Integrated Transceiver Circuit for Multi-Protocol OBD Pin Switching
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Solution Overview
Problem
Conventional bus transceivers are large in size and costly due to the need for relay switching and shared pins, which limits their application to high-speed protocols like CAN FD and increases 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 interface, then protocol compatibility is achieved, but circuit size becomes large and integration is impossible
Solution Approach 1:
The patent replaces mechanical relay switching with electronic MOS transistor gating controlled by control signals. The gating units use transistors to selectively connect transceiver pins to external interfaces or internal modules, eliminating the need for physical relay switches while maintaining protocol compatibility across multiple communication standards.
Solution Approach 2:
The patent integrates multiple transceiver modules (CAN, LIN, RS485, I2C) and their control circuits into a single integrated chip. The gating units and control logic are merged within the chip structure, allowing multiple protocols to be handled by a unified circuit architecture rather than separate discrete components.
2Adaptability or versatility
If multiple transceivers share certain OBD pins through fixed switching mode, then pin utilization is improved, but parasitic capacitance increases and high-speed protocols cannot be realized
Solution Approach 1:
The patent implements dynamic pin assignment where the gating units can selectively connect pins to different transceiver modules based on real-time communication needs. Unlike fixed switching modes, the control signals dynamically route pins to the active transceiver, reducing the number of simultaneously connected transceivers to a pin and minimizing parasitic capacitance for high-speed protocols like CAN FD.
3Ease of operation
If transceiver and matrix switch are integrated, then certain OBD pins can be switched, but chip area becomes large and application scenarios are limited
Solution Approach 1:
The patent designs gating units that can universally handle multiple communication protocols (CAN, LIN, RS485, I2C) through a single integrated structure. The same gating circuitry and control logic serve all protocol types, eliminating the need for separate matrix switch structures for each protocol and reducing overall chip area while expanding application scenarios.
Data Source
AI summary
Disclosed is 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.