Surge-proof interface circuit

1. A surge-proof illumination system DALI interface circuit ( 100 ) comprising:

a rectifier circuit ( 20 ) which is designed for providing, in dependence on a rectifier input voltage present at rectifier input terminals ( 20 a , 20 b ), a rectified rectifier output voltage at rectifier output terminals ( 20 c , 20 d ), and

a Darlington circuit ( 30 ) having at least two transistors (Q 3 , Q 4 ), wherein the Darlington circuit has a current path ( 35 ) on the output side, controllable in dependence on a drive signal ( 62 ), wherein the controllable current path ( 35 ) on the output side is coupled between the rectifier output terminals ( 20 c , 20 d ), and wherein the controllable current path ( 35 ) on the output side is designed for forming between the rectifier output terminals ( 20 c , 20 d ) a load variable in dependence on a drive signal ( 62 ).

2. The surge-proof illumination system DALI interface circuit ( 100 ) as claimed in claim 1 , wherein the surge-proof illumination DALI system interface circuit also has a capacitor (C 1 , C 7 ) which is coupled to a control terminal of a transistor (Q 3 , Q 4 ) of the Darlington circuit ( 30 ) and which is designed for counteracting a change of a current in a current path of the corresponding transistor (Q 3 , Q 4 ).

3. The surge-proof illumination system DALI interface circuit ( 100 ) as claimed in claim 2 , wherein the capacitor (C 1 , C 7 ) has a capacitance which is at least 100 times as large as a Miller capacitance of the transistor to the control terminal of which the capacitor (C 1 , C 4 ) is coupled.

4. The surge-proof illumination system DALI interface circuit ( 100 ) as claimed in claim 2 , wherein a capacitance value of the capacitor (C 1 , C 7 ) is selected in such a manner that a voltage pulse of 1000 volts across the controllable current path ( 35 ) on the output side does not lead to a turning-on of the controllable current path ( 35 ) on the output side in the case of an inactive drive signal ( 62 ).

5. The surge-proof illumination system DALI interface circuit ( 100 ) as claimed in claim 1 , which also has a second capacitor (C 1 , C 7 ) which is coupled to a control terminal of a second transistor (Q 3 , Q 4 ) of the Darlington circuit ( 30 ) and which is designed for counteracting a change of a current in a current path of the second transistor (Q 3 , Q 4 ).

6. The surge-proof illumination system DALI interface circuit ( 100 ) as claimed in claim 1 , in which the Darlington circuit ( 30 ) has bipolar transistors (Q 3 , Q 4 ) which have a dielectric collector-emitter strength of at least 500 V, at least 600 V or at least 1000 V.

7. The surge-proof illumination system DALI interface circuit ( 100 ) as claimed in claim 1 , wherein the Darlington circuit ( 30 ) has an at least 1500-fold current gain so that, in a turned-on state of the Darlington circuit ( 30 ), a current of between 1 mA and 300 mA is available in the controllable current path ( 35 ) on the output side.

8. The surge-proof illumination system DALI interface circuit ( 100 ) as claimed in claim 1 , which also has a current source ( 40 ) which is coupled between a first rectifier output terminal ( 20 c ) and a drive terminal ( 30 a ) of the Darlington circuit ( 30 ), wherein the current source is designed for limiting a drive current of the Darlington circuit.

9. The surge-proof illumination system DALI interface circuit ( 100 ) as claimed in claim 8 , which also has a node ( 70 ) which is electrically coupled between the current source ( 40 ), the drive terminal ( 30 a ) of the Darlington circuit ( 30 ) and a circuit arrangement ( 50 ) for voltage limiting.

10. The surge-proof illumination system DALI interface circuit ( 100 ) as claimed in claim 9 , wherein the node is also coupled to an optocoupler (Q 5 ) for receiving the drive signal ( 62 ) and wherein the optocoupler (Q 5 ) is coupled to a drive terminal ( 30 a ) of the Darlington circuit ( 30 ).

11. The surge-proof illumination system DALI interface circuit ( 100 ) as claimed in claim 9 , wherein the circuit arrangement ( 50 ) for voltage limiting comprises a light-emitting diode (LED) of an optocoupler which is designed for exciting a photoreceiver of the optocoupler on the basis of the signals present at the rectifier input terminals ( 20 a , 20 b ).

12. The surge-proof illumination system DALI interface circuit ( 100 ) as claimed in claim 8 , wherein the circuit arrangement ( 50 ) has a Zener diode (Z 3 ) arranged in the reverse direction.

13. The surge-proof illumination system DALI interface circuit ( 100 ) as claimed in claim 1 , which has a filter ( 85 ) preceding the rectifier input terminals ( 20 a , 20 b ), and wherein the filter ( 85 ) is designed for attenuating voltage pulses reaching the rectifier input terminals ( 20 a , 20 b ).

14. The surge-proof illumination system DALI interface circuit ( 100 ) as claimed in claim 1 , wherein the surge-proof illumination system interface circuit ( 100 ) is designed for exchanging control and/or data signals bidirectionally between a control unit (μC), which is coupled to the surge-proof illumination system interface circuit ( 100 ) via two optocouplers (Q 5 , Q 6 ), and a bus system ( 15 ), which is coupled to the surge-proof illumination system interface circuit ( 100 ) via the rectifier input terminals ( 20 a , 20 b ).

15. An electrical ballast for lighting means, comprising a surge-proof illumination system DALI interface circuit ( 100 ) as claimed in claim 1 .

16. An illumination system ( 300 ) for controlling lighting means, having a central control unit ( 310 ) for controlling an operating state of lighting means ( 210 ) and at least one electrical ballast ( 200 ) for lighting means ( 210 ) as claimed in claim 15 , wherein the central control unit ( 310 ) and the electrical ballast ( 200 ) for lighting means ( 210 ) are coupled electrically via a bus system ( 15 ) for the transmission of data and/or control signals.

17. The illumination system ( 300 ) for controlling lighting means as claimed in claim 16 , wherein the bus system ( 15 ) is a DALI bus system which is designed for transmitting data and/or control signals between the central control unit ( 310 ) and the electrical ballast ( 200 ) in accordance with a DALI protocol.

18. A surge-proof illumination system interface circuit ( 100 ) comprising:

a rectifier circuit ( 20 ) which is designed for providing, in dependence on a rectifier input voltage present at rectifier input terminals ( 20 a , 20 b ), a rectified rectifier output voltage at rectifier output terminals ( 20 c , 20 d ),

a Darlington circuit ( 30 ) having at least two transistors (Q 3 , Q 4 ), wherein the Darlington circuit has a current path ( 35 ) on the output side, controllable in dependence on a drive signal ( 62 ), wherein the controllable current path ( 35 ) on the output side is coupled between the rectifier output terminals ( 20 c , 20 d ),

a current source ( 40 ) which is coupled between a first rectifier output terminal ( 20 c ) and a drive terminal ( 30 a ) of the Darlington circuit ( 30 ), wherein the current source is designed for limiting a drive current of the Darlington circuit, and

a node ( 70 ) which is electrically coupled between the current source ( 40 ), the drive terminal ( 30 a ) of the Darlington circuit ( 30 ) and a circuit arrangement ( 50 ) for voltage limiting,

wherein the node is also coupled to an optocoupler (Q 5 ) for receiving the drive signal ( 62 ) and the optocoupler (Q 5 ) is coupled to a drive terminal ( 30 a ) of the Darlington circuit ( 30 ), or the circuit arrangement ( 50 ) for voltage limiting comprises a light-emitting diode (LED) of an optocoupler which is designed for exciting a photoreceiver of the optocoupler on the basis of the signals present at the rectifier input terminals ( 20 a , 20 b ).

19. A surge-proof illumination system interface circuit ( 100 ) comprising:

a rectifier circuit ( 20 ) which is designed for providing, in dependence on a rectifier input voltage present at rectifier input terminals ( 20 a , 20 b ), a rectified rectifier output voltage at rectifier output terminals ( 20 c , 20 d ),

a Darlington circuit ( 30 ) having at least two transistors (Q 3 , Q 4 ), wherein the Darlington circuit has a current path ( 35 ) on the output side, controllable in dependence on a drive signal ( 62 ), wherein the controllable current path ( 35 ) on the output side is coupled between the rectifier output terminals ( 20 c , 20 d ), and

a current source ( 40 ) which is coupled between a first rectifier output terminal ( 20 c ) and a drive terminal ( 30 a ) of the Darlington circuit ( 30 ), wherein the current source is designed for limiting a drive current of the Darlington circuit, and wherein the circuit arrangement ( 50 ) has a Zener diode (Z 3 ) arranged in the reverse direction.