on the detected abnormality conditions. By adjusting these parameters dynamically, the device can implement different control modes without requiring separate hardware circuits for each mode, thereby achieving adaptability while controlling the increase in device complexity.
3Measurement precision
If diagnostic signals are provided for each abnormality type, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The switch device incorporates diagnostic signals that provide real-time feedback about the status of various abnormality detection circuits. These feedback signals enable precise identification of specific abnormality types (overcurrent, overheating, voltage anomalies) and allow the control circuit to generate appropriate control signals. The feedback mechanism achieves high measurement precision through integrated monitoring points that directly sense critical parameters without requiring complex external measurement systems.
Data Source
AI summary
A switch device has a control circuit that turns on or off an output transistor disposed between two terminals in accordance with a control signal. When an abnormality is detected in an ON period of the output transistor, the control circuit turns off the output transistor or restricts a current value of the output transistor and switches a state of a diagnostic terminal from a first state to a second state, so as to switch a voltage level of the diagnostic terminal from a first level to a second level. During the ON period of the output transistor, when no abnormality is detected and the voltage level of the diagnostic terminal is changed from the first level to the second level, the control circuit turns off the output transistor.