Variable-Resistance Current Sensing for Wide-Range MOSFET Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current current sense circuits for transistor devices face a tradeoff between accuracy and efficiency, limiting their ability to accurately sense a wide range of currents with low power losses, particularly in high current applications like automotive systems.
Innovation Solution
An integrated circuit with a sensor component featuring an adjustable resistance and automatic ranging device that controls the duty cycle of the sensor component, allowing for scalable resistance and efficient current sensing across a broad range, reducing power consumption while maintaining high accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sense MOSFET is used with a low current ratio to improve accuracy, then measurement precision is improved, but power losses increase reducing efficiency
Solution Approach 1:
The patent applies dynamics by making the sense MOSFET's effective resistance adjustable through duty cycle control. The control circuit dynamically adjusts the sensing resistance based on the magnitude of the current being measured, allowing the system to optimize between accuracy and efficiency in real-time. This resolves the contradiction by enabling low resistance (high efficiency) for large currents and high resistance (high accuracy) for small currents.
Solution Approach 2:
The patent changes the resistance parameter of the sense MOSFET dynamically based on current magnitude. By adjusting the duty cycle of the sense MOSFET, the effective sensing resistance is modified to match the measurement requirements. This parameter change allows the system to achieve both high accuracy for small currents and high efficiency for large currents, resolving the tradeoff between these two opposing requirements.
2Loss of energy
If a sense MOSFET is used with a high current ratio to improve efficiency, then power losses are reduced, but measurement precision deteriorates
Solution Approach 1:
The system dynamically adjusts the sense MOSFET duty cycle based on current magnitude. For large currents where efficiency is paramount, the duty cycle is reduced, effectively lowering the sensing resistance and minimizing power losses. For small currents where accuracy is critical, the duty cycle is increased to maximize sensing resolution. This dynamic adaptation resolves the contradiction between efficiency and precision.
Solution Approach 2:
The effective sensing resistance parameter is changed dynamically through duty cycle modulation. When measuring large currents, the system uses a lower effective resistance to minimize I²R losses. When measuring small currents, the system switches to a higher effective resistance to maximize voltage signal for accurate measurement. This parameter adaptation resolves the tradeoff between efficiency and measurement precision.
3Device complexity
If a fixed resistance sensor is used, then device complexity is reduced, but adaptability to different current ranges is limited
Solution Approach 1:
The patent implements a dynamic sensing system where the sense MOSFET's effective resistance is adjusted based on the magnitude of the current being measured. The control circuit automatically selects appropriate duty cycles to match the current range, enabling the single sensor to adapt to wide current variations. This dynamic capability provides multi-range adaptability without requiring multiple fixed resistance sensors, balancing complexity and versatility.
Solution Approach 2:
The sense MOSFET is designed to perform multiple functions: it acts as a low-resistance path for large currents to minimize losses, and as a high-resistance precision sensor for small currents. By controlling the duty cycle, a single component achieves what would traditionally require multiple specialized sensors, enhancing versatility while managing 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
Enables accurate and high-resolution current measurement with low power consumption, achieving both high accuracy and efficiency in current sensing, suitable for various electronic devices including automotive applications.
Implementation Method 1
a sensor component coupled to the interface and configured to receive the current from the transistor device and to generate a responsive sensor voltage
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An apparatus, method and integrated circuit for broad-range current measurement using variable resistance are disclosed. Embodiments of an apparatus for sensing current through a transistor device may include an interface configured to receive a current from the transistor device for sensing. In an embodiment, the apparatus may also include a sensor component coupled to the interface and configured to receive the current from the transistor device and to generate a responsive sensor voltage, the sensor component comprising an adjustable resistance component, a resistance value of the adjustable resistance component being selectable in response to a level of the current received at the interface.