초록 ▼

The present invention relates to a multiple LED driver circuit in which each LED (15, 17) is controlled by a bypass switch (19, 21). The LEDs are supplied by a switched mode power supply (8) and are connected to a constant current source to draw a predetermined current through the LEDs. The switched

The present invention relates to a multiple LED driver circuit in which each LED (15, 17) is controlled by a bypass switch (19, 21). The LEDs are supplied by a switched mode power supply (8) and are connected to a constant current source to draw a predetermined current through the LEDs. The switched mode power supply is arranged to output different voltages depending on the number of switched-on LEDs. This is carried out by supplying the control signals (sw1, sw2) of the bypass switches to the switched mode power supply. In this way, the power dissipation of the constant current source can be kept at a low level.

대표청구항 ▼

The invention claimed is: 1. A LED lighting device comprising at least a first and a second LED supplied by a switched mode power supply, wherein the current through the first LED is controlled by a first bypass switch, connected in parallel with the first LED, the current through the second LED is

The invention claimed is: 1. A LED lighting device comprising at least a first and a second LED supplied by a switched mode power supply, wherein the current through the first LED is controlled by a first bypass switch, connected in parallel with the first LED, the current through the second LED is controlled by a second bypass switch, connected in parallel with the second LED, the first and second LEDs being connected in series between the switched mode power supply and a first constant current source, and wherein the switched mode power supply is arranged to supply a number of different output voltages depending on the state of the first and second bypass switches, such that the voltage depends on the number of LEDs emitting light; wherein the first and second LEDs emit light of a green and blue color, respectively, and are connected to the first constant current source via a third LED, which is controlled by a third bypass switch, wherein the first and second LEDs are connected to a second constant current source via a fourth LED, which is controlled by a fourth bypass switch, and wherein the third and fourth LEDs emit red or amber-colored light.