With System on Chip low power constraints becoming increasingly important, emphasis is moving to architectural level, optimum memory organisation and system run time management. The designer should consider this aspect at the beginning of a new project in order to explore and find the best mapping of system parameters like throughput, area, and power consumption. In this paper we present a dynamic power management system based on the AMBA bus. The system is applied to a flexible architecture described in SystemC, consisting of a microcontroller and a RAM connected to the AMBA bus.