| 摘要 |
PURPOSE:To make the circuit operation stable due to temperature change by deciding each of the operating start level and the operating stop level of a drive circuit by the ratio of 1st resistor to a 2nd resistor and the ratio of the 1st, 2nd and 3rd resistors so as to facilitate the circuit integration of the circuit. CONSTITUTION:A differential amplifier stage 19 comprising the 1st and 2nd transistors (TRs) 20, 21 is provided to the drive circuit of a load such as a pilot lamp, the input side of the current mirror circuit 22 is connected to the TR 20 and the output of the circuit 22 is connected to the TR 21. Moreover, the output amplifier stage 27 of the drive circuit is activated by the output of the differential amplifier stage 19. The operating start level of the drive circuit is set by the ratio of the 1st and 2nd resistors 25, 26 connected to the 3rd and 4th TRs 23, 24 of the mirror circuit 22. Furthermore, the operation stop level of the drive circuit is set by the ratio of the 3rd resistor 31 and the 1st, 2nd resistors 25, 26 connected between the mirror circuit 22 and the TR 30 operated by the output of the amplifier stage 27 to make always the operation of the drive circuit stable.
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