Transmitting Module for CAN XL Bus Emission Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing transmitting modules for CAN XL bus systems face challenges in complying with strict emission limit values, particularly due to the conversion of differential signals into common mode signals, which leads to interference emissions.
Innovation Solution
A transmitting module with a full bridge configuration of four transmission stages and a current limiting circuit that measures and evaluates currents through bleeder resistors to control the operating mode and limit current, ensuring compliance with emission standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a full bridge configuration with four transmission stages is used to generate differential bus signals, then the data transfer rate can be increased to meet CAN XL requirements (>10 Mbit/s), but the current consumption increases and may exceed emission limit values specified in IEC62228-3
Solution Approach 1:
The patent implements dynamic current limiting that adapts the current consumption of the full bridge circuit based on operational conditions. The current limiting circuit dynamically adjusts the current through the bleeder resistors to maintain differential signal transmission while preventing excessive current draw that would violate emission standards. This dynamic adjustment allows the system to operate at high data rates when needed while consuming acceptable current levels during normal operation.
Solution Approach 2:
The patent changes the electrical parameters of the transmission circuit by introducing controllable resistance elements (bleeder resistors) whose values can be adjusted to optimize the balance between signal integrity and current consumption. By modifying the resistance parameters in real-time based on operational mode and signal requirements, the system achieves high-speed data transfer capability while maintaining compliance with emission limits through parameter optimization.
2Speed
If transmission stages are designed to generate differential bus signals for high-speed operation, then common mode voltage variation occurs which causes electromagnetic emissions, but reducing the transmission power degrades signal quality and increases error rates
Solution Approach 1:
The patent converts the harmful common mode voltage variation into a controllable parameter by using bleeder resistors to deliberately introduce controlled current paths. These resistors create predictable voltage drops that can be compensated for, transforming the uncontrolled harmful effect into a manageable design parameter. The current limiting circuit then uses this controlled configuration to suppress emissions while maintaining signal integrity.
Solution Approach 2:
The bleeder resistors act as intermediary elements between the transmission stages and the bus lines. They provide a controlled path for current flow that mediates the interaction between the high-speed differential signals and the common mode emissions. This intermediary configuration allows the system to achieve high-speed operation while the current limiting circuit suppresses the harmful electromagnetic emissions through the controlled resistance paths.
3Object-generated harmful factors
If strict current limit values are enforced to comply with IEC62228-3 emission standards, then electromagnetic emissions are reduced, but the ability to maintain signal integrity at high data rates is compromised
Solution Approach 1:
The patent employs dynamic current limiting that adapts to real-time signal conditions rather than enforcing static current limits. The current limiting circuit continuously monitors the differential signal quality and adjusts the current through the bleeder resistors accordingly. This dynamic approach allows the system to maintain signal integrity at high data rates while keeping emissions within acceptable limits by optimizing the current level for each operational condition.
Solution Approach 2:
The patent implements a feedback mechanism where the current limiting circuit monitors both the current consumption and the signal quality on the bus. Based on this feedback information, the circuit adjusts the resistance values or current paths to maintain optimal signal integrity while complying with emission standards. The feedback loop ensures that signal quality requirements are met even under strict current limiting conditions by making real-time adjustments to the transmission parameters.
Data Source
AI summary
A transmitting module and a method for transmitting differential signals in a serial bus system. The transmitting module has a first to a fourth transmission stage connected in a full bridge, in which the first and fourth transmission stage are connected in series and the third and second transmission stages are connected in series, and a current limiting circuit for measuring and evaluating currents through a first and a second bleeder resistor which are connected to the full bridge. The first to fourth transmission stages generate differential bus signals for a bus in response to the two different values of a digital transmit signal such that the transmitting module generates, in its first operating mode, a first or second bus state on the bus and generates, in its second operating mode, a third or fourth bus state.