LIN Receiver Deglitching for ISO Pulse Immunity
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Solution Overview
Problem
Local Interconnect Network (LIN) receiver circuits are susceptible to Interrupt Source Output (ISO) pulses, leading to incorrect receiver output signals due to interference, despite existing designs providing immunity to radio frequency (RF) pulses.
Innovation Solution
A LIN receiver circuit incorporating comparator, voltage-adjusting, and deglitcher circuitry to filter and compare input signals with hysteresis threshold values, adjust voltages to shorten glitches, and remove effective glitches from the output signal, thereby providing immunity to ISO pulses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If known receiver circuits are designed in accordance with conformance testing and proper emission criteria to provide immunity to RF pulses, then RF pulse immunity is improved, but susceptibility to ISO pulses remains
Solution Approach 1:
The voltage-adjusting circuitry detects the ISO pulse condition and proactively adjusts the filtered signal voltage to shorten the glitch duration before it can cause harmful effects. This preliminary action prevents the glitch from propagating to the output stage, thereby resolving the ISO pulse susceptibility while maintaining RF pulse immunity
Solution Approach 2:
The filtered signal acts as an intermediary between the input signal and the hysteresis comparator. By adjusting the voltage of this intermediate signal, the circuit isolates the comparator from direct ISO pulse effects, allowing RF pulse immunity to be maintained while blocking ISO pulse propagation
2Reliability
If voltage-adjusting circuitry is added to shorten glitch duration, then ISO pulse immunity is improved, but circuit complexity increases
Solution Approach 1:
The voltage-adjusting circuitry is integrated into the existing receiver signal path and works cooperatively with the filtering and comparison stages. This multi-functional approach allows a single circuit block to serve both RF pulse rejection and ISO pulse mitigation functions, minimizing the increase in overall circuit complexity
3Manufacturing precision
If deglitcher circuitry is used to remove shortened effective glitch, then output signal quality is improved, but processing time increases
Solution Approach 1:
The voltage-adjusting circuitry performs preliminary glitch shortening before the signal reaches the deglitcher stage. This pre-processing reduces the glitch duration to a level where the deglitcher can remove it with minimal delay, thereby improving output signal quality while minimizing processing time penalty
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 prevents incorrect low states on the receiver output signal, ensuring the LIN receiver circuit operates within the specified immunity criteria, maintaining signal integrity against ISO pulses without introducing delays exceeding 7.5 μs.
Implementation Method 1
comparator circuitry operable to compare a filtered input signal to a first or second hysteresis threshold value and output a hysteresis signal
Implementation Method 2
voltage-adjusting circuitry operable, in response to the detection of said low transient voltage, to adjust a voltage of said filtered signal to shorten said effective glitch
Data Source
AI summary
A LIN receiver circuit includes filtering circuitry receiving an input signal and producing a filtered signal, a first comparator comparing the filtered signal to a threshold voltage, and a driver block producing the receiver output signal. The receiver circuit further includes an input comparator, signal-adjusting circuitry, and deglitching circuitry. The input comparator detects a low voltage on the input signal, and the signal-adjusting circuitry drives the filtered signal to a particular value to shorten the length of a glitch at the output of the first comparator. Meanwhile, the deglitching circuitry detects and removes the glitch to produce a deglitcher output signal. The deglitcher output signal is received by the driver block, which outputs the receiver output signal, wherein the receiver output signal contains no glitches, and is delayed by no more than 7.5 μs, thus providing immunity to ISO pulses.