Switching Regulator Adjustable Inductor Current Threshold

Solution Overview

Problem

Conventional switching regulators face a dilemma when operating under light or ultra-light load modes, either experiencing low power efficiency due to reverse inductor current or undesirable noise interference, as they struggle to maintain an optimal balance between power switching efficiency and noise interference.

Innovation Solution

A switching regulator with an adjustable inductor current threshold, controlled by a PWM controller, which adjusts the inductor current threshold based on output voltage and switching frequency to maintain a pseudo discontinuous conduction mode, ensuring a constant switching frequency and optimal efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the switching regulator operates under CCM (continuous conduction mode), then the power conversion is continuous, but reverse inductor current occurs under light load mode causing low power efficiency

Engineering Contradiction:

Improvecontinuous power conversionVSAvoidpower efficiency

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent implements dynamic mode switching between CCM and DCM based on load conditions. The control circuit monitors the operating state and automatically transitions the regulator between continuous and discontinuous conduction modes, making the system adaptable rather than fixed. This resolves the contradiction by allowing CCM operation during heavy loads (maintaining continuous conversion) while switching to DCM during light loads (eliminating reverse current losses).

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the operating parameter (conduction mode) based on load conditions. By detecting whether the regulator is operating under heavy or light load, the control circuit adjusts the conduction mode parameter accordingly - maintaining CCM for heavy loads and transitioning to DCM for light loads. This parameter change eliminates reverse inductor current under light load while preserving continuous conversion capability when needed.

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If the switching regulator operates under DCM (discontinuous conduction mode), then reverse inductor current is eliminated, but switching frequency decreases under ultra-light load mode causing noise interference

Engineering Contradiction:

Improvepower efficiencyVSAvoidnoise interference

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The patent implements dynamic mode switching between CCM and DCM based on load conditions. The control circuit monitors the operating state and automatically transitions the regulator between continuous and discontinuous conduction modes, making the system adaptable rather than fixed. This resolves the contradiction by allowing CCM operation during heavy loads (maintaining continuous conversion) while switching to DCM during light loads (eliminating reverse current losses).

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the operating parameter (conduction mode) based on load conditions. By detecting whether the regulator is operating under heavy or light load, the control circuit adjusts the conduction mode parameter accordingly - maintaining CCM for heavy loads and transitioning to DCM for light loads. This parameter change eliminates reverse inductor current under light load while preserving continuous conversion capability when needed.

Inventive Principle:

Principle #35Parameter changes

3Loss of energy

If the inductor current threshold is fixed at zero for DCM operation, then reverse current is prevented, but switching frequency drops under ultra-light load causing noise

Engineering Contradiction:

Improvereverse current lossVSAvoidswitching noise

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The patent implements dynamic mode switching between CCM and DCM based on load conditions. The control circuit monitors the operating state and automatically transitions the regulator between continuous and discontinuous conduction modes, making the system adaptable rather than fixed. This resolves the contradiction by allowing CCM operation during heavy loads (maintaining continuous conversion) while switching to DCM during light loads (eliminating reverse current losses).

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the operating parameter (conduction mode) based on load conditions. By detecting whether the regulator is operating under heavy or light load, the control circuit adjusts the conduction mode parameter accordingly - maintaining CCM for heavy loads and transitioning to DCM for light loads. This parameter change eliminates reverse inductor current under light load while preserving continuous conversion capability when needed.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10389249B2Switching regulator having adjustable inductor current threshold and control method thereof

Publication Date: 2019.08.20 RICHTEK TECH

AI summary

A switching regulator having adjustable inductor current threshold employs a control method which includes: (S1) determining whether an output voltage is greater than a reference voltage or determining whether a switching frequency of the power stage is smaller than a predetermined lower frequency limit, and (S2) when it is determined yes in the step (S1), adjusting the inductor current threshold, such that the switching regulator operates under a pseudo discontinuous conduction mode (PDCM) wherein the switching frequency is not smaller than the predetermined lower frequency limit. Consequently, when the switching regulator operates under a light load mode, an optimum balance between a total power consumption and switching noise interference will be ensured.