Common-Mode Transient Immunity Circuit for Isolated Signal Shutdown
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Solution Overview
Problem
Current isolated gate drivers face issues with common-mode transients, leading to voltage differences that can cause incorrect signal sampling and false outputs due to parasitic capacitance, which are not effectively suppressed by existing technologies.
Innovation Solution
A common-mode transient immunity circuit is introduced, comprising a first isolation circuit, common-mode bias circuit, and comparison circuit, which outputs an enable signal to stop the modulation or demodulation circuit when common-mode transients occur, preventing their influence on output signals. This circuit includes isolation capacitors and comparison units with comparators and logic gates to compare bias voltages with reference voltages, ensuring timely intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitive isolation technology is used to provide galvanic isolation between input and output, then electrical isolation is improved, but common-mode transient immunity deteriorates due to parasitic capacitance coupling paths
Solution Approach 1:
The patent introduces an intermediary detection mechanism (voltage difference detection circuit) between the isolated input and output grounds. This intermediary detects common-mode transient voltage differences and triggers a protective response by disabling the isolation capacitor, thereby mediating between the need for galvanic isolation and the need to prevent transient-induced errors
Solution Approach 2:
The patent applies preliminary anti-action by proactively detecting potential common-mode transient conditions and preemptively disabling the modulation/demodulation circuits before actual false outputs can occur. The voltage difference detection circuit monitors conditions and prevents harmful effects before they manifest
2Adaptability or versatility
If voltage difference between ground of transmitting circuit and ground of receiving circuit is allowed during common-mode transients, then common-mode transient response is improved, but signal accuracy deteriorates due to incorrect sampling and false outputs
Solution Approach 1:
The patent implements feedback by continuously monitoring the voltage difference between the isolated grounds and using this information to control the state of the modulation/demodulation circuits. When the voltage difference exceeds a threshold, the feedback mechanism disables the circuits to prevent incorrect sampling, thereby maintaining signal accuracy while allowing transient response
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 effectively prevents the impact of common-mode transients on output signals by stopping the modulation or demodulation process during transient events, ensuring accurate signal processing and avoiding false outputs.
Implementation Method 1
The first isolation circuit comprises a first isolation capacitor, connecting with the common-mode bias circuit and the comparison circuit, applied to transmitting a first common-mode bias voltage output by the common-mode bias circuit to the comparison circuit when common-mode transients occur
Data Source
AI summary
Common-mode transient immunity circuit and modulation-demodulation circuit, common-mode transient immunity circuit is applied to connecting with modulation circuit or demodulation circuit, comprising first isolation circuit, common-mode bias circuit, reference circuit and comparison circuit. Common-mode bias circuit provides common-mode bias voltage for first isolation circuit; first isolation circuit transmits common-mode bias voltage to comparison circuit; reference circuit provides reference voltage for comparison circuit; comparison circuit compares common-mode bias voltage with reference voltage, when common-mode bias voltage is larger than reference voltage, comparison circuit outputs enable signal to modulation circuit or demodulation circuit, and modulation circuit is driven to stop outputting modulation signal or demodulation circuit is driven to stop receiving modulation signal. According to invention, when common-mode transient occurs, enable signal is output to drive modulation circuit or demodulation circuit to stop working, so that influence of common-mode transient on output signal is avoided.