Bidirectional Isolation Circuit to Eliminate Bus Echo Back
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Solution Overview
Problem
Existing industrial control products face challenges in electrical isolation due to 'echo back' issues from separate isolation devices and limited design flexibility caused by wide current transfer ratios of optocouplers, as well as space and power constraints in hazardous environments.
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 and reducing the need for multiple isolation points, thereby eliminating 'echo back' and optimizing board space and power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate isolation devices are used for transmit and receive circuits, then electrical isolation integrity is maintained, but echo back occurs on the transmit signal
Solution Approach 1:
The patent combines the transmit and receive isolation functions into a single bidirectional isolation device. This single device includes a transformer with pulse generation and decode circuits that enable the isolation barrier to handle both transmit and receive signals simultaneously, eliminating the echo back problem caused by separate isolation devices while maintaining electrical isolation integrity.
2Reliability
If optocouplers are used for isolation, then electrical isolation is achieved, but the wide current transfer ratio tolerance (80%-300%) limits design ability to control tight current draw range
Solution Approach 1:
The patent replaces optocouplers with a transformer-based isolation mechanism. The transformer provides galvanic isolation through magnetic coupling rather than optical coupling, eliminating the wide CTR tolerance issue. The pulse generation and decode circuits work with the transformer to provide precise control over current draw while maintaining electrical isolation.
3Reliability
If optocouplers are used for isolation, then electrical isolation is provided, but high drive current is required which is not desirable for low power or loop powered products
Solution Approach 1:
The patent replaces the high-power optocoupler LED with a transformer-based isolation mechanism. The transformer requires minimal drive current to establish magnetic coupling, dramatically reducing power consumption while maintaining electrical isolation. This makes the solution suitable for low-power and loop-powered industrial control products.
4Reliability
If multiple isolation points are used for transmit and receive functions, then signal integrity is maintained, but board space (isolation footprint) increases
Solution Approach 1:
The patent merges multiple isolation functions into a single bidirectional isolation device. The transformer with integrated pulse generation and decode circuits provides both transmit and receive isolation through one component, reducing the isolation footprint on the PCB while maintaining signal integrity for both directions of communication.
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 board space and power consumption, while maintaining signal integrity and compliance with hazardous area standards, by using a single isolation point for both transmit and receive functions.
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
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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 (100b, 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).