Battery Pack Overcurrent Sensing Circuit With Lower Power Draw
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Solution Overview
Problem
Existing semiconductor devices for lithium-ion secondary batteries face challenges in reducing power consumption and improving overcurrent sensing accuracy, stability, reliability, and productivity due to the use of constant current sources and variations in transistor resistance values.
Innovation Solution
A semiconductor device incorporating a node, resistor, capacitor, and comparison circuit configuration, where the resistor converts current into a voltage added through a capacitor, and a comparator compares voltages to detect overcurrent, utilizing oxide semiconductors and multi-gate transistors for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a constant current source is used for sensing overcurrent, then the sensing function can be implemented, but power consumption increases
Solution Approach 1:
The patent extracts the constant current source from the sensing circuit and replaces it with a resistor-based voltage conversion approach. The resistor converts the current to be sensed into a voltage that can be directly compared by the comparison circuit, eliminating the need for a constant current source and thereby reducing power consumption while maintaining overcurrent sensing capability.
Solution Approach 2:
The patent substitutes the electrical constant current source mechanism with a passive resistor-based voltage conversion mechanism. By using the resistor's inherent property to convert current to voltage (V=IR), the system achieves sensing functionality without requiring an active constant current source, thus reducing power consumption.
2Reliability
If conventional transistors are used for charging and discharging, then the device can operate, but variation in resistance value affects sensing accuracy
Solution Approach 1:
The patent changes the material parameter of the transistors from conventional semiconductor to oxide semiconductor. This material parameter change results in transistors with more stable resistance characteristics, reducing variation in resistance values during operation. The oxide semiconductor transistors maintain reliable device operation while significantly improving overcurrent sensing accuracy by minimizing resistance fluctuations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves reduced power consumption, improved overcurrent sensing accuracy, stable operation, high reliability, and increased productivity by minimizing the impact of transistor resistance variations and leveraging oxide semiconductor technology.
Implementation Method 1
The resistor has a function of converting current flowing between the one of a positive electrode and a negative electrode of a secondary battery and the first terminal into a first voltage
Implementation Method 2
The first voltage is added to a voltage of the node ND2 through the capacitor
Data Source
AI summary
A semiconductor device with reduced power consumption is provided. The semiconductor device includes a node ND1, a node ND2, a resistor, a capacitor, and a comparison circuit. The resistor is electrically connected in series between one of a positive electrode and a negative electrode of a secondary battery and a first terminal. The resistor has a function of converting current flowing between the one of the positive electrode and the negative electrode of the secondary battery and the first terminal into a first voltage. The first voltage is added to a voltage of the node ND2 through the capacitor. The comparison circuit has a function of comparing a voltage of the node ND1 and the voltage of the node ND2. The comparison circuit outputs a signal that notifies detection of overcurrent when the voltage of the node ND2 is higher than the voltage of the node ND1.