Electric network power-fail detection circuit

Abstract

The invention provides an electric network power down test circuit, including alternative current test circuit and control circuit which respond to alternative current on input end, the alternative current test circuit is used for producing pulse signal relative to alternative current periodically, the control circuit tests pulse signal which is outputted from alternative current test circuit, for outputting the first control signal or the second control signal, according to the number of pulse signal or interval time of next pulse signal during the setting time. Because the commercial power is periodic alternative current, by a few of electric components, simple circuit and MCU intelligent judgment produce a control signal during a short period of time after AC is power down, and controlother circuits, it has merits of simple circuit, fast responding time, which is good for improving uninterrupted power supply electronic device or AC power down control device.

Description

【Technical field】 [0001] The invention relates to a grid power failure detection circuit, which is used for detecting whether the mains power is lost, so as to timely control the standby power supply or other circuits to perform corresponding actions when the mains power is lost. 【Background technique】 [0002] Today's world is an era of digital and electronic information explosion. With the widespread use of program-controlled switches, intelligent monitoring systems, and long-term unattended work systems, the demand for uninterruptible power supplies and power management systems has increased. The performance of AC mains power failure detection in the power management system directly affects the performance of the uninterruptible power supply. After the voltage is rectified and filtered, a stable DC voltage is generated as a detection signal. The disadvantage is that the detection signal has a slow response speed due to the existence of an energy storage circuit in the cir...

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