| 摘要 |
PURPOSE: A circuit for detecting a power fail is provided, which is very simple for a user to use, by making a reference voltage vary according to the variation of a power supply voltage. CONSTITUTION: A power supply voltage detecting part(20) outputs a high voltage or a low voltage according to a level of a reference voltage(REF) from inverters(INV21-INV23) by receiving the reference voltage of a reference voltage generation part(10) through gates of PMOS and NMOS transistor pairs((PM21,NM21),(PM22,NM22),(PM23,NM23)). Therefore, because transmission gates(TG31-TG33) of a reference voltage conversion part(30) are blocked, the reference voltage is output as a power fail sensing signal(DETOUT) by being inverted in sequence through inverters(INV41,INV42) of a power fail detection part(40).
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