| 摘要 |
PURPOSE:To decrease the number of the terminal in the integated circuit and thus to simplify the constitution as well as to minimize the size for the integrated circuit by deciding the operation state of the circuit through decision whether the signal potential applied to the input terminal is higher or lower than the divided voltage. CONSTITUTION:Decision circuit 6 is provided. Integrated circuit 1 forms the frequency synthesizer to generate the reference frequency signal for control of the revolution speed of the rotor such as the motor or the like. The output of oscillator circuit 2 is applied to dividers 3-5. Then circuit 6 decides whether the potential applied to input terminal 18 features the maximum level, i.e. the level near the potential of plus side feed terminal 12, the minimum level, i.e., the potential near minus side feed terminal 13, or the divided voltage level, i.e., the level near the potential of constant voltage output terminal 14 respectively. And the output of one of three dividers 3-5 is applied to programable divider 7. In such constitution, the number of the terminal can be reduced by four units compared with the conventional number, thus simplifying the the constitution of the device. |
