Adaptive control of the power supply is one of the most effective variables to achieve energy-efficient computation. In this work, we describe the development of a high-performance asynchronous micropipelined datapath that provides robust interfaces across voltage domains, performing appropriate voltage level conversions and operating between stages with fanout-of-four delays differing by almost two orders of magnitude. With software-specified throughput requirements, the power supply of the datapath is scaled from 2.5V to 600 mV using an on-chip dc-dc conversion system that combines linear regulators and switched-capacitor power supplies. Because of the asynchronous design style, the processor operates continuously during the voltage scaling transitions.