Impedance-Based Ground Disconnect Detection Across Isolated Voltage Domains
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Solution Overview
Problem
In automotive systems with multiple voltage domains, such as 12V and 48V batteries, ground disconnections can occur, leading to system malfunction, and existing technologies lack effective methods to detect such disconnections across isolation barriers.
Innovation Solution
An integrated circuit with separate voltage domains is configured to detect ground disconnections using a capacitive circuit with a barrier capacitor and an impedance detection module, where changes in impedance are monitored to identify disconnections by injecting signals across the capacitors, allowing for early detection of ground disconnection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ground terminals for separate voltage domains are connected together external to the module, then functional isolation between voltage domains is maintained, but ground disconnection cannot be detected
Solution Approach 1:
The patent introduces an intermediary detection circuit that includes capacitors and impedance detection modules. These intermediaries are placed between the isolated voltage domains to indirectly detect ground connection status without compromising the functional isolation. The capacitors couple the detection circuits across the isolation barrier, allowing ground disconnection detection while maintaining voltage domain separation.
Solution Approach 2:
The patent replaces direct electrical connection monitoring with an impedance-based detection mechanism. Instead of mechanically or electrically probing the ground connection directly, the system uses impedance changes across capacitive couplings to infer ground connection status. This substitution allows detection without direct contact across the isolation barrier.
2Reliability
If isolation barriers separate voltage domains, then safety and functional isolation are achieved, but ground disconnection detection across barriers becomes impossible
Solution Approach 1:
The patent uses capacitors as intermediaries to bridge the isolation barrier for detection purposes only. These capacitors allow the detection circuit to sense impedance changes related to ground connections while the isolation barrier remains intact for power and signal domains. The intermediary capacitor enables indirect measurement without compromising isolation.
Solution Approach 2:
The patent creates a copied detection path that mirrors the ground connection status across the isolation barrier. By placing detection circuits on both sides of the barrier and coupling them through capacitors, the system creates a redundant detection path that copies the ground connection information from one side to the other, enabling detection without direct barrier penetration.
3Measurement precision
If impedance detection circuits are added to detect ground disconnections, then detection capability is improved, but device complexity increases
Solution Approach 1:
The patent designs the impedance detection circuit to serve multiple functions: detecting ground disconnections, monitoring voltage domain isolation status, and providing system diagnostics. By making the detection circuit multi-functional, the patent reduces the need for separate dedicated circuits for each function, thereby limiting the increase in overall device complexity while maintaining high detection precision.
Solution Approach 2:
The patent combines the ground disconnection detection function with the existing isolation barrier structure and voltage domain management circuits. By merging the detection functionality into the existing architectural framework rather than adding completely separate systems, the patent minimizes the increase in device complexity while achieving precise ground disconnection detection.
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
The solution enables reliable detection of ground disconnections, preventing system failures by accurately identifying impedance changes caused by disconnections, ensuring proper operation of automotive systems with multiple voltage domains.
Implementation Method 1
capacitive coupling can be used to transfer information across a barrier
Implementation Method 2
the impedance of the capacitive circuit changes which can used to detect the ground disconnection
Data Source
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AI summary
Methods and apparatus for an IC package having an impedance detector module configured to have: a first connection to a first external energy source via a first IO pin of the IC package and a second connection to a detection component. In embodiments, the detection component is configured for connection to a first ground for the first external energy source via a second IO pin of the IC package, and to a barrier component, which is configured for connection to a second ground for a second external energy source via a third IO pin of the IC package. The impedance detector module is configured to detect a disconnection or degradation of a connection to ground.