Improvement of start-up and transient characteristics of digital-controlled DC-DC converter using switching-timing predictive PWM control

This paper proposes a new method for the control of a digital-controlled DC-DC converter. By using this method, both start-up and transient characteristics are improved. The dynamic characteristics at sampling time can be matched to a first-order system. Accordingly, the start-up waveform monotonically increases and the output voltage variation at load transient is small. This method is implemented in a digital signal processor (DSP) and its effectiveness is confirmed in circuit experiments. As a result, the output voltage variation at load transient is as small as 230 mV, which is 7.0% of the rated voltage of 3.3 V, and that at input transient is 43 mV (1.3%). In the start-up characteristics, this method enabled the output voltage to rise to the rated voltage smoothly without overshoot under any conditions.