| 摘要 |
PURPOSE:To supply power efficiently regardless of the value of a load resistance by providing a current control circuit which operates as a constant-current supply circuit when the load resistance is small or as a constant-resistance feeding circuit when large. CONSTITUTION:When the load 6 has small resistance 6, an operational amplifier 10 outputs a small negative voltage. An operational amplifier 19, however, is applied with a reference voltage VREF so a large negative output voltage is sent out almost without the influence of a load voltage detection signal. Therefore, a diode 18 is biased reversely and a control signal generating circuit 15 outputs a constant current control signal to supply a constant current to the load 6. When the load 6 is large, the operational amplifier 10 outputs a large negative voltage to turn on a diode 18. Consequently, the output voltage of a differential amplifier 26 varies at a specific ratio with the voltage VR across the load, so feeding characteristics are constant resistance characteristics. |
