High-Voltage Interface Circuit with Overvoltage Protection
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Solution Overview
Problem
High-voltage systems interfacing with low-voltage microcontrollers face potential failure points due to latent defects in voltage regulators, leading to overvoltage or overcurrent events that exceed the Absolute Maximum Rating (AMR) of the microcontroller, risking catastrophic failure.
Innovation Solution
An interface circuit with a voltage regulator, restrictor element, voltage suppressor, and diagnostic circuit is employed to prevent overvoltage and overcurrent events by disconnecting the voltage regulator from the I/O circuitry when thresholds are exceeded, and providing an early warning through a diagnostic signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voltage regulator is used to power the I/O circuitry, then the I/O circuitry can operate at the required voltage level, but latent defects in the voltage regulator may cause overvoltage or overcurrent events that exceed the Absolute Maximum Rating of the microcontroller
Solution Approach 1:
The diagnostic circuit proactively monitors the voltage regulator's output voltage and current before catastrophic failure occurs. By detecting latent defects early through continuous comparison of actual values against predetermined thresholds, the system can take preventive action (such as shutting down the voltage regulator or isolating the affected circuit) before overvoltage or overcurrent events damage the microcontroller.
Solution Approach 2:
The voltage suppressor acts as an intermediary protective element between the voltage regulator and the I/O circuitry. When the diagnostic circuit detects abnormal conditions, the voltage suppressor activates to limit voltage spikes and current surges, thereby protecting the microcontroller from harmful electrical events while allowing normal operation to continue.
2Reliability
If protection mechanics are implemented to electrically separate the auxiliary device from the controller, then electrical overstress or failure events are prevented, but the system complexity increases
Solution Approach 1:
The diagnostic circuit, voltage suppressor, and protection mechanics are merged into a single integrated interface circuit that operates between the voltage regulator and the I/O circuitry. This consolidation provides comprehensive protection and monitoring functionality while minimizing the number of discrete components and interconnections required, thereby reducing overall system complexity compared to implementing separate protection mechanisms.
Solution Approach 2:
The interface circuit performs multiple functions simultaneously: it regulates voltage to the I/O circuitry, monitors for abnormal conditions through diagnostic circuitry, suppresses voltage and current spikes, and provides electrical isolation when needed. This multi-functionality eliminates the need for separate dedicated protection circuits, reducing component count and simplifying the overall system architecture.
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 interface circuit enhances system dependability by preventing catastrophic failures and enabling compliance with safety standards like Automotive Safety Integrity Level D (ASIL D), ensuring reliable operation in safety-critical applications.
Implementation Method 1
a restrictor element that is disposed between the voltage regulator and the I/O circuitry, the restrictor element being disposed on a circuit path that connects the voltage regulator to the I/O circuitry, the restrictor element being configured to open the circuit path and disconnect the voltage regulator from the I/O circuitry when an electrical current that is being supplied to the I/O circuitry exceeds a threshold
Implementation Method 2
a voltage suppressor that is disposed on the circuit path that connects the voltage regulator to the I/O circuitry, the voltage suppressor being disposed between the restrictor element and the I/O circuitry, the voltage suppressor being configured to limit, to a first voltage value, a voltage that is input into the I/O circuitry
Implementation Method 3
a diagnostic circuit that is configured to: (i) compare a second voltage value to a voltage that is output by the voltage regulator, and (ii) when the voltage that is output by the voltage regulator matches the second voltage value, output an indication that the voltage regulator is malfunctioning
Data Source
AI summary
An interface circuit, comprising: I/O circuitry configured to couple one or more first terminals with one or more second terminals; a voltage regulator configured to power the I/O circuitry; a restrictor element that is disposed between the voltage regulator and the I/O circuitry, the restrictor element being disposed on a circuit path that connects the voltage regulator to the I/O circuitry, the restrictor element being configured to open the circuit path and disconnect the voltage regulator from the I/O circuitry when an electrical current that is being supplied to the I/O circuitry exceeds a threshold; and a voltage suppressor that is disposed on the circuit path that connects the voltage regulator to the I/O circuitry, the voltage suppressor being disposed between the restrictor element and the I/O circuitry, the voltage suppressor being configured to limit, to a first voltage value, a voltage that is input into the I/O circuitry.