High efficiency AOT-controlled boost converter with pseudo-constant switching frequency

Abstract

An on-time generator for boost converters is proposed to achieve an adaptive on-time (AOT) control with pseudo-constant frequency in continuous conduction mode (CCM). Since the first-order parasitic effect of the components and devices is considered in the design of the on-time generator, the switching frequency ($f_{sw}$) variation of the boost converter in CCM can be better suppressed with the load current ($I_{LOAD}$), input voltage ($V_{IN}$) and output voltage ($V_{OUT}$) changes, which can effectively solve the EMI noise problem. In addition, the idea of capacitor pre-charging is applied to simplifying circuit complexity. Meanwhile, an on-demand modulation strategy is applied to improve the conversion efficiency. Simulation results show that the boost converter based on the proposed on-time generator can realize the $f_{sw}$ variation of $0.4$ % in case of 200 mA $I_{LOAD}$ change. Moreover, the $V_{IN}$ may range from 0.8 to 1.5 V, the $V_{OUT}$ is set to 1.8 V, and the peak efficiency of the simulation is 96.9 %.