CN201926699U

CN201926699U - Low-voltage circuit for power failure detection

Info

Publication number: CN201926699U
Application number: CN201020676122XU
Authority: CN
Inventors: 汪军; 黄祖好; 赵科
Original assignee: FOSHAN SHUNDE REALDESIGN ELECTRONICS INDUSTRY Co Ltd
Current assignee: Guangdong Real Design Intelligent Technology Co Ltd
Priority date: 2010-12-23
Filing date: 2010-12-23
Publication date: 2011-08-10
Anticipated expiration: 2020-12-23

Abstract

The utility model relates to a low-voltage circuit for power failure detection, which is structurally characterized in that the low-voltage circuit comprises a +12V voltage dividing circuit, a triode switching circuit and a port detection circuit, wherein the input end of the +12V voltage dividing circuit is connected with a +12V power supply, the divided voltage output end of the +12V voltage dividing circuit is connected with the input end of the triode switching circuit, the output end of the triode switching circuit is connected with the input end of the port detection circuit, and the port detection circuit is provided with a power failure state detection port int0. By using two resistors for dividing +12V voltage, since the variation of the +12V voltage after power is failed causes a triode to be conducted and cut off, the power failure detection can be realized through a port voltage variation method and the effect of detecting power failure is reached by using four resistors and one triode. The low-voltage circuit for the power failure detection has the advantages that the number of circuit components is small, the circuit is easy and reliable to realize and the applicable scope is wide.

Description

A kind of low-voltage circuit that is used for detection of power loss

Technical field

The utility model relates to a kind of low-voltage circuit that is used for detection of power loss, is used for detecting the whether power down of forceful electric power of small household appliances, so that in time control standby power supply work or other circuit carry out corresponding action.

Background technology

At present, the part small household appliances require after power down, and product also need have memory function and can continue demonstration; So just require to have the whether power down of reliable detection forceful electric power in time of a kind of circuit, so that when detecting the forceful electric power power down, the pair that can be timely the clock of single-chip microcomputer be changed into low speed shake (32768HZ), and enter the IDLE or the STOP pattern of power saving, and by battery provide+voltage about 3V comes work.In the prior art, because the raising that European Union and 3C standard require energy consumption, cause most of products must adopt the Switching Power Supply scheme, at this type of switching power circuit, detect whether power down of forceful electric power, generally be to adopt circuit shown in Figure 2 to realize that this testing circuit is formed by connecting by optocoupler IC1, inductance D1 and resistance R 1, R3, R4, its principle is to detect whether power down of forceful electric power by optocoupler.This circuit exists circuit complexity, manufacturing cost height and the high shortcoming of stand-by power consumption.

In sum, in view of current demand to stand-by power consumption and manufacturing cost, need a kind of more practical, more cost-effective, more can reduce the circuit arrangement of stand-by power consumption.

The utility model content

The purpose of this utility model is to deposit circuit complexity, manufacturing cost height and the high shortcoming of stand-by power consumption for the detection of power loss that overcomes prior art, and a kind of low-voltage circuit that is used for detection of power loss is provided; It is few that this low pressure power-fail detection circuit also has circuit component quantity simultaneously, and circuit is realized simple and reliable, the characteristics that applicable scope is wide.

The purpose of this utility model can reach by following measure:

A kind of low-voltage circuit that is used for detection of power loss, its design feature is: comprise+the 12V bleeder circuit, transistor switching circuit and port testing circuit; Input end connection+12V the power supply of+12V bleeder circuit, its dividing potential drop output terminal connect the input end of transistor switching circuit, the input end of the output terminal connectivity port testing circuit of transistor switching circuit, the power-down state detection port int0 that the port testing circuit is provided with.

The purpose of this utility model can also reach by following measure:

A kind of embodiment of the present utility model is: described+12V bleeder circuit is formed by connecting by capacitor C 8, resistance R 14 and resistance R 15, transistor switching circuit is made of triode Q2, and the port testing circuit is by being formed by connecting by pull-up resistor R10 and port protection resistance R 13; Resistance R 14 back of connecting with resistance R 15 is in parallel with capacitor C 8, and the junction of resistance R 14 and capacitor C 8 is connected with+12V, and resistance R 15 is connected with earth terminal GND with the junction of capacitor C 8; The base stage of triode Q2 is connected with the tie point of resistance R 14, resistance R 15, and the emitter of triode Q2 connects the tie point of resistance R 15 and capacitor C 8; The end of pull-up resistor R10 and+3.2V is connected, its other end connects triode Q2 collector, the collector of triode Q2 connects power-down state detection port int0 by port protection resistance R 13.

In the practical application, dividing potential drop by resistance R 14,15 couples+12V of resistance R, guarantee+keep triode Q2 conducting when 12V is stable, the voltage of int0 port is dragged down, in case cause+12V electric voltage dropping to a suitable magnitude of voltage (herein for about 6V) because High Level AC Voltage disconnects, will cause triode Q2 to end, thereby make that the voltage of int0 port is drawn high, to reach the effect that detects the High Level AC Voltage power down.

The beneficial effects of the utility model are:

The utility model adopt 2 resistance right+the 12V dividing potential drop, because after the power down+variation of 12V voltage causes opening of triode and ends, thereby the method that makes port voltage change realizes the detection of power down, just reaches the effect that detects power down with 4 resistance and a triode.Because directly right+the 12V sampling, the influence that is not easy to receive the external interference signal also is different from and adopts the optocoupler scheme to increase cost like that and increased stand-by power consumption.It is few that the utility model also has circuit component quantity, and circuit is realized simple and reliable, the advantage that applicable scope is wide.

Description of drawings

Fig. 1 is the circuit theory diagrams of the utility model specific embodiment.

Fig. 2 is the circuit theory diagrams of the power-fail detection circuit that detects by optocoupler in the prior art.

Embodiment

Below in conjunction with drawings and Examples the utility model is described in further detail:

Specific embodiment 1:

With reference to Fig. 1, present embodiment comprises+12V bleeder circuit, transistor switching circuit and port testing circuit; Input end connection+12V the power supply of+12V bleeder circuit, its dividing potential drop output terminal connect the input end of transistor switching circuit, the input end of the output terminal connectivity port testing circuit of transistor switching circuit, the power-down state detection port int0 that the port testing circuit is provided with.

In the present embodiment, described+12V bleeder circuit is formed by connecting by capacitor C 8, resistance R 14 and resistance R 15, and transistor switching circuit is made of triode Q2, and the port testing circuit is by being formed by connecting by pull-up resistor R10 and port protection resistance R 13; Resistance R 14 back of connecting with resistance R 15 is in parallel with capacitor C 8, and the junction of resistance R 14 and capacitor C 8 is connected with+12V, and resistance R 15 is connected with earth terminal GND with the junction of capacitor C 8; The base stage of triode Q2 is connected with the tie point of resistance R 14, resistance R 15, and the emitter of triode Q2 connects the tie point of resistance R 15 and capacitor C 8; The end of pull-up resistor R10 and+3.2V is connected, its other end connects triode Q2 collector, the collector of triode Q2 connects power-down state detection port int0 by port protection resistance R 13.

Principle of work of the present utility model is as follows:

Power-up state: when powering on ,+12V is risen to by 0V in the process of 12V can turn-on transistor Q2, thereby has dragged down the voltage of int0 port, reaches and detects the purpose that powers on;

Power-down state: when power down, because+12V band carries greatlyyer, can drop into 0V rapidly, and this moment, triode Q2 can be cut off, thereby made the voltage of int0 port draw high, and reached the purpose that detects power down.

The above; it only is the preferable specific embodiment of the utility model; but protection domain of the present utility model is not limited thereto; anyly be familiar with those skilled in the art in the scope that the utility model discloses; be equal to replacement or change according to the technical solution of the utility model and utility model design thereof, all belonged to protection domain of the present utility model.

Claims

1. low-voltage circuit that is used for detection of power loss is characterized in that: comprise+the 12V bleeder circuit, transistor switching circuit and port testing circuit; Input end connection+12V the power supply of+12V bleeder circuit, its dividing potential drop output terminal connect the input end of transistor switching circuit, the input end of the output terminal connectivity port testing circuit of transistor switching circuit, the power-down state detection port int0 that the port testing circuit is provided with.

2. a kind of low-voltage circuit that is used for detection of power loss according to claim 1, it is characterized in that: described+12V bleeder circuit is formed by connecting by capacitor C 8, resistance R 14 and resistance R 15, transistor switching circuit is made of triode Q2, and the port testing circuit is by being formed by connecting by pull-up resistor R10 and port protection resistance R 13; Resistance R 14 back of connecting with resistance R 15 is in parallel with capacitor C 8, and the junction of resistance R 14 and capacitor C 8 is connected with+12V, and resistance R 15 is connected with earth terminal GND with the junction of capacitor C 8; The base stage of triode Q2 is connected with the tie point of resistance R 14, resistance R 15, and the emitter of triode Q2 connects the tie point of resistance R 15 and capacitor C 8; The end of pull-up resistor R10 and+3.2V is connected, its other end connects triode Q2 collector, the collector of triode Q2 connects power-down state detection port int0 by port protection resistance R 13.