| 摘要 |
<p>A reference voltage source (2) generates a reference voltage (Vdim) for current light control. A first current source (24) generates a first current (I1). A first current mirror circuit (28) has a plurality of output terminals (P1-P3) and copies the first current (I1) to output a plurality of first copy currents (Ic1a-Ic1c) from the plurality of output terminals (P1-P3). A plurality of first switches (SW1b, SW1c) are provided, respectively, on the passages of the plurality of first copy currents (Ic1a-Ic1c). A conversion resistor (R3) having a fixed potential at one end is provided on the passages of the plurality of first copy currents (Ic1a-Ic1c) outputted from the first current mirror circuit (28). A decoder circuit (40) receives a control signal (Sdim) from the outside and controls on/off of the plurality of first switches (SW1b, SW1c). The reference voltage source (2) outputs a voltage dependent on the voltage drop across the conversion resistor (R3) as the reference voltage (Vdim).</p> |
