| 摘要 |
<p>PURPOSE: To early detect and display the failure or interruption of AC power supply by detecting the non-existence of AC power supply with a 1st signal generator and applying a control signal to a microcomputer through a 2nd signal generator. CONSTITUTION: When more than two cycles of input AC disappears, the voltage of a stop signal generator 100 is attenuated to 0V. The level of the voltage is shifted down by voltage dive resistors R803, RX12 and the divided voltage is supplied to a charging pump circuit formed by a diode DX20 and a filter capacitor CX8. Voltage appearing on the capacitor CX8 is supplied to a detection terminal formed on the base of a transistor(TR) Q1. Thereby a stop signal is generated by the emitter voltage of the TR Q1 and supplied through a serial impedance resistor RX22. The microcomputer periodically samples an input pin 18, and when detecting the drop of stop voltage, a watch mode is started, and after 10 minites, a stop mode is started.</p> |
