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 (FSW) 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 FSW 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% ΔFSW/FSW and 2kHz/A ΔFSW/ΔILOAD over 1.5A load current change. Consequently, pseudo constant FSW with known noise spectrum strongly benefits the solution of electromagnetic interference (EMI) issue for system-on-chip (SoC).