Battery Protection Circuit Module with Common Drain Structure
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Solution Overview
Problem
Conventional battery protection circuit modules experience a significant reduction in battery duration due to voltage drops caused by peak current and on-resistance during discharging, leading to increased manufacturing costs and reduced stability in portable products, as they require high-rated devices and shared ground with stationary devices.
Innovation Solution
The battery protection circuit module selectively activates only the necessary MOSFET switches during charging and discharging, utilizing a common drain structure to reduce on-resistance to half and maintain insulation from stationary devices, allowing for the use of low-rated devices and preventing abnormal input influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two switches are connected in series in the conventional protection circuit module, then electrical insulation is achieved in both directions, but the on-resistance doubles causing significant voltage drop during discharging
Solution Approach 1:
The patent applies dynamics by making the switch configuration adaptive rather than static. The controller dynamically selects between two different switch configurations based on the operational mode (charging or discharging). During discharging, only one switch is activated to minimize on-resistance and voltage drop. During charging, both switches are activated to ensure electrical insulation. This dynamic reconfiguration allows the system to optimize performance for each specific operational requirement.
2Power
If high-rated devices are used to handle peak current, then the system can handle high peak current, but the manufacturing cost increases significantly
Solution Approach 1:
The patent applies partial action by activating only the necessary number of switches based on the operational requirements. During discharging, only one switch is activated instead of two, which reduces the total on-resistance and allows the use of lower-rated (cheaper) devices that can handle the peak current when only one switch is in the circuit. This approach avoids the need to overspecify components for the worst-case scenario of two switches in series, thereby reducing manufacturing costs while still maintaining the ability to handle peak current effectively.
3Device complexity
If the protection circuit module shares ground with stationary devices, then system integration is simplified, but the portable product becomes vulnerable to abnormal input from stationary devices
Solution Approach 1:
The patent applies segmentation by separating the ground references into two distinct domains: an internal ground domain for the portable product and an external ground domain for the stationary charging device. The isolation switch acts as a boundary between these two segmented ground domains. This segmentation allows the portable product to maintain its own independent ground reference, protecting it from abnormal inputs while still enabling integration with external charging devices through controlled switching. The controller manages the isolation switch to maintain this segmented ground structure.
Data Source
AI summary
Disclosed herein is a battery protection circuit module device. The battery protection circuit module device includes a charging unit, a battery protection circuit module, and a system. The charging unit includes first and second MOSFET switches, and supplies externally input power to a battery or a system. The battery protection circuit module includes the battery, third and fourth MOSFET switches configured to be selectively turned on and off, a resistor and a capacitor configured to supply the voltage of the battery to the PCM controller as driving power, and the PCM controller configured to control the third and fourth MOSFET switches. The system is operated using the voltage of the battery or externally input voltage. The third and fourth MOSFET switches of the battery protection circuit module are connected via a common drain structure and a common drain terminal is connected to an internal ground.