Programmable Battery Protection Circuit with Fuse-Based Threshold Adjustment
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Solution Overview
Problem
Conventional battery protection systems face challenges in accurately detecting overcurrent and short conditions due to variations in the on-resistance of charging and discharging FETs, leading to inadequate protection and potential safety risks.
Innovation Solution
A programmable battery protection system utilizing an array of fuses, latches, and MOSFETs, coupled with a comparator and fuse refresh circuit, generates a threshold voltage to detect overcurrent and short conditions by reading and refreshing the states of fuses, ensuring accurate disconnection of the battery from the load or charger.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional battery protection systems use fixed threshold values for overcurrent detection, then the system structure is simple, but the detection accuracy deteriorates due to FET on-resistance variations
Solution Approach 1:
The patent implements dynamic threshold adjustment by using a fuse array to store multiple threshold values and selectively activating them based on detected FET on-resistance variations. The system dynamically adapts the overcurrent threshold during operation rather than using a fixed value, thereby maintaining detection accuracy despite component parameter variations.
Solution Approach 2:
The system changes the detection threshold parameter based on the actual FET on-resistance characteristics. By measuring the on-resistance and selecting appropriate threshold values from the fuse array, the system adjusts the detection parameters to match the specific component characteristics, resolving the contradiction between simple structure and accurate detection.
2Measurement precision
If the system uses an array of fuses and latches to generate threshold voltage, then the detection accuracy improves, but the device complexity increases
Solution Approach 1:
The fuse array is pre-configured with multiple threshold voltage values during manufacturing. This preliminary action allows the system to have multiple detection thresholds ready in advance, eliminating the need for complex real-time calculation circuits while maintaining high detection accuracy through selective activation of appropriate thresholds.
Solution Approach 2:
The system uses its own operating parameters (FET on-resistance measurements) to automatically select and activate the appropriate threshold values from the fuse array. This self-service mechanism eliminates the need for external calibration or complex control logic, achieving accurate detection with moderate circuit complexity.
3Reliability
If the system automatically refreshes latch states from fuse array, then the reliability improves, but the use of energy increases
Solution Approach 1:
The system performs automatic refresh of latch states from the fuse array periodically or under specific trigger conditions rather than continuously. This periodic action maintains data reliability by ensuring latches reflect current fuse states while minimizing energy consumption by avoiding unnecessary refresh operations during normal operation.
Data Source
AI summary
A programmable battery protection system. Implementations may include: a battery, only two field effect transistors (FETs) coupled with the battery, and a battery protection integrated circuit (IC) coupled with the FETs. The battery protection IC may include an array of fuses, a plurality of latches coupled with the array of fuses, and a comparator coupled with the plurality of latches. The array of fuses and the plurality of latches may be coupled with a fuse refresh circuit coupled with a trigger circuit where the fuse refresh circuit is configured to refresh the states of the plurality of latches using states of the array of fuses in response to receiving one of a power on signal and an operating trigger signal generated by the trigger circuit. The plurality of latches may be used to generate a threshold voltage that is provided to the comparator.