In order to improve the efficiency over a wide loading range, nowadays the power converter of Internet of things (IoT) application work in dual or more modes. According to the different loads, the load detector is necessary for converter to work in the suitable mode. This paper proposed a mixed analog and digital load detection scheme. The proposed digital load detector, which is based on the counter and the intermittent operating clock, can reduce the static power consumption of the control circuit, thereby improve the conversion efficiency under light load. The proposed DC-DC converter is simulated and layout based on the SMIC 0.18μm standard CMOS process, and the core circuit area is 0.95×0.94mm 2 . The simulation results show that the input voltage range of the converter is 2.1V-3.3V, and the output voltage range is 1.2V-1.8V. The load current range of the converter is 1mA-300mA. Under the working condition of V IN =3.3V and V OUT =1.8V, the conversion efficiency over the whole load range is above 85%. When the load current is 100mA, the converter achieves a peak efficiency of 96.3%.