A PWM architecture of a microcontroller is disclosed that includes a fault module for regulating and detecting faults in current sensing or illuminating devices (e.g., LED strings). The fault module is part of a hardware regulation loop of LED voltage and LED current that allows the CPU to be placed in idle mode (“IDLE”) while an LED string is regulated in illumination. The microcontroller includes a PWM generator having a double channels PWM timer with a specific fault mode and an amplified comparator with a voltage reference. The architecture allows tuning of various parameters, including LED peak current, LED voltage supply, LED voltage regulation step and LED dimming value. In IDLE mode, the hardware regulation loop can regulate LED peak current and LED voltage supply without any CPU resource (microcontroller in IDLE mode). The fault module part of the hardware regulation loop can also detect and inform the CPU of: 1) an open LED; 2) a weak battery; and 3) an LED voltage that is under a target value.