LIN Bus Circuit With Adaptive dV/dt Control for EMI Immunity
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Solution Overview
Problem
Current Local Interconnected Network (LIN) transmitters face challenges with Electromagnetic Interference (EMI) and Electromagnetic Immunity due to radio frequency disturbances, which affect communication fidelity and emission performance, especially with varying load impedances on the LIN bus, and existing solutions either lack control over RF disturbances or compromise on emission performance.
Innovation Solution
A digital circuit arrangement with adaptive slope control is introduced, utilizing a current source driven by digital-analog converting means and digital comparing means to maintain a constant voltage dV/dt, incorporating digital feedback to correct current dI/dt variations, thereby improving EMI and immunity performance while allowing operation under RF disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a current output stage is used to prevent RF signals from disturbing the LIN bus, then EMI immunity is improved, but electromagnetic emission increases due to higher dV/dt with varying loads
Solution Approach 1:
The patent implements a feedback mechanism that monitors the actual dV/dt at the LIN bus output and adjusts the current output stage in real-time to maintain a constant dV/dt. This feedback loop compensates for load variations, preventing excessive electromagnetic emission while maintaining immunity to RF disturbances through the current output stage architecture.
Solution Approach 2:
The patent dynamically changes the output current parameters based on detected load conditions. By adjusting the current magnitude and timing in response to load variations, the system maintains constant dV/dt characteristics, thereby controlling electromagnetic emission while preserving EMI immunity performance across different operating conditions.
2Object-generated harmful factors
If voltage feedback output stage is used to control output under RF disturbance, then EMI emission is reduced, but control capability under RF disturbance is lost
Solution Approach 1:
The patent employs feedback control that continuously monitors the LIN bus conditions and adjusts the current output stage accordingly. This allows the system to maintain control capability under RF disturbances by detecting bus state changes and adapting the output current to preserve intended signal transmission despite interference.
Solution Approach 2:
The patent uses a current output stage with constant dV/dt control that is inherently more robust to RF disturbances than voltage feedback stages. The current output architecture provides natural immunity without requiring complex compensation circuits, making it a more reliable choice for RF-prone environments despite the need for dV/dt management.
3Object-affected harmful factors
If current source is used to control voltage on LIN bus line, then EMI immunity is improved, but manufacturing precision deteriorates due to load-dependent voltage variations
Solution Approach 1:
The patent implements feedback control that measures the actual voltage developed across the LIN bus line and adjusts the current source output to compensate for load variations. This ensures that despite changes in load impedance, the voltage control precision is maintained while retaining the EMI immunity benefits of the current source architecture.
Solution Approach 2:
The patent makes the current source dynamically adaptive by continuously adjusting its output based on detected load conditions and bus state. This dynamic adjustment capability allows the system to maintain precise voltage control across varying loads while preserving the inherent EMI immunity of current-mode operation.
Data Source
AI summary
Circuit arrangement, LIN comprising such circuit arrangement as well as method for processing input signals of the LIN In order to further develop a circuit arrangement (100)—for processing at least one input signal (12) from at least one data bus (10) of at least one LIN and—for providing the data bus (10) with at least one output signal (18), as well as a corresponding operating method in such way that EMI performance and/or EMI performance of the LIN (300) is improved, it is proposed to provide—at least one analog-digital converting circuit (ADC) for converting the analog input signal (12) into at least one digital signal (14) to be processed, and—at least one digital-analog converting circuit (DAC) for converting the processed digital signal (16) into the analog output signal (18).