Circuit Arrangement for Overvoltage Protection in Automotive Electronics
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Solution Overview
Problem
Conventional circuit arrangements for protecting electronic assemblies against overvoltages in the automotive sector face challenges such as significant voltage drops, power losses, and high costs due to the use of Zener diodes, which restrict their effectiveness in managing both positive and negative overvoltages, especially in analog sensor paths where energy must not be drawn from the signal within the regular voltage range.
Innovation Solution
A circuit arrangement featuring a comparator and an electronically controllable switch, specifically an IG-FET, which compares the voltage source with a reference voltage to control the switch's operation, ensuring minimal voltage drop and power loss by disconnecting the electronic assembly from the voltage source during overvoltage conditions, thereby protecting against both positive and negative overvoltages without drawing energy from the signal within the regular voltage range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Zener diodes are used for overvoltage protection, then protection against positive and negative overvoltages is achieved, but significant voltage drops and power losses occur
Solution Approach 1:
The patent employs dynamically controllable MOSFET switches instead of static Zener diodes. The MOSFETs are controlled by comparators that monitor voltage levels, enabling the protection circuit to adapt its behavior based on real-time voltage conditions. This dynamic control allows the circuit to maintain low impedance during normal operation (minimizing power loss) while providing effective protection during overvoltage events.
Solution Approach 2:
The invention changes the operating parameters of the protection circuit by using voltage-controlled resistance characteristics of MOSFETs. By adjusting the gate voltage of the MOSFETs through comparator-controlled switches, the circuit impedance can be dynamically changed from low (during normal operation) to high (during overvoltage protection), thereby reducing power loss while maintaining protection effectiveness.
2Reliability
If protective devices are added to protect against overvoltages, then operational safety is improved, but voltage drop increases affecting sensor signal accuracy
Solution Approach 1:
The protection circuit uses dynamically controllable MOSFET switches that remain in a low-impedance state during normal operation, allowing sensor signals to pass through with minimal distortion. Only when overvoltage conditions are detected do the MOSFETs switch to a high-impedance state, thereby maintaining measurement precision during normal operation while providing safety protection when needed.
Solution Approach 2:
The patent introduces comparator circuits as intermediary elements that monitor voltage levels and control the MOSFET switches. These comparators act as mediators between the sensor signals and the protective switching elements, ensuring that the protection mechanism is activated only when necessary, thus preserving signal accuracy during normal operation.
3Device complexity
If redundant electronic assemblies are powered by a common supply voltage, then system complexity is reduced, but common-origin faults can destroy all redundant assemblies
Solution Approach 1:
The patent implements segmentation by providing each redundant electronic assembly with its own independent protective device. This segmentation isolates fault propagation, so that a failure in one assembly's protection circuit does not affect other redundant assemblies. Each assembly maintains its own protection mechanism, ensuring fault independence while keeping the overall system relatively simple.
Solution Approach 2:
The protective devices act as intermediary elements between the common power supply and individual electronic assemblies. These intermediaries isolate each assembly from common-mode failures in the power supply, allowing the assemblies to remain electrically independent even when sharing a common power source, thereby preventing common-origin faults from destroying all redundant assemblies simultaneously.
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 provides reliable protection against overvoltages with negligible voltage drop and power loss, ensuring the electronic assembly operates within safe parameters without distorting analog sensor signals, thus meeting high security standards and reducing component costs.
Implementation Method 1
The comparator is configured to compare a voltage of the voltage source with a reference voltage and to control the switch accordingly
Implementation Method 2
The switch is connected in series with the electronic assembly... ensuring minimal voltage drop and power loss by disconnecting the electronic assembly from the voltage source during overvoltage conditions
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a circuit arrangement for protecting an electronic assembly (4), comprising the electronic assembly (4), a voltage source (1) and a first sub-circuit connected between the electronic assembly (4) and the voltage source (1), the first sub-circuit comprising a comparator (42) and an electronically controllable switch (43), the comparator (42) being designed to compare a voltage of the voltage source (1) with a comparison voltage and to control the switch (43) in dependence thereon, and the switch (43) being connected in series with the electronic assembly (4).