Overcurrent Protection Circuit with Dynamic Current Limiting
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Solution Overview
Problem
Existing overcurrent protection circuits in integrated circuits face challenges in effectively limiting current during overcurrent conditions without producing unnecessary static current and in accurately sizing fuses for adequate protection.
Innovation Solution
An overcurrent protection system comprising a comparator circuit and a control circuit that activate a switch between a supply voltage and an output voltage, limiting current to predetermined levels and using a temperature compensation control circuit to maintain constant current over a range of temperatures, reducing static current by deactivating components during normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a current limiting circuit is used to limit load current during overcurrent conditions, then the integrated circuit is protected against excessive loads, but the circuit produces a high level of static current (e.g., around at least 130 μA) which is not desirable for protection
Solution Approach 1:
The circuit dynamically switches between different operational states (normal operation vs. overcurrent protection) based on real-time conditions. The control circuit activates the current limiting function only when overcurrent is detected, allowing the circuit to adapt its behavior to minimize static current consumption during normal operation while providing protection when needed
Solution Approach 2:
The circuit changes its electrical parameters (current limiting threshold, switch resistance) based on the operational state. During normal operation, the circuit maintains low static current by keeping protection components in high-impedance states. When overcurrent is detected, parameters are adjusted to enable effective current limiting, thus resolving the contradiction between protection effectiveness and static current consumption
2Reliability
If fuses are used in the protection circuit to provide adequate protection during overcurrent conditions, then the circuit gains overcurrent protection capability, but it becomes difficult to properly size the fuses for adequate protection
Solution Approach 1:
The patent replaces the passive mechanical fuse with an active electronic protection circuit comprising switches, comparators, and control logic. This substitution eliminates the need for difficult fuse sizing calculations while providing programmable and adjustable protection thresholds, thereby maintaining protection effectiveness while reducing design complexity
Solution Approach 2:
The protection circuit incorporates feedback mechanisms that continuously monitor current levels and automatically adjust protection parameters. This feedback system eliminates the need for manual fuse sizing by dynamically adapting to actual operating conditions, simplifying the design process while ensuring adequate protection
3Stability of the object's composition
If a temperature compensation control circuit is added to maintain constant current over a range of temperatures, then the current remains substantially constant between predetermined first and second current levels over temperature variations, but the device complexity increases
Solution Approach 1:
The circuit utilizes temperature-dependent characteristics of semiconductor components to automatically compensate for temperature variations. By designing the protection circuit to exploit inherent thermal effects in transistors and resistors, the system achieves temperature-stable current limiting without requiring complex external compensation components, thus balancing stability improvement with minimal complexity increase
Data Source
AI summary
An overcurrent protection system and method are disclosed. In one embodiment the overcurrent protection system includes a first switch connected between a supply voltage and an output voltage. A comparator circuit provides a comparator output signal having first and second values that depend on a comparison of the output voltage relative to the supply voltage, the first value indicating an overcurrent condition. A control circuit is coupled to provide a control signal to a control node of the first switch for controlling the first switch in one of first and second operating modes according to the value of the comparator output signal. The control circuit controls the first switch in the first mode to limit the current through the first switch to a level between predetermined upper and lower current levels in response to the comparator output signal having the first value. The control circuit activating the first switch to a normally on condition in the absence of the comparator output signal having the first value.