CAN Bus Transceiver Emissions Reduction via Dynamic Voltage Control
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Solution Overview
Problem
The high differential bus voltage in CAN bus systems leads to increased radiated emissions, affecting electromagnetic compatibility (EMC) and power consumption, which existing transceivers struggle to mitigate effectively.
Innovation Solution
A transceiver with an emissions reduction unit that controls the differential bus voltage by measuring its level and adjusting it to a setpoint value, using a detector and evaluation unit to influence the driver circuit, thereby reducing stray radiation and adapting to varying bus topologies and load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the differential bus voltage VDIFF is increased to meet ISO standard requirements, then the reliability of data transmission is improved, but the radiated emissions at the bus lines increase
Solution Approach 1:
The transceiver dynamically adjusts the differential bus voltage VDIFF based on the actual number of subscriber stations connected to the bus. The control unit monitors the bus load and adapts the voltage level in real-time, using higher voltages when few stations are connected and lower voltages when many stations are connected, thus resolving the contradiction between maintaining reliable transmission and reducing radiated emissions.
Solution Approach 2:
The invention changes the operating parameter (differential bus voltage VDIFF) of the transceiver based on the bus configuration. By varying the voltage parameter according to the number of connected subscriber stations, the system achieves both reliable data transmission and reduced electromagnetic emissions, directly addressing the technical contradiction.
2Reliability
If the differential bus voltage VDIFF is increased to ensure reliable transmission, then the signal strength is improved, but the power consumption increases
Solution Approach 1:
The transceiver employs dynamic power management by adjusting the differential bus voltage according to the actual bus load. When fewer subscriber stations are connected, higher voltage is used to ensure reliable transmission. When more stations are connected, the voltage is reduced, thereby lowering power consumption while maintaining sufficient signal strength for reliable communication.
Solution Approach 2:
The invention changes the voltage parameter adaptively based on the number of connected subscriber stations. This parameter adjustment ensures that the transceiver consumes only the necessary power for reliable transmission in each specific configuration, resolving the contradiction between signal strength and power consumption.
3Adaptability or versatility
If a fixed high differential bus voltage is used to meet ISO standards, then the compatibility with different load resistances is improved, but the electromagnetic compatibility (EMC) deteriorates
Solution Approach 1:
The transceiver dynamically adapts the differential bus voltage to match the actual bus conditions. By monitoring the number of connected subscriber stations and adjusting the voltage accordingly, the system maintains compatibility with different load resistances while minimizing electromagnetic emissions, thus resolving the contradiction between load compatibility and EMC.
Solution Approach 2:
The invention changes the operating voltage parameter based on the actual bus configuration and load conditions. This adaptive parameter adjustment ensures compatibility with various load resistances while reducing electromagnetic emissions, directly addressing the contradiction between versatility and EMC.
Data Source
AI summary
A transceiver for a CAN bus system and a method for reducing line-associated emissions. The transceiver includes a transmitter for transmitting a transmitted signal to a first bus wire of a bus of the bus system, and for transmitting the transmitted signal to a second bus wire of the bus, the bus system being ensured exclusive, collision-free access of a subscriber station to the bus of the bus system at least temporarily; a receiver for receiving the bus signal transmitted on the bus wires; and an emissions reduction unit which is configured to control the signals for the bus wires on the basis of a measured level of a differential bus voltage of the signals on the bus wires, when a dominant state of the transmitted signal occurs.