Patent ID: 8299647

Claim:
A circuit arrangement with a switchable voltage supply for a control apparatus, wherein the circuit arrangement comprises: a DC voltage supply terminal for connection to a DC voltage source; and an AC voltage supply terminal for connection to an AC voltage source; a first capacitor, whose first terminal is coupled to the DC voltage supply terminal via a first nonreactive resistor so as to form a first node, and whose second terminal is coupled to a reference potential; a drive circuit for driving the switch of an inverter, wherein the drive circuit has a supply terminal, which is coupled to the first node; a charge pump, whose input is coupled to the AC voltage supply terminal, and whose output is coupled to the first node, wherein the AC voltage supply terminal is coupled to an AC voltage source, which provides an AC voltage only when the inverter is in operation; the control apparatus, wherein the control apparatus comprises at least one input, an output and at least one supply terminal; a first electronic switch, a second electronic switch and a third electronic switch, each having a control electrode, a reference electrode and a working electrode, wherein the reference electrode of the first electronic switch and of the second electronic switch is coupled to the first node; wherein the working electrode of the first electronic switch is coupled to the supply terminal of the control apparatus; wherein the control electrode of the first electronic switch is coupled to the reference potential via a first voltage limiting apparatus, wherein the control electrode of the first electronic switch is coupled to the working electrode of the third electronic switch, wherein the control electrode of the third electronic switch is coupled to the output of the control apparatus, and the reference electrode of the third electronic switch is coupled to the reference potential; wherein the control electrode of the second electronic switch is coupled to the reference potential via a second voltage limiting apparatus; wherein the working electrode of the second electronic switch is coupled to the supply terminal of the control apparatus via a first diode; and wherein at least one further load is coupled to the working electrode of the second electronic switch.