Power Supply Fault Detection Sequencer for Vehicle Safety
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Solution Overview
Problem
Conventional power circuit fault detection methods are delayed, and there is a risk of malfunction when shutting down power circuits, especially in vehicle-mounted systems that require rapid and safe fault detection to comply with safety standards like ISO 26262.
Innovation Solution
A semiconductor device with a power circuit, a power controller, a fault detector, and a sequencer that detects control signal faults and initiates a predetermined shutdown sequence, ensuring power blocks are turned off in order, and can automatically restart the power circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If fault detection is performed by monitoring output voltage or current abnormalities, then the fault detection method is simple, but there is a delay until the output becomes abnormal
Solution Approach 1:
The fault detector monitors control signals (enable signals) before they cause output abnormalities. By detecting faults in the control signals that drive the power blocks, the system identifies issues before they manifest as output voltage or current abnormalities, thereby reducing detection time while maintaining safety
2Loss of time
If power blocks are turned off simultaneously upon fault detection, then the shutdown response is fast, but it may cause malfunction due to input-output interrelationships
Solution Approach 1:
The shutdown process is segmented into a predetermined sequence where power blocks are turned off one by one in a specific order rather than simultaneously. The sequencer divides the shutdown operation into discrete steps, ensuring that dependencies between power blocks are respected, thus preventing malfunction while maintaining relatively fast shutdown response
3Reliability
If a predetermined shutdown sequence is implemented, then malfunction is prevented, but the shutdown process becomes more complex
Solution Approach 1:
A sequencer is introduced as an intermediary component that manages the complex shutdown sequencing logic. The sequencer receives fault detection signals and autonomously executes the predetermined shutdown sequence, isolating the complexity from the main control system and simplifying the overall control architecture while ensuring safe shutdown
Data Source
AI summary
A semiconductor device equipped with: a power supply circuit that contains multiple power supply blocks mutually having input/output relationships; a power supply control unit that outputs control signals to each of the power supply blocks indicating On/Off; a fault detection unit; and a sequencer. When the fault detection unit detects that any of the control signals indicates Off during startup of the power supply circuit, the sequencer moves to a prescribed shutdown sequence mode, and the power supply control unit performs a shutdown sequence in which the control signals are output so as to turn off the power supply blocks in a prescribed order.