Galvanically Isolated Bidirectional Serial Interface
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Solution Overview
Problem
Existing serial communication systems for battery management lack galvanic isolation, clock insensitivity, bi-directionality on a single link, and do not require isolated power supplies, leading to inefficiencies and increased complexity.
Innovation Solution
A bidirectional serial communication interface using a Serial Port Decoder and Timing Controller (SPDTC) with differential outputs and magnetic or capacitive coupling for galvanic isolation, eliminating the need for separate clock signals and isolated power supplies, and utilizing twisted pair cables with impedance-matched termination resistors for reliable communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If galvanic isolation is implemented using traditional isolated EIA-485/CAN interfaces, then noise immunity and voltage difference tolerance are improved, but device complexity and cost increase due to requiring galvanically isolated power supplies
Solution Approach 1:
The patent introduces an intermediary isolation barrier between the transmitter and receiver that allows signal transmission while blocking galvanic connection. This mediator enables noise immunity and voltage difference tolerance without requiring isolated power supplies, thus reducing system complexity while maintaining reliability
Solution Approach 2:
The patent extracts the essential function of galvanic isolation from the traditional isolated interface systems, separating the isolation barrier function from the power supply isolation requirement. This allows achieving galvanic isolation benefits without the complexity of isolated power supplies
2Ease of manufacture
If synchronous serial communication is used, then implementation simplicity is improved, but device complexity increases due to requiring separate clock signals and multiple signal paths
Solution Approach 1:
The patent merges the data transmission and clock synchronization functions into a single signal path. The receiver extracts timing information from the data stream itself, eliminating the need for separate clock signals and reducing the number of signal paths while maintaining implementation simplicity
Solution Approach 2:
The single communication line serves multiple functions: it carries both data information and timing synchronization signals. This multi-functional approach eliminates the need for dedicated clock lines and simplifies the overall system architecture
3Reliability
If bi-directional communication is implemented using separate transmission and reception paths, then reliability is improved, but device complexity and wire quantity increase
Solution Approach 1:
The patent implements a universal communication interface where the same physical line and circuitry are used for both transmission and reception operations. The interface can switch between transmit and receive modes, eliminating the need for separate dedicated paths and reducing overall system complexity while maintaining communication reliability
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 enables reliable, clock-independent, bi-directional communication over cables with reduced complexity and cost by eliminating the need for isolated power supplies and separate clock signals, while maintaining galvanic isolation and impedance matching.
Implementation Method 1
magnetic or capacitive coupling for galvanic isolation
Implementation Method 2
magnetic or capacitive coupling for galvanic isolation
Implementation Method 3
twisted pair cables with impedance-matched termination resistors for reliable communication
Data Source
AI summary
A method and interface for serial communication is provided. The interface includes a differential input/output having a first node and a second node. There are several input/output nodes arranged to receive serial interface signals. The interface includes a transmitter configured to drive a twisted pair cable at the differential input/output. There is a receiver coupled to the differential input/output that includes a window comparator. A serial port control unit provides serial data to the transmitter and receives serial data from the receiver. The serial communications interface transmits serial data to and receives serial data from a second serial communications interface independent of a reference clock and is galvanically isolated from the second serial communications interface.