A 1V∼1.2V battery input, 0.4V∼0.6V output low-power all-digital power management unit (PMU) composed of a high-efficiency digital buck converter (DBC) and a fast-transient digital low drop-out (DLDO) regulator is developed for energy-efficient SoC applications. A fully integrated 2-to-1 switched-capacitor DC-DC converter is combined together to reduce the quiescent current of digital control circuits. The digital pulse width modulation (DPWM) with clock frequency gating further reduces the power consumption of buck converter in steady state. From experiment results, the peak power efficiency of the proposed buck converter is 90% with an output power range of 30μW to 3mW and the peak current efficiency of DLDO is 98.8% at 5mW. Moreover, the proposed DLDO achieves 92ns/130ns transition time in 60mV voltage step to dynamically scaling the voltage of supply voltage in digital circuits. This chip is designed and fabricated in 65nm CMOS process for verification.