Secondary Battery Protecting IC Voltage Detection Accuracy
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Solution Overview
Problem
Conventional secondary battery protecting circuits inaccurately detect battery voltage due to voltage drops across transistors, leading to inefficient charging methods and prolonged charging times.
Innovation Solution
A secondary battery protecting integrated circuit with a switch circuit and abnormality detecting circuit that monitors the battery voltage by minimizing voltage drops through separate monitoring terminals and internal switches, allowing accurate detection and control of charging/discharging processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the charging IC monitors terminal voltage through transistors with ON resistance, then the battery can be protected from charge and discharge abnormalities, but the terminal voltage becomes higher than the actual battery voltage due to voltage drop, resulting in inaccurate battery voltage detection
Solution Approach 1:
The patent divides the voltage monitoring function into two separate paths: one path through transistors for protection control, and another dedicated sense terminal path for accurate voltage detection. This segmentation allows each path to perform its specific function without interference, resolving the contradiction between protection reliability and measurement accuracy.
Solution Approach 2:
The patent introduces a sense terminal as an intermediary component that provides a direct voltage sensing path bypassing the transistors. This intermediary element enables accurate battery voltage detection without being affected by the voltage drops in the protection transistor path.
2Reliability
If the charging IC switches to constant voltage charging earlier due to inaccurate voltage detection, then battery overcharging is prevented, but the constant current charging phase is shortened and overall charging time increases
Solution Approach 1:
The patent replaces the indirect voltage detection method (through transistor voltage drops) with a direct sensing mechanism via the sense terminal. This substitution eliminates the measurement error that caused premature switching, allowing the charging process to follow the optimal CC-CV timeline.
3Reliability
If transistors are used for charge and discharge control, then the battery can be protected from abnormalities, but the ON resistance of transistors causes voltage drop that affects voltage detection accuracy
Solution Approach 1:
The patent separates the power control function (performed by transistors) from the voltage sensing function (performed via sense terminal). This segmentation ensures that the control path handles protection while the sensing path maintains accurate voltage measurement without energy loss from transistor resistance.
Data Source
AI summary
A secondary battery protecting integrated circuit protects a secondary battery by controlling a switch circuit inserted in series on a path connected to a first electrode of the secondary battery. The secondary battery protecting integrated circuit includes: a sense terminal connected to a monitor terminal provided so that a first electric potential of the first electrode is monitorable; a first power supply terminal connected to the path; a second power supply terminal connected to a second electrode of the secondary battery; an internal wiring line configured to connect the first power supply terminal and the sense terminal; an internal switch on the internal wiring line; an abnormality detecting circuit configured to detect a predetermined abnormality; and a switch control circuit configured to turn on the internal switch when the predetermined abnormality is not detected, and configured to turn off the internal switch when the predetermined abnormality is detected.