CAN Transceiver Attenuation Circuit for Common-Mode EMI
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Solution Overview
Problem
Controller Area Network (CAN) transceivers in vehicles are vulnerable to electromagnetic interference, which causes common-mode voltage disturbances that affect signal integrity and robustness, leading to potential operational failures.
Innovation Solution
An attenuation device is introduced, which has two output nodes that change electrical output resistance states based on common-mode voltage levels, attenuating common-mode disturbances by switching between two resistance states, ensuring the differential signal remains unaffected and improving transceiver robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the attenuation device switches to a second device state in response to common mode voltage exceeding reference voltages, then the electrical output resistance decreases to attenuate common mode disturbances, but this state change may affect the differential signal transmission
Solution Approach 1:
The attenuation device applies different resistance values selectively to different signal components: high resistance for common mode disturbances and low resistance for differential signals. This local differentiation in resistance quality allows the device to attenuate harmful common mode voltage while preserving the useful differential signal transmission.
Solution Approach 2:
The attenuation device dynamically changes its electrical output resistance based on the detected common mode voltage level. When common mode voltage exceeds reference thresholds, the device switches from a first device state to a second device state, adjusting resistance values in real-time to maintain robustness against electromagnetic interference while preserving signal integrity.
2Productivity
If the attenuation device uses a first electrical output resistance during normal operation, then signal transmission is maintained, but the device becomes vulnerable to common mode voltage disturbances
Solution Approach 1:
The attenuation device dynamically adjusts its electrical output resistance between two states based on operating conditions. During normal operation, it maintains a first device state with appropriate resistance for signal transmission. When common mode voltage exceeds reference thresholds, it switches to a second device state with different resistance values to attenuate electromagnetic interference, thus maintaining both productivity and reliability.
Solution Approach 2:
The attenuation device changes its electrical resistance parameter in response to common mode voltage levels. By switching between a first device state and a second device state with different resistance values, the device adapts to varying electromagnetic conditions, ensuring reliable signal transmission during normal operation and robustness against interference during disturbance conditions.
Data Source
AI summary
An attenuation device for a CAN transceiver comprises two device output nodes configured to electrically couple the attenuation device via the device output nodes between two transceiver terminals of the CAN transceiver. The attenuation device is configured to change from a first device state to a second device state when a common mode voltage is applied to the device output nodes that is either greater than a first reference voltage or less than a second reference voltage that is less than the first reference voltage. The attenuation device causes a first electrical output resistance at each device output node during the first device state and causes a second electrical output resistance at each device output node during the second device state in which the second output resistance is less than the first output resistance.