Patent ID: 7844410

Claim:
For a field device, a field-device electronics fed by an external, electric energy supply, said external electric energy supply providing a supply voltage and delivering a variable supply current driven thereby, and said field-device electronics comprising: an electric current adjuster flowed-through by the supply current, said electric current adjuster being adapted to adjust and/or to modulate the supply current; an internal operating and evaluating circuit for controlling the field device; and an internal supply circuit feeding the internal operating and evaluating circuit and lying at an internal input voltage of the field-device electronics derived from the supply voltage, said internal supply circuit including a first useful-voltage controller flowed-through, at least at times, by an first current component of the supply current for providing in the field-device electronics a first internal, useful voltage controlled to be constant at a predeterminable, first voltage level, a second useful-voltage controller flowed-through, at least at times, by a second current component of the supply current for providing in the field-device electronics a second internal, useful voltage variable over a predeterminable voltage range, and a voltage adjuster, flowed-through, at least at times third current component of the supply current, for adjusting and maintaining the internal input voltage of the field-device electronics at a predeterminable voltage level; wherein the two useful-voltage controllers are galvanically separated from one another.