Stability of power converters has become more and more important in hybrid green energy systems because of its difficulties to maintain a stable dc-bus. This paper presents dynamic characteristics of a digital integral gain changeable control dc-dc converter to realize high stability with suppression of the output capacitance. The integral gain changeable control method uses a variable integral gain, which is changed by the value of load current. The stability analysis is conducted by Bode diagrams. It is shown that the transient response and stability of the integral gain changeable method are better than the conventional fixed integral gain control method even if the output capacitance is smaller than the conventional method. Simulation and experimental results show the effectiveness of our concept.