| 摘要 |
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.
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