| 摘要 |
PURPOSE:To stabilize an internal circuit, and to curtail the power consumption by connecting an input terminal for connecting an external vibrator, to an H or L level, in accordance with an input level to a signal selecting terminal from the outside. CONSTITUTION:Between the first input terminal 9 and a power source VDD, a P channel FET 8 whose on-resistance is several KOMEGA is connected as a switch element. Subsequently, an external vibrator is not connected to the first input terminal 9, but a signal of the second input terminal 12 is used, therefore, when a selecting terminal 11 is set to an H level, a gate of the FET 8 becomes an L level, the FET 8 is turned on, the input terminal 9 is fixed to an H level, and the input impedance of the input terminal 9 is low and stabilized. On the contrary, when the selecting terminal 11 is set to an L level, the gate of the FET 8 becomes H, the FET 8 is turned off, and the external vibrator is connected to the input terminal 9 and oscillated. In such a way, it becomes unnecessary to input a potential fixing signal to the input terminal 9 from the outside.
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