| 摘要 |
PURPOSE:To minimize an increase in the number of terminals of an integrated circuit by operating a switch function for stopping the oscillation operation of a voltage-controlled oscillator and that for forcible monaural switching by the same control signal. CONSTITUTION:When a DC voltage applied to an input terminal 26 reaches the 1st switch voltage, the 1st switch circuit 24 connected to a Schmitt trigger circuit 9 operates to turn off stereophonic switches 10 and 11, and thus while a stereophonic demodulator is placed in monaural mode, a stereophonic pilot lamp is turned off. When the potential of the input terminal 26 reaches the 2nd switch voltage, the 2nd switch circuit 25 connected to an oscillating circuit 16 operates to stop the oscillation of the circuit 16. Therefore, when a voltage higher than the 2nd switch voltage is applied to the terminal 26, the circuits 24 and 25 operate simultaneously to place the stereophonic demodulator in forcible monaural mode while putting a voltage-controlled oscillator in an oscillation stop state. |
