Interface Circuit Supply Interruption Detection via Signal Comparison
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Solution Overview
Problem
Existing interface circuits face challenges in detecting power supply interruptions without causing damage due to parasitic current paths and wide supply voltage ranges, which can lead to malfunctions and increased implementation costs.
Innovation Solution
An interface circuit with a protective circuit and an error detection circuit that compares the supply signal with a data signal to generate an error signal, using comparators and level reduction circuits to normalize signal levels and detect potential drops indicative of power supply interruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the protective circuit uses diodes connected between data inputs and supply inputs to protect against overvoltages, then the circuit is protected against ESD and overvoltage, but parasitic current paths are created that can cause damage when power supply is interrupted
Solution Approach 1:
The patent introduces an error detection circuit as an intermediary component that monitors the supply voltage and data signal levels. This circuit detects when parasitic current paths are active by comparing voltage levels, allowing the system to identify error conditions without the protective diodes themselves causing damage. The intermediary detection mechanism enables safe operation by recognizing when protective circuits are inadvertently conducting current.
Solution Approach 2:
The error detection circuit provides feedback about the operational state of the protective circuits. By continuously monitoring voltage levels at the data inputs and supply inputs, the system receives feedback that indicates when parasitic current paths are active. This feedback mechanism allows the system to respond appropriately to error conditions, preventing damage while maintaining the protective function.
2Reliability
If the error detection circuit compares supply signal with data signal directly, then power supply interruptions can be detected, but the wide supply voltage range causes measurement inaccuracies
Solution Approach 1:
The patent transforms the voltage comparison problem by changing the parameter being measured. Instead of directly comparing absolute voltage levels which are affected by wide supply voltage ranges, the error detection circuit detects voltage differences and transitions. This parameter change from absolute level to differential change allows accurate detection of power supply interruptions regardless of the nominal supply voltage level.
Solution Approach 2:
The error detection circuit dynamically adapts to different supply voltage levels by monitoring changes rather than fixed thresholds. The circuit responds to dynamic voltage transitions and differences, allowing it to function accurately across a wide range of supply voltages. This dynamic approach enables the system to detect power supply interruptions without being constrained by a narrow voltage range.
3Object-affected harmful factors
If series resistors are added to data inputs to prevent parasitic current flow, then damage is prevented during power supply interruption, but implementation costs and circuit complexity increase
Solution Approach 1:
The error detection circuit serves multiple functions: it detects power supply interruptions, identifies parasitic current path activation, and provides system state monitoring. By consolidating these detection functions into a single circuit block, the patent avoids the need for additional series resistors at each data input. This multi-functional approach reduces overall circuit complexity while achieving the same protective effect.
Solution Approach 2:
The patent combines the error detection and protective functions into an integrated circuit solution. Rather than adding separate series resistors to each data input line, the error detection circuit consolidates the protective functionality at a central location. This merging of functions reduces the total number of components and simplifies the overall circuit implementation while maintaining protection against parasitic current damage.
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
Effectively detects power supply interruptions without causing damage, ensuring stable operation and reducing implementation costs by preventing parasitic current flows and handling wide supply voltage ranges.
Implementation Method 1
an error detection circuit which is coupled to the supply input and to the at least one data input and which is designed to compare a supply signal applied to the supply input with a data signal applied to the at least one data input
Implementation Method 2
a diode 11, 12, 13, 14 is connected between each of the data inputs IN_D1, IN_Dn and each of the supply inputs IN_VDD, IN_VSS. The diodes 11, 13 connected between the data inputs IN_D1, IN_Dn and the first supply input IN_VDD ensure that the potentials at the data inputs IN_D1, IN_Dn can rise above the value of the positive supply potential VDDext by no more than the value of the forward voltage of a diode.
Data Source
AI summary
An interface circuit comprises at least one supply input and at least one data input with a protective circuit coupled between the at least one supply input and the at least one data input. A power supply circuit is coupled to the at least one supply input. The interface circuit further comprises an error detection circuit coupled to the supply input and to the at least one data input. The error detection circuit is designed to compare a supply signal applied to the supply input with a data signal applied to the at least one data input and to generate an error signal on the basis of the comparison result.