| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a power supply device that can supply a fixed current even if there happen power supply voltage fluctuations or load fluctuations. SOLUTION: A constant-current circuit 5 for supplying a constant current is installed on the power supply device 2 for lighting the white color light- emitting diode 6, and the base current for the current-supply transistor 51 in the circuit is supplied from the constant-current diode 53. Since the constant- current diode 51 outputs a fixed current, even when there happen fluctuations in the power supply voltage and load, the current into the shunt regulator 54 becomes a fixed current value, and a constant current is supplied to the light- emitting diode.</p> |
