A pseudo fixed switching frequency 2kHz/A in optimum on-time control buck converter with predicting correction technique for EMI solution

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% ΔF_SW/F_SW and 2kHz/A ΔF_SW/ΔI_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).