CN114158159A - LED drive circuit with protection function - Google Patents
LED drive circuit with protection function Download PDFInfo
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- CN114158159A CN114158159A CN202111490940.XA CN202111490940A CN114158159A CN 114158159 A CN114158159 A CN 114158159A CN 202111490940 A CN202111490940 A CN 202111490940A CN 114158159 A CN114158159 A CN 114158159A
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/30—Driver circuits
- H05B45/37—Converter circuits
- H05B45/3725—Switched mode power supply [SMPS]
- H05B45/375—Switched mode power supply [SMPS] using buck topology
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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
- H02H7/10—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 converters; for rectifiers
- H02H7/12—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 converters; for rectifiers for static converters or rectifiers
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
- H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Circuit Arrangement For Electric Light Sources In General (AREA)
- Dc-Dc Converters (AREA)
Abstract
The application provides a LED drive circuit with protect function includes: the device comprises a rectification transformation module, a power supply module and a protection module; the input end of the rectification transformation module is connected with external alternating current, and the output end of the rectification transformation module is connected with the power supply module, receives external alternating current input, and converts the external alternating current input into first direct current voltage output adaptive to the LED driving circuit with the protection function; the power supply module is connected with the rectification transformation module at the input end and connected with the LED load at the output end, comprises a first transformer, receives the first direct-current voltage output by the rectification transformation module, converts the first direct-current voltage into second direct-current voltage required by the LED load to output, and optionally outputs working voltage required by other modules in the LED drive circuit with the protection function; and the protection module is connected with the power supply module and used for performing overvoltage, demagnetization and overpower protection on the LED drive circuit with the protection function. The application can realize protection such as overvoltage (overcurrent), demagnetization and overpower.
Description
Technical Field
The application relates to the technical field of circuit design, in particular to an LED driving circuit with a protection function.
Background
At present, the safety requirements tend to be stricter and stricter for LED driving power supplies. For example, the European standard CE proposes that the shell temperature in an abnormal state cannot exceed 110 degrees, and the safety hazard can be caused when the shell temperature exceeds the limit. Generally, the LED driving power supply also needs to consider overvoltage (overcurrent) protection. In the circuit, if a transformer is used, the requirement of demagnetization is considered. The temperature of the housing does not exceed the limit in the circuit operating state, but some abnormal states are not excluded, although the current of the circuit operates under the design requirement, the voltage of the load end suddenly rises, so that the power rises, and the temperature rises. Therefore, it is necessary to consider the limitation of power, especially in circuits that can be regulated in multiple steps.
Disclosure of Invention
The application aims to provide an LED driving circuit with a relatively comprehensive protection function.
In order to achieve the above object, the present application provides an LED driving circuit with a protection function, including: the device comprises a rectification transformation module, a power supply module and a protection module;
the input end of the rectification transformation module is connected with external alternating current, and the output end of the rectification transformation module is connected with the power supply module, receives external alternating current input, and converts the external alternating current input into first direct current voltage output adaptive to the LED driving circuit with the protection function;
the power supply module is connected with the rectification transformation module at the input end and connected with the LED load at the output end, comprises a first transformer, receives the first direct-current voltage output by the rectification transformation module, converts the first direct-current voltage into second direct-current voltage required by the LED load to output, and optionally outputs working voltage required by other modules in the LED drive circuit with the protection function;
and the protection module is connected with the power supply module and used for performing overvoltage, demagnetization and overpower protection on the LED drive circuit with the protection function.
Further, the first transformer comprises a primary coil and a secondary coil, the primary coil is connected with the rectification transformation module, and the secondary coil is connected with the LED load;
the protection module comprises a protection chip and a second MOS tube; the sixth end of the protection chip is a sampling end and is connected with the source electrode of the second MOS tube, the source electrode of the second MOS tube is connected with the ground through a first sampling resistor, and the source electrode of the second MOS tube is also connected with the drain electrode of the second MOS tube through an eighth capacitor; the drain electrode of the second MOS tube is connected with the second end of the primary coil of the first transformer, and the first end of the primary coil of the first transformer is connected with the rectification transformation module to receive the first direct-current voltage; the grid electrode of the second MOS tube is connected with the source electrode of the second MOS tube through a fourth twelve resistor, the grid electrode of the second MOS tube is connected with the seventh end of the protection chip through a third twelve resistor, and the seventh end of the protection chip is a grid driving end.
Further, the first transformer further comprises an auxiliary coil, and the auxiliary coil and the primary coil are positioned on the same side; the first end of the auxiliary coil is connected with the ground through a twenty-ninth resistor and a thirty-first resistor which are sequentially connected in series, a twenty-eighth resistor and a fourteenth capacitor are further connected in parallel at two ends of the thirty-first resistor, a connecting point of the twenty-ninth resistor and the thirty-first resistor is connected with the third end of the protection chip, and the third end of the protection chip is a feedback end; the second end of the auxiliary coil is connected with the ground.
Further, the protection module further comprises a fourth diode and a sixty-sixth resistor, wherein the anode of the fourth diode is connected with the first end of the auxiliary coil, the cathode of the fourth diode is connected with one end of the sixty-sixth resistor, and the other end of the sixty-sixth resistor is connected with the sixth end of the protection chip.
Further, a first end of the auxiliary coil is connected with an anode of a third diode, a cathode of the third diode is connected with one end of a twentieth resistor, and the other end of the twentieth resistor is connected with the ground through a fourth electrolytic capacitor; the other end of the twentieth resistor is further connected with a collector of a third triode, the collector of the third triode is connected with a base of the third triode through a fifteenth resistor, the base of the third triode is connected with the ground through a first Zener diode, an emitter of the third triode is connected with the ground through a fourth capacitor, and the emitter of the third triode is further connected with the anode of the first diode; the cathode of the first diode is connected with the ground through a third electrolytic capacitor, the cathode of the first diode is further connected with the eighth end of the protection chip, and the eighth end of the protection chip is a power supply end and is further connected with the ground through the third capacitor.
Further, a first end of a primary coil of the first transformer is used as an input end of the power supply module and is connected with an output end of the rectification transformation module; the first end of the primary coil is also connected with the cathode of a seventh diode through an eleventh capacitor, and the anode of the seventh diode is connected with the second end of the primary coil; a twenty-fifth resistor, a twenty-sixth resistor, a twenty-third resistor and a twenty-fourth resistor which are sequentially connected in series are further connected in parallel at two ends of the eleventh capacitor, and the connection point of the twenty-fifth resistor and the twenty-sixth resistor is connected with the connection point of the twenty-third resistor and the twenty-fourth resistor; the first end of the secondary coil is connected with the second end of the secondary coil through a twenty-first diode and a second electrolytic capacitor which are sequentially connected in series, the second end of the secondary coil is connected with the ground, a fifty-th resistor is connected in parallel at two ends of the second electrolytic capacitor, and two ends of the fifty-th resistor serve as the output end of the power supply module through a third common-mode inductor.
Further, the rectification and transformation module comprises a rectifier bridge, a second transformer and a main control chip, wherein the input end of the rectifier bridge is connected with the external alternating current, the first output end of the rectifier bridge is connected with the first end of the primary coil of the second transformer, the second end of the primary coil of the second transformer is connected with the anode of a sixth diode, a first capacitor and a fifth diode are connected in parallel between the first end of the primary coil of the second transformer and the cathode of the sixth diode, the cathode of the sixth diode is connected with the second output end of the rectifier bridge and is connected with the ground through a first electrolytic capacitor, and the cathode of the sixth diode is used as the output end of the rectification and transformation module; the first end of the secondary coil of the second transformer is connected with the fifth end of the main control chip through a sixteenth resistor, the fifth end of the main control chip is a demagnetization end, and the second end of the secondary coil of the second transformer is connected with the ground.
Further, a first end of the primary coil of the second transformer is also connected with a drain electrode of a first MOS transistor, a source electrode of the first MOS transistor is connected with a second end of the primary coil of the second transformer through a second sampling resistor, a gate electrode of the first MOS transistor is connected with a seventh end of the main control chip through a first resistor, and the seventh end of the main control chip is a gate drive end; the grid electrode of the first MOS tube is connected with the ground through a twenty-first resistor, an eighteenth resistor and a twelfth capacitor which are sequentially connected in series, the connection point of the twenty-first resistor and the eighteenth resistor is connected with the source electrode of the first MOS tube, the connection point of the eighteenth resistor and the twelfth capacitor is connected with the fourth end of the main control chip, and the fourth end of the main control chip is a sampling end.
Furthermore, the cathode of the sixth diode is connected with the second end of the rectifier bridge through a fifth resistor, a sixth resistor, a seventh resistor and an eighth resistor which are sequentially connected in series, a sixteenth capacitor is further connected in parallel at two ends of the eighth resistor, the connection point of the seventh resistor and the eighth resistor is connected with the first end of the main control chip, and the first end of the main control chip is a feedback end.
Furthermore, a first end of the rectifier bridge is a high-voltage direct supply point, is connected with the ground through a second capacitor, and is connected with the cathode of the first diode through a thirteenth resistor, a fourteenth resistor and a fifteenth resistor which are sequentially connected in series; and a twenty-second resistor is connected in parallel between the emitter and the collector of the third triode, the emitter of the third triode is connected with the anode of a twelfth triode, the cathode of the twelfth triode is connected with the eighth end of the main control chip, and the eighth end of the main control chip is a power supply end and is connected with the ground through a fifth capacitor.
Further, the first sampling resistor and/or the second sampling resistor are a resistor network formed by connecting a plurality of resistors in parallel, and each parallel resistor branch is connected with a switch in series.
The LED drive circuit with the protection function can realize protection such as overvoltage (overcurrent), demagnetization and overpower.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic structural diagram of an LED driving circuit with a protection function provided in the present application;
fig. 2 is a schematic structural diagram of a power supply module and a protection module in an LED driving circuit with a protection function provided in the present application;
fig. 3 is a schematic structural diagram of a rectifying and transforming module in an LED driving circuit with a protection function provided in the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application. Furthermore, it should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the invention, are given by way of illustration and explanation only, and are not intended to limit the scope of the invention. In the present application, unless otherwise specified, the use of directional terms such as "upper", "lower", "left" and "right" generally refer to upper, lower, left and right in the actual use or operation of the device, and specifically to the orientation of the drawing figures.
The present application provides an LED driving circuit having a protection function, which will be described in detail below. It should be noted that the following description of the embodiments is not intended to limit the preferred order of the embodiments of the present application. In the following embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to related descriptions of other embodiments for parts that are not described in detail in a certain embodiment.
Referring to fig. 1, the present application provides an LED driving circuit with protection function, including: the device comprises a rectification transformation module, a power supply module and a protection module;
the input end of the rectification transformation module is connected with external alternating current, and the output end of the rectification transformation module is connected with the power supply module, receives external alternating current input, and converts the external alternating current input into first direct current voltage output adaptive to the LED driving circuit with the protection function;
the power supply module is connected with the rectification transformation module at the input end and connected with the LED load at the output end, comprises a first transformer, receives the first direct-current voltage output by the rectification transformation module, converts the first direct-current voltage into second direct-current voltage required by the LED load to output, and optionally outputs working voltage required by other modules in the LED drive circuit with the protection function;
and the protection module is connected with the power supply module and used for performing overvoltage, demagnetization and overpower protection on the LED drive circuit with the protection function.
As shown in fig. 2, the power supply module includes a first transformer T1. The first transformer T1 comprises a primary coil and a secondary coil; the primary coil is connected with the rectification transformation module and receives a first direct-current voltage output by the rectification transformation module; and the secondary coil is connected with the LED load and converts the first direct-current voltage output by the rectification transformation module into a second direct-current voltage required by the LED load to be output. In the present embodiment, the first transformer T1 further includes an auxiliary coil, and outputs an operating voltage required by another module in the LED driving circuit having the protection function, for example, an operating voltage required by the protection module (details will be described later).
The protection module comprises a protection chip U2 and a second MOS tube Q2; a sixth end of the protection chip U2 is a sampling end CS, and is connected to the source of the second MOS transistor Q2, the source of the second MOS transistor Q2 is connected to ground GND through a first sampling resistor, and the source of the second MOS transistor Q2 is further connected to the drain of the second MOS transistor Q2 through an eighth capacitor C8; the drain of the second MOS transistor Q2 is connected to the second end of the primary winding of the first transformer T1, and the first end of the primary winding of the first transformer T1 is connected to the rectification and transformation module, so as to receive the first direct-current voltage; the GATE of the second MOS transistor Q2 is connected to the source of the second MOS transistor Q2 through a fourth twelfth resistor R42, the GATE of the second MOS transistor Q2 is connected to the seventh end of the protection chip U2 through a third twelfth resistor R32, and the seventh end of the protection chip U2 is a GATE-driven terminal GATE.
Through the cooperation of the protection chip U2, the second MOS tube Q2 and the sampling resistor, the current of the primary coil of the first transformer T1 (which also reflects the magnitude of the load current) in the circuit is sampled and judged, and the on-off of the circuit (the on-off of the second MOS tube Q2) is further controlled, so that the overvoltage (overcurrent) protection of the whole circuit is realized. In this embodiment, the first sampling resistor is a resistor network formed by connecting a plurality of resistors R33, R34, R40, and R41 in parallel, and switches (not shown) are connected in series on branches of each of the resistors R33, R34, R40, and R41 connected in parallel, so that different resistors can be selected for sampling by switching the switches, thereby realizing overvoltage (overcurrent) protection of different levels to meet different requirements of the circuit.
As mentioned above, the first transformer T1 further includes an auxiliary coil, which is located on the same side as the primary coil; the first end of the auxiliary coil is connected with the ground GND through a twenty-ninth resistor R29 and a thirty-first resistor R31 which are sequentially connected in series, a twenty-eighth resistor R28 and a fourteenth capacitor C14 are further connected in parallel at two ends of the thirty-first resistor R31, a connection point of the twenty-ninth resistor R29 and the thirty-first resistor R31 is connected with a third end of the protection chip U2, and the third end of the protection chip U2 is a feedback end FB; the second end of the auxiliary coil is connected to ground GND. Through the cooperation of auxiliary winding and relevant circuit, realize to the demagnetization of first transformer T1 detects and the protection.
In addition, the protection module further includes a fourth diode D4 and a sixty-sixth resistor R66, an anode of the fourth diode D4 is connected to the first end of the auxiliary coil, a cathode of the fourth diode D4 is connected to one end of the sixty-sixth resistor R66, and the other end of the sixty-sixth resistor R66 is connected to a sixth end of the protection chip U2. During the actual operation of the circuit, the voltage at the load end may fluctuate suddenly, for example, rise, and at this time, the current of the primary winding of the first transformer T1 in the circuit still operates under the original overcurrent condition, which may cause the actual power at the load end to rise, and the temperature to rise, thereby bringing about a safety hazard. This application is responded to the voltage on the secondary coil through auxiliary coil (when load end voltage rises, voltage on the secondary coil also can rise), then through fourth diode D4, sixty-sixth resistance R66 with this voltage fluctuation that induces exert protection chip U2 on sixth end sample terminal CS, so the voltage that sixth end sample terminal CS of protection chip U2 sampled has actually been promoted by force, thereby let protection chip U2 judge that overvoltage (overcurrent) condition has been satisfied, and then close through seventh end grid drive end GATE control second MOS pipe Q2 of protection chip U2, with the electric current in the reduction circuit, reduce the actual power of load end, realize the overpower protection promptly.
The auxiliary coil may also provide an operating voltage to other modules in the circuit, for example, the protection chip U2 obtains the operating voltage from the auxiliary coil. A first end of the auxiliary coil is connected with an anode of a third diode D3, a cathode of the third diode D3 is connected with one end of a twentieth resistor R20, and the other end of the twentieth resistor R20 is connected with the ground GND through a fourth electrolytic capacitor RC 4; the other end of the twentieth resistor R20 is further connected to a collector of a third transistor Q3, the collector of the third transistor Q3 is connected to the base of the third transistor Q3 through a fifteenth resistor R35, the base of the third transistor Q3 is connected to ground GND through a first zener diode ZD1, the emitter of the third transistor Q3 is connected to ground GND through a fourth capacitor C4, and the emitter of the third transistor Q3 is further connected to the anode of a first diode D1; the cathode FLB _ VCC of the first diode D1 is connected to the ground GND through the third electrolytic capacitor EC3, the cathode of the first diode D1 is further connected to the eighth terminal of the protection chip U2, the eighth terminal of the protection chip U2 is a power supply terminal VCC, and the eighth terminal of the protection chip U2 is further connected to the ground GND through the third capacitor C3.
The specific configuration of the power supply module is described in detail next. A first end of a primary coil of the first transformer T1 is used as an input end of the power supply module and is connected with an output end of the rectification transformation module; the first end of the primary coil is also connected with the cathode of a seventh diode D7 through an eleventh capacitor C11, and the anode of the seventh diode D7 is connected with the second end of the primary coil; a twenty-fifth resistor R25, a twenty-sixth resistor R26, a twenty-third resistor R23 and a twenty-fourth resistor R24 which are sequentially connected in series are further connected in parallel at two ends of the eleventh capacitor C11, and connection points of the twenty-fifth resistor R25 and the twenty-sixth resistor R26 are connected with connection points of the twenty-third resistor R23 and the twenty-fourth resistor R24; the first end of the secondary coil is connected to the second end of the secondary coil through a twenty-first diode D21 and a second electrolytic capacitor EC2, which are connected in series, and the second end of the secondary coil is connected to ground SGND, where the ground is specifically referred to as signal SGND and the other ground is power ground GND. A fifty-th resistor R50 is connected in parallel to two ends of the second electrolytic capacitor EC2, and two ends of the fifty-th resistor R50 serve as an output end LED +, LED-of the power supply module through a third common mode inductor FL 3. Common mode interference can be better eliminated through the third common mode inductor FL 3.
And finally, describing the specific construction of the rectification and transformation module in detail. Referring to fig. 3, the rectification and transformation module includes a rectifier bridge DB1, a second transformer T2 and a main control chip U1, an input end of the rectifier bridge DB1 is connected to the external alternating current AC, a first output end of the rectifier bridge DB1 is connected to a first end of a primary coil of the second transformer T2, a second end of the primary coil of the second transformer T2 is connected to an anode of a sixth diode D2, a first capacitor C1 and a fifth diode D5 are connected in parallel between the first end of the primary coil of the second transformer T2 and a cathode of a sixth diode D6, a cathode of the sixth diode D6 is connected to a second output end of the rectifier bridge DB1 and connected to ground GND through a first electrolytic capacitor EC1, and a cathode of the sixth diode D6 is used as an output end of the rectification and transformation module VBUS; the first end of the secondary coil of the second transformer T2 is connected with the fifth end of the main control chip U1 through a sixteenth resistor R16, the fifth end of the main control chip U1 is a demagnetization end ZCD, and the second end of the secondary coil of the second transformer T2 is connected with the ground GND. The primary coil and the secondary coil of the second transformer T2 realize the functions of transformation and demagnetization detection protection at the same time. The magnitude of the first direct-current voltage output by the output end VBUS of the rectification transformation module is not particularly limited, and is mainly determined according to the magnitude of the voltage required by the whole circuit; for example, the size of the LED load to be driven by the circuit determines the size of the load voltage to be output by the circuit, i.e., the second dc voltage, and the size of the load voltage is implemented by the power supply module therein, and the power supply module performs conversion based on the first dc voltage. Generally, the first direct current voltage is larger than the second direct current voltage; for another example, the magnitude of the operating voltage required by each chip of each module in the circuit also affects how high the first dc voltage needs to be. In summary, it is sufficient that the first direct current voltage is adapted to the overall functionality of the circuit. In one embodiment, the alternating current AC is 220-240V, the first dc voltage is 400V, and the second dc voltage is 60V.
Further, the first end of the primary coil of the second transformer T2 is further connected to the drain of a first MOS transistor Q1, the source of the first MOS transistor Q1 is connected to the second end of the primary coil of the second transformer T2 through a second sampling resistor, the GATE of the first MOS transistor Q1 is connected to the seventh end of the main control chip U1 through a first resistor R1, and the seventh end of the main control chip U1 is a GATE-driven end GATE; the grid of the first MOS transistor Q1 is further connected with ground GND through a twenty-first resistor R21, an eighteenth resistor R18 and a twelfth capacitor C12 which are sequentially connected in series, a connection point of the twenty-first resistor R21 and the eighteenth resistor R18 is connected with the source electrode of the first MOS transistor Q1, a connection point of the eighteenth resistor R18 and the twelfth capacitor C12 is connected with the fourth end of the main control chip U1, and the fourth end of the main control chip U1 is a sampling end CS. Similarly, the current in the second transformer T2 is protected from overvoltage (overcurrent) through the cooperation of the main control chip U1, the first MOS transistor Q1 and the second sampling resistor. In addition, similarly, the second sampling resistor is also a resistor network formed by connecting a plurality of resistors R2, R3, and R4 in parallel, and a switch (not shown) is connected in series on each branch of the resistors R2, R3, and R4 connected in parallel, so that different resistors can be selected for sampling by switching the switches, so as to realize overvoltage (overcurrent) protection of different levels, thereby adapting to different requirements of the circuit. The first capacitor C1 and the fifth diode D5 can protect the first MOS transistor Q1 when the device is turned on.
Further, the cathode of the sixth diode D6 is connected to the second end of the rectifier bridge DB1 through a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, and an eighth resistor R8, which are connected in series in sequence, the two ends of the eighth resistor R8 are also connected in parallel with a sixteenth capacitor C16, the connection point of the seventh resistor R7 and the eighth resistor R8 is connected to the first end of the main control chip U1, and the first end of the main control chip U1 is the feedback end FB. Through the cooperation of the circuits, the whole rectification transformation module is subjected to feedback control from the external alternating current AC to the output of the first direct current voltage.
Finally, the output end of the rectifier bridge DB1 can directly supply power to each module, so that each module can start to work earlier, and power is obtained from other modules after each module works stably. The first end of the rectifier bridge DB1 is a high-voltage direct supply point V _ B, is connected to ground GND through a second capacitor C2, and is connected to the negative electrode of the first diode D1 through a thirteenth resistor R13, a fourteenth resistor R14, and a fifteenth resistor R15 which are connected in series in sequence. Therefore, the protection chip U2 may obtain the working voltage from the rectifier bridge DB1, and obtain the working voltage from the first transformer T1 after the first transformer T1 operates stably. In addition, a twenty-second resistor R22 is connected in parallel between the emitter and the collector of the third triode Q3, the emitter of the third triode Q3 is further connected with the anode of a twelfth diode D10, the cathode PFC _ VCC of the twelfth diode D10 is connected with the eighth end of the main control chip U1, the eighth end of the main control chip U1 is a power supply end VCC, and is connected with the ground GND through a fifth capacitor C5. Therefore, the protection chip U1 may also obtain the working voltage from the rectifier bridge DB1, and obtain the working voltage from the first transformer T1 after the first transformer T1 operates stably.
The LED drive circuit with the protection function can realize protection such as overvoltage (overcurrent), demagnetization and overpower.
The LED driving circuit with protection function provided by the present application is described in detail above, and the principle and the implementation of the present application are explained in this document by applying specific examples, and the description of the above examples is only used to help understanding the method and the core idea of the present application; meanwhile, for a person skilled in the art, according to the idea of the present application, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present application.
Claims (11)
1. An LED drive circuit with a protection function, characterized in that the LED drive circuit with the protection function comprises: the device comprises a rectification transformation module, a power supply module and a protection module;
the input end of the rectification transformation module is connected with external alternating current, and the output end of the rectification transformation module is connected with the power supply module, receives external alternating current input, and converts the external alternating current input into first direct current voltage output adaptive to the LED driving circuit with the protection function;
the power supply module is connected with the rectification transformation module at the input end and connected with the LED load at the output end, comprises a first transformer, receives the first direct-current voltage output by the rectification transformation module, converts the first direct-current voltage into second direct-current voltage required by the LED load to output, and optionally outputs working voltage required by other modules in the LED drive circuit with the protection function;
and the protection module is connected with the power supply module and used for performing overvoltage, demagnetization and overpower protection on the LED drive circuit with the protection function.
2. The LED driving circuit with protection function according to claim 1, wherein the first transformer comprises a primary coil and a secondary coil, the primary coil is connected with the rectification transformation module, and the secondary coil is connected with the LED load;
the protection module comprises a protection chip and a second MOS tube; the sixth end of the protection chip is a sampling end and is connected with the source electrode of the second MOS tube, the source electrode of the second MOS tube is connected with the ground through a first sampling resistor, and the source electrode of the second MOS tube is also connected with the drain electrode of the second MOS tube through an eighth capacitor; the drain electrode of the second MOS tube is connected with the second end of the primary coil of the first transformer, and the first end of the primary coil of the first transformer is connected with the rectification transformation module to receive the first direct-current voltage; the grid electrode of the second MOS tube is connected with the source electrode of the second MOS tube through a fourth twelve resistor, the grid electrode of the second MOS tube is connected with the seventh end of the protection chip through a third twelve resistor, and the seventh end of the protection chip is a grid driving end.
3. The LED driving circuit with protection function according to claim 2, wherein the first transformer further includes an auxiliary coil, the auxiliary coil being located on the same side as the primary coil; the first end of the auxiliary coil is connected with the ground through a twenty-ninth resistor and a thirty-first resistor which are sequentially connected in series, a twenty-eighth resistor and a fourteenth capacitor are further connected in parallel at two ends of the thirty-first resistor, a connecting point of the twenty-ninth resistor and the thirty-first resistor is connected with the third end of the protection chip, and the third end of the protection chip is a feedback end; the second end of the auxiliary coil is connected with the ground.
4. The LED driving circuit with protection function according to claim 3, wherein the protection module further includes a fourth diode and a sixty-sixth resistor, an anode of the fourth diode is connected to the first end of the auxiliary coil, a cathode of the fourth diode is connected to one end of the sixty-sixth resistor, and the other end of the sixty-sixth resistor is connected to the sixth end of the protection chip.
5. The LED driving circuit with protection function according to claim 4, wherein a first end of the auxiliary coil is connected to an anode of a third diode, a cathode of the third diode is connected to one end of a twentieth resistor, and the other end of the twentieth resistor is connected to ground through a fourth electrolytic capacitor; the other end of the twentieth resistor is further connected with a collector of a third triode, the collector of the third triode is connected with a base of the third triode through a fifteenth resistor, the base of the third triode is connected with the ground through a first Zener diode, an emitter of the third triode is connected with the ground through a fourth capacitor, and the emitter of the third triode is further connected with the anode of the first diode; the cathode of the first diode is connected with the ground through a third electrolytic capacitor, the cathode of the first diode is further connected with the eighth end of the protection chip, and the eighth end of the protection chip is a power supply end and is further connected with the ground through the third capacitor.
6. The LED driving circuit with protection function according to claim 5, wherein a first end of the primary coil of the first transformer is used as an input end of the power supply module and is connected with an output end of the rectification transformation module; the first end of the primary coil is also connected with the cathode of a seventh diode through an eleventh capacitor, and the anode of the seventh diode is connected with the second end of the primary coil; a twenty-fifth resistor, a twenty-sixth resistor, a twenty-third resistor and a twenty-fourth resistor which are sequentially connected in series are further connected in parallel at two ends of the eleventh capacitor, and the connection point of the twenty-fifth resistor and the twenty-sixth resistor is connected with the connection point of the twenty-third resistor and the twenty-fourth resistor; the first end of the secondary coil is connected with the second end of the secondary coil through a twenty-first diode and a second electrolytic capacitor which are sequentially connected in series, the second end of the secondary coil is connected with the ground, a fifty-th resistor is connected in parallel at two ends of the second electrolytic capacitor, and two ends of the fifty-th resistor serve as the output end of the power supply module through a third common-mode inductor.
7. The LED driving circuit with the protection function according to claim 6, wherein the rectification and transformation module comprises a rectifier bridge, a second transformer and a main control chip, the input end of the rectifier bridge is connected with the external alternating current, the first output end of the rectifier bridge is connected with the first end of the primary coil of the second transformer, the second end of the primary coil of the second transformer is connected with the anode of a sixth diode, a first capacitor and a fifth diode are connected in parallel between the first end of the primary coil of the second transformer and the cathode of the sixth diode, the cathode of the sixth diode is connected with the second output end of the rectifier bridge and connected with the ground through a first electrolytic capacitor, and the cathode of the sixth diode is used as the output end of the rectification and transformation module; the first end of the secondary coil of the second transformer is connected with the fifth end of the main control chip through a sixteenth resistor, the fifth end of the main control chip is a demagnetization end, and the second end of the secondary coil of the second transformer is connected with the ground.
8. The LED driving circuit with protection function according to claim 7, wherein the first end of the primary coil of the second transformer is further connected to a drain of a first MOS transistor, a source of the first MOS transistor is connected to the second end of the primary coil of the second transformer through a second sampling resistor, a gate of the first MOS transistor is connected to the seventh end of the main control chip through a first resistor, and the seventh end of the main control chip is a gate driving end; the grid electrode of the first MOS tube is connected with the ground through a twenty-first resistor, an eighteenth resistor and a twelfth capacitor which are sequentially connected in series, the connection point of the twenty-first resistor and the eighteenth resistor is connected with the source electrode of the first MOS tube, the connection point of the eighteenth resistor and the twelfth capacitor is connected with the fourth end of the main control chip, and the fourth end of the main control chip is a sampling end.
9. The LED driving circuit with the protection function according to claim 8, wherein a cathode of the sixth diode is further connected to the second end of the rectifier bridge through a fifth resistor, a sixth resistor, a seventh resistor, and an eighth resistor connected in series in sequence, a sixteenth capacitor is further connected in parallel to two ends of the eighth resistor, a connection point of the seventh resistor and the eighth resistor is connected to the first end of the main control chip, and the first end of the main control chip is a feedback end.
10. The LED driving circuit with protection function of claim 9, wherein the first end of the rectifier bridge is a high voltage direct supply point, and is connected to ground through a second capacitor, and is connected to the negative electrode of the first diode through a thirteenth resistor, a fourteenth resistor and a fifteenth resistor connected in series in sequence; and a twenty-second resistor is connected in parallel between the emitter and the collector of the third triode, the emitter of the third triode is connected with the anode of a twelfth triode, the cathode of the twelfth triode is connected with the eighth end of the main control chip, and the eighth end of the main control chip is a power supply end and is connected with the ground through a fifth capacitor.
11. The LED driving circuit with protection function according to claim 10, wherein the first sampling resistor and/or the second sampling resistor is a resistor network with a plurality of resistors connected in parallel, and each parallel resistor branch is connected in series with a switch.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202111490940.XA CN114158159A (en) | 2021-12-08 | 2021-12-08 | LED drive circuit with protection function |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202111490940.XA CN114158159A (en) | 2021-12-08 | 2021-12-08 | LED drive circuit with protection function |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115190682A (en) * | 2022-09-07 | 2022-10-14 | 深圳利普芯微电子有限公司 | Overvoltage protection circuit and LED drive power supply |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115190682A (en) * | 2022-09-07 | 2022-10-14 | 深圳利普芯微电子有限公司 | Overvoltage protection circuit and LED drive power supply |
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