Voltage Glitch Detector Circuit for MCU Supply Attack Response
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Solution Overview
Problem
Supply voltage glitches can cause unpredictable or unreliable circuit behavior, making electronic devices vulnerable to hacking and data breaches, particularly in microcontroller units (MCUs) of IoT devices.
Innovation Solution
A voltage glitch detector circuit comprising a current source, latch, and transistors is used to detect transient voltage deviations, triggering a reset or security action to protect against unauthorized commands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage glitch detection is implemented to improve security, then reliability is improved, but device complexity increases
Solution Approach 1:
The voltage glitch detector merges multiple functions into a single integrated circuit block within the MCU. The detector combines differential amplification, threshold comparison, and latch circuitry to simultaneously detect both over-voltage and under-voltage glitches, achieving comprehensive security protection without requiring separate detection circuits for each function.
Solution Approach 2:
The detector circuit is segmented into distinct functional modules: a differential amplifier stage for voltage comparison, a latch circuit for state retention, and trigger output mechanisms. This segmentation allows each module to perform its specific function efficiently while maintaining overall circuit simplicity and ease of integration into the MCU architecture.
2Reliability
If transient voltage deviations are detected to prevent hacking, then security is improved, but response time may be compromised by complex detection mechanisms
Solution Approach 1:
The detector employs preliminary action by continuously monitoring supply voltage through the differential amplifier before any glitch can affect CPU operation. The circuit is pre-configured with threshold levels and ready-to-trigger latch mechanisms that immediately respond to voltage deviations, eliminating detection delays and ensuring security actions are taken before hacking can occur.
Solution Approach 2:
The latch circuit provides feedback mechanisms that maintain the detected glitch state and trigger security responses. Once a voltage glitch is detected, the latch maintains the trigger signal to ensure security actions are executed, providing immediate feedback from detection to response without requiring additional processing delays.
Data Source
AI summary
In described examples, a voltage glitch detector includes a current source, a latch, and first, second, third, fourth, and fifth transistors. A source of the third transistor is coupled to a source of the second transistor, and a gate and drain of the third transistor is coupled to gates of the first and second transistors and a first terminal of the current source. A drain of the fourth transistor is coupled to a drain of the first transistor and an input of the latch. A source of the fifth transistor is coupled to a source of the fourth transistor and the second terminal of the current source. A gate and drain of the fifth transistor is coupled to a gate of the fourth transistor and a drain of the second transistor.