The power management module (PMM) manages all functions related to the power supply and its supervision for the device. Its primary functions are first to generate a supply voltage for the core logic, and second, to provide a mechanism for the supervision of both the voltage applied to the device at the DVcc pin and the internal voltage generated for the core. The PMM uses an integrated low-dropout voltage regulator to supply the core voltage while being powered from DVcc. The core voltage supplies the CPU, memories (flash/RAM), and the digital modules, while DVcc supplies the I/Os and all analog modules (including the oscillators). The FR59xx has a fixed internal core voltage level (1.2 V) and the device can be operated at the highest clock frequency of 16 MHz down to 1.8 V. Hence the frequency of operation is independent of the supply rail.