Sensor Device Power Dissipation Control via Voltage Limiting
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Solution Overview
Problem
Two-wire sensor devices experience excessive power dissipation and potential overheating due to their resistive output current characteristic, which can lead to reliability issues and damage, and existing solutions require additional complexity for current measurement.
Innovation Solution
A sensor device that maintains power dissipation control by switching between two supply current states based on a switching threshold, using a voltage limiter to limit supply voltage above a saturation threshold, thereby keeping output current independent of supply voltage, without the need for current measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the output current is kept proportional to supply voltage, then the sensor provides accurate measurement signals, but the power dissipation rises quadratically with supply voltage leading to overheating and reliability issues
Solution Approach 1:
The patent applies dynamics by making the current-output characteristic adaptive rather than static. The sensor automatically switches between two operating modes: linear mode (where output current is proportional to supply voltage for accurate measurement) and saturation mode (where output current is clamped to prevent excessive power dissipation). This dynamic adaptation allows the sensor to maintain measurement accuracy when needed while preventing overheating under high supply voltage conditions.
2Loss of energy
If a clamping function is engaged to limit output current at maximum value, then power dissipation is controlled, but additional device complexity and chip area are required for current measurement
Solution Approach 1:
The patent applies self-service by enabling the sensor to automatically monitor and regulate its own output current without requiring external current measurement circuits. The sensor uses its existing supply voltage detection capability to determine when to switch to saturation mode, and the clamping function is implemented through the voltage-to-current converter itself rather than requiring separate current sensing hardware. This self-regulating approach controls power dissipation while avoiding additional device complexity.
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
This approach effectively limits power dissipation and prevents overheating, enhancing the reliability and longevity of the sensor device while maintaining simplicity and reducing device complexity.
Implementation Method 1
the voltage limiter limits the applied voltage and outputs a limited voltage signal which is substantially independent of said supply voltage
Implementation Method 2
the voltage limiter limits the applied voltage and outputs a limited voltage signal which is substantially independent of said supply voltage. Hereby, 'substantially independent' is to be construed as not having a particular relation to the supply voltage. In this way the current signal at the sensor device output is kept at an acceptable level
Data Source
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AI summary
The present invention relates to a sensor device (1) comprising - a sensor (3) arranged to sense a physical quantity, to convert said physical quantity into an electrical quantity and to output an electrical signal representative of the electrical quantity, - a voltage limiter (4) arranged to receive an input signal related to a supply voltage and to output a voltage signal, said voltage signal having a limited value if said input voltage exceeds a voltage saturation threshold value, - a voltage-to-current converter (5) arranged to convert said voltage signal output by said voltage limiter to a supply current of a first value, thereby forming a first supply current state, - a switch (7) arranged to switch between said first supply current state and at least a second supply current state wherein the supply current is substantially independent of said supply voltage, whereby the switching is controlled by said electrical signal.