The design of a 40 nm CMOS technology embedded switched-mode power supply (SMPS) for low-power mobile silicon-on-chip (SoC) is presented. The embedded SMPS operates directly from a Li-Ion battery capable of a wide input voltage range of 2.3 to 5.5V while the maximum voltage rating of the transistors used is 2.75V. This is achieved using integrated low-power voltage regulators and a novel dip compensation scheme. In addition, the SMPS is designed to include PWM and PFM modes to achieve high power efficiency over a wide load current range. To take advantage of the advanced 40 nm process, the PWM controller is implemented digitally. The digital controller, consisting of a successive approximation (SAR) ADC, digital compensation filter, and digital sigma delta PWM, is implemented to minimize silicon area and achieve fast transient response. The SMPS switches at 4.5 MHz and has peak efficiency of 83%, delivering a load of 240 mW when converting from 3.6V to 1.2V. It is capable of delivering a maximum power of 960 mW.