Adjustable MOSFET Power Supply Circuit for Low-Loss Current Sensing

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Solution Overview

Problem

Existing power supply circuits face challenges with heat loss and inaccurate current detection due to the use of detection resistors, especially when currents are small, and they lack flexibility in meeting various circuit requirements with single control means.

Innovation Solution

A power supply circuit with adjustable channel switch impedance, utilizing N main channel MOS transistors, a control module, and a detection module, where the control module adjusts the impedance by detecting voltage drop information and adjusting the gate-source voltage of the MOS transistors, allowing for precise current detection and control without a detection resistor in the main channel, thereby reducing heat loss and enabling flexible impedance adjustment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a detection resistor is connected in series in the main current channel, then current detection can be achieved, but heat loss increases due to voltage drop on the detection resistor

Engineering Contradiction:

Improvecurrent detection capabilityVSAvoidheat loss in main channel

Core Design Contradiction:

Measurement precisionVSLoss of energy

Solution Approach 1:

The detection resistor is extracted from the main current channel and placed in a separate detection branch. The main channel now contains only the main channel MOS transistor, eliminating the voltage drop and heat loss caused by the detection resistor. Current detection is achieved by measuring the voltage across the detection resistor in the separate branch, which carries a mirrored copy of the main channel current.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

A second MOS transistor is introduced as an intermediary element to mirror the current from the main channel MOS transistor. This current mirror mechanism allows the detection resistor to measure the main channel current without being part of the main current path, thus eliminating direct heat loss while maintaining detection capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If only on-off control is implemented on the channel, then circuit control is simple, but various circuit requirements cannot be met

Engineering Contradiction:

Improvecontrol mechanism simplicityVSAvoidcircuit requirement flexibility

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The main channel MOS transistor impedance is made dynamically adjustable through a control module that receives detection signals and modifies the gate-source voltage accordingly. This enables continuous impedance adjustment rather than fixed on-off control, allowing the circuit to adapt to various requirements such as over-current protection, different load conditions, and optimization of detection precision while maintaining relatively simple circuit architecture.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The impedance parameter of the main channel MOS transistor is changed based on detection results and circuit requirements. By adjusting the gate-source voltage, the transistor operates in different regions (cutoff, triode, saturation) or with different impedance values, enabling versatile circuit control functions including over-current protection, current limiting, and optimization of detection accuracy without significantly increasing circuit complexity.

Inventive Principle:

Principle #35Parameter changes

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 solution effectively reduces heat loss and improves current detection precision by adjusting impedance to meet various circuit requirements, including over-current protection, without the limitations of fixed resistance detection resistors, ensuring accurate current detection across different current ranges.

Implementation Method 1

a gate-source voltage of the main channel MOS transistors and a gate-source voltage of first MOS transistor are configured to be consistent... adjust the current between a source and a drain of the first MOS transistor according to the voltage drop information so as to adjust a drain-source voltage of the first MOS transistor, so that the gate-source voltage of the main channel MOS transistors changes accordingly

Methodology Applied

Scientific EffectMOS transistor gate control effect:

Implementation Method 2

detect voltage drop information which can characterize a current of a load at two ends of the detection resistor

Methodology Applied

Scientific EffectOhm's law voltage drop detection: Ohm's Law

Data Source

PatentUS11838010B2Power supply circuit with adjustable channel switch impedance and electronic device

Publication Date: 2023.12.05 SHANGHAI YAOHUO MICROELECTRONICS CO LTD

AI summary

The present invention provides a power supply circuit with an adjustable channel switch impedance and an electronic device. The power supply circuit includes N main channel MOS transistors, a control module, an execution module and a detection module, wherein the execution module includes a first MOS transistor; the detection module includes a detection resistor and a second MOS transistor; a gate-source voltage of the main channel MOS transistors and a gate-source voltage of the first MOS transistor are configured to be consistent, and a source-drain voltage of the main channel MOS transistors and a source-drain voltage of the second MOS transistor are consistent; the control module is connected to the detection resistor and configured to: detect voltage drop information on voltage drop at two ends of the detection resistor, wherein the voltage drop information can represent a current of a load.