Duty-Cycled MOSFET Current Sensing for Wide Dynamic Range
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Solution Overview
Problem
Current current sensing technologies face a tradeoff between accuracy and efficiency, particularly in automotive applications where high current ranges need to be sensed accurately without causing substantial power losses, and existing solutions are limited to narrow current ranges with low resolution.
Innovation Solution
The implementation of an apparatus and method for broad-range current measurement using duty cycling, which includes a sensor component and a sense control circuit that adjusts the duty cycle ratio to control the activation period of the sensor component, allowing for high accuracy and efficiency by automatically scaling resistance in response to current magnitude and adjusting the resistance value based on the output voltage threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sense MOSFET is used to draw a small sensor current proportional to the main current, then current sensing accuracy is improved, but power losses increase
Solution Approach 1:
The patent applies periodic action by duty-cycling the sense MOSFET, activating it only during specific time intervals (e.g., during switching transitions) rather than continuously. This allows accurate current measurement at critical moments while minimizing power consumption during steady-state operation, directly resolving the contradiction between measurement accuracy and energy loss.
2Measurement precision
If the sense MOSFET size ratio is low to achieve accurate sensing, then measurement precision is improved, but efficiency deteriorates
Solution Approach 1:
By periodically activating the sense MOSFET only during brief measurement intervals rather than continuously, the patent achieves accurate sensing with minimal duty cycle activation. This periodic operation allows the use of smaller sense MOSFETs that provide adequate measurement precision while consuming significantly less power compared to continuous operation of larger sense devices.
3Measurement precision
If continuous sensing is used to maintain high resolution, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic sensing by activating the sense MOSFET and associated measurement circuitry only during specific time windows when current measurement is most critical (such as during switching transitions). This duty-cycled approach maintains high measurement resolution during these intervals while dramatically reducing average power consumption compared to continuous sensing operations.
Solution Approach 2:
The patent performs preliminary action by capturing current measurement data during brief critical intervals before the main current flow begins. By anticipating and measuring during these transition periods, the system achieves high-resolution sensing without requiring continuous high-power measurement operations throughout the entire current cycle.
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 enables accurate and high-resolution current measurement across a wide range while minimizing power consumption, achieving both high accuracy and efficiency, and reducing the circuit footprint by sharing ADCs and eliminating the need for large digital level shifters.
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
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AI summary
An apparatus, method and integrated circuit for broad-range current measurement using duty cycling 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. Additionally, embodiments may 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. Embodiments may also include a sense control circuit configured to control a duty cycle of the sensor component.