The XC9128/XC9129 series are synchronous step-up DC/DC converters with a 0.2 (TYP.) N-channel driver transistor and a synchronous 0.2 (TYP.) P-channel switching transistor built-in. A highly efficient and stable current can be supplied up to 1.0A by reducing ON resistance of the built-in transistors. With a high switching frequency of 1.2MHz, a small inductor is selectable making the series ideally suited for applications requiring low profile or space saving solutions.