MOSFET Voltage Switching Circuit for Seamless Boosted Supply Transfer

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Solution Overview

Problem

Existing load drive circuits using high side drivers with N-type semiconductor elements face issues of excessive power consumption and potential malfunctions due to sudden changes in battery voltage, particularly when using charge pump circuits for boosting voltages.

Innovation Solution

A load drive circuit with a booster circuit and a voltage switching circuit that seamlessly switches between power supply and boosted voltages using MOSFETs and a gate voltage generation circuit, eliminating the need for switches or determination circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a charge pump circuit is always used as the booster circuit, then the boosted voltage can be secured up to a region where the power supply voltage is low, but in a region where the power supply voltage is high, there is a problem that boosting capability becomes excessive and power consumption increases

Engineering Contradiction:

Improvestable operationVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies dynamics by making the booster circuit configuration changeable based on operating conditions. The system dynamically switches between a charge pump circuit (for low voltage regions) and a bootstrap circuit (for high voltage regions) to optimize performance and minimize power consumption across different power supply voltage levels

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of boosting capability by selecting different circuit configurations. The charge pump circuit provides high boosting capability when needed (low voltage), while the bootstrap circuit provides lower boosting capability when sufficient (high voltage), thereby adapting the boosting parameter to match actual requirements and reduce unnecessary power consumption

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the boosted voltage by the charge pump circuit is used when power supply voltage decreases, then voltage stability is improved, but there is a possibility of malfunction due to sudden change in battery voltage

Engineering Contradiction:

Improvevoltage stabilityVSAvoidmalfunction risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies beforehand cushioning by using the bootstrap circuit to provide a cushioned, gradual voltage transition instead of the charge pump circuit's sudden voltage changes. The bootstrap circuit inherently provides a more gradual charging process that cushions against sudden voltage transitions, preventing malfunctions while maintaining voltage stability

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Adaptability or versatility

If switching of voltage is performed using a switch or determination circuit, then voltage selection is achieved, but the switching is not seamless and may cause interruptions

Engineering Contradiction:

Improvevoltage selection capabilityVSAvoidswitching continuity

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies merging by combining the charge pump circuit and bootstrap circuit in parallel, with their output nodes connected together. This allows seamless switching between the two circuits without interruption, as both circuits can simultaneously supply voltage to the load, eliminating the need for mechanical or electronic switches that cause interruptions

Inventive Principle:

Principle #5Merging (Combining)

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 configuration reduces power consumption and enhances reliability by seamlessly switching power supply voltages, preventing malfunctions from sudden voltage changes.

Implementation Method 1

the voltage switching circuit includes a first MOSFET, a second MOSFET, and a gate voltage generation circuit that generates gate voltages of the first MOSFET and the second MOSFET

Methodology Applied

Scientific EffectMOSFET switching:

Implementation Method 2

a booster circuit that boosts an output from a power supply

Methodology Applied

Scientific EffectVoltage boosting:

Data Source

PatentUS12580484B2Load drive circuit, electronic control device, and control method for electronic control device

Publication Date: 2026.03.17 ASTEMO LTD

AI summary

Provided are a highly reliable load drive circuit that includes a switching circuit that selects a power supply voltage, and is capable of seamlessly switching the power supply voltage without using a switch or a determination circuit, an electronic control device using the load drive circuit, and a control method for the electronic control device. The load drive circuit includes: a booster circuit that boosts an output from a power supply; and a voltage switching circuit that switches the output from the power supply and an output from the booster circuit, in which the voltage switching circuit includes a first MOSFET, a second MOSFET, and a gate voltage generation circuit that generates gate voltages of the first MOSFET and the second MOSFET, gate terminals of the first MOSFET and the second MOSFET are connected to the gate voltage generation circuit, source terminals of the first MOSFET and the second MOSFET are connected to the same node, a drain terminal of the first MOSFET is connected to an output terminal of the booster circuit, a drain terminal of the second MOSFET is connected to an output terminal of the power supply, and the output from the power supply and the output from the booster circuit are seamlessly switched according to an output voltage from the power supply.