| 摘要 |
<p>PURPOSE:To prevent an overcurrent to be caused by the external noise, surges, etc., by comparing the input voltage with the output voltage of a power source circuit and initializing a microcomputer when the difference between both voltage levels is larger than the prescribed value. CONSTITUTION:The output voltage of a power source circuit 5 is applied to a power terminal VDD of a microcomputer MC 6 as well as to a reset IC 7 which transmits the initialization signal of the MC 6. The output of the IC 7 monitors the voltage applied to the MC 6 and produces the initialization signal of the MC 6 to reset the MC 6 when the applied voltage is less than a prescribed level. Furthermore a comparator 8 monitors the input voltage and the output voltage of the circuit 5. Thus the voltage drop of the resistance for high voltage is increased on a supply power line if an overcurrent flows in the MC 6. Then the output of the comparator 8 is inverted and the MC 6 is initialized. Thus it is possible to prevent the overcurrent from flowing to a low voltage transformer 1, a diode 2, a resistance 4, the circuit 5, the MC 6, etc.</p> |
