Dual-Die Current Sensor IC Layout for Isolation and Redundancy
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Solution Overview
Problem
Current sensor integrated circuits face challenges in meeting safety requirements and electrical isolation needs, particularly in high voltage and high current applications, where redundant circuits and heterogeneous sensing elements are used to ensure safety but may not adequately address isolation requirements.
Innovation Solution
The development of dual-die current sensor integrated circuits (ICs) that include two semiconductor die supporting current sensing elements and circuitry, with each die having a magnetic field sensing element configured to sense the magnetic field associated with the current through a primary conductor and generate an output signal. This design facilitates electrical connection between the die for diagnostics and includes insulation structures to meet electrical isolation requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant identical circuits are used in a sensor integrated circuit to meet safety requirements, then safety compliance is improved, but device complexity increases
Solution Approach 1:
The patent divides the sensor integrated circuit into two separate semiconductor die, each containing a heterogenous sensing element. This segmentation allows each die to be independently tested and validated, while maintaining safety through redundancy without requiring a single complex circuit to handle all safety functions
Solution Approach 2:
The patent changes the parameter of sensing element homogeneity to heterogeneity, using different types of sensing elements (e.g., Hall effect, magnetoresistive) on different die. This parameter change diversifies the failure modes and improves safety compliance while managing complexity through standardized die designs
2Reliability
If electrical isolation is maintained between primary conductor and signal leads to meet safety specifications, then electrical isolation is improved, but device complexity increases
Solution Approach 1:
The patent introduces an intermediary insulating structure positioned between the primary conductor and the semiconductor die. This intermediary element provides the necessary electrical isolation (creepage and clearance) without requiring complex isolation circuits or multiple isolation layers, simplifying the overall isolation architecture
Solution Approach 2:
The patent addresses electrical isolation by transitioning from planar isolation to three-dimensional spatial separation. By positioning semiconductor die on opposite sides of the primary conductor and using vertical insulation structures, the patent achieves required creepage and clearance distances without increasing lateral device complexity
3Reliability
If heterogenous sensing elements are used to meet safety standards, then safety compliance is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent segments the heterogenous sensing elements onto separate semiconductor die, allowing each die to be manufactured and tested independently with standardized processes. This segmentation reduces manufacturing precision requirements compared to integrating multiple heterogenous elements on a single die
Solution Approach 2:
The patent applies local quality by allowing different sensing element types on different die while maintaining standardized packaging and connection methods. Each die can be optimized for its specific sensing element type while the overall system maintains consistent manufacturing tolerances through modular assembly
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 dual-die current sensor ICs provide enhanced safety and compliance with safety standards by implementing redundant current sensing, while also ensuring electrical isolation necessary for high voltage and high current applications, thus addressing the limitations of existing technologies.
Implementation Method 1
A first magnetic field sensing element supported by the first surface of the first semiconductor die and configured to sense a magnetic field associated with a current through the primary conductor
Data Source
AI summary
A current sensor IC includes a lead frame having a first surface, a second opposite surface and including a primary conductor and signal leads. A first semiconductor die has a first surface adjacent to the first surface of the lead frame and supporting a first magnetic field sensing element and a second semiconductor die has a first surface adjacent to the second surface of the lead frame and a second opposite surface supporting a second magnetic field sensing element. Fabrication methods include a single mold method and a two-mold method in which a mold material can provide isolation between the first semiconductor die and the primary conductor. Also described is a current sensor IC in which both first and second semiconductor die are arranged in a flip-chip configuration. Diagnostic circuits and inter-die connections permit one semiconductor die to sense faults with the other semiconductor die.