— This paper presents a new power management technique integrated into a multithreaded microcontroller with builtin real-time scheduling schemes. Power management is done by hardware based on the Guaranteed Percentage scheduling scheme. The applied power saving mechanisms are frequency reduction, dynamic voltage scaling and pipeline gating. Our evaluation showed that for a given workload with an average processor utilization of 22.6% and a frequent change of utilization in the range of 0% to 58% energy consumption could be reduced to 12.7% of the energy required by a system running at top speed.