Bi-stable Silicon Overcurrent Limiter with Reset
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Solution Overview
Problem
Existing circuit protection devices, such as fuses, provide overcurrent protection but are non-reversible, rendering protected elements inactive until replacement, and do not simultaneously offer overvoltage protection functions effectively.
Innovation Solution
A bi-stable over-current limiter integrated into a silicon substrate with a series pass element and current sense element, switching between two resistance states to limit current when exceeding a predetermined level, and optionally combined with shunt overvoltage protection to manage voltage spikes independently or trigger current limiting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fuse is used for overcurrent protection, then current exceeding a predetermined limit is terminated, but the protected elements are rendered inactive until fuse replacement
Solution Approach 1:
The patent implements a bi-stable latch circuit that can be reset after triggering. When overcurrent is detected, the circuit switches to a high-resistance state to limit current, but unlike a fuse, it can be recovered by resetting the latch, allowing the protected circuit to resume normal operation without component replacement
Solution Approach 2:
The patent creates a dynamic protection system with two stable states (low resistance and high resistance) rather than a static one-way fuse. The circuit can transition between states based on current conditions and can be reset to return to normal operation, providing adaptive protection while maintaining circuit availability
2Reliability
If overvoltage protection devices are used, then voltage spikes are protected against, but they may not serve the same over current protection functions as a fuse
Solution Approach 1:
The patent combines overcurrent protection and overvoltage protection into a single integrated circuit. The device can detect and respond to both excessive current conditions (through the sense element monitoring current) and overvoltage conditions (through the avalanche diode), providing multi-functional protection in one component
3Reliability
If a series pass element switches to high resistance state to limit current, then overcurrent is prevented, but the circuit must be reset to return to low resistance state
Solution Approach 1:
The patent implements a self-resetting mechanism where the circuit automatically returns to its low-resistance state once the overcurrent condition is removed and a reset signal is applied. The bi-stable latch design allows the circuit to service itself by maintaining the protection state only as long as needed, then automatically recovering without requiring external intervention beyond a simple reset signal
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
Enables reversible current limiting, allowing the protection circuit to return to a low resistance state after an overcurrent condition is resolved, and provides simultaneous overvoltage protection without rendering protected elements inactive, enhancing circuit safety and functionality.
Implementation Method 1
a series current sense element integrated into the silicon substrate and configured to receive the input current and to output a sense voltage based upon the received input current
Implementation Method 2
a series pass element having a pass state characterized by a first electrical resistance and a limit state characterized by a second electrical resistance higher than the first electrical resistance
Data Source
AI summary
An overcurrent protection device may include an input terminal to receive an input current; an output terminal coupled to the input terminal; and a current limiter circuit integrated into the silicon substrate and arranged between the input terminal and output terminal. The current limiter circuit may include a series pass element having a pass state characterized by a first electrical resistance and a limit state characterized by a second electrical resistance higher than the first electrical resistance, the series pass element comprising a series current sense element integrated into the silicon substrate and configured to receive the input current and to output a sense voltage based upon the received input current, wherein the series pass element is configured to place the current limiter circuit into the limit state when the sense voltage indicates that the input current exceeds a predetermined level.