Semiconductor Device for Constant Discharge Current Impedance Measurement
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Solution Overview
Problem
Secondary batteries like lithium-ion batteries face challenges in accurately measuring internal impedance due to variations in discharge current caused by voltage and temperature, leading to inaccurate impedance measurement and safety concerns.
Innovation Solution
A semiconductor device with a face-down mounted chip-size package type, featuring a field-effect transistor and a resistor connected in series, along with a control circuit that maintains a constant discharge current regardless of applied voltage, ensuring a temperature difference of less than five degrees Celsius between the two components, thereby accurately measuring internal impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a discharge current is used to measure internal impedance, then measurement capability is provided, but current variation due to voltage and temperature causes measurement inaccuracy
Solution Approach 1:
The patent employs a feedback control mechanism where the control circuit continuously monitors the discharge current and adjusts the field-effect transistor gate voltage to maintain constant current flow despite variations in battery voltage or temperature, ensuring accurate impedance measurement
Solution Approach 2:
The patent changes the operating parameters of the field-effect transistor (gate voltage) in response to detected current variations, dynamically adjusting these parameters to compensate for voltage and temperature effects on discharge current stability
2Reliability
If high power loss area ratio is used to maintain constant current, then current control capability is improved, but heat generation increases causing temperature variation
Solution Approach 1:
The patent applies local quality by creating distinct thermal management zones within the semiconductor device, with heat dissipation structures strategically positioned near high-power components like the field-effect transistor and resistor to locally manage heat generation and maintain uniform temperature distribution
Solution Approach 2:
The patent converts the harmful effect of heat generation into a beneficial thermal equilibrium state by designing the device to distribute power loss and heat generation uniformly across components, where the heat generated by the field-effect transistor compensates for heat losses in the resistor, maintaining stable operating temperatures
3Reliability
If field-effect transistor and resistor are connected in series with high power loss, then constant current control is achieved, but heat concentration occurs in specific regions
Solution Approach 1:
The patent segments the power loss and heat generation across multiple components (field-effect transistor and resistor) connected in series, with each component designed to handle a portion of the total power dissipation, preventing heat concentration in a single location and enabling better thermal management
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 semiconductor device enables precise measurement of internal impedance by maintaining a constant discharge current and dispersing heat, reducing the influence of temperature variations and improving measurement accuracy.
Implementation Method 1
a power loss area ratio of at least 0.4 (W/mm2) obtained by dividing a power loss (W) in the semiconductor device at time of the discharge by an area (mm2) of the semiconductor device
Data Source
AI summary
A semiconductor device that is of a face-down mounted chip-size package type, discharges electric charges stored in an electric storage device (battery), and has a power loss area ratio of at least 0.4 (W/mm2) obtained by dividing a power loss (W) in the semiconductor device at time of the discharge by an area (mm2) of the semiconductor device, the semiconductor device comprising: a field-effect transistor of a horizontal type and a resistor that are connected in series in stated order between an inflow terminal and an outflow terminal; and a control circuit that causes a discharge current to be constant without depending on an applied voltage between the inflow terminal and the outflow terminal. A difference between a maximum temperature of a field-effect transistor portion and a temperature of a resistor portion is within five degrees Celsius in a discharge period.