| 摘要 |
PURPOSE:To obtain a constant current output independently of fluctuation of a power supply voltage by constituting the titled circuit that an output current (constant current) is obtained from a current being a sum between an increasing current and a decreasing current in response to the change in a power voltage. CONSTITUTION:A base-emitter voltage of transistors (TR)Q11, Q12 is almost constant and an emitter voltage of the TRQ12 becomes a prescribed voltage by a voltage drop component of a resistor R13. Thus, the relation between currents I1 and I2 is a gradually increasing relation in response to the increase in the current I1. On the other hand, since the voltage drop of the resistor R12 is increased in proportion to the current I1, the bias voltage of the TRQ13 is decreased gradually. Then the current I3 is decreased gradually as the current I1 is increased. Since collectors of the TRs Q12, Q13 are connected in common, a current being the sun of currents I2, I3 is obtained as an output current Iout. Thus, the output current Iout is a current nearly constant depending on the increase in the current I2 and the decrease in the current I3.
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