| 摘要 |
<p>PURPOSE:To eliminate the fluctuation of the driving capability of an oscillation inverter that is caused when the driving voltage is switched via a program by using plural oscillation inverters having the characteristics corresponding to the reference voltage to form an oscillation circuit and selecting this oscillation circuit in accordance with the driving voltage of a CPU. CONSTITUTION:A low frequency oscillation circuit 126 consists of an oscillation inverter 128 having the high driving ability, and an oscillation inverter 130 having the driving ability lower than that of the inverter 128. A selection control storage circuit 112 stores the selection signals to select the reference voltage generating circuits 114 and 116 based on the command given from a CPU 102. The analog switches 118 and 122 are opened based on the input of the selection signal, selectively output the reference voltage from the reference voltage generating circuits 114 and 116. At the same time, both inverters 128 and 130 are selected also based on the input of the selection signal. Then the selected reference voltage is supplied via the switches 118 and 122. Thus the stable oscillation is secured despite the switching of the power voltage of both oscillation circuits.</p> |
