Semiconductor Protection Circuit for Battery Pack Reverse Charger
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Solution Overview
Problem
Existing semiconductor protection circuits for rechargeable secondary batteries fail to maintain stable output voltage when a reverse charger connection state occurs, leading to parasitic transistor operation and leak currents that can damage the battery monitoring IC.
Innovation Solution
Incorporating a leak detection circuit with a switch and pull-down resistor to detect and mitigate leak currents, ensuring the output voltage of the regulator remains within a predetermined range by connecting the pull-down resistor to the output terminal when a reverse charger connection is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reverse charger connection state occurs, then the voltage at terminal P- rises and a parasitic transistor operates, but this generates a leak current that causes the output voltage of the regulator to rise and may damage the battery monitoring IC
Solution Approach 1:
The leak detection circuit proactively monitors for the presence of leak current before it can cause damage to the battery monitoring IC. When a reverse charger connection is detected and parasitic transistor operation begins, the circuit immediately activates the switch to connect the pull-down resistor, preventing the harmful voltage rise before it occurs.
Solution Approach 2:
The parasitic transistor, which initially causes harmful leak current, is converted into a useful detection mechanism. The leak current generated by parasitic transistor operation serves as a signal that triggers the protective response, transforming the harmful effect into a beneficial detection and protection mechanism.
2Reliability
If the output voltage of the regulator rises due to leak current, then damage to the battery monitoring IC may occur, but adding protection circuitry increases device complexity
Solution Approach 1:
The protection functionality is merged into the existing regulator circuit by integrating a leak detection circuit that shares the regulator's output terminal. The switch and pull-down resistor are combined with the regulator to form a unified protection system, eliminating the need for separate protection circuits and reducing overall device complexity.
Solution Approach 2:
The protection circuit serves itself by using the leak current generated during reverse charger connection as the trigger signal. The same parasitic transistor operation that creates the harmful effect also provides the detection signal, eliminating the need for external monitoring circuits and simplifying the overall system.
3Stability of the object's composition
If a switch is connected to the output terminal of the regulator to mitigate leak current, then the output voltage stability is improved, but the device complexity increases due to additional components
Solution Approach 1:
The protection circuit employs a dynamic switch that changes state based on the detection of reverse charger connection conditions. The switch is normally open and only closes when needed, allowing the circuit to adapt its configuration dynamically rather than requiring permanent additional components in the signal path.
Solution Approach 2:
The pull-down resistor acts as an intermediary element that safely dissipates the leak current through a controlled path. By introducing this intermediate component, the harmful direct connection is replaced with a mediated path that protects the battery monitoring IC while maintaining circuit functionality.
Data Source
AI summary
A semiconductor integrated circuit includes a regulator including an output terminal; a switch connected to the output terminal of the regulator; a pull-down resistor connected to the switch; and a leak detection circuit configured to detect a leak current generated in the semiconductor integrated circuit, and turn on the switch when the leak current is detected so that the pull-down resistor is connected via the switch to the output terminal of the regulator and a voltage output from the output terminal of the regulator is pulled down by the pull-down resistor.