CN208112211U - A kind of over-voltage that low cost is practical detection protection circuit - Google Patents

Abstract

The utility model discloses a kind of over-voltages that low cost is practical to detect protection circuit, including：DC power output end, 3rd resistor, the 4th resistance, NMOS tube, the 5th resistance, relay, PNP triode, normally closed switch and load；3rd resistor and the 4th resistance are connected in series between the DC power output end and ground, 3rd resistor connects the grid of NMOS tube with the common end of the 4th resistance, and the drain electrode of NMOS tube connects DC power output end by the 5th resistance；Voltage comparison is carried out by using 3rd resistor, the 4th resistance and NMOS tube substitution comparator, saves economic cost, while the encapsulation of NMOS tube is simple；Normally closed switch is controlled using relay and is connected, when input voltage is high voltage, power supply of the DC power supply to load is disconnected in time, avoids the damage of load, extend the service life of device；The circuit structure is simple, improves the reliability and stability of product, reduces circuit cost, the occasion not high suitable for over-voltage required precision.

Description

A kind of over-voltage that low cost is practical detection protection circuit

Technical field

The utility model belongs to protection circuit field, and in particular to a kind of over-voltage that low cost is practical detection protection circuit.

Background technique

Many equipment have over-voltage protecting function now, mainly since the fluctuation of network voltage leads to current rectifying and wave filtering circuit The DC voltage of output is also unstable, if equipment works long hours in high voltage input state, can reduce the reliability of equipment.

Currently used overvoltage crowbar is usually to be completed with comparator, and comparator is mainly used for the high field of required precision It closes.For the equipment that certain specific environments use, the cost is relatively high for comparator.The equipment that this specific environment uses simultaneously Improve the reliability of product it is hoped that there will be over-voltage protecting function, but the design cost of the entire product of hope control range it It is interior and of less demanding for over-voltage precision point, therefore one circuit structure of design is simple, it is not high suitable for over-voltage required precision Occasion over-voltage detection protection circuit be very it is necessary to.

Utility model content

To overcome technological deficiency of the existing technology, the utility model discloses a kind of over-voltage that low cost is practical detections Protect circuit.

Technical solution adopted by the utility model to solve its technical problems is a kind of over-voltage that low cost is practical detections to protect Protection circuit, including：DC power output end, 3rd resistor, the 4th resistance, NMOS tube, the 5th resistance, relay, tri- pole PNP Pipe, normally closed switch and load；3rd resistor and the 4th resistance, third electricity are connected in series between the DC power output end and ground Resistance connects the grid of NMOS tube with the common end of the 4th resistance, and the drain electrode of the source electrode ground connection of NMOS tube, NMOS tube passes through the 5th electricity Resistance connection DC power output end, the drain electrode of NMOS tube are also connected with the base stage of PNP triode, the grounded collector of PNP triode, The first end of the emitter connection relay of PNP triode, the second end of relay connect DC power output end, relay Second end is also connected with the first end of normally closed switch, the first end of the second end connection load of normally closed switch, and the second end of load is The circuit output end of over-voltage detection protection circuit, normally closed switch are also controlled with the control terminal of relay and are connected.

Preferably, the both ends of the relay are also connected in parallel over-voltage indicating circuit, and the over-voltage indicating circuit includes the Six resistance and the second light emitting diode, the first end of the 6th resistance connect DC power output end, and the second end of the 6th resistance connects Connect the anode of the second light emitting diode, the first end of the cathode connection relay of the second light emitting diode.

Preferably, inductance is also connected between the 5th resistance and the 6th resistance.

Preferably, the 7th resistance is also connected between the collector and ground of the PNP triode.

Preferably, the DC power output end connects AC power source conversion circuit, and the AC power source conversion circuit is adopted Use full bridge rectifier.

Preferably, the AC power source conversion circuit output end is also connected with filter circuit, and the filter circuit includes the One resistance and first capacitor, the output end of the first end connection AC power source conversion circuit of the first resistor, first resistor Second end connects the first end of first capacitor, the second end ground connection of first capacitor.

Preferably, the second end of the first resistor is also connected with the first end of second resistance, and the second end of second resistance connects Connect the anode of the first light emitting diode, the minus earth of the first light emitting diode.

The utility model has the beneficial effects that：By using 3rd resistor, the 4th resistance and NMOS tube substitute comparator into Row voltage compares, and saves economic cost, while the encapsulation of NMOS tube is simple；Normally closed switch is controlled using relay and is connected, When input voltage is high voltage, power supply of the DC power supply to load is disconnected in time, the damage of load is avoided, extends the use of device Service life；The circuit structure is simple, improves the reliability and stability of product, reduces circuit cost, is suitable for over-voltage required precision Not high occasion.

Detailed description of the invention

Fig. 1 is a kind of circuit diagram of the practical over-voltage detection protection circuit of low cost of the utility model.

Appended drawing reference：AC- AC power source, R1- first resistor, C1- first capacitor, R2- second resistance, L1- first shine Diode, R3- 3rd resistor, the 4th resistance of R4-, the 5th resistance of R5-, NMOS-NMOS tube, L- inductance, the 6th resistance of R6-, The second light emitting diode of L2-, J- relay, PNP- PNP triode, K- normally closed switch, RL- load, OUT- circuit output end, The 7th resistance of R7-.

Specific embodiment

More detailed description is done to the embodiments of the present invention below in conjunction with attached drawing and appended drawing reference, makes to be familiar with ability The technology people in domain can implement accordingly after studying this specification carefully.It should be appreciated that specific embodiment described herein is only to solve The utility model is released, is not used to limit the utility model.

A kind of over-voltage that low cost is practical detection protection circuit, including：DC power output end, 3rd resistor R3, the 4th Resistance R4, NMOS tube NMOS, the 5th resistance R5, relay J, PNP triode PNP, normally closed switch K and load RL；The direct current The public of 3rd resistor R3 and the 4th resistance R4,3rd resistor R3 and the 4th resistance R4 is connected in series between power output end and ground The grid of end connection NMOS tube NMOS, the source electrode ground connection of NMOS tube NMOS, the drain electrode of NMOS tube NMOS are connected by the 5th resistance R5 DC power output end is connect, the drain electrode of NMOS tube NMOS is also connected with the base stage of PNP triode PNP, the current collection of PNP triode PNP The second end connection DC power supply of pole ground connection, the first end of the emitter connection relay J of PNP triode PNP, relay J is defeated Outlet, the second end of relay J are also connected with the first end of normally closed switch K, and the second end connection of normally closed switch K loads the first of RL End, the second end for loading RL is the circuit output end OUT of over-voltage detection protection circuit, control of the normally closed switch K also with relay J Control connection in end processed；Specifically, the grid of 3rd resistor R3 and the 4th resistance R4 for divider resistance for NMOS tube NMOS provides electricity Pressure, since the operation level of NMOS tube NMOS gate has a threshold voltage, when only grid voltage is more than threshold voltage, NMOS The grid of pipe receives high level signal ON operation, since the source electrode of NMOS tube NMOS is grounded, the drain electrode of NMOS tube NMOS at this time Low level is exported, PNP triode PNP receives low level signal conducting, and electric current flows through relay J, and relay J actuation is opened normally closed It closes K to disconnect, DC power output end is no longer load RL power supply at this time, to have the function that overvoltage protection；By using Three resistance R3, the 4th resistance R4 and NMOS tube NMOS substitution comparator carry out voltage comparison, save economic cost, while NMOS tube The encapsulation of NMOS is simple；Normally closed switch K is controlled using relay J and is connected, when input voltage is high voltage, is disconnected in time straight Power supply of the galvanic electricity source to load RL, avoids the damage of load RL, extends the service life of device.

The both ends of the relay J are also connected in parallel over-voltage indicating circuit, and the over-voltage indicating circuit includes the 6th resistance The first end of R6 and the second light emitting diode L2, the 6th resistance R6 connect DC power output end, the second end of the 6th resistance R6 Connect the anode of the second light emitting diode L2, the first end of the cathode connection relay J of the second light emitting diode L2；Specifically, If output voltage is overpressure situation, NMOS transistor conduction, PNP triode PNP conducting, the second light emitting diode L2 is lighted at this time, Second light emitting diode L2 is green, and prompting staff, circuit is overvoltage condition at this time, is convenient for staff's observation analysis, the Six resistance R6 are current-limiting resistance, and the second light emitting diode L2 of protection will not be burnt out.

Inductance L is also connected between the 5th resistance R5 and the 6th resistance R6；The inductance L is the effect of filtering, defeated When entering voltage and increasing, the electric current in inductance L increases, therefore inductance L is by storage section magnetic field energy, when the current decreases, and will Energy releases, and keeps load RL electric current smoothened, and therefore, inductance L also has flat wave to act on, and enhances the stability of circuit.

The 7th resistance R7 is also connected between the collector and ground of the PNP triode PNP；The 7th resistance R7 is limited Leakage resistance improves circuit job stability.

The DC power output end connects AC power source conversion circuit, and the AC power source conversion circuit is whole using full-bridge Current circuit；The full bridge rectifier is used to AC power source being converted to DC power supply, for the lower PNP tri- of rated supply voltage Pole pipe PNP, the load devices such as RL and relay J use.

The AC power source conversion circuit output end is also connected with filter circuit, and the filter circuit includes first resistor R1 With first capacitor C1, the first end of the first resistor R1 connects the output end of AC power source conversion circuit, first resistor R1's Second end connects the first end of first capacitor C1, the second end ground connection of first capacitor C1；Wherein, first resistor R1 and first capacitor C1 forms filter, filters out the ripple after rectifying for the first time, improves PNP triode PNP, loads the devices such as RL and relay J Supply voltage stability.

The second end of the first resistor R1 is also connected with the first end of second resistance R2, the second end connection of second resistance R2 The anode of first light emitting diode L1, the minus earth of the first light emitting diode L1；The first light emitting diode L1 is for referring to Show circuit whether normal operation, the first light emitting diode L1 is red, if when normal operation circuit, the first light emitting diode L1 is hit Wear it is luminous, if circuit damage, the first light emitting diode L1 does not shine, wherein second resistance R2 be current-limiting resistance, the instruction electricity Line structure is simple, and personnel is facilitated to observe over-voltage detection protection circuit whether normal operation, easy to repair.

The above content is the further descriptions made in conjunction with specific preferred embodiment to the utility model, cannot recognize Determine specific embodiment of the present utility model to be only limited to these instructions.For the common skill of the utility model technical field For art personnel, the other embodiments obtained in the case where not departing from the technical solution of the utility model be should be included in practical In novel protection scope.

Claims (7)

1. a kind of over-voltage that low cost is practical detection protection circuit, it is characterised in that：Including：DC power output end, third electricity Resistance（R3）, the 4th resistance（R4）, NMOS tube（NMOS）, the 5th resistance（R5）, relay（J）, PNP triode（PNP）, normally closed open It closes（K）And load（RL）；3rd resistor is connected in series between the DC power output end and ground（R3）With the 4th resistance（R4）, 3rd resistor（R3）With the 4th resistance（R4）Common end connect NMOS tube（NMOS）Grid, NMOS tube（NMOS）Source electrode connect Ground, NMOS tube（NMOS）Drain electrode pass through the 5th resistance（R5）Connect DC power output end, NMOS tube（NMOS）Drain electrode also Connect PNP triode（PNP）Base stage, PNP triode（PNP）Grounded collector, PNP triode（PNP）Emitter connect Contact relay（J）First end, relay（J）Second end connect DC power output end, relay（J）Second end also connect Connect normally closed switch（K）First end, normally closed switch（K）Second end connect load（RL）First end, load（RL）Second End is the circuit output end of over-voltage detection protection circuit（OUT）, normally closed switch（K）Also with relay（J）Control terminal control Connection.

2. a kind of over-voltage that low cost is practical detection protection circuit as described in claim 1, it is characterised in that：The relay （J）Both ends be also connected in parallel over-voltage indicating circuit, the over-voltage indicating circuit includes the 6th resistance（R6）With second luminous two Pole pipe（L2）, the 6th resistance（R6）First end connect DC power output end, the 6th resistance（R6）Second end connection second Light emitting diode（L2）Anode, the second light emitting diode（L2）Cathode connect relay（J）First end.

3. a kind of over-voltage that low cost is practical detection protection circuit as claimed in claim 2, it is characterised in that：5th electricity Resistance（R5）With the 6th resistance（R6）Between be also connected with inductance（L）.

4. a kind of over-voltage that low cost is practical detection protection circuit as described in claim 1, it is characterised in that：The PNP tri- Pole pipe（PNP）Collector and ground between be also connected with the 7th resistance（R7）.

5. a kind of over-voltage that low cost is practical detection protection circuit as described in claim 1, it is characterised in that：The direct current Source output terminal connects AC power source conversion circuit, and the AC power source conversion circuit uses full bridge rectifier.

6. a kind of over-voltage that low cost is practical detection protection circuit as claimed in claim 5, it is characterised in that：The alternating current Power-switching circuit output end is also connected with filter circuit, and the filter circuit includes first resistor（R1）And first capacitor（C1）, The first resistor（R1）First end connection AC power source conversion circuit output end, first resistor（R1）Second end connection First capacitor（C1）First end, first capacitor（C1）Second end ground connection.

7. a kind of over-voltage that low cost is practical detection protection circuit as claimed in claim 6, it is characterised in that：First electricity Resistance（R1）Second end be also connected with second resistance（R2）First end, second resistance（R2）Second end connect the first light-emitting diodes Pipe（L1）Anode, the first light emitting diode（L1）Minus earth.