Switch Mode Power Supply Adaptive Pulse Skipping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing switch mode power supplies for personal audio devices face inefficiencies under light load conditions due to excessive power loss, particularly when transitioning between continuous and discontinuous conduction modes, and existing PFM control methods complicate design and increase costs.
Innovation Solution
A method and system for controlling a current mode switch mode power supply that detects peak inductor current, estimates load current, and implements adaptive pulse skipping based on a variable threshold to avoid discontinuous conduction mode, using an embedded adaptive PFM control circuit within a linear feedback loop to reduce power loss and simplify design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional switch mode power supply operates in discontinuous conduction mode to reduce power loss, then power efficiency improves under light load conditions, but excessive power loss occurs and efficiency degrades
Solution Approach 1:
The power supply dynamically transitions between continuous conduction mode (CCM) and discontinuous conduction mode (DCM) based on load conditions. The control system monitors the boundary condition current threshold and automatically adjusts the operating mode to optimize efficiency across varying load currents and input voltages, preventing excessive power loss while maintaining reliability.
Solution Approach 2:
The system changes the conduction mode parameter (CCM/DCM) based on detected boundary conditions. By comparing the load current against the estimated boundary condition current threshold, the power supply adjusts its operational parameters to maintain optimal efficiency across different loading scenarios.
2Loss of energy
If pulse-skipping or pulse-frequency modulation is employed to eliminate negative inductor current losses, then power efficiency improves, but design complexity and costs increase
Solution Approach 1:
The PFM control functionality is merged into the existing linear feedback control loop rather than implementing separate multiplexed control loops. The adaptive PFM control circuit integrates with the main control loop to detect boundary conditions and implement pulse skipping, eliminating the need for complex multiplexing while achieving the same power loss reduction benefits.
Solution Approach 2:
The control system uses the existing control loop variables to estimate the boundary condition current threshold and automatically determines when to implement pulse skipping. The system self-regulates by utilizing its own internal signals (error feedback control signal and peak inductor current) to make control decisions, reducing the need for additional external control circuitry.
Data Source
AI summary
A method for controlling a current mode switch mode power supply may include detecting a peak inductor current of a power inductor of the current mode switch mode power supply, estimating a load current based on a variable of a main control loop of the current mode switch mode power supply, detecting, within a main control loop of the current mode switch mode power supply, whether the load current is lower in magnitude than an estimated boundary condition current threshold, the estimated boundary condition current threshold defining a crossover threshold between operation of the current mode switch mode power supply in a continuous conduction mode and operation of the current mode switch mode power supply in a discontinuous conduction mode, and responsive to the load current being lower in magnitude than the estimated boundary condition current, causing pulse skipping of an output signal of the current mode switch mode power supply on an immediately subsequent switching cycle of the current mode switch mode power supply.