Power Supply Voltage Detection Circuit for Battery Capacity Estimation
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Solution Overview
Problem
Existing power supply voltage detection circuits can only accurately detect the stabilized voltage output from a regulator, making it difficult to determine the remaining battery capacity and allowing current inflow from unselected power supply potentials.
Innovation Solution
A power supply voltage detection circuit with a selection circuit that chooses between multiple power supply potentials and a variable voltage dividing circuit to detect both stabilized and unstabilized voltage levels, preventing current inflow from unselected nodes by using P-channel MOS transistors and control signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a power supply voltage detection circuit detects only the stabilized voltage output from a regulator, then the detection circuit is simple, but it cannot accurately determine the remaining battery capacity
Solution Approach 1:
The detection circuit is segmented into multiple detection paths: one path detects the stabilized voltage after regulation, while another path detects the raw battery voltage. This segmentation allows the system to obtain both the stabilized voltage information and the raw battery voltage information independently, enabling accurate battery capacity determination without overcomplicating the overall detection architecture
Solution Approach 2:
A selection circuit acts as an intermediary between the multiple voltage sources (stabilized voltage and raw battery voltage) and the detection circuit. This intermediary selectively connects different voltage sources to the detection circuit based on control signals, allowing the detection circuit to measure different voltages without direct permanent connections, thus maintaining relatively simple circuit structure while achieving multiple detection functions
2Adaptability or versatility
If a selection circuit uses multiple power supply potentials without proper isolation, then the circuit can access multiple voltage levels, but current inflow occurs from unselected power supply nodes
Solution Approach 1:
The selection circuit uses dynamically controllable switches (such as MOS transistors) that change their conductivity state based on control signals. When a particular power supply potential is selected, the corresponding switch is turned on to connect that voltage source, while other switches are turned off to disconnect unselected voltage sources. This dynamic switching mechanism enables the circuit to adaptively access different voltage levels while preventing harmful current inflow from unselected nodes
Solution Approach 2:
The harmful effect of current inflow is extracted and eliminated by using the selection circuit to isolate unselected power supply nodes from the detection circuit. By selectively connecting only the desired voltage source and disconnecting others through the switching mechanism, the system removes the harmful current path while preserving the necessary voltage selection capability
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
Enables accurate detection of the unstabilized power supply voltage from a battery, allowing for precise estimation of battery capacity and preventing current inflow from unselected power supply potentials.
Implementation Method 1
a selection circuit that selects one power supply potential from among a plurality of power supply potentials
Implementation Method 2
a variable voltage dividing circuit that divides a voltage between the power supply potential selected by the selected selection circuit and a reference potential by a set division ratio
Implementation Method 3
a comparator that outputs a signal representing a comparison result, by comparing the voltage divided by the variable voltage dividing circuit with the comparison voltage
Data Source
AI summary
A power supply voltage detection circuit can detect the power supply voltage obtained by stabilizing a power supply voltage supplied from outside and also the magnitude of the power supply voltage before being stabilized. This power supply voltage detection circuit includes a selection circuit that selects one power supply potential from among a plurality of power supply potentials including a first power supply potential supplied from outside and a second power supply potential obtained by stabilizing the first power supply potential, a variable voltage dividing circuit that divides the voltage between the power supply potential selected by the selection circuit and a reference potential by a set division ratio, a comparison voltage generation circuit that generates a comparison voltage based on a reference voltage, and a comparator that compares the voltage divided by the variable voltage dividing circuit with the comparison voltage and outputs a signal representing a comparison result.