A power supply using a microcontroller for circuit protection and an LED lighting system using the power supply are disclosed. A power supply according to embodiments of the present invention includes a floating converter and at least a first reference voltage source connected to a negative output terminal of the floating converter. A microcontroller is connected to the first reference voltage source and to a control input of the floating converter, which may be a floating buck converter. In some embodiments, a second reference voltage source is connected to the microcontroller. A voltage divider and/or a comparator can be used to provide one or both voltage reference sources.