Isolated Power Supply Gate Voltage Division for MOSFET Protection
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Solution Overview
Problem
Existing isolated power supply circuits face challenges in regulating gate voltages of MOS transistors, leading to high production costs due to the need for special processing to manage voltages that can reach three times that of the power supply.
Innovation Solution
An isolated power supply circuit with a resonant network and a gate voltage division circuit, including peak voltage detectors and capacitance controllers, to dynamically adjust voltage division resistances and capacitances, ensuring gate voltages remain within a safe range by comparing detected voltage peaks with thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If two power MOS transistors M1 and M2 are adopted to control an LC resonant network, then energy transfer efficiency is improved, but gate voltages reach three times of power supply voltage requiring special process production which increases cost
Solution Approach 1:
The patent introduces a gate voltage division circuit as an intermediary between the LC resonant network and the MOS transistor gates. This circuit divides the high voltage from the resonant network into lower voltage segments, allowing the MOS transistors to operate at manageable voltage levels while still controlling the high-voltage resonant network, thus eliminating the need for special high-voltage process production
Solution Approach 2:
The patent changes the voltage parameter by introducing a voltage division mechanism. The gate voltage division circuit transforms the three-times power supply voltage into a lower, manageable gate voltage through resistive or capacitive division, allowing standard process production to be used while maintaining the high-voltage control capability needed for efficient energy transfer
2Ease of operation
If gate voltages are allowed to reach three times of power supply voltage, then control capability of the resonant network is improved, but the lifespan of MOS transistors is reduced due to high voltage stress
Solution Approach 1:
The gate voltage division circuit serves as a protective intermediary that decouples the high-voltage control requirement from the MOS transistor voltage tolerance. It provides the necessary control capability by dividing the high voltage while protecting the MOS transistors from direct exposure to three-times power supply voltage, thereby extending their operational lifespan
Solution Approach 2:
The patent implements beforehand cushioning by pre-dividing the gate voltage through the voltage division circuit before it reaches the MOS transistors. This protective measure is built into the circuit architecture, cushioning the MOS transistors from high-voltage stress before it can cause damage, thus improving reliability without sacrificing control capability
3Manufacturing precision
If manual adjustments are made to regulate gate voltages, then precision of voltage control is improved, but time consumption and operational complexity increase
Solution Approach 1:
The gate voltage division circuit is designed to automatically regulate gate voltages through its inherent voltage division ratio. The circuit self-adjusts the gate voltage based on the resonant network output without requiring external manual intervention, thereby maintaining precise voltage control while eliminating time-consuming manual adjustments
Solution Approach 2:
The patent incorporates feedback mechanisms where the gate voltage division circuit continuously monitors and adjusts the gate voltage based on the resonant network's operating state. This automatic feedback control maintains precise voltage regulation without manual intervention, reducing both time consumption and operational complexity while preserving voltage control precision
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 effectively regulates gate voltages of MOS transistors, preventing them from becoming too high or low, thus extending their lifespan and maintaining output efficiency, while reducing the need for costly manual adjustments.
Implementation Method 1
The inductors Lp1 and Lp2 at the transformer primary sides Lp1 and Lp2 and a capacitor form a resonant network for transferring energy of the voltage source Vdd to inductors LS1 and LS2 at a transformer secondary side
Data Source
AI summary
The present invention provides an isolated power supply circuit, which includes: a transmitting unit and a receiving unit. The transmitting unit is connected with a voltage source and includes a resonant circuit and a gate voltage division circuit. The gate voltage division circuit includes: a first voltage division branch, wherein one terminal of the first voltage division branch is connected between a first inductor and an input terminal of a first MOS transistor; and a second voltage division branch, wherein one terminal of the second voltage division branch is connected between a second inductor and an input terminal of a second MOS transistor. Therefore, voltages at gates of the first MOS transistor and the second MOS transistor can be changed by regulating voltage division conditions of the first voltage division branch and the second voltage division branch.