CIRCUIT FOR ENHANCING RELIABILITY OF ION INTRODUCTION SYSTEM

摘要

PROBLEM TO BE SOLVED: To improve the reliability of a system by providing the system with a circuit for detecting the fault of a crystal oscillator for clocking a microprocessor. SOLUTION: The crystal oscillator is formed by connecting a rock crystal 100 having a frequency of about 32 kHz to an inverter 102 and square waves of about 32 kHz are inputted to the count input of counters 110 and 112. The counter 110 is clocked by output the RC oscillator 100 of 64 kHz. The counter 112 is clocked by a rock crystal 100 of 32 kHz. The output count of the counter 110 is inputted to a first logic circuit 114, by which the presence or absence of the fault of the rock crystal 100 is decided. The output count of the counter 112 is inputted to a secondary logic circuit 116, by which the presence or absence of the fault of the RC oscillator 104 is decided. Excess making and excessively small making may be prevented and the reliability may be improved.