Lighting arrangement
In a lighting arrangement comprising a LED array and a DC-DC-converter for supplying the LED array, the DC-DC-converter is an up-converter and the LED array is coupled between an input terminal and an output terminal. The up-converter generates a very low voltage over the LED array without making use of a transformer.
1. A lighting arrangement comprising a LED array and a circuit arrangement for supplying the LED array, the circuit arrangement comprising a DC-DC-converter for generating a DC output voltage V out out of a DC input voltage V in and equipped with
input terminals for connection to a supply voltage source supplying the DC input voltage V in ;
an inductive element;
a diode;
a switching element for controlling the current through the inductive element;
a control circuit coupled to a control electrode of the switching element for generating a control signal for rendering the switching element periodically alternately conductive and non-conductive; and
output terminals between which the DC output voltage V out is present during operation wherein a capacitor is coupled between the output terminals;
wherein the LED array is coupled between an input terminal and an output terminal.
2. A lighting arrangement as claimed in claim 1 , wherein the DC-DC-converter is an up-converter.
3. A lighting arrangement comprising a LED array and a circuit arrangement for supplying the LED array, the circuit arrangement comprising a DC-DC-converter for generating a DC output voltage V out out of a DC input voltage V in and equipped with
input terminals for connection to a supply voltage source supplying the DC input voltage V in ;
an inductive element;
a diode;
a switching element for controlling the current through the inductive element;
a control circuit coupled to a control electrode of the switching element for generating a control signal for rendering the switching element periodically alternately conductive and non-conductive; and
output terminals between which the DC output voltage V out is present during operation;
wherein the LED array is coupled between an input terminal and an output terminal;
wherein the control circuit is equipped with means for operating the DC-DC-converter in the critical discontinuous mode.
4. A lighting arrangement comprising a LED array and a circuit arrangement for supplying the LED array, the circuit arrangement comprising a DC-DC-converter for generating a DC output voltage V out out of a DC input voltage V in and equipped with
input terminals for connection to a supply voltage source supplying the DC input voltage V in ;
an inductive element;
a diode;
a switching element for controlling the current through the inductive element;
a control circuit coupled to a control electrode of the switching element for generating a control signal for rendering the switching element periodically alternately conductive and non-conductive; and
output terminals between which the DC output voltage V out is present during operation;
wherein the LED array is coupled between an input terminal and an output terminal;
wherein the DC-DC-converter is equipped with means I for controlling the average current through the LED array at a predetermined value.
5. A lighting arrangement as claimed in claim 4 , wherein the means I comprise means coupled to the input terminals and the output terminals for controlling a time lapse T on , during which the switching element is maintained in a conductive state during each period of the control signal, proportional to a mathematical expression that is a function of V in and V out .
6. A lighting arrangement as claimed in claim 5 , wherein the means I comprise means for controlling T on proportional to V out /V in 2 .
7. A circuit arrangement as claimed in claim 5 , wherein the DC-DC-converter is equipped with means II for substantially square wave modulating the amplitude of the current through the LED array.