a switched mode controller for properly handling an under - voltage condition in a power line which includes a current mirror for receiving current from the power line ; a reference current source coupled to the current mirror for supplying a reference current ; and a power transistor coupled to the reference current source , the power transistor generating a pulse width modulated signal when current from the power line exceeds the reference current , the power transistor being disabled when current from the power line is less than the reference current .