Switching Converter PFM Control for Stopband Noise Avoidance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Switching converters introduce noise at the switching frequency, which can interfere with other sensitive circuits, and fixed-frequency switching converters have limited efficiency.
Innovation Solution
A switching converter controller with a stopband controller and a pulse-frequency modulation (PFM) controller that selectively adjusts the clock signal to avoid predetermined stopbands, reducing noise interference while maintaining efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If fixed-frequency switching converters are used to avoid noise interference, then noise interference is reduced, but efficiency is limited
Solution Approach 1:
The patent implements dynamic frequency adjustment by introducing a stopband controller that continuously monitors the operating frequency and adjusts the switching frequency in real-time to avoid stopbands while maintaining high efficiency operation. This resolves the contradiction by making the frequency adaptive rather than fixed.
Solution Approach 2:
The patent changes the frequency parameter dynamically based on operating conditions. The stopband controller modifies the switching frequency according to the detected operating point, allowing the converter to operate in high-efficiency regions while avoiding noise-prone frequency bands.
2Object-affected harmful factors
If switching frequency is adjusted to avoid stopbands, then noise interference is reduced, but control complexity increases
Solution Approach 1:
The patent employs a feedback mechanism where the stopband controller monitors the operating frequency and provides feedback to adjust the switching frequency accordingly. This closed-loop control automatically avoids stopbands without requiring complex external intervention, resolving the contradiction between noise reduction and control complexity.
Solution Approach 2:
The stopband controller acts as an intermediary component between the fixed-frequency converter and the power stage. It introduces minimal complexity by solely responsible for frequency adjustment based on simple frequency comparison logic, avoiding the need for complex overall control architecture.
3Ease of operation
If fixed-frequency operation is used, then control simplicity is maintained, but adaptability to different operating conditions is limited
Solution Approach 1:
The patent transforms the static fixed-frequency operation into a dynamic adaptive system. The stopband controller enables the converter to automatically adapt its switching frequency to different operating conditions and load requirements while maintaining relatively simple control logic through frequency comparison and adjustment.
Data Source
AI summary
A switching converter controller includes: a stopband controller having a stopband controller input and a stopband controller output, the stopband controller is configured to provide stopband information at the stopband controller output responsive to a reference signal; a pulse-frequency modulation (PFM) controller having a first PFM controller input, a second PFM controller input and a PFM controller output, the first PFM controller input configured to receive a feedback error signal, the second PFM controller input coupled to the stopband controller output, and the PFM controller configured to selectively adjust a clock signal at the PFM controller output based on the feedback error signal and the stopband information; and a driver circuit having a driver circuit input coupled to the PFM controller output and configured to receive the clock signal, and having a driver circuit output adapted to be coupled to a power stage switch.