Improvement of transient response of switching power supply in light load region

The purpose of this paper is to present a new integral coefficient change method that is not required the load current detection. The integral coefficient is changed based on the on-time of main switch. It uses two kinds of hysteresis function for stable operation around the boundary point of continuous conduction mode and discontinuous conduction mode. One uses the shape of rectangular And another uses the asymmetrical inverted rectangular triangle hysteresis function. In both hysteresis functions, good regulation characteristics are obtained. Furthermore, in the transient response around the integral coefficient change point, the asymmetrical inverted rectangular triangle hysteresis´s one is superior compared to rectangular hysteresis. The undershoot is suppressed by up to 62 % and the convergence time is shortened by up to 92.5%.