CN202159973U - Voltage detection protection circuit - Google Patents

Abstract

The utility model discloses a voltage detection protection circuit comprising a voltage acquisition circuit, a voltage detection comparison circuit and an output comparison circuit, wherein the voltage detection comparison circuit comprises an overvoltage detection hysteresis comparator consisting of resistors R1, R2, R8, R7 and a comparator A and an under-voltage hysteresis comparator consisting of resistors R5, R6, R13, R12 and a comparator B, resistors R3, R4 form the voltage acquisition circuit, and resistors R9, R10 and a comparator C form the output comparison circuit. The technical scheme of the voltage detection protection circuit realizes an overvoltage and under-voltage detection hysteresis protection for the voltage to be measured, and the voltage detection protection circuit also has the advantages of quick response speed and high stability.

Description

A kind of voltage detecting protective circuit

Technical field

The utility model relates to a kind of protective device, particularly a kind of voltage detecting protective circuit.

Background technology

Along with the lifting of electric equipment automaticity and the complexity of using electricity system structure strengthen; When electric voltage exception appears in system power supply or some key point; During like under-voltage or overvoltage fault, possibly cause the afunction of power consumption equipment or whole system is impacted that damage equipment causes economic loss when serious; Therefore generally all can carry out voltage detecting protection, particularly overvoltage and under-voltage protection to input power supply or some collection point.

Existing over-and under-voltage protective device circuit structure is complicated; Adopt the chip microcontroller defencive function then to exist the response time long; The defective that control rate is slow; Signal is wrong may cause program error for single-chip microcomputer output, when the voltage frequent variations, also possibly cause output timing chaotic, causes circuit instruction errors even damage.

The utility model content

In order to overcome the deficiency of prior art, the utility model provide a kind of simple in structure, be quick on the draw, the voltage detecting protective circuit of reliable in action, the sluggish protection of realization over-and under-voltage.

The utility model solves its technical problem and takes following scheme to realize:

A kind of voltage detecting protective circuit; Comprise voltage collection circuit, voltage detecting comparison circuit and output comparison circuit; Said voltage detecting comparison circuit comprises that the overvoltage of resistance R 1, R2, R8, R7 and comparator A formation detects the under-voltage hysteresis comparator of hysteresis comparator and resistance R 5, R6, R13, R12 and comparator B formation; Resistance R 3, R4 constitute voltage collection circuit, and resistance R 9, R10 and comparator C constitute the output comparison circuit.

Voltage Vin to be measured inserts the inverting input of comparator A and comparator B after resistance R 3, R4 dividing potential drop; Reference voltage REF inserts the in-phase input end of comparator A and comparator B respectively after resistance R 1, R2 and resistance R 5, R6 dividing potential drop; The inverting input of the output termination comparator C of comparator A also connects reference voltage REF through pull-up resistor R7; The output of comparator B connects the in-phase input end of comparator C and connects reference voltage REF through pull-up resistor R11 through resistance R 12; Be connected with resistance R 8, R13 respectively between the output of comparator A and comparator B and the in-phase input end of self, the inverting input of comparator C meets pull down resistor R10.

Said comparator A is same phase comparator, and comparator B, C are the anti-phase comparator.

The utility model compared with prior art has significant advantage and beneficial effect, is embodied in the following aspects:

Overvoltage detection and undervoltage detection circuit in the voltage detecting comparison circuit all have the voltage lag function, have avoided protective circuit near the overvoltage/undervoltage value, to vibrate, and guarantee the stability of circuit.

Compare the employing Single-chip Controlling, present technique adopts the simple logic hardware circuit to realize that overvoltage/undervoltage detects protection, and cost is low, and response speed is fast, and good stability can improve the reliability of institute's application system.

Description of drawings

Fig. 1 is the utility model voltage detecting protective circuit schematic diagram.

Embodiment

Come technical scheme is detailed below in conjunction with physical circuit given in the accompanying drawing.

The voltage detecting protective circuit of the utility model is as shown in Figure 1, and R3, R4 are that divider resistance is used to gather supply voltage to be measured; Resistance R 1, R2, R8, R7 and comparator A constitute the overvoltage delay comparator, are used for overvoltage and detect.Resistance R 5, R6, R13, R12 and comparator B constitute under-voltage hysteresis comparator, are used for under-voltage detection.Resistance R 9, R10 and comparator C constitute the output state decision circuitry, are used to export judged result.

The comparator that present embodiment adopts all is the comparator of OC output, adopts reference voltage REF power supply, and the dividing potential drop of resistance R 1, R2 is about 2/3REF generally speaking, and the dividing potential drop of R5 and R6 is about 1/3REF.In order to make the comparator C steady operation, the resistance value ratio of getting R7 and R10 in the present embodiment is about 1: 2, and the resistance value ratio of R11, R12 is about 2: 1.Also can select other ratio as required.

Circuit working principle under the different conditions is described below.

Voltage to be measured just often.Comparator A end of oppisite phase voltage is exported high level less than in-phase end voltage.Comparator B end of oppisite phase voltage is greater than in-phase end voltage, output low level.This moment, output state was determined by R7, R10, R11, R12, and the dividing potential drop of preset R7, R10 is greater than the dividing potential drop of R11, R12, comparator C output low level.

During under-voltage to be measured.Comparator A end of oppisite phase voltage is exported high level less than in-phase end voltage.Comparator B end of oppisite phase voltage is exported high level less than in-phase end voltage.Comparator C in-phase end voltage approaches REF, and end of oppisite phase voltage is about 2/3REF, comparator C output high level.

During electric voltage over press to be measured.Comparator A end of oppisite phase voltage is greater than in-phase end voltage, output low level.Comparator B end of oppisite phase voltage is greater than in-phase end voltage, output low level.Comparator C in-phase end voltage connects and is about 1/3REF, and end of oppisite phase voltage approaches ground, comparator C output high level.

Voltage to be measured is reduced to process just often by overvoltage again by normally being increased to overvoltage.Just often, comparator A output is a high-impedance state, in order to make calculating easy, establishes R1=R7, R2=R10, in-phase end voltage at this moment $U_{A_1}=\frac{\mathrm{REF}*R2}{R1+R2},$

After the overvoltage, comparator A output is a low level, at this moment in-phase end voltage

$U_{A_1}^{\′}=\frac{\mathrm{REF}*\frac{R2*R8}{R2+R8}}{R1+\frac{R2*R8}{R2+R8}}$

Can find out U _A1Less than U _A1'.After being overvoltage, comparator A end of oppisite phase voltage will drop to the following U of overpressure value _A1-U _A1In ' time, just can overturn is normal condition.So just formed a hysteresis voltage, prevented that effectively circuit from vibrating near overpressure value.

Voltage to be measured is under-voltage by normally reducing to, again by the under-voltage process that is increased to just often.Just often, comparator B output is a low level, at this moment in-phase end voltage

$U_{B_1}=\frac{\mathrm{REF}*\frac{R6*R13}{R6+R13}}{R5+\frac{R6*R13}{R6+R13}}$

After under-voltage, comparator B output is a high-impedance state, at this moment in-phase end voltage

$U_{B_1}^{\′}=\frac{\mathrm{REF}*R6}{R6+\frac{R5(R11+R12+R13)}{R5+R11+R12+R13}}$

Can find out U _B1Less than U _B1'.After being overvoltage, comparator B end of oppisite phase voltage will rise to the above U of under-voltage value _B1'-U _B1The time, just can overturn is normal condition.So just formed a hysteresis voltage, prevented that effectively circuit from vibrating near under-voltage value.

Claims (2)

1. voltage detecting protective circuit; It is characterized in that: comprise voltage collection circuit, voltage detecting comparison circuit and output comparison circuit; Said voltage detecting comparison circuit comprises that the overvoltage of resistance R 1, R2, R8, R7 and comparator A formation detects the under-voltage hysteresis comparator of hysteresis comparator and resistance R 5, R6, R13, R12 and comparator B formation; Resistance R 3, R4 constitute voltage collection circuit, and resistance R 9, R10 and comparator C constitute the output comparison circuit;

Voltage Vi to be measured inserts the inverting input of comparator A and comparator B after resistance R 3, R4 dividing potential drop; Reference voltage REF inserts the in-phase input end of comparator A and comparator B respectively after resistance R 1, R2 and resistance R 5, R6 dividing potential drop; The inverting input of the output termination comparator C of comparator A also connects reference voltage REF through pull-up resistor R7; The output of comparator B connects the in-phase input end of comparator C and connects reference voltage REF through pull-up resistor R11 through resistance R 12; Be connected with resistance R 8, R13 respectively between the output of comparator A and comparator B and the in-phase input end of self, the inverting input of comparator C meets pull down resistor R10.

2. a kind of voltage detecting protective circuit according to claim 1 is characterized in that: said comparator A is same phase comparator, and comparator B, C are the anti-phase comparator.

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