Integrated OBD Transceiver Circuit for Multi-Protocol Bus Switching
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Solution Overview
Problem
Conventional bus transceivers require relay switching, leading to large circuit size and high cost, and cannot support high-speed bus protocols due to shared pins causing excessive parasitic capacitance.
Innovation Solution
An integrated transceiver circuit with a transmitting matrix, receiving matrix, drive circuits, differential impedance control, and hysteresis comparators, allowing for adjustable voltage and current to meet various communication protocols, reducing component size and parasitic components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If relay switching is used to control gating between transceiver and external OBD interface, then the transceiver can support different protocols, but the circuit size becomes large and cost increases
Solution Approach 1:
The patent integrates multiple transceiver functions and protocol support capabilities into a single integrated circuit device. The transceiver includes multiple transmit and receive channels that can be selectively activated through internal switching mechanisms, eliminating the need for separate relay components. This merging of functions reduces overall circuit size while maintaining protocol versatility.
Solution Approach 2:
The integrated transceiver is designed with multi-functional capabilities to support multiple communication protocols simultaneously. The device includes configurable transmit and receive channels that can be programmed to handle different protocol requirements, making a single device universal enough to replace multiple protocol-specific transceivers and relay combinations.
2Ease of operation
If fixed switching mode is used with transceiver and matrix switch, then certain OBD pins can be switched, but some pins are shared by multiple transceivers causing excessive parasitic capacitance
Solution Approach 1:
The patent implements dynamic switching control within the integrated transceiver, where the switching configuration can be programmatically adjusted based on the active communication protocol and channel requirements. This dynamic approach ensures that only the necessary pins are activated for each protocol, preventing shared pins from accumulating excessive parasitic capacitance while maintaining ease of pin switching capability.
3Device complexity
If shared pins are used by multiple transceivers, then pin count is reduced, but high-speed bus protocols such as CAN FD cannot be realized
Solution Approach 1:
The integrated transceiver is segmented into multiple independent transmit and receive channels, each with dedicated switching control. This segmentation allows specific channels to be allocated to high-speed protocols like CAN FD with dedicated pin assignments, while other channels handle lower-speed protocols. The segmentation ensures that high-speed channels do not share pins with other functions, maintaining signal integrity and enabling high-speed operation despite reduced overall pin count.
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AI summary
The application provides an integrated transceiver circuit, which can be applied to signal transceiving between an external control device and an external diagnostic device. A communication channel between each GPIO port of the external control device and any OBD terminal is constructed by using the transmitting matrix and receiving matrix, meanwhile, a drive circuit is arranged. On the one hand, signals from external control devices are converted into an output drive signal with matchable voltage, current and load through the drive circuit and differential impedance control unit, so that signals from GPIO ports can be sent according to the voltage, current and load requirements of various communication protocols. On the other hand, signals from the OBD terminal is received according to the voltage requirements of the communication protocol through the hysteresis comparator in the drive circuit.