CN113708341A - Undervoltage protection circuit - Google Patents
Undervoltage protection circuit Download PDFInfo
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- CN113708341A CN113708341A CN202111034815.8A CN202111034815A CN113708341A CN 113708341 A CN113708341 A CN 113708341A CN 202111034815 A CN202111034815 A CN 202111034815A CN 113708341 A CN113708341 A CN 113708341A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/24—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to undervoltage or no-voltage
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H1/00—Details of emergency protective circuit arrangements
- H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
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Abstract
The application discloses undervoltage protection circuit, it includes the bus power supply, detect the partial pressure module, prevent voltage backflow return difference module, control module and trigger module, bus power supply connection detects the partial pressure module, detect the partial pressure module and prevent voltage backflow return difference module and control module connection, control module, be used for through detecting the partial pressure module and preventing voltage backflow return difference module, detect the partial pressure to the bus voltage of bus power supply, still be used for as power undervoltage protection trigger back control module, through detecting the partial pressure module and preventing voltage backflow return difference module, detect the partial pressure to the bus voltage of bus power supply, obtain first detection voltage, contrast the size between first detection voltage and the threshold value and control trigger module and trigger undervoltage protection. The application enables the voltage range of the power supply under-voltage protection to be increased, reduces the misoperation of triggering the power supply under-voltage protection by the trigger module, and further reduces abnormal faults generated when the switching power supply is repeatedly switched between normal and protection.
Description
Technical Field
The invention relates to the field of switching power supplies, in particular to an undervoltage protection circuit.
Background
At present, according to the power formula
The power P is invariable in the circuit, when the circuit produces reasons such as short circuit fault or the voltage unstability of power supply electric wire netting, voltage U diminishes, and electric current I will grow, because the resistance of each device is the invariable state in the circuit, so the electric current increase can lead to the calorific capacity increase of device, finally probably lead to the circuit to take place accidents such as fire, so need carry out undervoltage protection to the circuit, undervoltage protection is when line voltage reduces critical voltage, the action of protection electrical apparatus, or be called undervoltage protection.
In the related art, the under-voltage protection is usually provided with a critical voltage, when the external voltage is greater than the critical voltage, the circuit normally works, and when the external voltage is less than the critical voltage, the circuit is cut off, so that the occurrence of power supply accidents caused by low voltage is reduced.
With respect to the related art among the above, the inventors consider that the following drawbacks exist: when the external voltage fluctuates repeatedly at the critical voltage, the power supply will switch repeatedly between normal and protection, resulting in abnormal failure of the user system.
Disclosure of Invention
In order to solve the problem that the switching power supply is repeatedly switched between normal and protection due to the fact that external voltage fluctuates repeatedly at a critical point, the application provides an under-voltage protection circuit.
The application provides an under-voltage protection circuit adopts following technical scheme:
an under-voltage protection circuit comprises a bus power supply, a detection voltage division module, a voltage backflow prevention return difference module, a control module and a trigger module;
the bus power supply is connected with the detection voltage division module;
the detection voltage division module is connected with the voltage-resistant reverse-filling return difference preventing module and the control module;
the control module is used for detecting and dividing the bus voltage of the bus power supply through the voltage detection and division module and the voltage backflow prevention and difference return module to obtain a first detection voltage;
when the first detection voltage is not less than a threshold value, controlling the trigger module to output a first level value, wherein the first level value is a low level;
when the first detection voltage is smaller than a threshold value, controlling the trigger module to output a second level value, wherein the second level value is a high level;
the triggering module is used for triggering power supply under-voltage protection according to the second level value;
and the control module is also used for detecting and dividing the bus voltage of the bus power supply through the detection voltage division module after the power supply under-voltage protection is triggered to obtain a second detection voltage.
By adopting the technical scheme, the voltage value of the bus power supply is the voltage value of an external power grid, when the voltage of the bus power supply fluctuates, the detection voltage division module detects and divides the bus power supply, the control module detects and divides the bus voltage of the bus power supply through the detection voltage division module and the voltage backflow prevention difference module to obtain a first detection voltage, when the first detection voltage is not less than a threshold value, the trigger module is controlled to output a first level value, the first level value is a low level, when the first detection voltage is less than the threshold value, the trigger module is controlled to output a second level value, the second level value is a high level, the trigger module triggers power supply under-voltage protection according to the second level value, and the control module is also used for detecting and dividing the bus voltage of the bus power supply through the detection voltage division module after the power supply under-voltage protection is triggered, and obtaining a second detection voltage, so that the voltage range of the power supply under-voltage protection can be increased, the false operation of triggering the power supply under-voltage protection by the trigger module is reduced, and the abnormal fault generated when the switching power supply is repeatedly switched between normal and protection is reduced.
Optionally, the detection voltage division module includes a first resistor, a second resistor, a third resistor, a fourth resistor, and a fifth resistor;
the first resistor, the second resistor and the third resistor are sequentially connected in series, one end of the first resistor is connected with the bus power supply, and the fourth resistor and the fifth resistor are connected in parallel and are respectively connected with the third resistor in series.
Through adopting above-mentioned technical scheme, increase the load through setting up of first resistance, second resistance, third resistance, fourth resistance and fifth resistance, make and carry out the partial pressure to the circuit, the accessible measures the voltage at first resistance, second resistance, third resistance, fourth resistance or fifth resistance both ends simultaneously and measures the voltage of control module department.
Optionally, the voltage division detecting module further includes a capacitor, the capacitor is connected in parallel with the fourth resistor and the fifth resistor, and the fourth resistor, the fifth resistor and one end of the capacitor far away from the third resistor are connected to the control module and the triggering module respectively and grounded.
By adopting the technical scheme, the capacitor is connected with the fourth resistor and the fifth resistor in parallel, so that the voltage of the bus power supply can be filtered, the voltage of the bus power supply is more stable, and the movement of the control module caused by the fluctuation of the bus power supply is reduced.
Optionally, the voltage backflow difference preventing module includes a sixth resistor and a diode, the sixth resistor is connected in parallel with the fourth resistor, the fifth resistor and the capacitor, respectively, one end of the sixth resistor, which is far away from the fifth resistor, is connected to the trigger module, the diode is disposed between the sixth resistor and the fifth resistor, the diode is connected in series with the sixth resistor, and one end of the diode, which is close to the fifth resistor, is an anode.
By adopting the technical scheme, the sixth resistor is connected with the fourth resistor, the fifth resistor is connected with the capacitor in parallel, so that the overall resistance of the voltage division module can be reduced, the first detection voltage is smaller than the threshold value, the return difference between the first detection voltage and the threshold value is formed, the diode prevents the voltage of the trigger module from flowing backwards, and the influence of the voltage of the trigger module flowing backwards on the accuracy of the undervoltage detection is reduced.
Optionally, the control module is a three-terminal bipolar transistor, a threshold is preset in the three-terminal bipolar transistor, and if the voltage of a reference electrode of the three-terminal bipolar transistor is lower than the threshold, the three-terminal bipolar transistor is turned off;
and the reference electrodes of the three-terminal bipolar transistor are respectively connected with the capacitor, the third resistor, the fourth resistor and the fifth resistor, the anode of the three-terminal bipolar transistor is connected with the other end of the capacitor, and the cathode of the three-terminal bipolar transistor is connected with the trigger module.
By adopting the technical scheme, the reference electrode of the three-terminal bipolar transistor is connected with the capacitor, the third resistor, the fourth resistor and the fifth resistor, and meanwhile, the three-terminal bipolar transistor is provided with the threshold value, so that the reference electrode of the three-terminal bipolar transistor can compare the bus voltage of the bus power supply through the threshold value, the conduction state of the three-terminal bipolar transistor is controlled through the comparison result, and the level value output by the trigger module is further controlled.
Optionally, an eighth resistor is connected between the cathode of the three-terminal bipolar transistor and the trigger module.
By adopting the technical scheme, the eighth resistor reduces the short circuit of the three-terminal bipolar transistor, so that the three-terminal bipolar transistor is protected.
Optionally, the trigger module includes a first triode, a second triode, a power supply, and a level sensing terminal;
the emitter of the first triode is connected with the power supply, the base of the first triode is connected with the cathode of the three-terminal bipolar transistor, the collector of the first triode is connected with the base of the second triode and grounded, and a seventh resistor is connected between the base and the emitter of the first triode;
an emitter and a base of the second triode are respectively grounded, and a collector of the second triode is connected with the power supply; the level sensing end is connected between the collector of the second triode and the power supply and is used for measuring the level at the collector of the second triode;
the level sensing end is used for sensing the level of a corresponding row generated by the voltage at the emitter of the second triode, an eleventh resistor is connected between the power supply and the level sensing end, and one end, far away from the third resistor, of the sixth resistor is connected to the power supply and the level sensing end.
By adopting the technical scheme, the power supply supplies power to the first triode, and the three-terminal bipolar transistor detects the bus voltage of the bus power supply to obtain a first detection voltage;
when first detected voltage is greater than the threshold value, the three-terminal bipolar transistor switches on, and there is voltage in the base of first triode, makes first triode switch on, and then makes the second transistor be in the conducting state, and the voltage of the collector of the second triode that level induction end sensed is the voltage of the projecting pole of corresponding second triode, and the level induction pipe senses the low level this moment, and the power is normally worked.
When first detected voltage is less than the threshold value, the disconnection of three-terminal bipolar transistor, the base voltage of first triode is 0, makes first triode be in the off-state to the projecting pole collector voltage that makes first triode is 0, and then makes the second transistor be in the off-state, the voltage of the projecting pole of the second triode that level inductive end sensed, for the voltage behind the voltage of power supply minus eleventh resistance load's voltage, thereby make level inductive end sense the high level, trigger power supply undervoltage protection.
Optionally, a ninth resistor and a tenth resistor are connected in series between the collector of the first triode and the emitter of the second triode, one end of the tenth resistor is connected to the base of the second triode and the ninth resistor respectively, and the other end of the tenth resistor is connected to the collector of the second triode and grounded.
By adopting the technical scheme, the ninth resistor and the tenth resistor divide the voltage of the power supply respectively, so that the voltage at the emitter of the second triode is reduced, and the voltage at the second triode is the voltage at the corresponding low level.
In summary, the present application includes at least one of the following beneficial technical effects:
1. the voltage range of the power supply under-voltage protection is increased through a sixth resistor of the voltage backflow preventing module, the misoperation that the trigger module triggers the power supply under-voltage protection is reduced, and the abnormal fault generated when the switching power supply is repeatedly switched between normal and protection is further reduced;
2. the voltage of the trigger module is prevented from flowing backwards through a diode of the voltage backflow prevention module, so that the influence of the voltage backflow of the trigger module on the accuracy of the undervoltage detection is reduced;
3. and the reference electrode of the three-terminal bipolar transistor is connected with the capacitor, the third resistor, the fourth resistor and the fifth resistor, and is provided with a threshold value, so that the reference electrode of the three-terminal bipolar transistor can compare the bus voltage of the bus power supply through the threshold value, the conduction state of the three-terminal bipolar transistor is controlled through a comparison result, and the level value output by the trigger module is further controlled.
Drawings
Fig. 1 is a circuit diagram of an under-voltage protection circuit according to an embodiment of the present application.
Reference numerals: 100. a voltage division detection module; 200. the voltage backflow preventing and return difference preventing module; 300. a control module; 400. and a triggering module.
Detailed Description
The present application is described in further detail below with reference to the attached drawings.
The embodiment of the application discloses an undervoltage protection circuit.
Referring to fig. 1, an under-voltage protection circuit includes a bus power supply, a voltage-detecting and voltage-dividing module 100, a voltage-backflow-preventing and return-difference-preventing module 200, a control module 300 and a trigger module 400;
the bus power supply is an external power grid, the bus power supply is defined as HV, the circuit performs under-voltage protection for the change corresponding to HV, when HV is greatly reduced, the power supply under-voltage protection is triggered, in the embodiment, the voltage of the under-voltage protection is less than or equal to 80Vac, namely, when the voltage of the bus power supply is less than or equal to 80Vac, the power supply under-voltage protection is performed, an under-voltage recovery point is less than or equal to 88Vac, namely, after the voltage of the bus power supply rises to the under-voltage recovery point, the power supply can automatically recover normal work, the difference value between the under-voltage protection voltage and the under-voltage recovery point is set as a return difference value, the return difference value is greater than or equal to 5V, the power supply is a switch power supply using the bus power supply, and when the power grid suddenly changes and other extreme severe conditions, the power supply triggers the under-voltage protection to protect other devices connected with the power supply.
The detection voltage division module 100 includes a first resistor, a second resistor, a third resistor, a fourth resistor, and a fifth resistor, where the first resistor is defined as a resistor R1, the second resistor is defined as a resistor R2, and the third resistor is defined as a resistor R3, in this embodiment, the resistances of the first resistor R1, the second resistor R2, and the third resistor R3 are all 330K ohms, and the types are all 1206 types, and in consideration of the loss and the withstand voltage degradation of the first resistor R1, the second resistor R2, and the third resistor R3, the fourth resistor is defined as R4, the resistance of the fourth resistor R4 is 12K ohms, the type of the fourth resistor R4 is 0603, the fifth resistor is defined as a resistor R5, and the type of the fifth resistor R5 is NC0603, so that the fifth resistor R5 is a reserved bit and is not soldered to the circuit, and in other embodiments, each resistor is another resistor;
the first resistor R1, the second resistor R2 and the third resistor R3 are sequentially connected in series, and one end of the first resistor R1 is connected with a bus power supply HV; the fourth resistor R4 is connected in parallel with the fifth resistor R5, and is connected in series with the third resistor R3, respectively.
The detection voltage division module 100 further includes a capacitor, which is defined as C1, the capacitor C1 is connected in parallel with the fourth resistor R4 and the fifth resistor R5, respectively, and the ends of the fourth resistor R4, the fifth resistor R5 and the capacitor C1 far away from the third resistor C3 are connected to the control module 300 and the trigger module 400, respectively, and are grounded.
The voltage backflow-preventing module 200 includes a sixth resistor and a diode, the sixth resistor is defined as R6, in this embodiment, the resistance value of the R6 is 150K ohms, the model of the sixth resistor R6 is 0603, the diode is defined as D1, the model of the D1 is LBAS16, the sixth resistor R6 is connected in parallel with the fourth resistor R4 and the fifth resistor R5 and the capacitor C1, one end of the sixth resistor R6, which is far away from the fifth resistor R5, is connected to the trigger module 400, the diode D1 is disposed between the sixth resistor R6 and the fifth resistor R5, the diode D1 is connected in series with the sixth resistor R6, and one end of the diode D1, which is near the fifth resistor R5, is an anode of the diode D1.
The bus voltage HV detects the divided voltage through R1, R2, R3, R4, R5 and R6, C1 filters, and the voltage of the bus voltage HV when the normal work is recovered is calculated according to the parameters as follows:
HV=Vref/(R4//R6)*(R1+R2+R3+(R4//R6))=1.24/(12//120)*(680+680+680+(12//120))=113.770V
wherein, R4// R6= R4 × R6/(R4+ R6);
the voltage of the bus power supply HV is: AC = HV/1.414=113.770/1.414= 80.460V;
that is, the input grid voltage is 80.460V;
according to the parameter calculation, when the circuit performs the undervoltage protection, the voltage of the bus power supply HV can be: HV = Vref/R4 = (R1+ R2+ R3+ R4) =1.24/(12 × (680+680+680+12) = 103.540V;
the input grid voltage is: AC = HV/1.414=103.54/1.414= 73.225V;
from the above, it can be seen that: the return difference between the input under-voltage point and the recovery point is as follows: 80.460-73.225=7.235V, and effectively prevents the switching power supply from repeatedly operating by setting a return difference.
The control module 300 is a three-terminal bipolar transistor, which includes a reference electrode, a cathode electrode and an anode electrode, and is defined as U1, in this embodiment, the model of the three-terminal bipolar transistor U1 is AZ432AN, a threshold is preset in the three-terminal bipolar transistor U1, the threshold of the three-terminal bipolar transistor U1 is defined as Vref, Vref =1.24V, and when the voltage of the reference electrode of the three-terminal bipolar transistor U1 is lower than the threshold, the three-terminal bipolar transistor U1 is turned off.
A reference electrode of the three-terminal bipolar transistor U1 is respectively connected with the capacitor C1, the third resistor R3, the fourth resistor R4 and the fifth resistor R5, an anode of the three-terminal bipolar transistor U1 is connected with the other end of the capacitor C1, a cathode of the three-terminal bipolar transistor U1 is connected with the trigger module 400, and an eighth resistor R8 is connected between the cathode of the three-terminal bipolar transistor U1 and the trigger module 400.
The trigger module 400 is configured to trigger power supply under-voltage protection according to the second level value, where the trigger module 400 includes a first triode, a second triode, a power supply, and a level sensing terminal, and defines the first triode as Q1, in this embodiment, the model of Q1 may be MMBT4403LT1G, the voltage of the emitter of Q1 is Vbe, Vbe = -0.95V, and the voltage of the collector of Q1 is Vce, Vce = -0.4V. Defining the second triode as Q2, where the model of Q2 may be MMBT4401LT1G, the voltage of the emitter of Q2 is Vbe, Vbe =0.75V, the voltage of the collector of Q2 is Vce, Vce =0.4V, the power supply is VCC, the VCC voltage is 12V, the level sensing terminal is UVP, the level sensing terminal UVP senses the voltage of the emitter of Q2 by sensing the voltage of the collector of Q2 to generate different level values, and the level value is low when Q2Vce is less than 0.4V;
an emitting electrode of the first triode Q1 is connected with a power supply VCC, a base electrode of the first triode Q1 is connected with a cathode of the three-terminal bipolar transistor U1, a collector electrode of the first triode Q1 is connected with a base electrode of the second triode Q2 and grounded, a seventh resistor is connected between the base electrode and the emitting electrode of the first triode Q1, the seventh resistor is defined as R7, and the resistance value of the seventh resistor R7 is 10K ohms in the embodiment, and the model is 0603.
An emitter and a base of the second triode Q2 are respectively grounded, and a collector of the second triode Q2 is connected with a power supply VCC; a level sensing terminal UVP is connected between the collector of the second triode Q2 and the power supply VCC, and is used for measuring the level at the collector of the second triode Q2;
the level sensing terminal UVP is configured to sense a level of a corresponding row generated by a voltage at the emitter of the second transistor Q2, an eleventh resistor is connected between the power supply VCC and the level sensing terminal UVP, the eleventh resistor is defined as R11, in this embodiment, a resistance of the eleventh resistor R11 is 5.1K, the type of the eleventh resistor R3526 is 0603, and one end of the sixth resistor R6, which is far away from the third resistor R3, is connected to the power supply VCC and the level sensing terminal UVP.
A ninth resistor and a tenth resistor are connected in series between the collector of the first triode Q1 and the emitter of the second triode Q2, in this embodiment, the ninth resistor is defined as R9, the resistance of R9 is 10K, the model is 0603, the tenth resistor is defined as R10, the resistance of R10 is 5.1K, the model is 0603, one end of the tenth resistor R10 is connected to the bases of the ninth resistor R9 and the second triode Q2, and the other end of the tenth resistor R10 is connected to the collector of the second triode Q2 and grounded.
The bus power supply HV is connected with the detection voltage division module 100; the detection voltage division module 100 is connected with the voltage backflow prevention difference module 200 and the control module 300; the control module 300 is used for detecting and dividing the bus voltage of the bus power supply HV through the voltage detection and division module 100 and the voltage backflow prevention and difference module 200 to obtain a first detection voltage;
when the first detection voltage is not less than the threshold, the control module 300 controls the trigger module 400 to output the first level value, the first level value is a low level, that is, when the first detection voltage is not less than 1.24V, U1 is turned on, Q1 is turned on, VCC divides voltage through Q1, R9 and R10, the voltage (i.e., Q2 Vbe) on V _ R10 is greater than 0.75V to turn on Q2, Q2Vce is 0.4V, UVP is a low level, and the power supply normally operates. At this time, the R6 is embedded into the input detection line, so that the R4, the R5 and the R6 are connected in parallel, and therefore, when the input under-voltage protection is performed, the input voltage is reduced a little more to trigger the input under-voltage protection.
When the first detection voltage is smaller than the threshold value, the trigger module 400 is controlled to output a second level value, the second level value is a high level, namely when the voltage of the bus power supply HV is reduced, the HV detects the divided voltage through resistors R1/R2/R3/R4/R5, C1 filtering is performed, when the voltage is compared with the U1 reference voltage 1.24V and is smaller than 1.24V, U1 is turned off, Q1 is turned off, VCC cannot be divided through Q1, R9 and R10, the voltage (namely Q2 Vbe) on the tenth resistor R10 is smaller than 0.75V so that Q2 is turned off, VCC provides voltage for UVP through R11, UVP is a high level, and under-voltage protection is performed on the power supply. At this time, R6 cannot be embedded into the input detection line because Q2 is turned off, and R6 does not function because D1 blocks VCC to form a loop through R11, R6 and R5.
The control module 300 is further configured to detect and divide the bus voltage of the bus power supply by the detection voltage division module 100 after the power under-voltage protection is triggered, so as to obtain a second detection voltage, where the second detection voltage is used for comparing with a threshold value.
The implementation principle of an under-voltage protection circuit in the embodiment of the application is as follows: the voltage value of the bus power supply is the voltage value of an external power grid, when the voltage of the bus power supply fluctuates, the detection voltage division module 100 detects and divides the bus power supply, the control module 300 detects and divides the bus voltage of the bus power supply through the detection voltage division module 100 and the voltage backflow prevention difference module 200 to obtain a first detection voltage, when the first detection voltage is not less than a threshold value, the trigger module 400 is controlled to output a first level value, the first level value is a low level, when the first detection voltage is less than the threshold value, the trigger module 400 is controlled to output a second level value, the second level value is a high level, the trigger module 400 triggers power supply under-voltage protection according to the second level value, the control module 300 is further used for detecting and dividing the bus voltage of the bus power supply through the detection voltage division module 100 after the power supply under-voltage protection is triggered, the second detection voltage is obtained, so that the voltage range of the power supply under-voltage protection can be increased, the false operation of triggering the power supply under-voltage protection by the trigger module 400 is reduced, and the probability of generating abnormal faults when the switching power supply is repeatedly switched between normal and protection is reduced.
The above embodiments are preferred embodiments of the present application, and the protection scope of the present application is not limited by the above embodiments, so: all equivalent changes made according to the structure, shape and principle of the present application shall be covered by the protection scope of the present application.
Claims (8)
1. An undervoltage protection circuit, its characterized in that: the bus voltage-difference detection circuit comprises a bus power supply, a voltage division detection module (100), a voltage backflow-preventing difference module (200), a control module (300) and a trigger module (400);
the bus power supply is connected with the detection voltage division module (100);
the voltage detecting and dividing module (100) is connected with the voltage backflow preventing and difference returning module (200) and the control module (300);
the control module (300) is used for detecting and dividing the bus voltage of the bus power supply through the detection voltage dividing module (100) and the voltage backflow preventing module (200) to obtain a first detection voltage;
when the first detection voltage is not less than a threshold value, controlling the trigger module (400) to output a first level value, wherein the first level value is a low level;
when the first detection voltage is less than a threshold value, controlling the trigger module (400) to output a second level value, wherein the second level value is a high level;
the trigger module (400) is used for triggering power supply undervoltage protection according to the second level value;
the control module (300) is further configured to detect and divide the bus voltage of the bus power supply through the detection voltage division module (100) after the power under-voltage protection is triggered, so as to obtain a second detection voltage.
2. The undervoltage protection circuit of claim 1, wherein: the detection voltage division module (100) comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor;
the first resistor, the second resistor and the third resistor are sequentially connected in series, one end of the first resistor is connected with the bus power supply, and the fourth resistor and the fifth resistor are connected in parallel and are respectively connected with the third resistor in series.
3. The undervoltage protection circuit of claim 2, wherein: the detection voltage division module (100) further comprises a capacitor, the capacitor is connected with the fourth resistor and the fifth resistor in parallel, and one end, far away from the third resistor, of the fourth resistor, the fifth resistor and one end, far away from the third resistor, of the capacitor are connected with the control module (300) and the trigger module (400) respectively and are grounded.
4. The undervoltage protection circuit of claim 3, wherein: the voltage backflow preventing and return difference preventing module (200) comprises a sixth resistor and a diode, the sixth resistor is connected with the fourth resistor, the fifth resistor and the capacitor in parallel respectively, one end, far away from the fifth resistor, of the sixth resistor is connected with the trigger module (400), the diode is arranged between the sixth resistor and the fifth resistor, the diode is connected with the sixth resistor in series, and one end, close to the fifth resistor, of the diode is an anode.
5. The undervoltage protection circuit of claim 4, wherein: the control module (300) is a three-terminal bipolar transistor, a threshold value is preset on the three-terminal bipolar transistor, and the voltage of a reference electrode of the three-terminal bipolar transistor is lower than the threshold value, so that the three-terminal bipolar transistor is disconnected;
and the reference electrodes of the three-terminal bipolar transistor are respectively connected with the capacitor, the third resistor, the fourth resistor and the fifth resistor, the anode of the three-terminal bipolar transistor is connected with the other end of the capacitor, and the cathode of the three-terminal bipolar transistor is connected with the trigger module (400).
6. The undervoltage protection circuit of claim 5, wherein: an eighth resistor is connected between the cathode of the three-terminal bipolar transistor and the trigger module (400).
7. The undervoltage protection circuit of claim 6, wherein: the trigger module (400) comprises a first triode, a second triode, a power supply and a level sensing end;
the emitter of the first triode is connected with the power supply, the base of the first triode is connected with the cathode of the three-terminal bipolar transistor, the collector of the first triode is connected with the base of the second triode and grounded, and a seventh resistor is connected between the base and the emitter of the first triode;
an emitter and a base of the second triode are respectively grounded, and a collector of the second triode is connected with the power supply; the level sensing end is connected between the collector of the second triode and the power supply and is used for measuring the level at the collector of the second triode;
the level sensing end is used for sensing the level of a corresponding row generated by the voltage at the emitter of the second triode, an eleventh resistor is connected between the power supply and the level sensing end, and one end, far away from the third resistor, of the sixth resistor is connected to the power supply and the level sensing end.
8. The undervoltage protection circuit of claim 7, wherein: a ninth resistor and a tenth resistor are connected in series between the collector of the first triode and the emitter of the second triode, one end of the tenth resistor is connected with the base of the second triode and the ninth resistor respectively, and the other end of the tenth resistor is connected with the collector of the second triode and grounded.
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| CN203722215U (en) * | 2014-03-07 | 2014-07-16 | 新誉集团有限公司 | A storage battery under-voltage protection device for railway vehicles |
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| CN109449880A (en) * | 2018-10-26 | 2019-03-08 | 北京卫星制造厂有限公司 | A kind of high-power aerospace modular power source input undervoltage protection circuit |
| CN209344761U (en) * | 2019-01-29 | 2019-09-03 | 广州视源电子科技股份有限公司 | Overvoltage and undervoltage protection circuit, circuit board and LED display device |
| CN211629858U (en) * | 2020-04-07 | 2020-10-02 | 广州致远电子有限公司 | Input undervoltage protection circuit and switching power supply system |
| CN212785964U (en) * | 2020-06-30 | 2021-03-23 | 深圳市崧盛电子股份有限公司 | Input undervoltage and overvoltage protection circuit of LED (light emitting diode) driving power supply and LED driving power supply |
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2021
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| CN103474954A (en) * | 2013-10-10 | 2013-12-25 | 济南沃尔电子有限公司 | Overvoltage and undervoltage protective circuit based on three-end adjustable shunt reference source |
| CN203722215U (en) * | 2014-03-07 | 2014-07-16 | 新誉集团有限公司 | A storage battery under-voltage protection device for railway vehicles |
| CN204103461U (en) * | 2014-08-05 | 2015-01-14 | 惠州比亚迪电池有限公司 | The undervoltage protection device of Switching Power Supply and there is its Switching Power Supply |
| CN206931988U (en) * | 2017-06-30 | 2018-01-26 | 深圳市崧盛电子股份有限公司 | High reliability under-voltage protecting circuit and power supply |
| CN109449880A (en) * | 2018-10-26 | 2019-03-08 | 北京卫星制造厂有限公司 | A kind of high-power aerospace modular power source input undervoltage protection circuit |
| CN209344761U (en) * | 2019-01-29 | 2019-09-03 | 广州视源电子科技股份有限公司 | Overvoltage and undervoltage protection circuit, circuit board and LED display device |
| CN211629858U (en) * | 2020-04-07 | 2020-10-02 | 广州致远电子有限公司 | Input undervoltage protection circuit and switching power supply system |
| CN212785964U (en) * | 2020-06-30 | 2021-03-23 | 深圳市崧盛电子股份有限公司 | Input undervoltage and overvoltage protection circuit of LED (light emitting diode) driving power supply and LED driving power supply |
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