Current Sensor Isolation Structure for High-Voltage Sensing
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Solution Overview
Problem
Current current sensors have limited sensitivity and operational ranges, and their isolation characteristics restrict the voltage levels of sensed signals, making them inadequate for applications requiring higher current sensing capabilities.
Innovation Solution
The creation of an isolation region in a leadframe by etching increases the distance between the die and the current conductor, enhancing electrical isolation, and the use of SOI processes and configurations further improves the isolation capabilities of the current sensor, allowing for higher voltage levels and extended sensing ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the distance between the die and current conductor is increased to improve electrical isolation, then isolation level is improved, but sensitivity deteriorates
Solution Approach 1:
The patent introduces a vertical isolation region that etches downward into the leadframe, creating a three-dimensional isolation structure. This vertical dimension allows the isolation region to extend below the die without increasing the horizontal distance, thus maintaining sensitivity while achieving high electrical isolation through increased creepage path length in the vertical direction.
Solution Approach 2:
The isolation region acts as an intermediary structure between the die and the current conductor. By creating this intermediate etched region filled with insulative material, the patent provides a controlled transition zone that enhances electrical isolation while maintaining the necessary magnetic coupling for sensitivity.
2Reliability
If SOI processes are used to enhance isolation, then electrical isolation is improved, but device complexity increases
Solution Approach 1:
The patent segments the leadframe into distinct regions including an etched isolation region and non-etched portions. This segmentation allows the isolation function to be concentrated in specific areas while maintaining simple overall structure, reducing the need for complex isolation measures throughout the entire device.
Solution Approach 2:
The patent changes the physical parameter of the leadframe by creating an etched isolation region with specific depth and fill material properties. This parameter change (creating a recess and filling with insulative material) provides enhanced isolation through material and geometric modification rather than through complex circuit-level isolation techniques.
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
This approach enhances the sensitivity and operational range of current sensors, enabling them to accurately measure higher currents while maintaining high isolation levels, thus addressing the limitations of existing sensors.
Implementation Method 1
a magnetic field sensing element positioned in relation to the current conductor for detecting a magnetic field generated by current flow through the current conductor
Data Source
AI summary
Methods and apparatus for providing a high isolation current sensor. In embodiments, a current sensor includes a leadframe having a current conductor first portion and a second portion, a magnetic field sensing element positioned in relation to the current conductor for detecting a magnetic generated by current flow through the current conductor, and a die supported by at least a portion of the first and/or second portions of the leadframe, wherein the first portion of the lead frame includes an isolation region aligned with a first edge of the die. In embodiments, a current sensor includes SOI processing and features to enhance active layer isolation.