| 摘要 |
PURPOSE:To reduce the number of elements of a circuit and to reduce power consumption and the total offset of an amplifier by converting the output current from the amplifier to a voltage with a resistance, impressing this voltage to the base of a transistor TR and obtaining a feedback control output from the collector of the TR. CONSTITUTION:When a control voltage VIN higher than a reference voltage VREF inputted to an inverting terminal 22 is inputted to a non-inverting terminal 21, an output current corresponding to the product between the input difference between both voltages and a mutual conductance gm is obtained from an amplifier 28. This output current is converted to a voltage VB by a diode D1 and a resistance 25. Since it is impressed to the base of a TR TR7, the TR TR7 is turned on. A motor current ICC is converted to a voltage by a resistance 10 connected to a feedback terminal 9, and this voltage is impressed to a feedback signal input terminal 27 as a feedback voltage VNP. Consequently, the number of elements is reduced and the total offset is reduced because the amplifier has the one-stage constitution. |
