Galvanically Isolated Power Package With Integrated Current Sensing
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Solution Overview
Problem
Integrated power device packages face challenges in providing electrical isolation between high voltage power switching devices and low voltage gate driver devices in a space-efficient manner, while also requiring current sensing functionality without increasing package footprint.
Innovation Solution
A semiconductor package with a galvanically isolated switching device configuration, featuring an input side with an input driver die and an output side with power transistor dies, where the output driver die is communicatively coupled via an isolation structure, and directly connected to the power transistor dies' load terminals, allowing for current sensing without external high voltage pins, thus reducing package size and improving creepage and clearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical isolation structures are added between high voltage and low voltage domains, then device protection and reliability are improved, but package footprint and complexity increase
Solution Approach 1:
The patent combines multiple functions into the high voltage sense amplifier: it performs both the isolation function (through the transformer coupling between low voltage and high voltage domains) and the current sensing function (through the differential amplifier measuring voltage across the sense resistor). This integration eliminates the need for separate isolation structures and sense resistor components, reducing package footprint while maintaining reliability.
Solution Approach 2:
The high voltage sense amplifier serves multiple purposes: it provides galvanic isolation between voltage domains through transformer coupling, performs current sensing by measuring voltage across the sense resistor, and drives the high voltage output. This multi-functionality reduces the number of discrete components needed and minimizes the overall package area.
2Measurement precision
If dedicated high voltage pins are added for current sensing, then measurement accuracy is improved, but package complexity and footprint increase
Solution Approach 1:
The patent merges the current sensing function with the high voltage output driver by using the same high voltage node to sense current through a sense resistor. The differential amplifier measures the voltage drop across this resistor, and this sensing is integrated into the existing high voltage output structure, eliminating the need for dedicated sense pins.
Solution Approach 2:
The high voltage output driver circuit serves itself by incorporating the current sensing capability directly into its structure. The sense resistor is placed in series with the high voltage output, and the differential amplifier uses the voltage across this resistor to both sense current and control the output, making the circuit self-sufficient without external sense pins.
3Reliability
If separate input and output driver dies are used with galvanic isolation, then voltage domain isolation is improved, but device area and manufacturing complexity increase
Solution Approach 1:
The patent integrates the input driver, output driver, and isolation transformer into a single monolithic integrated circuit. The transformer provides galvanic isolation between the low voltage input domain and high voltage output domain, while all driver circuits are fabricated on the same semiconductor substrate, reducing the overall device area compared to discrete component implementations.
Solution Approach 2:
The patent implements a nested structure where the low voltage input driver is embedded on one side of the transformer, the transformer provides isolation in the middle, and the high voltage output driver is embedded on the other side. This nested arrangement efficiently uses space by organizing functional blocks in a compact, integrated manner.
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 a compact semiconductor package with integrated current sensing, eliminating the need for dedicated high voltage pins and reducing the package footprint, while ensuring electrical isolation and efficient communication between voltage domains.
Implementation Method 1
an isolation structure that galvanically isolates the input side from the output side
Data Source
AI summary
A semiconductor package includes an input side including input pins an output side including high voltage pins, an isolation structure that galvanically isolates the input side from the output side, an input driver die mounted on the input side and electrically connected with the input pins, first and second power transistor dies mounted on the output side and each having a first load terminal electrically connected with the high voltage pins, an output driver die that is communicatively coupled to the input driver die driver die via the isolation structure and is electrically connected with gate terminals of the first and second power transistor dies, and one or more electrically conductive structures forming a direct electrical connection between load terminals of the first and second power transistor dies, wherein the output driver die is mounted on one of the one or more electrically conductive structures.