Isolated Switching Circuit for Low-Cost High-Voltage Protection
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Solution Overview
Problem
Existing semiconductor devices require high-withstand-voltage processes, which are costly and increase manufacturing complexity, especially in applications like vehicle-mounted power supply and motor driving devices.
Innovation Solution
A semiconductor device configuration using a transformer chip that isolates a primary circuit system from a secondary circuit system, allowing the use of common low-to middle-withstand-voltage processes, reducing the need for dedicated high-withstand-voltage processes and lowering manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-withstand-voltage processes are used to ensure device reliability, then reliability is improved, but manufacturing cost and process complexity increase
Solution Approach 1:
The device is divided into two electrically isolated circuit systems (first and second circuit systems) with different voltage requirements. Each system operates independently with its own power supply voltage, allowing the high-voltage portion to be isolated from low-voltage control circuits. This segmentation enables each segment to be manufactured with appropriate process requirements rather than requiring the entire device to use costly high-withstand-voltage processes throughout.
Solution Approach 2:
An insulation structure is introduced as an intermediary element between the first and second circuit systems. This insulation layer physically and electrically separates the high-voltage power supply circuit from the low-voltage control circuit, enabling independent voltage operation. The intermediary insulation structure allows low-voltage processes to be used for the control portion while maintaining high-voltage capability where needed, resolving the contradiction between reliability and manufacturing ease.
2Reliability
If high-withstand-voltage processes are used for the entire device, then voltage isolation reliability is improved, but device complexity and manufacturing steps increase
Solution Approach 1:
Different regions of the device are assigned different voltage withstand requirements based on their functional needs. The power supply circuit portion requires high-withstand-voltage characteristics, while the control circuit portion can use standard low-voltage processes. This local differentiation of quality requirements optimizes the device by applying high-voltage processes only where necessary, reducing overall device complexity and manufacturing steps while maintaining voltage isolation reliability.
Solution Approach 2:
The device structure is segmented into distinct high-voltage and low-voltage regions separated by insulation structures. This segmentation allows independent process optimization for each region, enabling the use of simpler, less costly manufacturing processes for the low-voltage control circuits while maintaining robust high-voltage isolation where required, thereby reducing overall device complexity.
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 reduces manufacturing costs by eliminating the need for high-withstand-voltage processes, making it suitable for vehicle-mounted devices such as power supply and motor driving systems in various electric vehicles.
Implementation Method 1
a transformer chip that isolates a primary circuit system from a secondary circuit system
Data Source
AI summary
In a target transistor, a first conductive electrode, a second conductive electrode, and a control electrode are respectively connected to first, second, and third wirings. The control circuit responds to an input control signal so as to supply a high side voltage or a low side voltage to the third wiring, thereby controlling the target transistor to be ON or OFF. If the low side voltage is lower than the voltage of the second wiring by a predetermined threshold voltage or more, an overvoltage signal in an asserted state is output. When the overvoltage signal in the asserted state is output, the control circuit supplies the low side voltage to the third wiring regardless of the input control signal, and a protection switching element, which is disposed between the second wiring and a fourth wiring applied with the low side voltage, is set to be ON.