| 摘要 |
PROBLEM TO BE SOLVED: To provide a power-on reset circuit which is restrained from increasing in circuit scale and capable of surely executing a power-on reset, even if a power supply voltage starts rises slow when the voltage of a battery decreases or the like. SOLUTION: Threshold voltage|Vthp|of a p-channel MOS transistor P1, connected between the output terminal of the CMOS inverter 3 of a Schmidt buffer and a power supply terminal VDD, is set smaller than that of an N- channel MOS transistor N1 of the CMOS inverter 3; the MOS transistors P1 and N1 are so set as to make the drain current of the MOS transistor P1 larger than that of the MOS transistor N1, when the power supply voltage is lower than a specific voltage VT, and to make the drain current of the MOS transistor P1 smaller than that of the MOS transistor N1, when the power supply voltage is higher than the specific voltage VT. Reset output signals are also determined by the DC voltage characteristics of the MOS transistors P1 and N1, so that the reset output signals can be generated, even if a power supply voltage is built up slow.
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