Output Circuit Isolation for High-Voltage Sensor Protection
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Solution Overview
Problem
In-vehicle semiconductor electronic circuits face breakage risks due to high voltages supplied through erroneous connections, and existing solutions compromise signal characteristics and noise resistance.
Innovation Solution
An electronic circuit with a voltage monitor circuit that disconnects the output terminal when a voltage exceeds a predetermined value, using low withstand voltage transistors for signal generation and high withstand voltage transistors for switching to prevent breakage while maintaining signal characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the output transistor is configured to have a high withstand voltage structure to prevent breakage from high voltage, then the reliability is improved, but the current-voltage characteristics deteriorate and electromagnetic radiation noise increases
Solution Approach 1:
The patent divides the transistor functionality into two separate components: a protection transistor with high withstand voltage structure dedicated to preventing breakage from high voltage, and a signal output transistor with low withstand voltage structure optimized for current-voltage characteristics. This segmentation allows each transistor to be specialized for its specific function, resolving the contradiction between reliability and electromagnetic radiation noise.
Solution Approach 2:
The protection transistor acts as an intermediary between the power supply and the signal output transistor. It monitors the voltage and disconnects the power supply when high voltage is detected, thereby protecting the signal output transistor from high voltage damage while allowing the signal output transistor to maintain its optimized low withstand voltage structure for minimal electromagnetic radiation noise.
2Reliability
If the output transistor has a high withstand voltage structure to prevent breakage, then the reliability is improved, but the output signal characteristics deteriorate due to large current flow and signal fluctuation
Solution Approach 1:
The patent segments the transistor functions into a protection transistor with high withstand voltage structure and a signal output transistor with low withstand voltage structure. The signal output transistor is optimized for precise current-voltage characteristics and controlled rising/falling times, while the protection transistor handles high voltage protection. This segmentation ensures that the output signal characteristics are not compromised by the high withstand voltage requirements.
Solution Approach 2:
The protection transistor serves as an intermediary that isolates the signal output transistor from high voltage conditions. By monitoring the voltage and disconnecting the power supply when high voltage is detected, it prevents high voltage from affecting the signal output transistor's operation, thereby maintaining precise output signal characteristics without the need for the signal transistor to have high withstand voltage capability.
3Device complexity
If a single transistor is used for both signal output and high voltage protection, then the device complexity is reduced, but the adaptability to different voltage conditions deteriorates
Solution Approach 1:
The patent segments the transistor functions into two specialized transistors: a protection transistor optimized for high voltage protection and a signal output transistor optimized for signal characteristics. This segmentation allows the circuit to adapt to different voltage conditions effectively, as each transistor is specialized for its specific function. The protection transistor handles high voltage conditions while the signal output transistor maintains optimal performance under normal operating conditions.
Solution Approach 2:
While the patent uses two transistors, the overall output circuit achieves multi-functionality by combining the protection transistor and signal output transistor. The protection transistor provides high voltage protection, while the signal output transistor delivers precise signal output. This multi-functional design allows the circuit to adapt to different voltage conditions and maintain optimal performance across various operating scenarios.
Data Source
AI summary
An electronic circuit including an output circuit capable of reducing breakage while satisfying the characteristics of an output signal is provided. For this purpose, the electronic circuit includes output signal generation elements 201 and 202 configured to generate an output signal, switches 203 and 204, and a voltage monitor circuit 205 configured to monitor a voltage applied to an output terminal 112. Here, the output signal generation elements 201 and 202 are connected to the output terminal 112 via the switches 203 and 204, and the voltage monitor circuit 205 is configured to be able to measure a voltage higher than a power supply voltage VDD connected to the output signal generation element 201 and controls the switches 203 and 204 so as to disconnect the output signal generation elements 201 and 202 and the output terminal 112 when the voltage of the output terminal 112 becomes equal to or higher than a predetermined value set higher than the power supply voltage VDD.