CN203535107U

CN203535107U - Low power AC power-off alarming circuit

Info

Publication number: CN203535107U
Application number: CN201320724933.6U
Authority: CN
Inventors: 王小强
Original assignee: Taicang T&W Electronics Co Ltd
Current assignee: Taicang T&W Electronics Co Ltd
Priority date: 2013-11-15
Filing date: 2013-11-15
Publication date: 2014-04-09
Anticipated expiration: 2023-11-15

Abstract

The utility model discloses low power AC power-off alarming circuit. The low power AC power-off alarming circuit comprises an input rectification and filtering circuit which is composed of resistors R1 to R4, capacitors C1 to C4, and a rectification bridge D7; a voltage detection circuit which is composed of resistors R3 to R5, a capacitor C4, and a comparison reference device U4; and a serial connection drop-down alarming circuit which is composed of resistors R6 to R7, a capacitor C5, and a light coupler U1, wherein the input rectification and filtering circuit provides an input voltage signal for the voltage detection circuit, and the voltage detection circuit drives the serial connection drop-down alarming circuit to send out an alarming signal when the voltage signal is detected by the voltage detection circuit. The low power AC power-off alarming circuit achieves direct current isolation and alternate current communication through serially connecting a capacitor to an input terminal of the input rectification and filtering circuit, so that the defect of lackness of alarm when the input is converted into a direct current power supply. The voltage detection circuit employs the comparison reference device U4, which has an extreme small driving current, to reduce power consumption of high voltage driving. The low power AC power-off alarming circuit is reasonable in circuit design, and safe and reliable in use.

Description

Low-power consumption AC power failure warning circuit

Technical field

The utility model relates to a kind of power down warning circuit, especially a kind of low-power consumption AC power failure warning circuit.

Background technology

At present, common AC power-fail detection circuit mostly adopts triode to drive optocoupler, as main detection means, because triode is current drive-type device, when base current is larger, could allow triode completely in the full conducting state of closing, thereby drive optocoupler, because ideal base drive current is to pick up from high pressure (AC), even if drive current is very little, loss power is still larger. cause energy dissipation.This kind of circuit be when changing direct current supply into, there is no AC simultaneously, normally alarm.As shown in Figure 1, it comprises detection of power loss input circuit to conventional AC power-fail detection circuit, detection of power loss output circuit.Detection of power loss input circuit is by resistance R 1, R2, R3, diode D1, D2, and capacitor C 1 forms rectifying and wave-filtering series circuit, and detection of power loss output circuit is by resistance R 4, R5 and optocoupler U1, and triode Q1 forms isolation feedback output circuit.Its principle of work is: when input end L N normal power supply, AC is by diode D1, D2 rectification, resistance R 1, R2 current limliting, capacitor C 1 filtering is given, and resistance R 3 dividing potential drops are to triode Q1 power supply, triode Q1 conducting, drive optocoupler U1, optocoupler conducting, alarm signal end PG is low level, not alarm.When input end L N power down, input end does not have voltage, and triode Q1 closes, and optocoupler U1 primary current is interrupted, and the PG signal port that feeds back to U1 level of optocoupler is high level, sends alarm.When its input end converts direct current supply to, triode Q1 is in running order can not close, thereby cannot realize alarm.

Utility model content

The utility model technical issues that need to address are to provide a kind of safe and reliable, and it is little that power consumption consumes, and input end converts the also normal power failure warning circuit of alarm of DC power supply to.

For addressing the above problem, technical solution adopted in the utility model is: a kind of low-power consumption AC power failure warning circuit, comprise by resistance R 1～R4, capacitor C 1～C4, the input rectifying filtering circuit that rectifier bridge D7 forms, by resistance R 3～R5, capacitor C 4, the voltage detecting circuit that benchmark device U4 forms, by resistance R 6～R7, capacitor C 5, the drop-down warning circuit of series connection that optocoupler U1 forms, wherein input rectifying filtering circuit provides input voltage signal for voltage detecting circuit, voltage detecting circuit detects voltage signal, drive the drop-down warning circuit of series connection to send alarm signal.

In described input rectifying filtering circuit, capacitor C 1 is connected with resistance R 1, and capacitor C 2 is connected with resistance R 2, connects respectively the input end of rectifier bridge D7, and wherein capacitor C 1 and capacitor C 2 are the capacitance during for direct current supply.

In described voltage detecting circuit, resistance R 3, R4 are divider resistance.

The beneficial effect that adopts technique scheme to produce is: the utility model seals in electric capacity by the input end in input rectifying filtering circuit and realizes every straight-through friendship, eliminated the defect of not reporting to the police while converting direct current supply to, in voltage detecting circuit, adopted the minimum benchmark device U4 of drive current, effectively reduce the power consumption of high drive, this circuit design is reasonable, safe and reliable.

Accompanying drawing explanation

Fig. 1 is the schematic diagram of the power failure warning circuit of prior art;

Fig. 2 is power failure warning circuit schematic diagram of the present utility model;

Embodiment

Below in conjunction with accompanying drawing, utility model is described in further detail: this novel comprising by resistance R 1～R4, capacitor C 1～C4, the input rectifying filtering circuit that rectifier bridge D7 forms, by resistance R 3～R5, capacitor C 4, the voltage detecting circuit that benchmark device U4 forms, by resistance R 6～R7, capacitor C 5, the drop-down warning circuit of series connection that optocoupler U1 forms, wherein input rectifying filtering circuit provides input voltage signal for voltage detecting circuit, voltage detecting circuit detects voltage signal, drives the drop-down warning circuit of series connection to send alarm signal.

In described input rectifying filtering circuit, capacitor C 1 is connected with resistance R 1, and capacitor C 2 is connected with resistance R 2, connects respectively the input end of rectifier bridge D7, and wherein capacitor C 1 and capacitor C 2 are the capacitance during for direct current supply, and capacitor C 3 is for filtering.

In described voltage detecting circuit, resistance R 3, R4 are divider resistance, resistance R 5 current limlitings, and benchmark device U4 is used for voltage ratio compared with driver output.

Described driving is connected, and optocoupler U1 is for isolation drive in drop-down warning circuit, and resistance R 6, R7 are current-limiting resistance, and capacitor C 5 is for filtering.

Principle of work:

When circuit is in being normally operated in AC civil power, resistance R 1～R4, capacitor C 1～C4, the input rectifying filtering circuit that rectifier bridge D7 forms is given by resistance R 3～R5, capacitor C 4, the voltage detecting circuit power supply that benchmark device U4 forms, voltage is provided, benchmark device U4 conducting, thereby drive by resistance R 6～R7, capacitor C 5, the drop-down warning circuit of series connection that optocoupler U1 forms, make optocoupler in conducting state, PG end is low level, during power down suddenly, benchmark device U4 can't detect input voltage, U1 elementary (emission side) transfers cut-off to by conducting, U2 the utmost point (photosensitive sensitive side) turn-offs, PG end transfers high level alarm to.

When circuit conversion becomes direct current supply, due to C1, the existence of C2 capacitance, cannot provide electric energy to rear class, and PG is high level, realizes and reporting to the police simultaneously.

Claims

1. a low-power consumption AC power failure warning circuit, it is characterized in that: comprise by resistance R 1～R4, capacitor C 1～C4, the input rectifying filtering circuit that rectifier bridge D7 forms, by resistance R 3～R5, capacitor C 4, the voltage detecting circuit that benchmark device U4 forms, by resistance R 6～R7, capacitor C 5, the drop-down warning circuit of series connection that optocoupler U1 forms, wherein input rectifying filtering circuit provides input voltage signal for voltage detecting circuit, and voltage detecting circuit detects voltage signal, drives the drop-down warning circuit of series connection to send alarm signal.

2. low-power consumption AC power failure warning circuit according to claim 1, it is characterized in that in described input rectifying filtering circuit, capacitor C 1 is connected with resistance R 1, capacitor C 2 is connected with resistance R 2, the input end that connects respectively rectifier bridge D7, wherein capacitor C 1 and capacitor C 2 are the capacitance during for direct current supply.

3. low-power consumption AC power failure warning circuit according to claim 1, is characterized in that in described voltage detecting circuit, resistance R 3, R4 are divider resistance.