Regulation characteristics of the digitally controlled DC-DC converter

The output characteristics of the digitally controlled dc-dc converter is analyzed theoretically and experimentally and the regulation characteristics is steady-state is defined for the changes of the input voltage and the load. As a result, it is revealed that the regulation of the output voltage is often circumscribed within the comparative narrow ranges of the input voltage and the load, and that the circumscription of the regulation range is due to the overflow or the underflow phenomenon in the integral mode control circuit and can be satisfactorily extended by determining adequately the circuit parameters and variables in the digital feedback control circuit. Also, the transfer function between the small variations in the on-time interval of the switch and the output voltage of the dc-dc converter is defined, and then the proportional gain, the reset time and the rate time are approximately derived as a function of the proportional, integral and derivative (P-I-D) coefficients in the digital control circuit, respectively.