A power management circuit that has multiple sets of circuits to provide certain same power management functionalities in different power modes, such as voltage, current and temperature sensing and/or measuring, generating of reference states or biases to effectuate circuit protection in various conditions, such as under voltages, over voltages, etc. One set of circuits is configured to operate during a normal mode and is optimized for performance, speed and/or accuracy. Another set of circuits is configured to operate during a sleep mode and is optimized for reduced power consumption where the performance, speed and/or accuracy may be inferior to the circuits for the normal mode but the functionality is maintained within the low power consumption constraint.