CAN Bus Transceiver Ring Suppression Circuit
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Solution Overview
Problem
Increased CAN bus speeds have led to ringing issues due to improper electrical termination, causing bit errors as the transceiver misinterprets ringing as a dominant bit, especially during transitions from a dominant to a recessive state.
Innovation Solution
A CAN bus transceiver with a transient-triggered ring suppression circuit that attenuates ringing by enabling a circuit configuration upon transitioning to the recessive state, utilizing switches, resistors, capacitors, and NMOS/PMOS transistors to dissipate ringing signals, thereby reducing amplitude and duration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CAN bus speed is increased, then data transmission efficiency is improved, but ringing occurs causing bit errors
Solution Approach 1:
The ring suppression circuit is activated in advance during the transition from dominant to recessive state, before ringing can cause bit errors. The circuit prepares to attenuate ringing signals by enabling suppression transistors and adjusting termination resistors prior to the actual ringing occurrence, preventing bit errors before they can happen.
Solution Approach 2:
A ring suppression circuit is introduced as an intermediary component between the driver stage and the bus terminals. This circuit includes suppression transistors, termination resistors, and capacitors that mediate the interaction between the driver and the bus, attenuating ringing signals and preventing them from causing bit errors while allowing normal data transmission to proceed.
2Reliability
If transient-triggered ring suppression circuit is enabled, then ringing attenuation is improved, but device complexity increases
Solution Approach 1:
The ring suppression circuit is designed to be dynamic rather than static. It is enabled only during specific transitions (from dominant to recessive state) when ringing occurs, and disabled during normal operation. This dynamic activation uses control signals to switch suppression transistors and adjust termination resistors only when needed, reducing overall circuit complexity while maintaining effective ringing attenuation.
Solution Approach 2:
The ring suppression circuit applies localized corrections at specific points in the circuit where ringing occurs. Rather than redesigning the entire CAN bus system, the invention introduces targeted suppression elements (suppression transistors, termination resistors, capacitors) at strategic locations near the driver stage and bus terminals, achieving effective ringing attenuation with minimal added complexity.
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 effectively reduces bit errors by minimizing and shortening ringing signals, ensuring accurate data transmission and applicability to other bus protocols.
Implementation Method 1
The transient-triggered ring suppression circuit is configured to attenuate ringing on at least one of the first or second bus terminals
Data Source
AI summary
A transceiver includes a driver stage and a transient-triggered ring suppression circuit. The driver stage has a first transistor coupled between a supply voltage terminal and a first bus terminal and a second transistor coupled between a ground and a second bus terminal. The transient-triggered ring suppression circuit is coupled to the first and second transistors. The transient-triggered ring suppression circuit is configured to be enabled upon transition of the transceiver from a dominant state to a recessive state. Further, while the transceiver is in the recessive state, the transient-triggered ring suppression circuit is configured to attenuate ringing on at least one of the first or second bus terminals.