Digitally-controlled DC-DC converter with variable switching frequency

An increasing trend to utilize digitally-implemented control laws to regulate Switch-Mode Power Supplies (SMPS) is apparent, because such solutions offer several opportunities for advanced control schemes. This paper presents a digital compensator to regulate a Point-of-Load (PoL) Buck converter. The regulator varies both the duty cycle as well as the switching frequency by controlling not only the on-time, but also the off-time of the switching period. During the modeling stage, the transfer functions relating the on- and the off-time to the output voltage are derived. Subsequently, a digital controller with multiple feedback loops, which achieves tight voltage regulation and an excellent dynamic performance, is proposed. Simulation results are provided to prove the effectiveness of the proposed control structure.