Fault protection circuit for chopping and toning switching power supply

Abstract

The utility model relates to the technical field of switching power supplies, in particular to a fault protection circuit for a chopping and toning switching power supply, which comprises a buck module and a chopping module. The chopper module is provided with at least one chopper MOS tube, and the positive electrode and the negative electrode of the output end of the buck module are coupled with the chopper MOS tubes in a one-to-one correspondence mode to form a chopper loop. Comprising a sampling device RS, a fault judgment module and a discharge module, the sampling device RS is arranged between the negative electrode of the output end of the buck module and the source electrode of the chopping MOS tube, the sampling device RS is coupled to the input end of the fault judgment module, the output end of the fault judgment module is electrically connected with the discharging module, and the discharging module is coupled between the chopping MOS tube and the GND ground end; when the fault judgment module detects a fault condition through the sampling device RS, the discharge module is conducted; the problem that chopping MOS tubes of a plurality of chopping loops cannot be effectively protected when faults occur is solved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of switching power supply, especially a fault protection circuit for chopping dimming switching power supply. BACKGROUND

[0002] In the traditional switching power supply, a boost PFC circuit + high-voltage buck topology structure is often used in the constant current circuit. This circuit architecture is complex and has a high cost. Due to the influence of the minimum dimming capability of the main control IC, there is a difference between the limit color temperature and the ideal color temperature, especially in the case of low brightness level, the color temperature is inaccurate. Therefore, a MOS tube chopping circuit (for example, a two-way MOS tube chopping circuit, depending on the dimming requirement) is added to the output end of the buck circuit to further adjust the color, which can greatly optimize the color adjustment effect.

[0003] However, the electrolytic capacitor at the output end of the buck circuit can store energy. When a fault occurs, the abnormal current generated is very large, which can easily cause the chopping MOS tube to fail, be damaged, or even explode. For example, when a short circuit fault occurs, and the buck circuit is in a high-voltage environment, the short circuit current greatly exceeds the bearing value of the chopping MOS tube, resulting in an explosion. SUMMARY

[0004] In view of the above defects, the purpose of the utility model is to provide a fault protection circuit for a chopping dimming switching power supply, which solves the problem that the chopping MOS tube in multiple chopping loops cannot be effectively protected when a fault occurs.

[0005] To achieve this purpose, the utility model adopts the following technical scheme:

[0006] A fault protection circuit for a chopping dimming switching power supply, the chopping dimming switching power supply includes a buck module and a chopping module; the chopping module is provided with at least one chopping MOS tube, and the positive and negative electrodes of the output end of the buck module are coupled one-to-one with the chopping MOS tube to form a chopping loop; including a sampling device RS, a fault judgment module and a discharge module; the sampling device RS is arranged between the negative electrode of the output end of the buck module and the source electrode of the chopping MOS tube, the sampling device RS is coupled to the input end of the fault judgment module, the output end of the fault judgment module is electrically connected with the discharge module, and the discharge module is coupled between the chopping MOS tube and the GND ground end;

[0007] When the fault judgment module detects a fault condition through the sampling device RS, the discharge module is turned on.

[0008] Further, a time module is further included; the time module is coupled between the output end of the fault judging module and the discharging module; the time module is used for presetting a maintaining time, and maintaining the conduction of the fault judging module to the discharging module according to the maintaining time.

[0009] Further, the sampling device RS is a sampling resistor, and the sampling device RS is connected in series between the negative electrode of the output end of the buck module and the source electrode of the chopper MOS tube.

[0010] Further, the fault judging module includes an amplifier and a comparator U12A; the input end of the amplifier is used as the input end of the fault judging module, and the output end of the comparator U12A is used as the output end of the fault judging module.

[0011] The output end of the amplifier and the negative input end of the comparator U12A are electrically connected, and the positive input end of the comparator U12A is connected with a reference source.

[0012] Further, the amplifier includes a resistor R128, a resistor R129, a resistor R130, a resistor R131 and an operational amplifier U12B; one end of the resistor R128 and one end of the resistor R130 are both used as the input end of the amplifier, and the output end of the operational amplifier U12B is used as the output end of the amplifier.

[0013] The common connection point of the sampling device RS and the negative electrode of the output end of the buck module is electrically connected with one end of the resistor R128, the other end of the resistor R128 and one end of the resistor R129 are both electrically connected with the negative input end of the operational amplifier U12B, and the other end of the resistor R129 and the output end of the operational amplifier U12B are electrically connected.

[0014] The common connection point of the sampling device RS and the source electrode of the chopper MOS tube is electrically connected with one end of the resistor R130, the other end of the resistor R130 and one end of the resistor R131 are both electrically connected with the positive input end of the operational amplifier U12B, and the other end of the resistor R131 is connected with a GND ground end.

[0015] Further, the discharging module includes a resistor R124, a triode Q16, a resistor R123, a triode Q12, a resistor R122 and at least one diode D25; the number of the diodes D25 is equal to the number of the chopper MOS tubes.

[0016] The output end of the fault judging module is electrically connected with the base of the triode Q16 through the resistor R124, the collector of the triode Q16 is electrically connected with the base of the triode Q12 through the resistor R123, the emitter of the triode Q16 is connected with the GND ground end, the emitter of the triode Q12 and one end of the resistor R122 are electrically connected, the cathode of the diode D25 is electrically connected with the other end of the resistor R122, the anode of the diode D25 and the gate of the chopper MOS tube are electrically connected one by one, and the source of the chopper MOS tube is electrically connected with the collector of the triode Q12.

[0017] Further, the time module is composed of a timing chip U9 and a peripheral circuit thereof, the input end of the timing chip U9 is electrically connected with the output end of the fault judging module, and the output end of the timing chip U9 is electrically connected with the discharging module.

[0018] The technical scheme provided by the utility model can have the following beneficial effects: the sampling device RS is arranged in the chopper loop of the chopper color adjusting switching power supply, the fault condition of each chopper loop is detected, for example, the generated sampling voltage is compared with the preset voltage threshold of the fault judging module, whether there is an abnormal fault is judged by the fault judging module; when there is a fault condition (especially when there is a short circuit fault), the discharging module is turned on, the chopper MOS tube is directly connected with the GND ground end, and the energy stored in the electrolytic capacitor CE2 at the output end of the buck module is discharged when the chopper MOS tube is turned off, so that the chopper MOS tube is effectively prevented from being invalid, damaged or exploded, the safety and reliability of the chopper color adjusting switching power supply are remarkably improved, and the service life of the circuit is prolonged. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a circuit diagram of a fault protection circuit for a chopper color adjusting switching power supply of one embodiment of the utility model.

[0020] Among them: buck module 1, chopper module 2, sampling device RS, fault judging module 3, discharging module 4, time module 5, amplifier 31, comparator U12A, resistor R128, resistor R129, resistor R130, resistor R131, operational amplifier U12B, resistor R124, triode Q16, resistor R123, triode Q12, resistor R122, diode D25, timing chip U9. DETAILED DESCRIPTION

[0021] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0022] In the description of embodiments of this utility model, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of embodiments of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0023] In the description of the embodiments of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this utility model according to the specific circumstances.

[0024] The following is combined Figure 1 This invention describes a fault protection circuit for a chopper-controlled color-tuning switching power supply according to an embodiment of the present invention.

[0025] A fault protection circuit for a chopper-controlled color-tuning switching power supply, the chopper-controlled color-tuning switching power supply including a buck module 1 and a chopper module 2; the chopper module 2 is provided with at least one chopper MOSFET, and the positive and negative terminals of the output terminal of the buck module 1 are coupled to the chopper MOSFET to form a chopper circuit; it includes a sampling device RS, a fault judgment module 3 and a discharge module 4; the sampling device RS is disposed between the negative terminal of the output terminal of the buck module 1 and the source terminal of the chopper MOSFET, the sampling device RS is coupled to the input terminal of the fault judgment module 3, the output terminal of the fault judgment module 3 is electrically connected to the discharge module 4, and the discharge module 4 is coupled between the chopper MOSFET and the GND ground terminal;

[0026] When the fault judgment module 3 detects a fault condition through the sampling device RS, it turns on the discharge module 4.

[0027] This utility model proposes a preferred embodiment of a fault protection circuit for a chopper-controlled color-tuning switching power supply, such as... Figure 1As shown, the sampler RS is arranged in the chopper loop (for example, after the positive electrode of the output end of the buck module 1 is connected to the positive electrode of the load through the inductor LF3, the negative electrode of the load is connected to the negative electrode of the output end of the buck module 1 through the inductor LF3 and the chopper MOS tube Q10 or Q11) of the chopper color control switching power supply, to detect the fault condition of each chopper loop, such as comparing the generated sampling voltage with the preset voltage threshold of the fault judgment module 3, to determine whether there is an abnormal fault by the fault judgment module 3; when there is a fault condition (especially when there is a short circuit fault), the discharge module 4 is turned on, so that the chopper MOS tube is directly connected to the GND ground terminal, and the discharge not only closes the chopper MOS tube, but also discharges the energy stored in the electrolytic capacitor CE2 at the output end of the buck module 1, thereby effectively preventing the chopper MOS tube from failing, being damaged or exploding, significantly improving the safety and reliability of the chopper color control switching power supply, and prolonging the service life of the circuit.

[0028] It should be noted that there are many ways to form the circuit structure of the buck module 1 and the chopper module 2. Figure 1 For example, the output end part of the circuit structure of the buck module 1 usually outputs the dimming current to the load end (i.e. LED+, LED2-, LED-) through the common mode inductor L8 (the FB1 end is mainly used to feedback to the buck dimming chip) and the filter, anti-reverse current and other structures, and then the load is externally connected to the load for dimming. As can be seen, it actually forms multiple dimming output loops to connect multiple loads, and the chopper MOS tube is arranged in one-to-one correspondence with the dimming output loop, so that the chopper loop can be changed, and different color control is performed on multiple different loads. For this purpose, the color control chip U2 (for example, BP5929) is arranged, and the controller (such as MCU) controls the color control chip U2 to control the color control of the chopper MOS tube (such as Q10, Q11) through the PWM_color signal. The peripheral circuit of the color control chip U2 is built according to the chip manual, which is not limited here.

[0029] Further, the time module 5 is further included; the time module 5 is coupled between the output end of the fault judgment module 3 and the discharge module 4; the time module 5 is used to preset the maintenance time, and the maintenance time is used to maintain the conduction of the discharge module 4 by the fault judgment module 3.

[0030] In the embodiment, the way that the fault judging module 3 drives the discharging module 4 to conduct is triggered, and the fault judging module only outputs a short triggered signal to the discharging module 4 each time, and the discharging module 4 only conducts for a short time. When the fault condition is unstable, the chopping MOS tube is restarted constantly, and the purpose of fault protection is far from being achieved. Therefore, the time module 5 is arranged between the output end of the fault judging module 3 and the discharging module 4, and when the fault judging module 3 drives the discharging module 4 to conduct, the time module 5 maintains the conduction according to the preset maintaining time, thereby ensuring the reliability of the fault protection and improving the flexibility of the fault protection.

[0031] Further, the sampling device RS is a sampling resistor, and the sampling device RS is connected in series between the negative output end of the buck module 1 and the source of the chopping MOS tube.

[0032] In the embodiment, the sampling device RS is preferably a sampling resistor, and the sampling resistor is directly connected in series and then the voltage between the two ends of the sampling resistor is sampled to detect the working condition of the chopping circuit in real time; and the sampling device RS is connected in series at the negative output end, and only one sampling resistor is needed to monitor multiple chopping circuits at the same time.

[0033] Further, the fault judging module 3 comprises an amplifier 31 and a comparator U12A; the input end of the amplifier 31 is used as the input end of the fault judging module 3, and the output end of the comparator U12A is used as the output end of the fault judging module 3.

[0034] The output end of the amplifier 31 and the negative input end of the comparator U12A are electrically connected, and the positive input end of the comparator U12A is connected to a reference source.

[0035] In the embodiment, after the sampling voltage obtained from the sampling device RS is amplified by the amplifier 31, the sampling voltage is compared with the reference voltage provided by the reference source by the fault judging module 3, so that whether the chopping circuit is faulty is known; the comparison type judging accelerates the fault response speed. It should be noted that there are various ways to set the reference source, for example, the reference source is obtained by connecting a 3.3V power supply voltage through a resistor R127 and a resistor R132. Figure 1

[0036] Further, the amplifier 31 comprises a resistor R128, a resistor R129, a resistor R130, a resistor R131 and an operational amplifier U12B; one end of the resistor R128 and one end of the resistor R130 are both used as the input end of the amplifier 31, and the output end of the operational amplifier U12B is used as the output end of the amplifier 31.

[0037] ​The common connection point of the sampling device RS and the negative output terminal of the buck module 1 is electrically connected to one end of the resistor R128, the other end of the resistor R128 and one end of the resistor R129 are electrically connected to the negative input terminal of the operational amplifier U12B, and the other end of the resistor R129 and the output terminal of the operational amplifier U12B are electrically connected.

[0038] The common connection point of the sampling device RS and the source of the chopper MOS tube is electrically connected to one end of the resistor R130, the other end of the resistor R130 and one end of the resistor R131 are electrically connected to the positive input terminal of the operational amplifier U12B, and the other end of the resistor R131 is connected to the GND ground terminal.

[0039] In this embodiment, the amplifier 31 is a differential amplifier composed of the resistors R128, R129, R130, R131 and the operational amplifier U12B, which can more effectively suppress common-mode interference, reduce nonlinear distortion and improve the detection accuracy of weak sampling signals compared with ordinary amplifiers.

[0040] Further, the discharge module 4 includes the resistor R124, the triode Q16, the resistor R123, the triode Q12, the resistor R122 and at least one diode D25; the number of diodes D25 is equal to the number of chopper MOS tubes;

[0041] The output terminal of the fault judgment module 3 (this terminal can also be electrically connected to the controller to feed back the Out_short signal to inform the controller of the fault condition) is electrically connected to the base of the triode Q16 through the resistor R124, the collector of the triode Q16 is electrically connected to the base of the triode Q12 through the resistor R123, the emitter of the triode Q16 is connected to the GND ground terminal, the emitter of the triode Q12 and one end of the resistor R122 are electrically connected, the cathodes of the diodes D25 are electrically connected to the other end of the resistor R122, the anodes of the diodes D25 and the gates of the chopper MOS tubes are electrically connected one by one, and the sources of the chopper MOS tubes are electrically connected to the collector of the triode Q12.

[0042] In this embodiment, the cleverness of the circuit design of the discharge module 4 lies in: first, the double triodes are used to form the switch of the discharge path, which can quickly control the on-off of the discharge path and respond quickly; second, the unidirectional conductivity of the diodes D25 is used to prevent the interference of the reverse current on the chopper MOS tube during normal operation.

[0043] Further, the time module 5 is composed of a timing chip U9 and its peripheral circuit, the input terminal of the timing chip U9 is electrically connected to the output terminal of the fault judgment module 3, and the output terminal of the timing chip U9 is electrically connected to the discharge module 4.

[0044] In the embodiment, the preset maintaining time function of the time module 5 is mainly realized by the timing chip U9, the timing chip has stable performance and accurate time setting, and can maintain the conduction of the discharging module 4 according to the preset maintaining time. For example, the NE555 chip, in the peripheral circuit of which, the resistance R125 and the capacitor C49 determine the maintaining time of the driving signal (for example, high level) sent by the output end of the timing chip U9 after the input end of the timing chip U9 receives a trigger signal (for example, low level). It can be known that the chip model selected by the timing chip U9 has the function of receiving a signal and outputting an output signal lasting for a period of time (i.e. the preset maintaining time), and the chip selection is not limited here.

[0045] Other configurations and operations of the fault protection circuit for the chopper dimmer switching power supply according to the embodiments of the present application are known to those skilled in the art, and will not be described in detail here.

[0046] In the description of the present specification, the description referring to the terms "embodiment", "example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0047] Although the embodiments of the present application have been shown and described, those skilled in the art can understand that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the claims and their equivalents.

Claims

1. A fault protection circuit for a chopper dimming switching power supply, the chopper dimming switching power supply comprising a buck module and a chopper module; the chopper module is provided with at least one chopper MOS tube, the positive and negative poles of the output end of the buck module are coupled in one-to-one correspondence with the chopper MOS tube to form a chopper loop; characterized in that: The sampling device RS, the fault judging module and the discharging module are included; the sampling device RS is arranged between the negative output terminal of the buck module and the source of the chopper MOS tube, and is coupled to the input terminal of the fault judging module; the output terminal of the fault judging module is electrically connected with the discharging module; and the discharging module is coupled between the chopper MOS tube and the GND ground terminal. When the fault judging module detects a fault condition through the sampling device RS, the discharging module is turned on.

2. The fault protection circuit for a chopper-dimming switching power supply according to claim 1, wherein: A time module is further included, which is coupled between the output terminal of the fault judging module and the discharging module; the time module is used for presetting a maintenance time, and maintaining the turn-on of the discharging module by the fault judging module according to the maintenance time.

3. The fault protection circuit for a chopper-controlled color-tuning switching power supply according to claim 1, characterized in that: The sampling device RS is a sampling resistor, which is connected in series between the negative output terminal of the buck module and the source of the chopper MOS tube.

4. A fault protection circuit for a chopper colour switching power supply as claimed in claim 3, wherein: The fault judging module includes an amplifier and a comparator U12A; the input terminal of the amplifier is used as the input terminal of the fault judging module, and the output terminal of the comparator U12A is used as the output terminal of the fault judging module. The output terminal of the amplifier is electrically connected with the negative input terminal of the comparator U12A, and the positive input terminal of the comparator U12A is connected with a reference source.

5. A fault protection circuit for a chopper colour switching power supply as claimed in claim 4, wherein: The amplifier includes resistors R128, R129, R130, R131 and an operational amplifier U12B; one end of the resistor R128 and one end of the resistor R130 are used as the input terminal of the amplifier, and the output terminal of the operational amplifier U12B is used as the output terminal of the amplifier. The common connection point of the sampling device RS and the negative output terminal of the buck module is electrically connected with one end of the resistor R128, and the other end of the resistor R128 and one end of the resistor R129 are electrically connected with the negative input terminal of the operational amplifier U12B; the other end of the resistor R129 is electrically connected with the output terminal of the operational amplifier U12B. The common connection point of the sampling device RS and the source of the chopper MOS tube is electrically connected with one end of the resistor R130, and the other end of the resistor R130 and one end of the resistor R131 are electrically connected with the positive input terminal of the operational amplifier U12B; the other end of the resistor R131 is connected with the GND ground terminal.

6. The fault protection circuit for a chopper-dimming switching power supply of claim 1, wherein: The discharging module includes resistors R124, Q16, R123, Q12, R122 and at least one diode D25; the number of the diodes D25 is equal to the number of the chopper MOS tubes. The output end of the fault judging module is electrically connected with the base of the triode Q16 through the resistor R124, the collector of the triode Q16 is electrically connected with the base of the triode Q12 through the resistor R123, the emitter of the triode Q16 is connected with the GND ground end, the emitter of the triode Q12 and one end of the resistor R122 are electrically connected, the cathode of the diode D25 is electrically connected with the other end of the resistor R122, the anode of the diode D25 and the gate of the chopper MOS tube are electrically connected one by one, and the source of the chopper MOS tube is electrically connected with the collector of the triode Q12.

7. The fault protection circuit for a chopper-dimming switching power supply of claim 2, wherein: The time module is composed of a timing chip U9 and its peripheral circuit, the input end of the timing chip U9 is electrically connected with the output end of the fault judging module, and the output end of the timing chip U9 is electrically connected with the discharging module.

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