By raising the zero-cross frequency, the response characteristic is improved. If the resistance is increased, the zero-cross frequency rises, and so the circuit can be adjusted in the direction of improved response characteristics. However, if the resistance is increased too much, the phase margin disappears, and oscillation may occur. In this case, the capacitance is reduced, and this adjustment secures a phase margin. When it is necessary to improve the transient characteristics as well, an output capacitor could be added to reduce fluctuations in the output voltage. When an output capacitor is added, the frequency characteristics also change, and so it is necessary to again check the frequency characteristics and study whether the ITH pin resistor and capacitor need adjustment.