Floating Zero-Crossing Detection in High-Side Switch Control
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Solution Overview
Problem
High-side semiconductor switches face challenges in detecting zero-crossings due to the need for high-voltage comparators and level shifters, which introduce delays in processing signals, affecting electromagnetic compatibility and switching speed.
Innovation Solution
Integrating zero-crossing detection into the floating control logic of high-side semiconductor switches, eliminating the need for high-voltage comparators and level shifters by using a series circuit of a capacitor and a resistor with a comparator, and utilizing the drain-gate or gate-source capacitance of a MOS transistor for edge detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a ground-related zero-crossing detector with high-voltage comparator is used, then zero-crossing detection capability is achieved, but signal processing delay increases due to level shifter requirements
Solution Approach 1:
The patent combines the zero-crossing detection function with the floating control logic by integrating a comparator into the floating supply domain. This merging eliminates the need for separate level shifting stages, as the comparator directly processes floating signals and generates floating output signals that can be immediately processed by the floating control logic, thereby reducing signal processing delay.
Solution Approach 2:
The patent introduces a level shifter as an intermediary component that converts ground-related signals to floating signals in a controlled manner. This level shifter is specifically designed to work with the floating control logic, enabling seamless signal transfer between different voltage domains while maintaining timing accuracy for zero-crossing detection.
2Strength
If a high-voltage comparator is used in the zero-crossing detector, then high-voltage switching capability is achieved, but circuit complexity increases due to additional level shifting requirements
Solution Approach 1:
The patent merges the high-voltage comparator functionality directly into the floating control logic block. By placing the comparator within the floating supply domain, the design eliminates the need for separate level shifting circuits that would otherwise be required to interface ground-related detection circuits with floating control logic, thereby reducing overall circuit complexity while maintaining high-voltage switching capability.
3Measurement precision
If separate ground-related zero-crossing detection is used, then detection function is achieved, but additional level shifting components are required
Solution Approach 1:
The patent integrates the edge detection functionality (zero-crossing detection) directly into the floating control logic by incorporating a comparator that operates in the floating voltage domain. This integration eliminates the need for separate ground-related detection circuits and their associated level shifting components, thereby reducing the total number of components while maintaining accurate edge detection capability.
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 reduces delay times and eliminates the requirement for additional level shifting, enabling faster detection of zero-crossings and improved switching operations while maintaining electromagnetic compatibility.
Implementation Method 1
the means for detecting an edge in the output signal can comprise a series circuit of a capacitor and a resistor connected between the first supply terminal and the output terminal
Implementation Method 2
a comparator whose first input terminal is connected with the common node of the capacitor and the resistor, and a reference voltage source connected between a second input terminal of the comparator and the output terminal
Data Source
AI summary
A circuit arrangement comprising a high-side semiconductor switch with a first load terminal connected to a first supply terminal receiving an input voltage, a second load terminal connected to an output terminal providing an output signal, and a control terminal, a floating driver circuit connected to the control terminal for driving the semiconductor switch, a level shifter receiving an input signal and providing a floating input signal dependent on the input signal, a floating control logic receiving the output signal and the floating input signal and providing at least one control signal to the floating driver circuit, wherein the floating control logic comprises means for detecting an edge in the output signal and means for generating the control signal dependent on the result of the edge detection.