Switch Mode Regulator Audio Frequency Deadband Control
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Solution Overview
Problem
Conventional switch mode regulators face inefficiencies at lighter loads, particularly in consumer electronic devices, where they either waste energy or generate audible noise due to uncontrolled switching frequencies, which is undesirable in audio-sensitive applications.
Innovation Solution
A regulator that operates in continuous conduction mode (CCM) at higher loads, switches to discontinuous conduction mode (DCM) as loads decrease, and further switches to audio discontinuous conduction mode (ADCM) to prevent audible noise by maintaining a super-sonic switching frequency, thereby balancing efficiency and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If switch mode regulators operate in discontinuous conduction mode (DCM) at lighter loads, then efficiency is improved, but audible noise is generated due to uncontrolled switching frequencies
Solution Approach 1:
The regulator dynamically switches between CCM and DCM based on load conditions, and within DCM, dynamically adjusts the switching frequency using audio frequency sensing to maintain operation above audible thresholds while preserving DCM efficiency benefits at light loads
Solution Approach 2:
The patent implements audio frequency sensing that detects audible noise components from switching operations and provides feedback to adjust the switching frequency, creating a closed-loop system that eliminates audible noise while maintaining efficient DCM operation
2Object-generated harmful factors
If switch mode regulators operate in continuous conduction mode (CCM) at lighter loads, then audible noise is reduced, but efficiency deteriorates due to energy waste
Solution Approach 1:
The system dynamically transitions between CCM and DCM based on load conditions, ensuring CCM is used when loads are heavy enough to justify the efficiency trade-off for noise reduction, while DCM is used at lighter loads with frequency control to maintain both efficiency and low noise
3Object-generated harmful factors
If switching frequency is increased to prevent audible noise, then noise reduction is achieved, but efficiency deteriorates due to increased switching losses
Solution Approach 1:
The patent changes the switching frequency parameter dynamically based on audio frequency sensing, adjusting it only enough to push operation above audible thresholds rather than continuously operating at high frequencies, thereby minimizing switching losses while achieving noise reduction
Data Source
AI summary
A controller for controlling operation of a switching regulator including a modulator, a discontinuous conduction mode (DCM) controller, an audible DCM (ADCM) controller, and a sub-sonic discontinuous conduction mode (SBDCM) controller. The modulator generally operates in a continuous conduction mode. The DCM controller modifies operation to DCM during low loads. The ADCM controller detects when the switching frequency is less than a super-sonic frequency threshold and modifies operation to maintain the switching frequency at a super-sonic frequency level. The SBDCM controller detects a sub-sonic operating condition during ADCM operation and responsively inhibits operation of the ADCM mode controller to allow a SBDCM mode within a sub-sonic switching frequency range. The SBDCM operating mode allows for efficient connected standby operation. The SBDCM controller allows operation to return to other modes when the switching frequency increases above the subsonic level.