| 摘要 |
<p>PURPOSE:To apply a titled circuit to a CMOS integrated circuit and to form a detecting point in conformity with a designed value even if the characteristics of an element have production dispersion, by setting up required detecting voltage by the changing characteristics of the threshold voltage of a CMOS inverter and the output voltage of a constant voltage generating part. CONSTITUTION:When the threshold voltage VT of an inverter INV1 is set up to Vcc/2, the value is straight line passing through the intermediate coordinates between the horizontal axis and a 45 deg. line. When Vcc is low and MOS FETs Q5, Q6 are off, voltage Va rises while following up the Vcc by an FET Q1, and when the Vcc almost exceeds two stages of threshold voltages of the FETs Q5, Q6, the value is fixed to a constant value corresponding to the constant voltage characteristics. Therefore, Va>VT is formed when Vcc<VD by determining the voltage VD of an intersecting point between the voltage VT and Va as the border and output Vout of the inverter INV1 is turned to ''L''. When Vcc>VD, VT>Va is formed and the output Vout is turned to ''H''. Consequently, the power source voltage can be detected and detected voltage enabled to be turned to ''L'' and ''H'' stepwise with the voltage VD as the border.</p> |
