A Pseudo Fixed Switching Frequency 2kHz/A in Optimum On-Time Control Buck Converter with Predicting Correction Technique for EMI Solution

Abstract

This paper repots an optimum on-time (OOC) control with predicting correction technique (PCT) for ripple-based buck converter. The switching frequency (F-SW) variation is analyzed with completely considering the parasitic resistances of the components and devices. The proposed converter achieved nearly constant switching frequency over a wide load range without extra clock controlled circuits and current sensing circuits. The parameters of the parasitic resistances almost cause no influence and no restriction on F-SW performance. Actually, only the input voltage is necessary to predict the optimum on-time, and this work benefits the decease on total pin numbers. The simulation results demonstrate 0.375% Delta F-SW/F-SW and 2kHz/A Delta F-SW/Delta I-LOAD over 1.5A load current change. Consequently, pseudo constant F-SW with known noise spectrum strongly benefits the solution of electromagnetic interference (EMI) issue for system-on-chip (SoC).