Current Sensor IC Packaging for Isolated Primary Conductor Routing
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Solution Overview
Problem
Conventional current sensors face challenges in effectively isolating the primary conductor and secondary leads, leading to potential electrical interference and reduced accuracy in sensing magnetic fields generated by current-carrying conductors.
Innovation Solution
A current sensor integrated circuit package is manufactured using a lead frame with a primary conductor and secondary leads, where the primary conductor is configured to carry current through die attach portions and a current conductor portion, with magnetic field sensing elements supported by a semiconductor die, and encased in insulating molds to provide isolation and reduce interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional current sensors are positioned near current-carrying conductors to sense magnetic fields, then current sensing function is achieved, but electrical interference and reduced sensing accuracy occur due to insufficient isolation
Solution Approach 1:
An insulator portion is introduced as an intermediary element between the primary conductor and secondary leads. This insulator extends beyond the edges of the primary conductor and provides electrical isolation, preventing harmful electrical interference while allowing the magnetic field sensing function to operate accurately.
Solution Approach 2:
The package structure is segmented into distinct isolated regions: the primary conductor region, the secondary leads region, and the insulator portion separating them. This segmentation creates physical and electrical separation, reducing interference between high-current paths and sensitive sensing elements.
2Area of stationary object
If the primary conductor and secondary leads are positioned close together for compact packaging, then device size is reduced, but electrical isolation and sensing accuracy deteriorate
Solution Approach 1:
The insulator portion extends vertically beyond the edges of the primary conductor, utilizing the vertical dimension to provide isolation. This allows compact horizontal packaging while maintaining adequate electrical isolation distance through vertical extension of the insulating material.
Solution Approach 2:
The insulator portion serves as a mediator that enables close positioning of primary conductor and secondary leads while maintaining electrical isolation. It fills the space between these components and provides the necessary creepage and clearance distances for reliable operation.
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 enhances isolation between the primary conductor and secondary leads, improving the accuracy and reliability of current sensing by minimizing external magnetic field interference and allowing for differential sensing configurations.
Implementation Method 1
at least one magnetic field sensing element supported by the semiconductor die and positioned near the current conductor portion
Implementation Method 2
The at least one magnetic field sensing element is one of a planar Hall effect element, a vertical Hall effect element
Implementation Method 3
providing a first mold of an insulating material to partially enclose part of the output portion, the first and second die attach portions, and the at least two secondary leads
Data Source
AI summary
A packaged current sensor integrated circuit includes a primary conductor having an input portion and an output portion configured to carry a current to be measured by one or more magnetic sensing elements supported by a semiconductor die adjacent to the primary conductor. A method of fabricating the packaged current sensor integrated circuit includes partially encasing the lead frame in a first mold material, applying an insulator to one or more die attach pads, attaching a die to the insulator, electrically connecting the die to secondary leads, and providing a second mold to the subassembly. The package is configured to provide increased voltage isolation.