CN105788556A - Overvoltage protection circuit and method and liquid crystal drive circuit - Google Patents
Overvoltage protection circuit and method and liquid crystal drive circuit Download PDFInfo
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- CN105788556A CN105788556A CN201610341350.3A CN201610341350A CN105788556A CN 105788556 A CN105788556 A CN 105788556A CN 201610341350 A CN201610341350 A CN 201610341350A CN 105788556 A CN105788556 A CN 105788556A
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- overvoltage crowbar
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
- G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/20—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for electronic equipment
Abstract
The invention provides an overvoltage protection circuit and method and a liquid crystal drive circuit. The overvoltage protection circuit comprises a detection node, a control unit, switch units and a voltage reducing unit, wherein the control unit is used for judging whether the voltage at the detection node is higher than a reference voltage or not; if so, a first control signal is output by a signal output end of the control unit and makes the first switch unit in an on state and the second switch unit in an off state; otherwise, a second control signal is output by the signal output end of the control unit and makes the first switch unit in an off state and the second switch unit in an on state; and the voltage reducing unit is used for converting the voltage at a voltage input end of the overvoltage protection circuit to match the working voltage of a load when the first switch unit is in the on state. According to the overvoltage protection circuit provided by the invention, in the case of connection with a high voltage by mistake, the load still can work normally, and the problem of damage caused by excessive current is avoided.
Description
Technical field
The present invention relates to electronic technology field, particularly relate to a kind of overvoltage crowbar and method, liquid crystal display drive circuit.
Background technology
Each Circuits System in liquid crystal display has different running voltages; it is generally divided into 5V and 12V; in the input circuit of the Circuits System of existing 5V; often at the two ends of the Circuits System of 5V, a voltage stabilizing value in parallel is the Zener diode of 6V; concrete circuit connecting relation is as shown in Figure 1; in figure, load is the Circuits System of 5V, and Zener diode can make the input voltage value of the Circuits System of 5V remain stable for, thus reaching the purpose of the Circuits System of protection 5V.
But when assembling liquid crystal display, if the Circuits System of 5V is arranged on the power supply of 12V by mistake, owing to 12V voltage exceedes the voltage stabilizing value of Zener diode, therefore, Zener diode will always be in conducting state, electric current also can become very big, being easy to cause because electric current is excessive damaging, in this case, the Circuits System of 5V is by the power supply being directly coupled to 12V, cause that in the Circuits System of 5V, some or all of module is burned out, and causes waste.
Summary of the invention
The embodiment of the present invention provides a kind of overvoltage crowbar and method, liquid crystal display drive circuit, to solve to be linked in the circuit of high pressure by load and cause that load damages the problem that cannot work by mistake.
The embodiment of the present invention provides a kind of overvoltage crowbar, and it includes the voltage input end of overvoltage crowbar, detecting node, control unit, the first switch element, second switch unit and pressure unit；
Described detecting node, is connected with the voltage input end of described overvoltage crowbar；
Described control unit, including detecting voltage input end, reference voltage input terminal and signal output part, wherein, described detecting voltage input end is connected with described detecting node, and described reference voltage input terminal is used for input reference voltage；
Described first switch element and second switch unit; all include signal input part, voltage input end and voltage output end; wherein; the signal input part of described first switch element is connected with the signal output part of described control unit; the voltage input end of described first switch element is connected with the voltage input end of described overvoltage crowbar, and the voltage output end of described first switch element is connected with described load by described pressure unit；
The signal input part of described second switch unit is connected with the signal output part of described control unit; the voltage input end of described second switch unit is connected with the voltage input end of described overvoltage crowbar, and the voltage output end of described second switch unit is connected with load；
Wherein, whether described control unit is used for the voltage judging described detecting node place more than described reference voltage, if so, then exports the first control signal by the signal output part of described control unit, making described first switch element in the conduction state, described second switch unit is off；If it is not, then export the second control signal by the signal output part of described control unit so that described first switch element is off, described second switch unit is in the conduction state；
Described pressure unit, for when the first switch element is in the conduction state, matching the voltage transformation of the voltage input end of overvoltage crowbar to the running voltage with load.
In the overvoltage crowbar described in the embodiment of the present invention, described first switch element includes:
Oneth P type field effect transistor, its source electrode is connected with the voltage input end of described overvoltage crowbar, and drain electrode is connected with described pressure unit；
First N-type field effect transistor; its source electrode is connected with ground wire; drain electrode is connected with the grid of a described P type field effect transistor; and first the drain electrode of N-type field effect transistor be connected by the voltage input end of resistance with described overvoltage crowbar, the grid of the first N-type field effect transistor is connected with the signal output part of described control unit.
In the overvoltage crowbar described in the embodiment of the present invention, described second switch unit includes:
2nd P type field effect transistor, its source electrode is connected with the voltage input end of described overvoltage crowbar, and drain electrode is connected with load, and grid is connected with the signal output part of described control unit.
In the overvoltage crowbar described in the embodiment of the present invention, described overvoltage crowbar also protects the first voltage regulation unit, and described first voltage regulation unit includes:
Second N-type field effect transistor, its source electrode is connected with ground wire, and drain electrode is connected by the voltage input end of the first Zener diode with described overvoltage crowbar, and grid is connected with the signal output part of described control unit.
In the overvoltage crowbar described in the embodiment of the present invention, described overvoltage crowbar also protects the second voltage regulation unit, and described second voltage regulation unit includes:
3rd N-type field effect transistor, its source electrode is connected with ground wire, and drain electrode is connected by the voltage input end of the second Zener diode with described overvoltage crowbar；
4th N-type field effect transistor; its source electrode is connected with ground wire; drain electrode is connected with the grid of described 3rd N-type field effect transistor; and the drain electrode of described 4th N-type field effect transistor is connected by the voltage input end of resistance with described overvoltage crowbar, and the described grid of the 4th N-type field effect transistor is connected with the signal output part of described control unit.
In the overvoltage crowbar described in the embodiment of the present invention, described control unit includes comparator.
In the overvoltage crowbar described in the embodiment of the present invention, the voltage stabilizing value of described first Zener diode is 12V.
In the overvoltage crowbar described in the embodiment of the present invention, the voltage stabilizing value of described second Zener diode is 6V.
The embodiment of the present invention also provides for a kind of over-voltage protection method, and it is applied to any one overvoltage crowbar above-mentioned, and described over-voltage protection method includes:
Judge that whether the voltage at described detecting node place is more than described reference voltage；
If; then export the first control signal by the signal output part of described control unit; make described first switch element in the conduction state; described second switch unit is off, and is matched to the running voltage with load by the voltage transformation of the voltage input end of overvoltage crowbar by described pressure unit；
If it is not, then export the second control signal by the signal output part of described control unit so that described first switch element is off, described second switch unit is in the conduction state.
The embodiment of the present invention provides again a kind of liquid crystal display drive circuit, and described liquid crystal display drive circuit includes any one overvoltage crowbar above-mentioned.
Compared with prior art; the overvoltage crowbar of embodiment of the present invention offer and method; by arranging control unit, switch element and pressure unit; wherein control unit is for judging that whether the voltage detecting node place is more than reference voltage; if; control unit will send the first control signal so that the first switching means conductive, thereby through pressure unit, by voltage, the running voltage dropped to load matches；If it is not, control unit will send the second control signal so that second switch unit turns on, thus load being connected with the voltage input end of overvoltage crowbar.Adopting overvoltage crowbar provided by the invention and method, when load misconnection enters on higher power supply, it not only can well be protected, it is also possible to normal operation, does not have and causes burning the problem that cannot work on higher power supply because misconnection enters.
The embodiment of the present invention also provides for a kind of liquid crystal display drive circuit; it adopts overvoltage crowbar provided by the invention; liquid crystal display drive circuit provided by the invention is used more flexible; certain load system misconnection in liquid crystal display drive circuit enters high pressure; its load still can normal operation; do not have, because misconnection enters, higher power supply causes burning the problem that cannot work, greatly reduce the scrappage of liquid crystal display drive circuit.
Accompanying drawing explanation
Fig. 1 is the circuit diagram of the protection circuit of existing load；
The circuit diagram of the overvoltage crowbar that Fig. 2 provides for first preferred embodiment of the invention；
The circuit diagram of the overvoltage crowbar that Fig. 3 provides for second preferred embodiment of the invention；
The circuit diagram of the overvoltage crowbar that Fig. 4 provides for third preferred embodiment of the invention；
The flow chart of the over-voltage protection method that Fig. 5 provides for the preferred embodiment of the present invention.
Detailed description of the invention
In order to be illustrated more clearly that the embodiment of the present invention or technical scheme of the prior art, below the accompanying drawing used required in embodiment is briefly described.Accompanying drawing in the following describes is only the section Example of the present invention, for those of ordinary skills, under the premise not paying creative work, it is also possible to obtain other accompanying drawing according to these accompanying drawings.
Refer to Fig. 2; Fig. 2 is the circuit diagram of overvoltage crowbar in first preferred embodiment of the invention; in this preferred embodiment; overvoltage crowbar includes the voltage input end of overvoltage crowbar; the voltage input end of overvoltage crowbar is connected with extraneous power supply; being easy to extraneous power supply and provide voltage by the voltage input end of overvoltage crowbar to overvoltage crowbar and load, in fig. 2, we use VinRepresent the voltage input end of overvoltage crowbar.
Overvoltage crowbar also includes detecting node A, control unit the 10, first switch element 21, second switch unit 22 and pressure unit 30.
The detecting node A voltage input end V by resistance R1 with overvoltage crowbarinBeing connected, access ground wire by resistance R2, certainly, in other examples, detecting node A can also directly and the voltage input end V of overvoltage crowbarinIt is connected, is not specifically limited at this.
The detecting voltage input end 10a of control unit 10 is connected with the detecting node A in overvoltage crowbar, and the reference voltage input terminal 10b of control unit 10 is used for input reference voltage Vref；The signal input part 22a of the signal output part 10c of control unit 10 and the signal input part 21a of the first switch element 21 and second switch unit 22 is connected；The voltage input end 10d of the control unit 10 and voltage input end V of overvoltage crowbarinIt is connected.
The voltage input end 21b of the first switch element 21 and voltage input end 22b of second switch unit 22, all with the voltage input end V of overvoltage crowbarinBeing connected, the voltage output end 21c of the first switch element 21 is connected with load by pressure unit 30, and the voltage output end 22c of second switch unit 22 is connected with load.
In the overvoltage crowbar that this preferred embodiment provides, control unit 10 is for judging that whether the voltage detecting node A place is more than reference voltage Vref, if so, then export the first control signal by the signal output part 10c of control unit 10 so that the first switch element 21 turns on, and second switch unit 22 disconnects, and pressure unit 30 is by the voltage input end V of overvoltage crowbarinVoltage transformation match to the running voltage with load so that load can normal operation, solve in prior art because load to be directly connected in high voltage power supply the problems such as the damage that produces by mistake；If it is not, then export the second control signal by the signal output part 10c of control unit 10 so that second switch unit 22 turns on, and the first switch element 21 disconnects so that load accesses the voltage input end V of overvoltage crowbarin, thus working normally.
The overvoltage crowbar that this preferred embodiment provides; when the voltage input end of overvoltage crowbar accesses higher than time on the power supply of the running voltage of load; effect by control unit the 10, first switch element 21 and pressure unit 30; load can work normally; make load will not cause, because misconnection enters high voltage, problems such as burning; meanwhile, when the voltage input end of overvoltage crowbar accesses on the power supply that the running voltage with load matches, load can also work normally.
Refer to Fig. 3; the circuit diagram of the overvoltage crowbar that Fig. 3 provides for second preferred embodiment of the invention; in the preferred embodiment; overvoltage crowbar includes the voltage input end of overvoltage crowbar; the voltage input end of overvoltage crowbar is connected with extraneous power supply; being easy to extraneous power supply and provide voltage by the voltage input end of overvoltage crowbar to overvoltage crowbar and load, in figure 3, we use VinRepresent the voltage input end of overvoltage crowbar.
The overvoltage crowbar that this preferred embodiment provides also includes detecting node A, control unit the 10, first switch element 21, second switch unit 22 and pressure unit 30.
The annexation between concrete structure and all parts of overvoltage crowbar is described in detail below in conjunction with Fig. 3.
The detecting node A voltage input end V by resistance R1 with overvoltage crowbarinBeing connected, access ground wire by resistance R2, certainly, in other examples, detecting node A can also directly and the voltage input end V of overvoltage crowbarinIt is connected, is not specifically limited at this.
In the preferred embodiment, control unit 10 is comparator 101, and certainly in other examples, control unit 10 can be other 1 device or is made up of multiple devices, as long as the function of control unit 10 can be realized, is not particularly limited at this.
The detecting voltage input end 101a of comparator 101 is connected with the detecting node A in overvoltage crowbar, and the reference voltage input terminal 101b of comparator 101 is used for input reference voltage Vref, in the preferred embodiment, the running voltage of load is 5V, reference voltage VrefThe voltage obtaining detecting node A place, resistance R1, resistance R2 and reference voltage V can be calculated according to the resistance value of resistance R1 and resistance R2refOccurrence can set according to practical situation, be not specifically limited at this.
The signal input part of the signal output part 101c of comparator 101 and the signal input part of the first switch element 21 and second switch unit 22 is connected, it should be noted that, for the terseness of circuit diagram, in Fig. 3, the first switch element 21 is collectively labeled as Output with each needs in second switch unit 22 with the signal output part 101c of comparator 101 signal input part being connected.Concrete annexation between signal output part 101c and signal input part and the signal input part of second switch unit 22 of the first switch element 21 of comparator 101 is introduced in more detail below.
First switch element 21 includes P type field effect transistor the 211, first N-type field effect transistor 212 and a resistance R3, wherein, and the source electrode of a P type field effect transistor 211 and the voltage input end V of overvoltage crowbarinBeing connected, drain electrode is connected with load by pressure unit 30；The source electrode of the first N-type field effect transistor 212 is connected with ground wire, and drain electrode is connected with the grid of a P type field effect transistor 211, and the voltage input end V that the drain electrode of the first N-type field effect transistor 212 is by resistance R3 Yu overvoltage crowbarinBeing connected, the grid of the first N-type field effect transistor 212 is connected with the signal output part 101c of comparator 101.
Second switch unit 22 includes the 2nd P type field effect transistor 221, the source electrode of the 2nd P type field effect transistor 221 and the voltage input end V of overvoltage crowbarinBeing connected, drain electrode is connected with load, and grid is connected with the signal output part 101c of comparator 101.
In the preferred embodiment, the type of P type field effect transistor the 211, a 2nd P type field effect transistor 221 and the first N-type field effect transistor 212 is enhancement mode field effect transistor.
In the preferred embodiment, the voltage input end V of the source electrode of a P type field effect transistor 211 and the 2nd P type field effect transistor 221 and overvoltage crowbarinConnection for being indirectly connected to, i.e. the source electrode of a P type field effect transistor 211 and the 2nd P type field effect transistor 221 voltage input end V by an electric fuse and overvoltage crowbarinBeing connected, certainly in other examples, the source electrode of a P type field effect transistor 211 and the 2nd P type field effect transistor 221 can also directly and the voltage input end V of overvoltage crowbarinIt is connected.
In the overvoltage crowbar that this preferred embodiment provides, as the voltage input end V of overvoltage crowbarinWhen the magnitude of voltage of input is higher than loaded work piece voltage, for instance, access 12V voltage, and the running voltage of load is 5V, the magnitude of voltage at the detecting node A place that the detecting voltage input end 101a of comparator 101 obtains will be greater than reference voltage Vref, namely now comparator 101 judges that the voltage at detecting node A place is more than reference voltage VrefThe signal output part 101c of comparator 101 will export the first control signal, and wherein, the first control signal is high level signal, first switch element 21 is by the conduction state, and second switch unit 22 will be off, by the effect of pressure unit 30 so that 12V voltage is down to 5V, namely it is down to the running voltage with load to match, thus realizing entering in high-tension situation in misconnection, load can also normal operation, and the problems such as damage will not be caused because electric current is excessive.
Voltage input end V when overvoltage crowbarinDuring the running voltage 5V that magnitude of voltage is load inputted, the magnitude of voltage at the detecting node A place that the detecting voltage input end 101a of comparator 101 obtains will be not more than reference voltage VrefNow; the signal output part 101c of comparator 101 will export the second control signal; wherein; second control signal is low level signal; second switch unit 22 is by the conduction state, and the first switch element 21 will be off, and now load is by the voltage input end V of second switch unit 22 with overvoltage crowbarinIt is connected, and keeps normal duty.
The overvoltage crowbar that this preferred embodiment provides, as the voltage input end V of overvoltage crowbarinDuring high input voltage; when being namely higher than the running voltage of load; effect by comparator the 101, first switch element 21 and pressure unit 30; make load can in its running voltage normal operation; avoid in prior art; because load being accessed high voltage and causes the problems such as damage by mistake, meanwhile, as the voltage input end V of overvoltage crowbarinDuring the running voltage of input load, by the effect of comparator 101 and second switch unit 22 so that load can keep normal work.
Refer to the circuit diagram of the overvoltage crowbar that the third preferred embodiment that Fig. 4, Fig. 4 are the present invention provides.In the preferred embodiment; overvoltage crowbar includes the voltage input end of overvoltage crowbar; the voltage input end of overvoltage crowbar is connected with extraneous power supply; it is easy to extraneous power supply and provides voltage by the voltage input end of overvoltage crowbar to overvoltage crowbar and load; in the diagram, we use VinRepresent the voltage input end of overvoltage crowbar.
The overvoltage crowbar that this preferred embodiment provides also includes detecting node A, control unit the 10, first switch element 21, second switch unit 22, pressure unit the 30, first voltage regulation unit 40 and the second voltage regulation unit 50.
The annexation between concrete structure and all parts of overvoltage crowbar is described in detail below in conjunction with Fig. 4.
The detecting node A voltage input end V by resistance R1 with overvoltage crowbarinBeing connected, access ground wire by resistance R2, certainly, in other examples, detecting node A can also directly be connected with the voltage input end of overvoltage crowbar, is not specifically limited at this.
In the preferred embodiment, control unit 10 is comparator 101, and certainly in other examples, control unit 10 can be other 1 device or is made up of multiple devices, as long as the function of control unit 10 can be realized, is not particularly limited at this.
The detecting voltage input end 101a of comparator 101 is connected with the detecting node A in overvoltage crowbar, and the reference voltage input terminal 101b of comparator 101 is used for input reference voltage Vref, in the preferred embodiment, the running voltage of load is 5V, reference voltage VrefThe voltage obtaining detecting node A place, resistance R1, resistance R2 and reference voltage V can be calculated according to the resistance value of resistance R1 and resistance R2refOccurrence can set according to practical situation, be not specifically limited at this.
The signal input part of the signal output part 101c of comparator 101 and the signal input part of the first switch element 21 and second switch unit 22 is connected, it should be noted that, for the terseness of circuit diagram, in Fig. 4, the first switch element 21 is collectively labeled as Output with each needs in second switch unit 22 with the signal output part 101c of comparator 101 signal input part being connected.Concrete annexation between signal output part 101c and signal input part and the signal input part of second switch unit 22 of the first switch element 21 of comparator 101 is introduced in more detail below.
First switch element 21 includes P type field effect transistor the 211, first N-type field effect transistor 212 and a resistance R3, wherein, and the source electrode of a P type field effect transistor 211 and the voltage input end V of overvoltage crowbarinBeing connected, drain electrode is connected with load by pressure unit 30；The source electrode of the first N-type field effect transistor 212 is connected with ground wire, and drain electrode is connected with the grid of a P type field effect transistor 211, and the voltage input end V that the drain electrode of the first N-type field effect transistor 212 is by resistance R3 Yu overvoltage crowbarinBeing connected, the grid of the first N-type field effect transistor 212 is connected with the signal output part 101c of comparator 101.
Second switch unit 22 includes the 2nd P type field effect transistor 221, the source electrode of the 2nd P type field effect transistor 221 and the voltage input end V of overvoltage crowbarinBeing connected, drain electrode is connected with load, and grid is connected with the signal output part 101c of comparator 101.
First voltage regulation unit 40 includes the second N-type field effect transistor 401 and the first Zener diode 402, and the source electrode of the second N-type field effect transistor 401 is connected with ground wire, and drain the voltage input end V by the first Zener diode 402 with overvoltage crowbarinBeing connected, grid is connected with the signal output part 101c of comparator 101.First voltage regulation unit 40 is for when the first switch element 21 is in the conduction state so that pressure unit 30 and load are in stable voltage environment, protect load further.
Second voltage regulation unit 50 includes the 3rd N-type field effect transistor the 501, the 4th N-type field effect transistor the 502, second Zener diode 503 and resistance R4; wherein; the source electrode of the 3rd N-type field effect transistor 501 is connected with ground wire, and drain the voltage input end V by the second Zener diode 503 with overvoltage crowbarinIt is connected；The source electrode of the 4th N-type field effect transistor 502 is connected with ground wire, and drain electrode is connected with the grid of the 3rd N-type field effect transistor 501, and the voltage input end V that the drain electrode of the 4th N-type field effect transistor 502 is by resistance R4 Yu overvoltage crowbarinBeing connected, the grid of the 4th N-type field effect transistor 502 is connected with the signal output part 101c of comparator 101.Second voltage regulation unit 50 is for when second switch unit 22 is in the conduction state so that load is under stable voltage environment, protects load further.
In the preferred embodiment, the voltage stabilizing value of the first Zener diode 402 is 12V, and the voltage stabilizing value of the second Zener diode 503 is 6V；The type of the oneth P type field effect transistor the 211, the 2nd P type field effect transistor the 221, first N-type field effect transistor the 212, second N-type field effect transistor the 401, the 3rd N-type field effect transistor 501 and the 4th N-type field effect transistor 502 is enhancement mode field effect transistor.
In the preferred embodiment, the voltage input end V of the source electrode of a P type field effect transistor 211, the source electrode of the 2nd P type field effect transistor 221, the first Zener diode 402 and the second Zener diode 503 and overvoltage crowbarinConnection for being indirectly connected to, i.e. the source electrode of a P type field effect transistor 211, the source electrode of the 2nd P type field effect transistor 221, the first Zener diode 402 and the second Zener diode 503 voltage input end V by an electric fuse with overvoltage crowbarinBeing connected, certainly in other examples, the source electrode of a P type field effect transistor 211, the source electrode of the 2nd P type field effect transistor 221, the first Zener diode 402 and the second Zener diode 503 can also directly and the voltage input end V of overvoltage crowbarinIt is connected.
In the overvoltage crowbar that this preferred embodiment provides, as the voltage input end V of overvoltage crowbarinWhen the magnitude of voltage of input is higher than loaded work piece voltage, for instance, access 12V voltage, and the running voltage of load is 5V, the magnitude of voltage at the detecting node A place that the detecting voltage input end 101a of comparator 101 obtains will be greater than reference voltage Vref, namely now comparator 101 judges that the voltage at detecting node A place is more than reference voltage VrefThe signal output part 101c of comparator 101 will export the first control signal, and wherein, the first control signal is high level signal, first switch element 21 is by the conduction state, and second switch unit 22 will be off, by the effect of pressure unit 30 so that 12V voltage is down to 5V, namely it is down to the running voltage with load to match, thus realizing entering in high-tension situation in load misconnection, load can also normal operation, and the problems such as damage will not be caused because electric current is excessive.
Simultaneously, first control signal of the signal output part 101c output of comparator 101 makes the second N-type field effect transistor 401 in the first voltage regulation unit 40 in an ON state, namely the first voltage regulation unit 40 is in the conduction state, and the 4th N-type field effect transistor 502 in the second voltage regulation unit 50 is in an ON state, 3rd N-type field effect transistor 501 is off, namely the second voltage regulation unit 50 is off, namely circuit is played voltage-stabilizing protection effect by the first voltage regulation unit 40 in overvoltage crowbar, protection load and pressure unit further, it is in stable voltage environment.
Voltage input end V when overvoltage crowbarinDuring the running voltage 5V that magnitude of voltage is load inputted, the magnitude of voltage at the detecting node A place that the detecting voltage input end 101a of comparator 101 obtains will be not more than reference voltage VrefNow; the signal output part 101c of comparator 101 will export the second control signal; wherein; second control signal is low level signal; second switch unit 22 is by the conduction state, and the first switch element 21 will be off, and now load is by the voltage input end V of second switch unit 22 with overvoltage crowbarinIt is connected, and keeps normal duty.
Simultaneously; second control signal of the signal output part 101c output of comparator 101 makes the second voltage regulation unit 50 in the conduction state; and the first voltage regulation unit 40 is off; make the second voltage regulation unit 50 that circuit play the effect of voltage-stabilizing protection; protect load further so that it is be in stable voltage environment.
In the preferred embodiment; by arranging the first voltage regulation unit 40 and the second voltage regulation unit 50; no matter the voltage input end making overvoltage crowbar is input 5V or 12V; all there are voltage regulation unit protection load or load and pressure unit so that it is be in stable voltage status, certainly; in other examples; can also only have the first voltage regulation unit 40 or the second voltage regulation unit 50 or more voltage regulation unit, be not particularly limited at this.
The overvoltage crowbar that this preferred embodiment provides, as the voltage input end V of overvoltage crowbarinDuring high input voltage; when being namely higher than the running voltage of load; effect by comparator the 101, first switch element 21 and pressure unit 30; load can be worked in its running voltage; avoid in prior art; because causing the problems such as damage when load accesses high voltage by mistake, the first voltage regulation unit 40 can protect load and pressure unit further simultaneously so that it is is in stable voltage environment.Voltage input end V when overvoltage crowbarinDuring the running voltage of input load, by the effect of comparator 101 and second switch unit 22 so that load can keep normal work; simultaneously; circuit is played the effect of voltage-stabilizing protection by the second voltage regulation unit 50, protects load further so that it is be in stable voltage environment.
Refer to the flow chart of the over-voltage protection method that Fig. 5, Fig. 5 provide for the preferred embodiment of the present invention.The over-voltage protection method that this preferred embodiment provides, it is applied to overvoltage crowbar provided by the invention, owing to above describing structure and the operation principle thereof of overvoltage crowbar in detail, will not be described in great detail in the preferred embodiment.
The over-voltage protection method that this preferred embodiment provides includes:
Step S101: judge that whether the voltage at described detecting node place is more than described reference voltage；
Step S102: if; then export the first control signal by the signal output part of described control unit; make described first switch element in the conduction state; described second switch unit is off, and is matched to the running voltage with load by the voltage transformation of the voltage input end of overvoltage crowbar by described pressure unit；
Step S103: if it is not, then export the second control signal by the signal output part of described control unit so that described first switch element is off, described second switch unit is in the conduction state.
The situation during overvoltage crowbar that the over-voltage protection method that this preferred embodiment is described in detail below to be provided is applied in Fig. 3.
In step S101 and S102, comparator 101 judges that whether the voltage at detecting node A place is more than reference voltage VrefIf the determination result is YES; then the signal output part 101c of comparator 101 will export the first control signal; wherein; first control signal is high level signal, and the first switch element 21 is by the conduction state, and second switch unit 22 will be off; now, load is by the voltage input end V of pressure unit 30 and the first switch element 21 and overvoltage crowbarinIt is connected, through the hypotensive effect of pressure unit 30 so that the voltage input end V of overvoltage crowbarinThe running voltage that drops to load of voltage match so that load can work normally.
In step s 103; if judged result is no; then the signal output part 101c of comparator 101 will export the second control signal; wherein; second control signal is low level signal; second switch unit 22 is by the conduction state, and the first switch element 21 will be off, and now load is by the voltage input end V of second switch unit 22 with overvoltage crowbarinIt is connected, and keeps normal duty.
The over-voltage protection method that this preferred embodiment provides; by judging that the voltage input end of current overvoltage crowbar accesses the situation of voltage; and the first control signal or the second control signal is exported according to judged result; control the first switch element 21 or second switch unit 22 turns on; if the first switch element 21 turns on; then by the hypotensive effect of pressure unit 30, the running voltage that the voltage of the voltage input end of overvoltage crowbar drops to load is matched so that load can work normally；If second switch unit 22 turns on, then load is connected with the voltage input end of overvoltage crowbar by second switch unit 22 so that load is in normal duty.The method can be effectively prevented from the voltage because load misconnection enters mistake and the problems such as the damage caused.
This preferred embodiment provides a kind of liquid crystal display drive circuit; it adopts overvoltage crowbar provided by the invention; when certain the load system misconnection in liquid crystal display drive circuit enters high pressure; under the effect of overvoltage crowbar; load still can normal operation; do not have, because misconnection enters, higher power supply causes burning the problem that cannot work, greatly reduce the scrappage of liquid crystal display drive circuit.
In sum; although the present invention is disclosed above with preferred embodiment; but above preferred embodiment is also not used to the restriction present invention; those of ordinary skill in the art; without departing from the spirit and scope of the present invention; all can doing various change and retouching, the scope that therefore protection scope of the present invention defines with claim is as the criterion.
Claims (10)
1. an overvoltage crowbar, including the voltage input end of overvoltage crowbar, it is characterised in that described overvoltage crowbar also includes detecting node, control unit, the first switch element, second switch unit and pressure unit；
Described detecting node, is connected with the voltage input end of described overvoltage crowbar；
Described control unit, including detecting voltage input end, reference voltage input terminal and signal output part, wherein, described detecting voltage input end is connected with described detecting node, and described reference voltage input terminal is used for input reference voltage；
Described first switch element and second switch unit; all include signal input part, voltage input end and voltage output end; wherein; the signal input part of described first switch element is connected with the signal output part of described control unit; the voltage input end of described first switch element is connected with the voltage input end of described overvoltage crowbar, and the voltage output end of described first switch element is connected with described load by described pressure unit；
The signal input part of described second switch unit is connected with the signal output part of described control unit; the voltage input end of described second switch unit is connected with the voltage input end of described overvoltage crowbar, and the voltage output end of described second switch unit is connected with described load；
Wherein, whether described control unit is used for the voltage judging described detecting node place more than described reference voltage, if so, then exports the first control signal by the signal output part of described control unit, making described first switch element in the conduction state, described second switch unit is off；If it is not, then export the second control signal by the signal output part of described control unit so that described first switch element is off, described second switch unit is in the conduction state；
Described pressure unit, for when the first switch element is in the conduction state, matching the voltage transformation of the voltage input end of described overvoltage crowbar to the running voltage with load.
2. overvoltage crowbar according to claim 1, it is characterised in that described first switch element includes:
Oneth P type field effect transistor, its source electrode is connected with the voltage input end of described overvoltage crowbar, and drain electrode is connected with described pressure unit；
First N-type field effect transistor; its source electrode is connected with ground wire; drain electrode is connected with the grid of a described P type field effect transistor; and first the drain electrode of N-type field effect transistor be connected by the voltage input end of resistance with described overvoltage crowbar, the grid of the first N-type field effect transistor is connected with the signal output part of described control unit.
3. overvoltage crowbar according to claim 1, it is characterised in that described second switch unit includes:
2nd P type field effect transistor, its source electrode is connected with the voltage input end of described overvoltage crowbar, and drain electrode is connected with load, and grid is connected with the signal output part of described control unit.
4. overvoltage crowbar according to claim 2, it is characterised in that described overvoltage crowbar also protects the first voltage regulation unit, and described first voltage regulation unit includes:
Second N-type field effect transistor, its source electrode is connected with ground wire, and drain electrode is connected by the voltage input end of the first Zener diode with described overvoltage crowbar, and grid is connected with the signal output part of described control unit.
5. overvoltage crowbar according to claim 3, it is characterised in that described overvoltage crowbar also protects the second voltage regulation unit, and described second voltage regulation unit includes:
3rd N-type field effect transistor, its source electrode is connected with ground wire, and drain electrode is connected by the voltage input end of the second Zener diode with described overvoltage crowbar；
4th N-type field effect transistor; its source electrode is connected with ground wire; drain electrode is connected with the grid of described 3rd N-type field effect transistor; and the drain electrode of described 4th N-type field effect transistor is connected by the voltage input end of resistance with described overvoltage crowbar, and the described grid of the 4th N-type field effect transistor is connected with the signal output part of described control unit.
6. overvoltage crowbar according to claim 1, it is characterised in that described control unit includes comparator.
7. overvoltage crowbar according to claim 4, it is characterised in that the voltage stabilizing value of described first Zener diode is 12V.
8. overvoltage crowbar according to claim 5, it is characterised in that the voltage stabilizing value of described second Zener diode is 6V.
9. an over-voltage protection method, is applied in claim 1 to 8 any one overvoltage crowbar, it is characterised in that described over-voltage protection method includes:
Judge that whether the voltage at described detecting node place is more than described reference voltage；
If; then export the first control signal by the signal output part of described control unit; make described first switch element in the conduction state; described second switch unit is off, and is matched to the running voltage with load by the voltage transformation of the voltage input end of described overvoltage crowbar by described pressure unit；
If it is not, then export the second control signal by the signal output part of described control unit so that described first switch element is off, described second switch unit is in the conduction state.
10. a liquid crystal display drive circuit, it is characterised in that described liquid crystal display drive circuit includes any one overvoltage crowbar in claim 1 to 8.
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| CN201610341350.3A CN105788556B (en) | 2016-05-20 | 2016-05-20 | A kind of overvoltage crowbar and method, liquid crystal display drive circuit |
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| CN201610341350.3A CN105788556B (en) | 2016-05-20 | 2016-05-20 | A kind of overvoltage crowbar and method, liquid crystal display drive circuit |
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| CN108303580A (en) * | 2017-04-13 | 2018-07-20 | 深圳市三诺电子有限公司 | A kind of excess temperature overvoltage crowbar |
| CN109147692A (en) * | 2018-08-31 | 2019-01-04 | 重庆惠科金渝光电科技有限公司 | Driving circuit, drive system and display |
| CN109410868A (en) * | 2018-12-06 | 2019-03-01 | 深圳市华星光电半导体显示技术有限公司 | Display panel drive device |
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| US11456677B2 (en) | 2020-12-10 | 2022-09-27 | Rolls-Royce Corporation | Power converter protection circuit |
| CN113012611A (en) * | 2021-02-26 | 2021-06-22 | 深圳市华星光电半导体显示技术有限公司 | Voltage detection circuit, display device and display driving method thereof |
| CN113012611B (en) * | 2021-02-26 | 2022-10-04 | 深圳市华星光电半导体显示技术有限公司 | Voltage detection circuit, display device and display driving method thereof |
| CN114664269A (en) * | 2022-04-21 | 2022-06-24 | 京东方科技集团股份有限公司 | Working power supply conversion circuit, display drive board and liquid crystal display screen |
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