Switching Regulator Peak Current Signal Gain Control
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Solution Overview
Problem
Conventional switching regulators experience sub-harmonic oscillation when peak current signal is adjusted according to frequency signal, leading to performance issues under light load conditions.
Innovation Solution
A switching regulator design that includes a control circuit with a peak current generator to regulate the gain of the peak current signal between contiguous switching cycles to be less than one, using a filter circuit with an inductor and output capacitor, and a feedback circuit to control the ON and OFF of power switches based on current and feedback signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the switching frequency is decreased under light load to improve efficiency, then energy efficiency is improved, but output voltage ripple increases and dynamic response slows down
Solution Approach 1:
The patent implements dynamic frequency adjustment based on load conditions. The control circuit automatically switches between PFM mode (for light load efficiency) and PWM mode (for heavy load stability) based on real-time load detection, allowing the system to optimize efficiency without sacrificing output voltage stability when needed
2Speed
If the peak current signal is adjusted according to frequency signal to maintain switching frequency above lower limit, then switching frequency is maintained, but sub-harmonic oscillation is caused
Solution Approach 1:
The patent employs a feedback mechanism where the control circuit continuously monitors the actual switching frequency and load conditions, then adjusts the peak current signal accordingly. This closed-loop feedback prevents sub-harmonic oscillation by ensuring the peak current signal adjustments are proportional and stable, rather than directly coupled to frequency variations which cause oscillation
Data Source
AI summary
A switching regulator including: a power stage having a first power switch and a second power switch coupled in series; a filter circuit having an inductor and an output capacitor; a feedback circuit configured to provide a feedback signal indicating an output voltage of the regulator; and a control circuit configured to provide a switching signal to control the ON and OFF of the first power switch so as to regulate the energy supplied to a load; wherein the control circuit has a peak current generator configured to generate a peak current signal, wherein the gain of a variation of the peak current signal between the contiguous switching cycles is less than one.