1 Introduction

With the advantages of high efficiency and better EMI performance, LLC is becoming a popular DC/DC topology in power supply applications. As the single PSU power requirement is increasing, interleaved technique has become an efficient way to achieve a higher power level without significantly upgrading the power devices. In recent years, as a typical interleaved topology, three-phase interleaved LLC is widely used in telecom and server PSU. Compared to a paralleled topology, three-phase interleaved LLC can significantly reduce current ripple and is easier to implement current balance. Combined with special magnetic component design, the size of inductor and transformer could be reduced as well.

However, as a typical PFM (frequency-changing) control topology, the frequency and phase-shift between phases are varying cycle-by-cycle. Thus, it requires a highly flexible PWM peripheral to make sure the PWM is in the correct order all of the time. This application report discusses how to leverage type-4 PWM on C2000 to implement the PWM signals of a three-phase interleaved LLC.