Current Control Circuit Temperature Compensation
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Solution Overview
Problem
Current control circuits in mobile phone camera motors face instability due to temperature-induced fluctuations in the resistance value of sense resistors, leading to inaccurate current supply to the motor.
Innovation Solution
A current control circuit configuration that includes a constant current source and a second resistor with similar temperature characteristics to the sense resistor, allowing for accurate current control by generating a reference voltage and using a control signal generation circuit to stabilize the current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sense resistor is used to monitor current in a current control circuit, then current monitoring capability is improved, but the resistance value fluctuates with temperature changes causing current instability
Solution Approach 1:
The patent implements a feedback mechanism where the control signal generation circuit continuously monitors the voltage across the sense resistor and adjusts the MOS transistor gate voltage accordingly. This feedback loop compensates for temperature-induced resistance changes by dynamically adjusting the control signal to maintain stable current flow, thus resolving the contradiction between measurement precision and reliability.
Solution Approach 2:
The patent changes the operating parameters of the sense resistor by providing it with a dedicated bias current that is temperature-compensated. By adjusting the bias current parameter based on temperature conditions, the sense resistor maintains more stable resistance characteristics, thereby improving current stability while preserving measurement capability.
2Stability of the object's composition
If a current control circuit is used to supply stable current to the motor, then motor operation stability is improved, but temperature changes cause sense resistor resistance fluctuations leading to current instability
Solution Approach 1:
The control signal generation circuit uses feedback from the sense resistor voltage to continuously adjust the MOS transistor control signal. This feedback mechanism compensates for temperature-induced resistance changes in real-time, maintaining stable current supply to the motor and resolving the contradiction between motor operation stability and current stability.
Solution Approach 2:
The patent replaces passive resistance-based current limiting with an active electronic control system using MOS transistors and control circuits. This substitution allows for dynamic compensation of temperature effects through electronic feedback, achieving stable current supply despite temperature variations in the sense resistor.
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 proposed solution ensures a stable and accurate current supply to the motor, independent of temperature changes, by canceling out temperature fluctuations in the sense resistor and reference resistor, thus maintaining high accuracy and reliability.
Implementation Method 1
A current control circuit configuration that includes a constant current source and a second resistor with similar temperature characteristics to the sense resistor, allowing for accurate current control by generating a reference voltage and using a control signal generation circuit to stabilize the current flow
Implementation Method 2
the control signal generation circuit generates a control signal for the MOS transistor on the basis of a comparison result of a voltage generated based on a current value and a predetermined reference value
Data Source
AI summary
A current control circuit in accordance an exemplary aspect of the present invention includes a first transistor that controls a current flowing to a load, a first resistor through which a current flows according to a current flowing through the first transistor, a control signal generation circuit that generates a control signal used to control the first transistor based on a comparison voltage and a predetermined reference voltage, the comparison voltage being determined based on a resistance value of the first resistor and a current flowing through the first resistor, and a reference voltage generation circuit that generates the reference voltage, the reference voltage generation circuit including a constant current source and a second resistor connected in series with the constant current source.