The XC9511 series consists of a step-down DC/DC converter and a high-speed LDO regulator connected in parallel with the DC/DC converter's output. A voltage detector is also built-in. Since the input for the LDO voltage regulator block comes from the input power supply, it is suited for use with various applications. The DC/DC converter block incorporates a P-channel driver transistor and a synchronous N-channel switching transistor. With an external coil, diode and two capacitors, the XC9511 can deliver output currents up to 800mA at efficiencies over 90%. The XC9511 is designed for use with small ceramic capacitors. A choice of three switching frequencies are available, 300 kHz, 600 kHz, and 1.2 MHz. Output voltage settings for the DC/DC and VR are set-up internally in 100mV steps within the range of 0.9V to 4.0V (2.0%). For the VD, the range is of 0.9V to 5.0V (2.0%). The soft start time of the series is internally set to 5ms. With the built-in U.V.L.O. (Under Voltage Lock Out) function, the internal P-channel driver transistor is forced OFF when input voltage becomes 1.4 V or lower.