Capacitive Battery Voltage Detection With Low-Current Comparator Switching
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Solution Overview
Problem
Conventional battery voltage detection circuits consume current through resistors, leading to increased area requirements and difficulty in miniaturization due to the need for higher resistances to reduce current consumption.
Innovation Solution
A semiconductor device and battery monitoring system utilizing capacitors and switching elements to detect battery voltage, allowing for low current consumption and miniaturization by using capacitors instead of resistors and enabling flexible detection threshold settings through capacitance ratios and reference voltage switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If resistors are used in the detection circuit to reduce current consumption, then current consumption decreases, but the area required for disposing the resistors increases
Solution Approach 1:
The patent changes the fundamental parameter from resistance to capacitance for voltage detection. By using capacitors instead of resistors, the circuit achieves ultra-low current consumption (near-zero steady-state current) while capacitors occupy significantly less area than high-value resistors would require.
Solution Approach 2:
The patent substitutes the resistive voltage division mechanism with a capacitive voltage division mechanism. The capacitive divider (C1, C2) replaces the resistive divider (R1, R2), fundamentally changing how voltage is sampled and processed in the circuit.
2Use of energy by moving object
If high resistance values are used to suppress current consumption, then current consumption is reduced, but the overall area of the detection circuit increases
Solution Approach 1:
The patent changes the fundamental parameter from resistance to capacitance for voltage detection. By using capacitors instead of resistors, the circuit achieves ultra-low current consumption (near-zero steady-state current) while capacitors occupy significantly less area than high-value resistors would require.
3Measurement precision
If a differential amplifier with resistors is used for voltage detection, then voltage detection is achieved, but current consumption increases
Solution Approach 1:
The patent substitutes the resistive voltage division mechanism with a capacitive voltage division mechanism. The capacitive divider (C1, C2) replaces the resistive divider (R1, R2), fundamentally changing how voltage is sampled and processed in the circuit.
Solution Approach 2:
The patent employs periodic switching of the capacitors between charging phases (connected to battery terminals) and detection phases (connected to comparator). This time-multiplexed operation allows voltage detection without continuous current draw, achieving periodic measurement with near-zero average current consumption.
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 low current consumption and miniaturization of the battery monitoring system, allowing for efficient detection of battery voltage states, including overcharge and overdischarge conditions, while reducing the size and complexity of the detection circuit.
Implementation Method 1
a first capacitor group including a first capacitor C1 and a second capacitor C2, wherein one end of the first capacitor C1 is switchable to be connected to one of a positive electrode and a negative electrode of a battery cell V, and one end of the second capacitor C2 is switchable to be connected to the other electrode opposite to the electrode to which the first capacitor C1 is connected
Implementation Method 2
The third capacitor C3 is connected in series with a first switching element S1 between a first node and the first switching element S1, and the first node is between the first capacitor C1 and the first input terminal of the comparator CMP0, and the first switching element S1 switches a connection state with any one of a ground voltage source that supplies a ground voltage and at least one reference voltage source
Data Source
AI summary
A semiconductor device, a battery monitoring system, and a detection method are provided. An end of the capacitor (C1) is switchable to be connected to one of a positive electrode and a negative electrode of a battery cell. An end of a capacitor (C2) is switchable to be connected to the other electrode. A comparator includes a non-inverted input terminal connectable to the battery cell via the capacitor (C1), and an inverted input terminal connectable to the battery cell via the capacitor (C2). A capacitor (C3) is located between a node (inp) and a switch (S1) that switches a connection state between a ground voltage source and any one of reference voltage sources. A capacitor (C4) is located between a node (inn) and a switch (S2) that switches a connection state between the ground voltage source and any one of the reference voltage sources.