XC9131 series are synchronous step-up DC/DC converters with a 0.2?(TYP.) N-channel driver transistor and a 0.2?(TYP.) synchronous 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. The series are able to start operation under the condition which has 0.9V input voltage to generate 3.3V output voltage with a 33?load resistor, suitable for mobile equipment using only one Alkaline battery or one Nickel metal hydride battery. During the operation of a shutdown, the load disconnection function enables to cut the current conduction path from the input to the output. The series has 0.5V (