| 摘要 |
PURPOSE:To simplify a control circuit for a DC motor so that the scale of the circuit can be reduced by generating a constant voltage having a prescribed negative temperature coefficient from a constant-voltage generating circuit and giving an input offset voltage with a positive temperature coefficient having the same absolute value as the negative temperature coefficient of the constant voltage to a reference current generating circuit. CONSTITUTION:A control circuit for DC motor is provided with a constant- voltage generating circuit 21, reference current generating circuit A1 which generates a reference current Irf based on a reference current generating voltage Vrf obtained by amplifying the constant-voltage V1 of the circuit 21, and rotating speed control circuit 26 which controls the rotating speed of a DC motor 36 based on the reference current Irf. In such a control circuit, the circuit 21 generates the constant voltage V1 having a prescribed negative temperature coefficient. The circuit A1 has an input circuit composed of differential paired transistors, to the emitters of which a current ratio per unit area is set, so that the circuit A1 can have an input offset voltage with a positive temperature coefficient having the same absolute value as the negative temperature coefficient of the voltage V2 has. |
