The power source reset circuit and the scope error indicatory prevention system null which uses

摘要

PURPOSE:To constitute a power reset circuit without using either of enhancement and depression type processes. CONSTITUTION:Reference voltage REF2 is generated, by use of a transistor Tr incidental to an MOS process, and a Zener diode connected thereto. This reference voltage REF2 drops at a gradient approximately equal to the case of power voltage VDD, when the voltage VDD is equal to or above the breakdown voltage of another Zener diode ZD. In this case, another reference voltage REF1 is available from the division of the voltage VDD with resistors R3 and R4. The reference voltage REF1 is compared with the reference voltage RE2 via a comparator 10. When the reference voltage REF1 is higher than the reference voltage REF2, a power reset signal RESET is generated at high level.