Bi-directional Regulator Circuit for Isolation Transient Immunity
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Solution Overview
Problem
Existing isolation technologies, such as opto-isolators, are susceptible to common mode input transients and suffer from inefficient operation due to the need for external resistors, which reduce efficiency and introduce power dissipation, and are dependent on current strength for switching characteristics.
Innovation Solution
A bi-directional regulator circuit that generates a stable voltage across power supply nodes in response to input current polarity, independent of current strength, using diode-connected MOS transistor devices and ESD protection to enhance immunity to common mode transients and improve efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If opto-isolators are used to provide isolation between voltage domains, then isolation is achieved, but the output is dependent on current strength and susceptibility to common mode transients occurs
Solution Approach 1:
The patent introduces an intermediary voltage regulator circuit between the opto-isolator and the 5V logic domain. This regulator acts as a mediator that converts the variable voltage output from the opto-isolator into a stable 5V output, isolating the logic system from common mode transients while maintaining reliable isolation. The regulator serves as a buffer that prevents harmful transients from affecting the controlled system.
2Reliability
If external resistors are used to overdrive LED to maintain operation during common mode transients, then immunity to transients is improved, but power dissipation increases and efficiency decreases
Solution Approach 1:
The voltage regulator circuit is designed to automatically detect and respond to voltage drops caused by common mode transients. When a transient occurs and LED current decreases, the regulator detects the resulting voltage drop at its input and automatically increases the drive current to the LED to maintain proper operation. This self-correcting mechanism eliminates the need for external overdrive resistors that would continuously dissipate power, achieving transient immunity only when needed.
3Reliability
If current strength is increased to maintain LED operation during transients, then transient immunity is improved, but power consumption increases
Solution Approach 1:
The system dynamically adjusts the LED drive current based on real-time voltage conditions rather than using a fixed high current. The voltage regulator continuously monitors its input voltage and modulates the LED current accordingly - maintaining normal operation during steady state and increasing current only when transients cause voltage drops. This dynamic response achieves transient immunity while minimizing average power consumption compared to static overdrive approaches.
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 bi-directional regulator circuit provides improved immunity to common mode transients and enhanced operating efficiency by maintaining stable voltage over a wide current range, reducing power consumption, and enabling efficient communication across isolation barriers.
Implementation Method 1
The bi-directional regulator circuit is configured to generate a voltage across a first power supply node and a second power supply node in response to an input current flowing through the first terminal and the second terminal with a first polarity. The bi-directional regulator circuit is also configured to generate the voltage across the first power supply node and the second power supply node in response to the input current flowing through the first terminal and the second terminal with a second polarity opposite the first polarity.
Implementation Method 2
using diode-connected MOS transistor devices and ESD protection to enhance immunity to common mode transients and improve efficiency
Implementation Method 3
Although the isolation prevents the electromechanical system from being coupled to the monitor or control system by a direct conduction path, an isolation channel allows communication between the two systems.
Data Source
AI summary
An apparatus includes a first terminal, a second terminal, a bi-directional regulator circuit, and functional circuitry. The bi-directional regulator circuit generates a voltage across a first power supply node and a second power supply node in response to an input current flowing through the first terminal and the second terminal with a first polarity. The bi-directional regulator circuit also generates the voltage across the first power supply node and the second power supply node in response to the input current flowing through the first terminal and the second terminal with a second polarity opposite the first polarity. The functional circuitry is powered by the voltage and is configured to generate a signal using the voltage. The signal is indicative of the input current in response to the input current being supplied to the first terminal and is indicative of the input current in response to presence of the input current.