The improved DC-DC converter apparatus includes a primary side circuit and a secondary side circuit that is galvanically isolated from the primary. The primary side induces a voltage in the secondary side that provides an output voltage for driving POLs. A controller in the primary senses a reflected output voltage signal that is coupled from the secondary and is proportional to the secondary output voltage with respect to a voltage regulation point determined by either a voltage divider circuit or the zener voltage in the secondary. The voltage regulation point is established by wide-tolerance electrical components, such as a zener diode, a resistor, or a combination, connected in the coupling device circuit.