| 摘要 |
<p>PURPOSE:To prevent the malfunction of an electronic device using a microprocessor, by deteting the level reduction of a supply voltage before the voltage reaches its working threshold and keeping the microprocessor in the holding state. CONSTITUTION:When the level of a power supply voltage -EO begins to lower and then lowered down to the Zener voltage of a Zener diode Z1, the diode Z1 is turned off. Thus no current flows into the photodiode in a photocoupler PH1, and the H signal is supplied to a holding terminal HOLD of a microprocessor CPU. When the CPU judges that the holding state should be kept, then stops its operation by the fact that the level of the terminal HOLD is set at H.</p> |
