Bidirectional Isolation Circuit for Echo-Free Bus Transceivers
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Solution Overview
Problem
Industrial control products face challenges in hazardous and electrically noisy environments due to limitations in current electrical isolation methods, including half-duplex communication issues, wide current transfer ratios in optocouplers, and limited component options for AC-powered devices, which result in increased power consumption and board space requirements.
Innovation Solution
A bidirectional isolation circuit with a transformer and pulse generation/decode circuits is used to separate portions of an electronics system, allowing for simultaneous transmission and reception of signals, reducing echo back effects and board space, and optimizing current control with a single isolation point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two separate isolation devices are used for transmit and receive circuits, then signal integrity is maintained, but echo back occurs and board space increases
Solution Approach 1:
The patent combines transmit and receive isolation functions into a single bidirectional isolation device. The isolation device includes a first isolation path for transmit signals and a second isolation path for receive signals, both implemented within one integrated device rather than two separate devices. This merging eliminates the echo back problem caused by separate isolation devices while maintaining signal integrity through dedicated isolation paths.
2Reliability
If optocouplers are used for isolation, then electrical isolation is achieved, but current transfer ratio tolerance is wide (80%-300%) and power consumption is high
Solution Approach 1:
The patent transitions from optocoupler-based isolation to transformer-based isolation. This parameter change in the isolation mechanism eliminates the wide current transfer ratio tolerance issue. The transformer provides magnetic coupling with predictable transfer characteristics, enabling precise control of current transfer ratio while maintaining electrical isolation. The transformer-based approach also reduces power consumption compared to optocouplers.
3Reliability
If multiple isolation devices are used, then communication integrity is maintained, but board space and power consumption increase
Solution Approach 1:
The patent merges multiple isolation functions into a single bidirectional isolation device that handles both transmit and receive paths. This consolidation reduces the number of isolation devices from two to one, thereby reducing board space requirements while maintaining communication integrity through dedicated isolation paths for each direction.
Solution Approach 2:
The bidirectional isolation device performs multiple functions within a single component: it provides isolation for transmit signals, isolation for receive signals, and eliminates echo back. This multi-functionality replaces what previously required two separate isolation devices, reducing board space while maintaining all necessary isolation functions.
4Reliability
If optocouplers with high drive current requirements are used, then isolation is achieved, but power consumption increases
Solution Approach 1:
The patent changes the isolation mechanism from optocoupler-based to transformer-based. This parameter change fundamentally alters the power consumption characteristics. The transformer requires minimal drive current compared to optocouplers, thereby reducing power consumption while maintaining reliable electrical isolation.
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
This solution enables efficient electrical isolation with reduced power consumption and board space, eliminating echo back issues and meeting hazardous area standards, while maintaining waveform integrity for protocols like HART.
Implementation Method 1
A bidirectional isolation circuit with a transformer and pulse generation/decode circuits is used to separate portions of an electronics system
Data Source
AI summary
An electronics (100, 200) including an electrical isolation is provided. The electronics (100, 200) include a bidirectional isolation circuit (110, 210) separating a first portion (100a, 200a) from a second portion (100, 200b) and a bus transceiver switch (120b, 220b) disposed in the second portion (100b, 200b). The bus transceiver switch (120b, 220b) is communicatively coupled to the bidirectional isolation circuit (110, 210). The bus transceiver switch (120b, 220b) receives from the bidirectional isolation circuit (110, 210) a communication control signal provided by the first portion (100a, 200a).