Self-Diagnosis Circuit for Startup Fault Detection
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Solution Overview
Problem
Existing self-diagnosis circuits for ICs, such as power supply ICs, fail to effectively diagnose fault detection/protection functions during startup due to reliance on output voltage stabilization, leading to potential output of abnormal voltages before faults are detected.
Innovation Solution
A self-diagnosis circuit configuration that includes a first comparator, a voltage switch circuit, and path switch circuits, controlled by a control portion, allowing diagnosis regardless of the fault sensing target voltage by switching voltage levels using reference voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If self-diagnosis is performed after output voltage stabilization, then diagnosis reliability is improved, but startup time is extended and abnormal voltage output may occur before fault detection
Solution Approach 1:
The patent performs self-diagnosis operations before the output voltage stabilizes during startup. The control portion activates the voltage switch circuit and path switch circuit to inject test signals and verify comparator functionality early in the startup sequence, before normal operation begins. This preliminary diagnosis prevents abnormal voltage output while reducing startup time penalty.
Solution Approach 2:
The patent introduces a voltage switch circuit as an intermediary component that can selectively connect different voltage sources to the comparator input. During self-diagnosis, this intermediary injects known test voltages to verify comparator operation without requiring the output voltage to be stable, enabling early diagnosis before normal operation.
2Loss of time
If self-diagnosis is performed before output voltage stabilization, then startup time is reduced, but diagnosis reliability may deteriorate due to unstable voltage conditions
Solution Approach 1:
The voltage switch circuit acts as an intermediary that decouples the diagnosis process from the unstable output voltage conditions. By injecting known reference voltages through the switch circuit during startup, the system can reliably test comparator functionality regardless of output voltage instability.
Solution Approach 2:
The patent changes the input parameters for diagnosis by using fixed reference voltages from the voltage switch circuit instead of relying on the unstable output voltage. This parameter substitution enables reliable diagnosis during transient startup conditions when the output voltage is not yet stable.
3Adaptability or versatility
If voltage switch circuit and path switch circuit are added for self-diagnosis, then diagnosis capability is improved, but device complexity increases
Solution Approach 1:
The voltage switch circuit and path switch circuit are designed to serve dual purposes: normal operation voltage routing and self-diagnosis signal injection. The same switches and control logic are used for both functional operation and diagnostic testing, reducing the need for separate dedicated diagnosis components and minimizing overall circuit complexity.
Solution Approach 2:
The patent merges the self-diagnosis functionality with the existing voltage routing infrastructure. The control portion integrates diagnosis control with normal operation control, and the switch circuits handle both operational voltage switching and diagnostic signal routing, combining multiple functions into unified circuit blocks.
Data Source
AI summary
A self-diagnosis circuit (BST1) configured to diagnose a fault detection circuit (20) including a first comparator (CMP1) configured to be fed with a voltage based on a fault sensing target voltage (Vo1) and a first reference voltage (Vref1) includes a voltage switch circuit (50) configured to switch the level of a voltage based on a second reference voltage (Vref2) and output the resulting voltage, a first path switch circuit (51) configured to switch between a path through which the voltage output from the voltage switch circuit is fed to the first comparator and a path through which the voltage based on the fault sensing target voltage is fed to the first comparator, and a control circuit (15) configured to control the voltage switch circuit and the path switch circuit.