Output Driver Feedback Circuit for Open and Short Fault Detection

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Solution Overview

Problem

Existing electronic systems face challenges in detecting faults at output drivers, particularly open and short circuit conditions, which can lead to serious implications such as system failures in critical applications like automotive emergency braking systems.

Innovation Solution

A feedback signal system is introduced to detect faults at output drivers by monitoring transition times and using error logic to identify anomalies, which can be applied to both voltage and current-based interfaces, enabling detection of open and short circuit faults and other anomalous load characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If test-scan technology is used to evaluate latch devices, then logic state detection is improved, but fault detection at output drivers remains insufficient

Engineering Contradiction:
Improvelogic state detectionVSAvoidfault detection capability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where the output driver's signal is fed back through the transmission medium to a receiver that compares the received signal with the transmitted signal. This feedback loop enables detection of faults in the transmission medium and output driver by identifying discrepancies between transmitted and received signals, directly addressing the insufficiency of conventional test-scan technology for output driver fault detection.

Inventive Principle:
Principle #23Feedback

2Reliability

If built-in self-test is used to validate functional blocks, then operational validation is improved, but output driver fault identification becomes more difficult

Engineering Contradiction:
Improveoperational validationVSAvoidoutput driver fault detection
Core Design Contradiction:
ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent introduces an intermediary receiver component that acts as a mediator between the output driver and the test system. This receiver includes comparison logic that directly compares transmitted and received signals, serving as an intermediary mechanism that simplifies output driver fault detection while maintaining operational validation capabilities through the same feedback pathway.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of manufacture

If conventional testing protocols are used, then manufacturing process is simple, but fault detection capability at output drivers is insufficient

Engineering Contradiction:
Improvetesting protocol simplicityVSAvoidfault detection precision
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent merges the functional operation pathway with the fault detection pathway by using the same output driver, transmission medium, and receiver for both normal operation and fault detection. This consolidation eliminates the need for separate test circuitry, maintaining manufacturing simplicity while achieving precise fault detection through the integrated feedback comparison mechanism.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3477317B1Method for identifying a fault at a device output and system therefor
Publication Date: 2021.04.07 NXP BV
  • EP3477317B1 patent drawingFigure 1
  • EP3477317B1 patent drawingFigure 2
  • EP3477317B1 patent drawingFigure 3

AI summary

A device comprising includes an output terminal and a first current path from the output terminal to a first reference voltage. The first current path includes a series connection of current electrodes of a first transistor and a second transistor. The first transistor receives at a control electrode a signal to set a desired level of current to be conducted by the first current path. The second transistor generates at a control electrode a feedback signal indicative of an actual current conducted by the first transistor.