High-Side MOSFET Driver Using Charge Storage Threshold Switching
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Solution Overview
Problem
Conventional gate drive circuits for high-frequency high-power switching elements, particularly those using N-channel MOSFETs, require complex and costly circuitry to manage high-voltage power supplies, often necessitating insulating components or voltage shift circuits, which complicates the design and increases costs without achieving sufficient performance improvements.
Innovation Solution
A high-side driver circuit that employs a charge storage circuit and a voltage detection-capable switch to autonomously turn on an N-channel MOSFET by detecting a specific voltage threshold, eliminating the need for insulating elements or voltage shift circuits, and optionally includes a parallel P-channel MOSFET for enhanced control, along with a voltage conversion and backflow prevention circuit for efficient ON and OFF operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an N-channel MOSFET is used as the main switch in the gate drive circuit, then the switching performance and drive capability are improved, but the circuit complexity increases due to the need for bootstrap circuits, level shift circuits, or insulating components to manage high-voltage power supplies
Solution Approach 1:
The patent extracts and removes the complex bootstrap circuit, level shift circuit, and insulating components from the gate drive circuit. By using a P-channel MOSFET instead of an N-channel MOSFET as the main switch, the circuit eliminates the need for these additional components, thereby reducing circuit complexity while maintaining switching performance through the inherent characteristics of the P-channel MOSFET
Solution Approach 2:
The patent inverts the conventional approach by using a P-channel MOSFET instead of an N-channel MOSFET as the main switch. This inversion allows the source terminal to be connected to the output terminal and the drain terminal to be connected to the plus-side voltage terminal, eliminating the need for complex voltage management circuits while achieving effective switching control
2Reliability
If insulating components or voltage shift circuits are added to manage high-voltage power supplies, then the safety and reliability are improved, but the manufacturing cost increases
Solution Approach 1:
The patent removes insulating components and voltage shift circuits from the circuit by adopting a P-channel MOSFET configuration that inherently manages high-voltage power supplies without additional safety components. The circuit achieves reliable operation by connecting the source terminal to the output terminal and utilizing the P-channel MOSFET's natural voltage handling characteristics
Solution Approach 2:
The patent replaces expensive insulating components and voltage shift circuits with a simpler P-channel MOSFET configuration that achieves the same safety and reliability functions at lower cost. The solution uses standard P-channel MOSFETs without requiring additional protective components, thereby reducing manufacturing costs while maintaining operational safety
3Device complexity
If a P-channel MOSFET is used as the main switch, then the circuit complexity is reduced, but the switching speed and drive capability deteriorate due to higher ON resistance and fewer available types
Solution Approach 1:
The patent applies preliminary action by pre-charging a capacitor through a diode during the period when the P-channel MOSFET is off. This stored charge is then rapidly discharged through the P-channel MOSFET when switching is required, enabling fast switching action despite the P-channel MOSFET's inherently higher resistance. The preliminary charging of the capacitor compensates for the slower switching characteristics of P-channel devices
Solution Approach 2:
The patent employs periodic action through the alternating charging and discharging of the capacitor. The capacitor is periodically charged through the diode when the P-channel MOSFET is off, and then periodically discharged through the P-channel MOSFET when switching is needed. This periodic charge-discharge cycle enables rapid switching action while maintaining the simplicity of the P-channel MOSFET-based circuit
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
The solution simplifies the circuit configuration, reduces costs, and enables efficient high-speed driving of power semiconductor switches without the need for insulating components, while maintaining high noise resistance and ensuring uninterrupted OFF operations.
Implementation Method 1
a series circuit of a diode D1 and a capacitor C1 is connected between the OUT terminal 7 and the plus-side voltage terminal 4
Implementation Method 2
a series circuit of a diode D1 and a capacitor C1 is connected between the OUT terminal 7 and the plus-side voltage terminal 4
Data Source
AI summary
A high-side driver circuit is a circuit that drives a power semiconductor switch. The high-side driver circuit comprises a main switch N-channel MOSFET that has a drain terminal that is connected to a plus-side Vdc of a power supply and has a source terminal that is connected to an OUT terminal for a signal that drives the power semiconductor switch, a charge storage circuit that stores charge from the Vdc, and a voltage detection-capable switch that detects the voltage difference between an output terminal of the charge storage circuit and the Vdc and, upon detecting that the output terminal voltage of the charge storage circuit is at least a specific voltage higher than the voltage of a plus-side Vcc of the power supply, applies part or all of the output voltage of the charge storage circuit to a gate terminal of the main switch N-channel MOSFET.