CN206323124U - Over-voltage and under-voltage protection circuit, backlight circuit and liquid crystal television - Google Patents
Over-voltage and under-voltage protection circuit, backlight circuit and liquid crystal television Download PDFInfo
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- CN206323124U CN206323124U CN201621395999.5U CN201621395999U CN206323124U CN 206323124 U CN206323124 U CN 206323124U CN 201621395999 U CN201621395999 U CN 201621395999U CN 206323124 U CN206323124 U CN 206323124U
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- 239000004973 liquid crystal related substance Substances 0.000 title claims description 10
- 238000005070 sampling Methods 0.000 claims abstract description 42
- 239000004065 semiconductor Substances 0.000 claims description 23
- 230000005611 electricity Effects 0.000 claims description 16
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- 238000004519 manufacturing process Methods 0.000 abstract description 8
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Abstract
The utility model provides a cross undervoltage protection circuit, backlight circuit and LCD TV, it crosses undervoltage protection circuit and includes that power input port, power output port, reference end input have a voltage comparator, first sampling circuit, the second sampling circuit of settlement reference voltage, be used for controlling the first switching circuit of first sampling circuit break-make and be used for controlling the second switching circuit of break-make between power input port and the power output port; wherein a sampling coefficient of the first sampling circuit is larger than a sampling coefficient of the second sampling circuit. The utility model also provides a backlight circuit and LCD TV. The utility model discloses a voltage comparator just can realize the overvoltage protection and the undervoltage protection's of circuit function, consequently the utility model discloses a circuit structure is simple and low in production cost.
Description
Technical field
The utility model is related to technical field of circuit design, more particularly, to a kind of over under-voltage protection circuit, backlight circuit
And liquid crystal TV set.
Background technology
In the operating circuit of electronic equipment, work can be all had influence on when the input voltage of operating circuit is too high or too low
Make the normal work of circuit.For the normal work of the operating circuit that ensures electronic equipment, typically it can all be answered in operating circuit
With there is over under-voltage protection circuit, when operating circuit overtension or it is too low when, over under-voltage protection circuit can be stopped
The output of input voltage in circuit, so as to protect operating circuit.For example, the non-isolated boost type in liquid crystal TV set is carried on the back
In optical circuit, when the input voltage of backlight circuit is too high, backlight glimmer can be caused, when input voltage is too low, step-up ratio mistake
Greatly, backlight circuit job insecurity can be caused, and by then can be in backlight using over under-voltage protection circuit in backlight circuit
Input voltage it is too high or too low when stop backlight circuit input voltage output, so as to protect backlight circuit.
But existing over under-voltage protection circuit typically can all include two voltage comparators, one of voltage ratio compared with
Device is used for overvoltage protection, and another voltage comparator is used for under-voltage protection.A kind of such as existing over under-voltage protection circuit, such as schemes
Shown in 1, it includes two voltage comparators：U1A and U1B.Wherein, sampling voltage is divided into two-way, wherein sampling voltage all the way
Wherein voltage comparator U1A 3 pin are inputted after R1, R2, R3, R4 partial pressure, such as sampling voltage is higher than the 2 of voltage comparator U1A
The reference voltage of pin, voltage comparator U1A 1 pin output high level, so as to allow subsequent conditioning circuit (such as control being connected with output end
Device processed) gone to control the shut-off of circuit according to the high level, so as to reach overvoltage protection；Another road sampling voltage through R7, R8, R9,
The reference voltage of 5 pin of input voltage comparator U1B 6 pin after R10 partial pressures, such as sampling voltage less than voltage comparator U1B, electricity
Comparator U1B 7 pin output high level is pressed, so as to allow subsequent conditioning circuit (such as the controller being connected with output end) according to height electricity
The flat shut-off for going to control circuit, so as to reach under-voltage protection.Because existing over under-voltage protection circuit needs to use two voltages
Comparator, therefore circuit is more complicated, and also production cost is higher.
Utility model content
Regarding to the issue above, the purpose of this utility model is to provide a kind of mistake that circuit structure is simple and production cost is low
Under-voltage protecting circuit and also reside in offer include the backlight circuit of the over under-voltage protection circuit and including the backlight circuit
Liquid crystal TV set.
To achieve these goals, on the one hand the utility model provides a kind of over under-voltage protection circuit, and it includes power supply
Input port, output port of power source, reference edge input have the voltage comparator of reference voltage of setting, the first sample circuit,
Second sample circuit, the first switch circuit for controlling the first sample circuit break-make and for controlling the power supply defeated
Inbound port and the second switch circuit of the break-make of the output port of power source between the two；Wherein, first sample circuit
Downsampling factor is bigger than the downsampling factor of second sample circuit；
The input of first sample circuit is connected with the power input port, the sampling of first sample circuit
End is connected with the input of the first switch circuit, and controlled end and the power input port of the first switch circuit connect
Connect, the output end of the first switch circuit is connected with the comparison end of the voltage comparator；Second sample circuit it is defeated
Enter end to be connected with the power input, the sampling end of second sample circuit connects with the test side of the voltage comparator
Connect；The output end of the voltage comparator is connected with the controlled end of the second switch circuit, the second switch circuit it is defeated
Enter end to be connected with the power input port, the output end of the second switch circuit is connected with the output port of power source.
Preferably, the first switch circuit includes voltage-regulator diode, at least one first resistor, the first NPN triode
And at least one diode, the negative pole of the voltage-regulator diode is connected with the power input port, the voltage-regulator diode
Positive pole be connected by the first resistor with the base stage of first NPN triode, the colelctor electrode of first NPN triode
It is connected with the sampling end of first sample circuit, the grounded emitter of first NPN triode；The positive pole of the diode
Between the sampling end for being connected to the colelctor electrode of first NPN triode and first sample circuit, the diode it is negative
Pole is connected with the comparison end of the voltage comparator.
Preferably, first sample circuit includes at least one second resistance and at least one 3rd resistor, described
One end of second resistance is connected with the power input, and the other end of the second resistance is defeated with the first switch circuit
Enter end connection, one end of the 3rd resistor is connected with the output end of the first switch circuit, the 3rd resistor it is another
End ground connection.
Preferably, second sample circuit includes at least one 3rd resistor and at least one the 4th resistance, described
Power input passes sequentially through the 4th resistance and is grounded with the 3rd resistor, and the comparison end of the voltage comparator is connected to
Between the 3rd resistor and the 4th resistance.
Preferably, the model TL431, the TL431 of the voltage comparator reference pole are opened with described first respectively
The sampling end connection of the output end on powered-down road and second sample circuit, the negative electrode of the TL431 is respectively with described second
The controlled end of on-off circuit and power input port connection, the plus earth of the TL431.
Preferably, the second switch circuit include the second NPN triode, p-type metal-oxide-semiconductor, at least one the 5th resistance with
And at least one the 6th resistance, one end of the 5th resistance is connected with the power input port, the 5th resistance it is another
One end is connected with the output end of the voltage comparator, and the base stage of second NPN triode is connected to the voltage comparator
Output end and the 5th resistance between, the grounded emitter of second NPN triode, the collection of the NPN triode
Electrode is connected with the grid of the p-type metal-oxide-semiconductor, and the source electrode of the p-type metal-oxide-semiconductor is connected with the power input port, the p-type
The drain electrode of metal-oxide-semiconductor is connected with the output port of power source, and one end of the 6th resistance is connected with the source electrode of the p-type metal-oxide-semiconductor,
The other end of 6th resistance is connected with the grid of the p-type metal-oxide-semiconductor.
The utility model still further aspect provides a kind of backlight circuit, and it includes overvoltage/undervoltage protection electricity as described above
Road.
The utility model still further aspect additionally provides a kind of liquid crystal TV set, and it includes backlight circuit as described above.
The over under-voltage protection circuit including the backlight electricity of the over under-voltage protection circuit that the utility model is provided
Road and the liquid crystal TV set including the backlight circuit, when the voltage that the power input port is inputted is protected less than under-voltage
When protecting voltage, therefore the voltage of the controlled end for the first switch circuit being connected with the power input port will not enough break
First sample circuit is driven, now the sampling end of the sampling end of first sample circuit and second sample circuit is equal
It is connected with the comparison end of the voltage comparator, because the downsampling factor of the first sample circuit is big, therefore the voltage comparator
Comparison end sampled voltage it is higher than the reference voltage of its reference edge so that the voltage comparator output end output one
The level signal of the disconnection of the individual control second switch circuit, and then make it that the power input port is exported with the power supply
The connection of both ports disconnects, therefore can reach the function of under-voltage protection.When the voltage that the power input port is inputted is high
In under-voltage protection voltage and less than overvoltage protection voltage when, the first switch circuit being connected with the power input port
The voltage of controlled end can reach bias voltage, therefore the first switch circuit disconnects first sample circuit, at this moment by
It is relatively low in the downsampling factor of second sample circuit, thus the comparison end of the voltage comparator sampled voltage than its benchmark
The reference voltage at end is low, so that the output end of the voltage comparator exports a control second switch closing of circuit
Level signal, and then make it that both the power input port and described output port of power source are turned on and be connected, therefore circuit can
With normal work.When the voltage that the power input port is inputted is higher than overvoltage protection voltage, second sample circuit
The voltage of sampling end can be very high so that the benchmark electricity of the sampled voltage than its reference edge at the comparison end of the voltage comparator
Pressure is high, so that the output end of the voltage comparator exports the level letter of the disconnection of a control second switch circuit
Number, and then make it that the connection of the power input port and both output port of power source disconnects, therefore overvoltage can be reached
The function of protection.In summary, the utility model can just reach overvoltage protection and under-voltage guarantor by a voltage comparator
The function of shield, therefore in terms of existing technologies, circuit structure of the present utility model is simple and production cost is low.
Brief description of the drawings
, below will be attached to what is used needed for embodiment in order to illustrate more clearly of the technical solution of the utility model
Figure is briefly described, it should be apparent that, drawings in the following description are only some embodiments of the present utility model, for
For those of ordinary skill in the art, on the premise of not paying creative work, other can also be obtained according to these accompanying drawings
Accompanying drawing.
Fig. 1 is a kind of circuit diagram for over under-voltage protection circuit that prior art is provided；
Fig. 2 is a kind of circuit diagram for over under-voltage protection circuit that the utility model embodiment is provided；
Fig. 3 is a kind of circuit diagram for preferred over under-voltage protection circuit that the utility model embodiment is provided.
Embodiment
Below in conjunction with the accompanying drawing in the utility model embodiment, the technical scheme in the utility model embodiment is carried out
Clearly and completely describe, it is clear that described embodiment is only a part of embodiment of the utility model, rather than whole
Embodiment.Based on the embodiment in the utility model, those of ordinary skill in the art are not under the premise of creative work is made
The every other embodiment obtained, belongs to the scope of the utility model protection.
Refer to Fig. 2, on the one hand this practicality provides a kind of over under-voltage protection circuit, it include power input port Vn,
Output port of power source Vo, reference edge input have a voltage comparator U1 of the reference voltage of setting, the first sample circuit 1, second
Sample circuit 2, the first switch circuit 3 for controlling the break-make of the first sample circuit 1 and for controlling the power supply defeated
Inbound port Vn and the second switch circuit 4 of the break-makes of the output port of power source Vo between the two；Wherein, the first sampling electricity
The downsampling factor on road 1 is bigger than the downsampling factor of second sample circuit 2；
The input of first sample circuit 1 is connected with the power input port Vn, first sample circuit 1
Sampling end is connected with the input of the first switch circuit 3, controlled end and the power input of the first switch circuit 3
Port Vn connections, the output end of the first switch circuit 3 is connected with the comparison end of the voltage comparator U1；Described second adopts
The input of sample circuit 2 is connected with the power input, sampling end and the voltage comparator of second sample circuit 2
U1 test side connection；The output end of the voltage comparator U1 is connected with the controlled end of the second switch circuit 4, and described
The input of two on-off circuits 4 is connected with the power input port Vn, output end and the electricity of the second switch circuit 4
Source output terminal mouthful Vo connections.
In the utility model embodiment, when the power input port Vn voltages inputted are less than under-voltage protection voltage
When, therefore the voltage of the controlled end for the first switch circuit 3 being connected with the power input port Vn will not enough disconnect
The sampling end of first sample circuit 1, the now sampling end of first sample circuit 1 and second sample circuit 2
Comparison end with the voltage comparator U1 is connected, because the downsampling factor of the first sample circuit 1 is big, therefore the voltage ratio
The sampled voltage at the comparison end compared with device U1 is higher than the reference voltage of its reference edge, so that the output of the voltage comparator U1
The level signal of the disconnection of one control second switch circuit 4 of end output, so cause the power input port Vn with
Both output port of power source Vo connection disconnects, therefore can reach the function of under-voltage protection.When the power input
When the voltage of mouth Vn inputs is higher than under-voltage protection voltage and is less than overvoltage protection voltage, it is connected with the power input port Vn
The voltage of the controlled end of the first switch circuit 3 can reach bias voltage, thus the first switch circuit 3 disconnect it is described
First sample circuit 1, at this moment because the downsampling factor of second sample circuit 2 is relatively low, therefore the voltage comparator U1
The sampled voltage for comparing end is lower than the reference voltage of its reference edge, so that the output end output one of the voltage comparator U1
The level signal that the individual control second switch circuit 4 is closed, and then make it that the power input port Vn and the power supply are defeated
Both exit port Vo conducting connections, therefore circuit can be with normal work.When the power input port Vn voltages inputted are higher than
During overvoltage protection voltage, the voltage of the sampling end of second sample circuit 2 can be very high so that the voltage comparator U1
Comparison end sampled voltage it is higher than the reference voltage of its reference edge so that the voltage comparator U1 output end output
The level signal of the disconnection of one control second switch circuit 4, and then cause the power input port Vn and the electricity
Both source output terminal mouthful Vo connection disconnects, therefore can reach the function of overvoltage protection.In summary, the utility model passes through
One voltage comparator U1 can just reach the function of overvoltage protection and under-voltage protection, therefore in terms of existing technologies,
Circuit structure of the present utility model is simple and production cost is low.
In order to which the technical solution of the utility model is better described, a kind of citing of the present utility model, such as Fig. 3 are provided herein
Shown, Fig. 3 is a kind of circuit diagram of preferred over under-voltage protection circuit of the present utility model.
Fig. 3 is referred to, in this citing, the first switch circuit 3 includes voltage-regulator diode D1, at least one first electricity
Hinder R1, the first NPN triode Q1 and at least one diode D1, the voltage-regulator diode Z1 negative pole and the power input
Port Vn connections, the positive pole of the voltage-regulator diode Z1 passes through the first resistor R1 and the base of first NPN triode Q1
Pole is connected, and the colelctor electrode of first NPN triode Q1 is connected with the sampling end of first sample circuit 1, the first NPN
Triode Q1 grounded emitter；The positive pole of the diode D1 is connected to colelctor electrode and the institute of first NPN triode Q1
Between the sampling end for stating the first sample circuit 1, the negative pole of the diode D1 is connected with the comparison end of the voltage comparator U1.
Fig. 3 is referred to, in this citing, first sample circuit 1 is including at least one second resistance R2 and at least
One 3rd resistor R3, one end of the second resistance R2 is connected with the power input Vn, and the second resistance R1's is another
One end is connected with the input of the first switch circuit 3, one end of the 3rd resistor R1 and the first switch circuit 3
Output end is connected, the other end ground connection of the 3rd resistor R1.Wherein, the second resistance R2 and the first switch circuit 3
Output end connection one end be first sample circuit 1 sampling end.
Fig. 3 is referred to, in this citing, second sample circuit 2 is including at least one 3rd resistor R3 and at least
One the 4th resistance R4, the power input Vn pass sequentially through the 4th resistance R4 and 3rd resistor R3 and are grounded, institute
The comparison end for stating voltage comparator is connected between the 3rd resistor R1 and the 4th resistance R4.Wherein, the 4th electricity
One end that resistance R4 is connected with the 3rd resistor R3 is the sampling end of second sample circuit 2.
Fig. 3 is referred to, in this citing, reference pole R points of the model TL431, the TL431 of the voltage comparator
It is not connected with the output end of the first switch circuit 3 and the sampling end of second sample circuit 2, the moon of the TL431
Pole K is connected with the controlled end and the power input port Vn of the second switch circuit 4 respectively, the anode A of the TL431
Ground connection.Wherein, from the TL431 as the voltage comparator U1, circuit can power without individually to the TL431,
So that the structure of circuit is simpler.It should be noted that the voltage comparator U1 can also be the ratio of other models
Compared with device, such as LM324 or LM358, it is not specifically limited herein.
Refer to Fig. 3, in this citing, the second switch circuit 4 include the second NPN triode Q2, p-type metal-oxide-semiconductor Q3,
At least one the 5th resistance R5 and at least one the 6th resistance R6, the 5th resistance R5 one end and the power input
Mouth Vn connections, the other end of the 5th resistance R5 is connected with the output end of the voltage comparator U1, the poles of the 2nd NPN tri-
Pipe Q2 base stage is connected between the output end of the voltage comparator U1 and the 5th resistance R5, the 2nd NPN tri-
Pole pipe Q2 grounded emitter, the colelctor electrode of the NPN triode is connected with the grid of the p-type metal-oxide-semiconductor Q3, the p-type MOS
Pipe Q3 source electrode is connected with the power input port Vn, and drain electrode and the output port of power source Vo of the p-type metal-oxide-semiconductor Q3 connect
Connect, one end of the 6th resistance R6 is connected with the source electrode of the p-type metal-oxide-semiconductor Q3, the other end of the 6th resistance R6 and institute
State p-type metal-oxide-semiconductor Q3 grid connection.
The operation principle of this citing is as follows：When the input voltage of the power input port Vn is less than under-voltage protection voltage
When, the voltage-regulator diode Z1 is ended due to undertension, the base stage of first NPN triode Q1 be low level so that
The first NPN triode Q1 cut-off is obtained, at this moment the diode D1 forward conductions, so that the second resistance R2 passes through
The diode D1 is connected with the comparison end of the voltage comparator U1, thus the TL431 now reference pole R and institute
The sampling end connection of the sampling end and second sample circuit 2 of the first sample circuit 1 is stated, so the reference of the TL431
Pole R sampled voltage is turned on higher than the reference voltage built in it, now the negative electrode K of the TL431 with anode A, and the power supply is defeated
Inbound port Vn flows to ground by the 5th resistance R5, therefore the base stage of the second NPN triode Q2 is low level, so that
The second NPN triode Q2 cut-offs are obtained, now the grid of the p-type metal-oxide-semiconductor Q3 passes through the 5th resistance R5 and the electricity
Source input port Vn connections, thus grid and its source electrode of the p-type metal-oxide-semiconductor Q3 voltage with the power input port Vn
Input voltage it is equal, so the p-type metal-oxide-semiconductor Q3 end so that the power input port Vn and the power supply are defeated
Exit port Vo is disconnected, therefore can complete the under-voltage protection to circuit.
When the input voltage of the power input port Vn is higher than under-voltage protection voltage either higher than overvoltage protection electricity
During pressure, voltage-regulator diode Z1 conducting, so that first NPN triode Q1 is turned on, the now second resistance R2
By first NPN triode Q1 be grounded, therefore the diode D1 end so that the second resistance R2 with it is described
3rd resistor R3 disconnects (the comparison end disconnection of the sampling end of i.e. described first sample circuit 1 and the voltage comparator U1
Connection), thus flow to the electric current of the 4th resistance R4 lacked the second resistance R2 this all the way, now overvoltage/undervoltage protection
Circuit has two kinds of operative scenarios.
Operative scenario one is：When power input port Vn input voltage is higher than under-voltage protection voltage and less than overvoltage protection
During voltage, because the downsampling factor of second sample circuit 2 is smaller, therefore the voltage of its sampling end is not also high so that institute
The sampled voltage for stating TL431 reference pole R is cut less than the reference voltage built in it, therefore the negative electrode K of the TL431 with anode A
Only, the base stage of the second NPN triode Q2 is high level, the second NPN triode Q2 conductings, the p-type metal-oxide-semiconductor Q3's
Grid is low level, therefore the p-type metal-oxide-semiconductor Q3 is turned on, so that the power input port Vn is exported with the power supply
Vo connections in port are turned on, so that circuit normal work.
Operative scenario two is：Although the downsampling factor of second sample circuit 2 is than the sampling of first sample circuit
Coefficient is small, but when power input port Vn input voltage is higher than overvoltage protection voltage, the 4th resistance and described the
Partial pressure between three resistance can become very high, so that the reference pole R of TL431 sampled voltage is higher than built in it
Reference voltage, now the negative electrode K of the TL431 and anode A conducting, the second NPN triode Q2 cut-offs, the p-type metal-oxide-semiconductor
Q3 is also switched off, so that the power input port Vn is disconnected with the output port of power source Vo, therefore can be completed
To the overvoltage protection of circuit.
In summary, in this citing, it can just be completed pair by a voltage comparator U1 (i.e. described TL431)
The overvoltage protection and under-voltage protection function of circuit, therefore can allow the structure of circuit to become simple and can reduce to be produced into
This.
, can be with further, since first sample circuit 1 and second sample circuit 2 share the 3rd resistor R3
Further simplify the structure of circuit, so as to further reduce production cost.
It should be noted that can be adjusted by the resistance size for adjusting the second resistance R2 and the 3rd resistor R3
The downsampling factor of first sample circuit 1, by the resistance size for adjusting the 3rd resistor R3 and the 4th resistance R4
The downsampling factor of second sample circuit 2 can be adjusted.
The utility model still further aspect provides a kind of backlight circuit, and it includes overvoltage/undervoltage protection electricity as described above
Road.
In the utility model embodiment, the backlight circuit, therefore can by applying above-mentioned over under-voltage protection circuit
To allow its circuit structure to become simpler and production cost can be reduced.
The utility model still further aspect additionally provides a kind of liquid crystal TV set, and it includes backlight circuit as described above.
In the utility model embodiment, the liquid crystal TV set includes the over under-voltage protection circuit by application
The backlight circuit, therefore the circuit structure that it can be allowed internal becomes simpler and can reduce production cost.
The above, embodiment only of the present utility model, but protection domain of the present utility model do not limit to
In this, any those skilled in the art is disclosed in the utility model in technical scope, the change that can be readily occurred in
Change or replace, should all cover within protection domain of the present utility model.Therefore, protection domain of the present utility model should be with described
Scope of the claims is defined.
Claims (8)
1. a kind of over under-voltage protection circuit, it is characterised in that including power input port, output port of power source, reference edge input
Have a voltage comparator of the reference voltage of setting, the first sample circuit, the second sample circuit, for controlling first sampling
The first switch circuit of connecting and disconnecting of the circuit and for controlling the power input port and the output port of power source between the two
Break-make second switch circuit；Wherein, sampling of the downsampling factor of first sample circuit than second sample circuit
Coefficient is big；
The input of first sample circuit is connected with the power input port, the sampling end of first sample circuit with
The input connection of the first switch circuit, the controlled end of the first switch circuit is connected with the power input port,
The output end of the first switch circuit is connected with the comparison end of the voltage comparator；The input of second sample circuit
It is connected with the power input, the sampling end of second sample circuit is connected with the test side of the voltage comparator；Institute
The output end for stating voltage comparator is connected with the controlled end of the second switch circuit, the input of the second switch circuit with
The power input port connection, the output end of the second switch circuit is connected with the output port of power source.
2. over under-voltage protection circuit according to claim 1, it is characterised in that the first switch circuit includes voltage stabilizing two
Pole pipe, at least one first resistor, the first NPN triode and at least one diode, the negative pole of the voltage-regulator diode with
The power input port connection, the positive pole of the voltage-regulator diode passes through the first resistor and first NPN triode
Base stage connection, the colelctor electrode of first NPN triode is connected with the sampling end of first sample circuit, described first
The grounded emitter of NPN triode；The positive pole of the diode is connected to the colelctor electrode of first NPN triode and described the
Between the sampling end of one sample circuit, the negative pole of the diode is connected with the comparison end of the voltage comparator.
3. over under-voltage protection circuit according to claim 1, it is characterised in that first sample circuit includes at least one
Individual second resistance and at least one 3rd resistor, one end of the second resistance are connected with the power input, and described
The other end of two resistance is connected with the input of the first switch circuit, one end of the 3rd resistor and the first switch
The output end connection of circuit, the other end ground connection of the 3rd resistor.
4. over under-voltage protection circuit according to claim 1, it is characterised in that second sample circuit includes at least one
Individual 3rd resistor and at least one the 4th resistance, the power input pass sequentially through the 4th resistance and the described 3rd electricity
Resistance ground connection, the comparison end of the voltage comparator is connected between the 3rd resistor and the 4th resistance.
5. over under-voltage protection circuit according to claim 1, it is characterised in that the model of the voltage comparator
TL431, the TL431 reference pole respectively with the output end of the first switch circuit and adopting for second sample circuit
Sample end is connected, and the negative electrode of the TL431 connects with the controlled end of the second switch circuit and the power input port respectively
Connect, the plus earth of the TL431.
6. the over under-voltage protection circuit according to claim 1 to 5 any one, it is characterised in that the second switch electricity
Road includes the second NPN triode, p-type metal-oxide-semiconductor, at least one the 5th resistance and at least one the 6th resistance, the 5th electricity
One end of resistance is connected with the power input port, and the other end of the 5th resistance connects with the output end of the voltage comparator
Connect, the base stage of second NPN triode is connected between the output end of the voltage comparator and the 5th resistance, institute
The grounded emitter of the second NPN triode is stated, the colelctor electrode of the NPN triode is connected with the grid of the p-type metal-oxide-semiconductor, institute
The source electrode for stating p-type metal-oxide-semiconductor is connected with the power input port, and drain electrode and the output port of power source of the p-type metal-oxide-semiconductor connect
Connect, one end of the 6th resistance is connected with the source electrode of the p-type metal-oxide-semiconductor, the other end and the p-type of the 6th resistance
The grid connection of metal-oxide-semiconductor.
7. a kind of backlight circuit, it is characterised in that including the over under-voltage protection circuit as described in claim 1 to 6 any one.
8. a kind of liquid crystal TV set, it is characterised in that including backlight circuit as claimed in claim 7.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201621395999.5U CN206323124U (en) | 2016-12-19 | 2016-12-19 | Over-voltage and under-voltage protection circuit, backlight circuit and liquid crystal television |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201621395999.5U CN206323124U (en) | 2016-12-19 | 2016-12-19 | Over-voltage and under-voltage protection circuit, backlight circuit and liquid crystal television |
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| Publication Number | Publication Date |
|---|---|
| CN206323124U true CN206323124U (en) | 2017-07-11 |
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|---|---|---|---|
| CN201621395999.5U Active CN206323124U (en) | 2016-12-19 | 2016-12-19 | Over-voltage and under-voltage protection circuit, backlight circuit and liquid crystal television |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108429239A (en) * | 2018-04-24 | 2018-08-21 | 广州金升阳科技有限公司 | A kind of output overvoltage protection circuit and the power supply comprising the circuit |
| CN113300321A (en) * | 2021-04-23 | 2021-08-24 | 上海卫星工程研究所 | Intelligent power distribution circuit based on MOSFET (metal-oxide-semiconductor field effect transistor), and satellite power distribution equipment |
-
2016
- 2016-12-19 CN CN201621395999.5U patent/CN206323124U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108429239A (en) * | 2018-04-24 | 2018-08-21 | 广州金升阳科技有限公司 | A kind of output overvoltage protection circuit and the power supply comprising the circuit |
| CN113300321A (en) * | 2021-04-23 | 2021-08-24 | 上海卫星工程研究所 | Intelligent power distribution circuit based on MOSFET (metal-oxide-semiconductor field effect transistor), and satellite power distribution equipment |
| CN113300321B (en) * | 2021-04-23 | 2023-03-14 | 上海卫星工程研究所 | Intelligent power distribution circuit based on MOSFET (metal-oxide-semiconductor field effect transistor), and satellite power distribution equipment |
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