Galvanically Isolated Current Sensing in Power Switch Over-Current Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electronic switches lack integrated over-current protection without increasing the number of pins, necessitating external control circuits, which complicates circuit design.
Innovation Solution
An electronic switch with integrated over-current protection circuitry that uses a magnetic field sensor to detect current, a comparator to signal threshold violations, and a latch to control the power transistor's gate, all powered internally via the input terminal, eliminating the need for additional supply pins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external control circuits are used to provide over-current protection, then protection function is achieved, but circuit design complexity increases
Solution Approach 1:
The patent combines the over-current protection circuitry directly within the electronic switch device itself, merging the protection function with the power switching function. This integration eliminates the need for separate external control circuits, thereby maintaining reliability while reducing overall circuit design complexity.
Solution Approach 2:
The electronic switch device is designed to perform multiple functions: power switching and over-current protection. By making the device universal and self-sufficient, it eliminates the need for additional dedicated protection circuits, simplifying the overall system design while ensuring reliable operation.
2Reliability
If smart switches with integrated protection circuitry are used, then over-current protection is provided, but the number of pins increases
Solution Approach 1:
The patent merges the protection circuitry with the existing power switch structure, utilizing the same pinout. The over-current detection and control functions are integrated into the device without requiring additional pins, thereby maintaining pin compatibility while providing enhanced protection functionality.
3Reliability
If additional supply pins are added for protection circuitry, then over-current protection functionality is enhanced, but device simplicity is reduced
Solution Approach 1:
The existing supply pins of the electronic switch are made multi-functional, serving both the power switching operation and the over-current protection circuitry. This approach allows the protection function to be fully integrated without requiring additional supply pins, preserving device simplicity while enhancing functionality.
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 over-current protection without additional supply pins, simplifying circuit design and ensuring safe operation within the safe operating area.
Implementation Method 1
a magnetic field sensor arranged adjacent to the line to sense the magnetic field and configured to provide a current sense signal, which represents the load current
Data Source
AI summary
A circuit includes a power transistor with a first and a second load electrode and a line connected to the first or the second load electrode and configured to carry a load current that causes a magnetic field around the line. The circuit further includes a magnetic field sensor arranged adjacent to the line to sense the magnetic field and provide a current sense signal, which represents the load current. The circuit further includes a protection circuit including a comparator, a latch, and a first electronic switch, wherein the comparator is configured to signal, at its output, that the current-sense signal exceeds a first threshold value. The latch is set based on an output signal of the comparator, and the first electronic switch is coupled to a control electrode of the power transistor and configured to discharge the control electrode when the latch is set to switch the power transistor off.