LED driving circuit

Abstract

The application provides an LED driving circuit, comprising: an input rectification module, configured to convert alternating current (AC) power into first direct current (DC); a power supply module, configured to convert the first DC into second DC with a lower voltage than the first DC for an LED load; and a power supply switching module, connected to the input rectification module and the power supply module, configured to supply power to the input rectification module and the power supply module; the power supply switching module has two working states, including a first working state and a second working state; in the first working state, the LED load is turned on, and the power supply switching module supplies power to the input rectification module and the power supply module simultaneously; in the second working state, the LED load is open-circuited, the power supply switching module stops supplying power to the input rectification module and supplies power to the power supply module only. The LED driving circuit provided by the application automatically switches to supply power to the power supply module only and not to the input rectification module when the LED load is open-circuited, thereby reducing standby power consumption in an idle state.

Description

Technical Field

[0001] This application relates to the field of circuit design technology, specifically to an LED driver circuit. Background Technology

[0002] With the improvement of living standards, LED lighting is increasingly used in many scenarios, and many LED driver solutions have emerged. Among them, the high power factor isolation two-stage solution is a commonly used circuit architecture. This circuit architecture is usually a two-stage isolation architecture, with the input rectification section achieving the high power factor function and the power output section achieving the step-down constant current isolation function. However, as society's requirements for energy conservation and environmental pollution control have gradually increased, especially in recent years, the European Union issued the Ecodesign Directive 2009 / 125 / EC (ErP Directive), which establishes a framework for ecodesign requirements of energy-related products. This directive clearly requires that the standby power consumption of LED drivers under no-load conditions be less than 0.5W. However, the current high power factor isolation two-stage solution has power supply circuits, magnetic components, power components, etc., in the input rectification section and the power output section under no-load conditions, resulting in high power consumption in no-load conditions. This not only wastes energy but also fails to meet the ErP requirement that the standby power consumption under no-load conditions be less than 0.5W. Summary of the Invention

[0003] The purpose of this application is to provide an LED driver circuit with low standby power consumption in no-load conditions.

[0004] To achieve the above objectives, this application provides an LED driver circuit, comprising:

[0005] An input rectifier module is used to convert AC mains power into a first DC power.

[0006] A power module, which is connected to the input rectifier module, is used to convert the first DC power into a second DC power with a voltage lower than the first DC power to supply the LED load.

[0007] A power supply switching module is connected to the input rectifier module and the power supply module, and is used to supply power to the input rectifier module and the power supply module;

[0008] The power supply switching module has two operating states: a first operating state and a second operating state. In the first operating state, the LED load is turned on, and the power supply switching module supplies power to both the input rectifier module and the power supply module simultaneously. In the second operating state, the LED load is open, and the power supply switching module stops supplying power to the input rectifier module and supplies power only to the power supply module.

[0009] In one embodiment, the power supply switching module includes a first transistor, a second transistor, a first diode, a Zener diode, a first electrolytic capacitor, a first resistor, a second resistor, a third resistor, a fourth resistor, and a first capacitor; the emitter of the first transistor is connected to the input rectifier module to provide a first operating voltage to the input rectifier module; the collector of the first transistor is connected to the power supply module to provide a second operating voltage to the power supply module; the collector of the first transistor is also connected to the second terminal of the first resistor, the second terminal of the second resistor, the cathode of the first diode, the first terminal of the third resistor, and the first terminal of the first electrolytic capacitor; the base of the first transistor is connected to the first terminal of the first resistor and the collector of the second transistor; the first terminal of the second resistor is connected to the input rectifier module and the power supply module; the anode of the first diode is connected to the power supply module; the second terminal of the third resistor is connected to the cathode of the Zener diode, and the anode of the Zener diode is connected to the base of the second transistor, the first terminal of the first capacitor, and the first terminal of the fourth resistor; the emitter of the second transistor, the second terminal of the first capacitor, the second terminal of the fourth resistor, and the second terminal of the first electrolytic capacitor are grounded.

[0010] In one embodiment, the input rectification module includes a first control chip, a first rectification unit, and a first boost unit, and further includes a second diode, a second electrolytic capacitor, a fifth resistor, a sixth resistor, an eighth resistor, a first MOSFET, a third capacitor, and a fourth capacitor; a first pin of the first control chip is connected to the second terminal of the fifth resistor and the first terminal of the sixth resistor, the first terminal of the fifth resistor is connected to the cathode of the second diode and the first terminal of the second electrolytic capacitor, the anode of the second diode is connected to the first boost unit and the drain of the first MOSFET, and the second terminal of the second electrolytic capacitor is grounded; a second pin of the first control chip is connected to the first terminal of the third capacitor, and the second terminal of the third capacitor is grounded; a fourth pin of the first control chip is connected to the first terminal of the eighth resistor and the source of the first MOSFET, and the second terminal of the eighth resistor is grounded; a fifth pin of the first control chip is connected to the first boost unit; a sixth pin of the first control chip is grounded; a seventh pin of the first control chip is connected to the gate of the first MOSFET; an eighth pin of the first control chip is connected to the second terminal of the fourth capacitor and the emitter of the first transistor of the power supply switching module, and the first terminal of the fourth capacitor is grounded.

[0011] In one embodiment, the first rectifier unit includes a rectifier bridge, a second capacitor, a first input terminal, and a second input terminal; the first input terminal is connected to the second terminal of the rectifier bridge, the second input terminal is connected to the third terminal of the rectifier bridge, the fourth terminal of the rectifier bridge is grounded, the first terminal of the rectifier bridge is connected to the first terminal of the second capacitor and the first boost unit, and the second terminal of the second capacitor is grounded.

[0012] In one embodiment, the first boost unit includes a second transformer and a seventh resistor. The first pin of the second transformer is connected to the positive terminal of the second diode and the drain of the first MOSFET. The fifth pin of the second transformer is connected to the first terminal of the second capacitor. The eighth pin of the second transformer is connected to the first terminal of the seventh resistor. The second terminal of the seventh resistor is connected to the fifth pin of the first control chip. The ninth pin of the second transformer is grounded.

[0013] In one embodiment, the power module includes a second control chip, a first buck unit, and a first output rectifier unit, and further includes a second MOSFET, a ninth resistor, a tenth resistor, and a twelfth resistor; a first pin of the second control chip is connected to the collector of the first transistor of the power supply switching module; a third pin of the second control chip is connected to the second terminal of the ninth resistor and the first terminal of the tenth resistor, the first terminal of the ninth resistor is connected to the anode of the first diode of the power supply switching module and the first buck unit, and the second terminal of the tenth resistor is grounded; a fifth pin of the second control chip is grounded; a sixth pin of the second control chip is connected to the first terminal of the twelfth resistor and the source of the second MOSFET, and the second terminal of the twelfth resistor is grounded; a seventh pin of the second control chip is connected to the gate of the second MOSFET.

[0014] In one embodiment, the first step-down unit includes a first transformer, a third diode, a fifth capacitor, and an eleventh resistor; the first terminal of the eleventh resistor is connected to the first terminal of the second resistor of the power supply switching module, the first terminal of the fifth capacitor, and the first pin of the first transformer; the second terminal of the eleventh resistor is connected to the second terminal of the fifth capacitor and the negative terminal of the third diode; the positive terminal of the third diode is connected to the third pin of the first transformer; the fifth pin of the first transformer is connected to the positive terminal of the first diode of the power supply switching module and the first terminal of the ninth resistor; the sixth pin of the first transformer is grounded; and the eighth and seventh pins of the first transformer are connected to the first output rectifier unit.

[0015] In one embodiment, the first output rectifier unit includes a fourth diode, a third electrolytic capacitor, a first output terminal, and a second output terminal; the anode of the fourth diode is connected to the seventh pin of the first transformer, and the cathode of the fourth diode is connected to the second terminal of the third electrolytic capacitor and the first output terminal; the first terminal of the third electrolytic capacitor is connected to the eighth pin of the first transformer and the second output terminal.

[0016] In one embodiment, the power module includes a second control chip, a first buck unit, and a first output rectifier unit, and further includes a sixth capacitor, a ninth resistor, a tenth resistor, and a twelfth resistor; a first pin of the second control chip is grounded; a second pin of the second control chip is connected to a first terminal of the sixth capacitor, and a second terminal of the sixth capacitor is grounded; a third pin of the second control chip is connected to a second terminal of the ninth resistor and a first terminal of the tenth resistor, the first terminal of the ninth resistor is connected to the power supply switching module and the first buck unit, and a second terminal of the tenth resistor is grounded; a fourth pin of the second control chip is connected to a first terminal of the twelfth resistor, and a second terminal of the twelfth resistor is grounded; a fifth pin and a sixth pin of the second control chip are connected to the first buck unit; and an eighth pin of the second control chip is connected to the power supply switching module.

[0017] In one embodiment, the input rectifier module includes a first control chip, a first rectifier unit, and a first boost unit, and further includes a second diode, a second electrolytic capacitor, a fifth resistor, a sixth resistor, an eighth resistor, a thirteenth resistor, a fourteenth resistor, a first MOSFET, a third capacitor, and a fourth capacitor; a first pin of the first control chip is connected to a first terminal of the third capacitor, a second terminal of the fifth resistor, and a first terminal of the sixth resistor; the first terminal of the fifth resistor is connected to the cathode of the second diode and a first terminal of the second electrolytic capacitor; the anode of the second diode is connected to the first boost unit and the drain of the first MOSFET; and the second terminal of the second electrolytic capacitor is grounded; a second pin of the first control chip is connected to the third capacitor. The second terminal of the first control chip; the third pin of the first control chip is connected to the second terminal of the thirteenth resistor and the first terminal of the fourteenth resistor, the first terminal of the thirteenth resistor is connected to the first rectifier unit and the first boost unit, and the second terminal of the fourteenth resistor is grounded; the fourth pin of the first control chip is connected to the first terminal of the eighth resistor and the source of the first MOSFET, and the second terminal of the eighth resistor is grounded; the fifth pin of the first control chip is connected to the first boost unit; the sixth pin of the first control chip is grounded; the seventh pin of the first control chip is connected to the gate of the first MOSFET; the eighth pin of the first control chip is connected to the second terminal of the fourth capacitor and the power supply switching module, and the first terminal of the fourth capacitor is grounded.

[0018] Beneficial Effects: This application provides an LED driver circuit, comprising: an input rectifier module for converting AC mains power into a first DC power; a power supply module connected to the input rectifier module for converting the first DC power into a second DC power with a voltage lower than the first DC power to supply the LED load; and a power supply switching module connected to the input rectifier module and the power supply module for supplying power to both the input rectifier module and the power supply module. The power supply switching module has two operating states: a first operating state and a second operating state. In the first operating state, the LED load is on, and the power supply switching module supplies power to both the input rectifier module and the power supply module simultaneously. In the second operating state, the LED load is open-circuited, and the power supply switching module stops supplying power to the input rectifier module and only supplies power to the power supply module. The LED driver circuit of this application, by automatically switching off power supply to the input rectifier module and supplying power only to the power supply module when the LED load is open-circuited, reduces standby power consumption under no-load conditions. Furthermore, it effectively saves energy and reduces energy loss without requiring manual operation, thus broadening its application scenarios and improving the user experience. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a structural block diagram of an LED driver circuit provided in this application;

[0021] Figure 2 This is a circuit diagram of an LED driving circuit provided in one embodiment of this application;

[0022] Figure 3 This is a circuit diagram of an LED driving circuit provided in another embodiment of this application;

[0023] Figure 4 This is a circuit diagram of an LED driving circuit provided in another embodiment of this application. Detailed Implementation

[0024] This application provides an LED driving circuit. To make the objectives, technical solutions, and effects of this application clearer and more explicit, the following detailed description is provided with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0025] In the implementation methods and scope of the claims, unless otherwise specified in the text, the terms "a," "an," "the," and "the" may also include plural forms. If the embodiments of this application involve descriptions of "first," "second," etc., such descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features.

[0026] It should be further understood that the term "comprising" as used in this application means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when we say an element is "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements. Furthermore, "connected" or "coupled" as used herein can include wireless connections or wireless coupling. The term "and / or" as used herein includes all or any unit and all combinations of one or more associated listed items.

[0027] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0028] Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0029] This application provides an LED driving circuit, which will be described in detail below. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments of this application. Furthermore, the descriptions of each embodiment have their own emphasis; parts not described in detail in a certain embodiment can be referred to in the relevant descriptions of other embodiments.

[0030] like Figure 1 As shown, the LED driving circuit provided in this application includes: an input rectifier module 100, a power supply module 200, and a power supply switching module 300. Specifically, the input rectifier module 100 is used to convert AC mains power into a first DC power; the power supply module 200 is connected to the input rectifier module 100 and is used to convert the first DC power into a second DC power with a voltage lower than the first DC power to supply the LED load; the power supply switching module 300 is connected to the input rectifier module 100 and the power supply module 200 and is used to supply power to the input rectifier module 100 and the power supply module 200. The power supply switching module 300 has two working states: a first working state and a second working state; in the first working state, the LED load is turned on, and the power supply switching module 300 simultaneously supplies power to the input rectifier module 100 and the power supply module 200; in the second working state, the LED load is open-circuited, and the power supply switching module 300 stops supplying power to the input rectifier module 100 and only supplies power to the power supply module 200. Specifically, in one embodiment, the input rectifier module 100 converts AC mains power into the first DC power, the voltage of which is 400V. Then, the power supply module 200 converts the first DC power into the second DC power to power the LED load, the voltage of which is 36V.

[0031] Please see Figure 2As shown, one embodiment of this application provides an LED driving circuit, wherein the input rectifier module 100 includes a first control chip U1, a first rectifier unit, and a first boost unit, and further includes a second diode D2, a second electrolytic capacitor EC2, a fifth resistor R5, a sixth resistor R6, an eighth resistor R8, a first MOSFET Q3, a third capacitor C3, and a fourth capacitor C4; the first pin FB of the first control chip U1 is connected to the second terminal of the fifth resistor R5 and the first terminal of the sixth resistor R6, the first terminal of the fifth resistor R5 is connected to the cathode of the second diode D2 and the first terminal of the second electrolytic capacitor EC2, the anode of the second diode D2 is connected to the first boost unit and the drain of the first MOSFET Q3, and the second terminal of the second electrolytic capacitor EC2 is grounded; The second pin COM of the first control chip U1 is connected to the first terminal of the third capacitor C3, and the second terminal of the third capacitor C3 is grounded; the third pin NC of the first control chip U1 is left floating; the fourth pin CS of the first control chip U1 is connected to the first terminal of the eighth resistor R8 and the source of the first MOSFET Q3, and the second terminal of the eighth resistor R8 is grounded; the fifth pin ZCD of the first control chip U1 is connected to the first boost unit; the sixth pin GND of the first control chip U1 is grounded; the seventh pin GATE of the first control chip U1 is connected to the gate of the first MOSFET Q3; the eighth pin VCC of the first control chip U1 is connected to the second terminal of the fourth capacitor C4 and the power supply switching module 300, and the first terminal of the fourth capacitor C4 is grounded. Specifically, the first control chip U1 is used to control the internal operation of the input rectifier module 100. In one embodiment, the first control chip U1 is a BP2628 chip manufactured by Shanghai Jingfeng Mingyuan Semiconductor Co., Ltd. The BP2628 chip is a PFC constant voltage control chip with extremely low harmonics, which can well realize the function of the input rectifier module 100. It should be noted that the above chip is not intended to limit this application, but is only an example. Any equivalent substitution of this application with a control chip with the same function is included within the protection scope of this application.

[0032] Furthermore, such as Figure 2As shown, the first rectifier unit includes a rectifier bridge DB1, a second capacitor C2, a first input terminal L, and a second input terminal N. The first input terminal L is connected to the second terminal of the rectifier bridge DB1, the second input terminal N is connected to the third terminal of the rectifier bridge DB1, the fourth terminal of the rectifier bridge DB1 is grounded, the first terminal of the rectifier bridge DB1 is connected to the first terminal of the second capacitor C2 and the first boost unit, and the second terminal of the second capacitor C2 is grounded. The function of the rectifier bridge DB1 is to convert AC power into the first DC power. The second capacitor C2 is connected in parallel with the output terminal of the rectifier bridge DB1, and the second capacitor C2 serves to prevent voltage surges and absorb overvoltages during peak conditions.

[0033] Furthermore, such as Figure 2 As shown, the first boost unit includes a second transformer T2 and a seventh resistor R7. The first pin of the second transformer T2 is connected to the positive terminal of the second diode D2 and the drain of the first MOSFET Q3; the fifth pin of the second transformer T2 is connected to the first terminal of the first capacitor C1; the eighth pin of the second transformer T2 is connected to the first terminal of the seventh resistor R7; the second terminal of the seventh resistor R7 is connected to the fifth pin ZCD of the first control chip U1; and the ninth pin of the second transformer T2 is grounded.

[0034] The power module 200 includes a second control chip U2, a first buck unit, and a first output rectifier unit, and also includes a second MOSFET Q4, a ninth resistor R9, a tenth resistor R10, and a twelfth resistor R12. The first pin VCC of the second control chip U2 is connected to the power switching module 300; the second pin CTRL of the second control chip U2 is left floating; the third pin FB of the second control chip U2 is connected to the second terminal of the ninth resistor R9 and the first terminal of the tenth resistor R10, the first terminal of the ninth resistor R9 is connected to the power switching module 300 and the first buck unit, and the second terminal of the tenth resistor R10 is grounded; the fifth pin GND of the second control chip U2 is grounded; the sixth pin CS of the second control chip U2 is connected to the first terminal of the twelfth resistor R12 and the source of the second MOSFET Q4, and the second terminal of the twelfth resistor R12 is grounded; the seventh pin GATE of the second control chip U2 is connected to the gate of the second MOSFET Q4; and the eighth pin PWM of the second control chip U2 is left floating. The power module 200 is used to convert the first DC power from the input rectifier module 100 into a second DC power with a voltage lower than the first DC power to supply the LED load.

[0035] Further, the first step-down unit includes a first transformer T1, a third diode D3, a fifth capacitor C5, and an eleventh resistor R11; the first end of the eleventh resistor R11 is connected to the power supply switching module 300, the first end of the fifth capacitor C5, and the first pin of the first transformer T1; the second end of the eleventh resistor R11 is connected to the second end of the fifth capacitor C5 and the negative terminal of the third diode D3; the positive terminal of the third diode D3 is connected to the third pin of the first transformer T1; the fifth pin of the first transformer T1 is connected to the power supply switching module 300 and the first end of the ninth resistor R9; the sixth pin of the first transformer T1 is grounded; the eighth and seventh pins of the first transformer T1 are connected to the first output rectifier unit.

[0036] Further, the first output rectifier unit includes a fourth diode D4, a third electrolytic capacitor EC3, a first output terminal LED+, and a second output terminal LED-. The positive terminal of the fourth diode D4 is connected to the seventh pin of the first transformer T1, and the negative terminal of the fourth diode D4 is connected to the second terminal of the third electrolytic capacitor EC3 and the first output terminal LED+. The first terminal of the third electrolytic capacitor EC3 is connected to the eighth pin of the first transformer T1 and the second output terminal LED-. The first and third pins of the first transformer T1 are the primary winding, the fifth and sixth pins are the auxiliary winding, and the eighth and seventh pins are the secondary winding.

[0037] The second control chip U2 is used to control the internal operation of the power module 200. In one embodiment, the second control chip U2 is a BP3179F chip manufactured by Shanghai Jingfeng Mingyuan Semiconductor Co., Ltd. After being stepped down and rectified by the first transformer T1 and the fourth diode D4, the power module 200 obtains a second DC current across the third electrolytic capacitor EC3 (i.e., the first output terminal LED+ and the second output terminal LED-), which supplies power to the LED load. In one embodiment, the voltage of the second DC current across the third electrolytic capacitor EC3 is 36V, but it can also be other voltages, which can be set according to the actual application. It should be noted that the above-described chip is not intended to limit this application, but is only an example. Any equivalent substitution of this application with a control chip of the same function is included within the protection scope of this application.

[0038] The power supply switching module includes a first transistor Q1, a second transistor Q2, a first diode D1, a Zener diode ZD1, a first electrolytic capacitor EC1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a first capacitor C1. The emitter of the first transistor Q1 is connected to the eighth pin VCC of the first control chip U1 of the input rectifier module 100, for providing a first operating voltage to the input rectifier module 100. The collector of the first transistor Q1 is connected to the first pin VCC of the second control chip U2 of the power module 200, for providing a second operating voltage to the power module 200. The collector of the first transistor Q1 is also connected to the second terminal of the first resistor R1, the second terminal of the second resistor R2, the cathode of the first diode D1, the first terminal of the third resistor R3, and the first terminal of the first electrolytic capacitor EC1. The base of transistor Q1 is connected to the first terminal of the first resistor R1 and the collector of the second transistor Q2; the first terminal of the second resistor R2 is connected to the cathode of the second diode D2 of the input rectifier module 100, the first terminal of the second electrolytic capacitor EC2, and the first pin of the first transformer T1 of the power supply module 200; the anode of the first diode D1 is connected to the first terminal of the ninth resistor R9 of the power supply module 200 and the fifth pin of the first transformer T1; the second terminal of the third resistor R3 is connected to the cathode of the Zener diode ZD1, and the anode of the Zener diode ZD1 is connected to the base of the second transistor Q2, the first terminal of the first capacitor C1, and the first terminal of the fourth resistor R4; the emitter of the second transistor Q2, the second terminal of the first capacitor C1, the second terminal of the fourth resistor R4, and the second terminal of the first electrolytic capacitor EC1 are grounded.

[0039] Specifically, the third resistor R3 is connected in series with the Zener diode ZD1. The third resistor R3 is the current-limiting resistor of the Zener diode ZD1 to prevent abnormal high voltage from damaging the Zener diode ZD1. The first capacitor C1 is the bypass capacitor of the second transistor Q2 to prevent high-frequency interference from causing abnormality in the second transistor Q2. The fourth resistor R4 is the pull-down resistor of the second transistor Q2 to prevent interference to the base of the second transistor Q2, which could lead to abnormal conduction.

[0040] In practical applications, the power supply switching module 300 has two operating states: a first operating state and a second operating state. In the first operating state, the LED load is on, and the power supply switching module 300 simultaneously supplies power to the input rectifier module 100 and the power supply module 200. In the second operating state, the LED load is open-circuited, and the power supply switching module 300 stops supplying power to the input rectifier module 100, supplying power only to the power supply module 200. The first operating state includes a startup state and a normal operating state, and the second operating state includes an output open-circuit state. Specifically, the startup state refers to the situation where, when AC mains power is first connected, the voltage of the control chips of the input rectifier module 100 and the power supply module 200 is lower than their respective operating voltage thresholds. Therefore, neither the input rectifier module 100 nor the power supply module 200 is working. At this time, the second electrolytic capacitor EC2 is being charged by the rectified AC power. Simultaneously, the second electrolytic capacitor EC2 charges the first electrolytic capacitor EC1 through the second resistor R2. The first electrolytic capacitor EC1 continuously provides base current to the first transistor Q1 through the first resistor R1, causing the first transistor Q1 to conduct and charge the fourth capacitor C4, thus providing the first operating voltage to the input rectifier module 100. When the first operating voltage reaches the operating voltage threshold of the first control chip U1, the first control chip U1 starts working, and the entire input rectifier module 100 starts working. The first control chip U1 then outputs a PWM square wave to drive the first MOSFET Q3. The first electrolytic capacitor EC1 provides a second operating voltage to the power module 200. When the second operating voltage reaches the operating voltage threshold of the second control chip U2, the second control chip U2 starts working, outputting a PWM square wave to drive the second MOSFET Q4, and the entire power module 200 begins normal operation. Since the operating voltage thresholds of the first control chip U1 and the second control chip U2 are different, the startup time is also different. Which of the first control chip U1 and the second control chip U2 starts first has no impact on the working logic of the drive circuit. At the same time, the third resistor R3 and the Zener diode ZD1 are connected to the first terminal of the first electrolytic capacitor EC1. At this time, the voltage across the first electrolytic capacitor EC1 is lower than the Zener voltage of the Zener diode ZD1, so no current flows through the Zener diode ZD1. That is, no current flows into the base of the second transistor Q2, and the base current is zero. Therefore, the second transistor Q2 does not work. In other words, the collector of the second transistor Q2 is continuously at a high potential, which can ensure that the first transistor Q1 continues to conduct.

[0041] Furthermore, the normal operating state of the LED driving circuit is as follows: after the startup state, the input rectifier module 100 operates normally, the first MOSFET Q3 is in the conducting state, causing the voltage on the second electrolytic capacitor EC2 to continuously rise. Simultaneously, the power supply module 200 operates normally, the second MOSFET Q4 is in the operating state, and the power supply module 200 converts the first DC power into the second DC power supplied to the two ends of the third electrolytic capacitor EC3. The fifth pin of the auxiliary winding of the first transformer T1 supplies power to the first electrolytic capacitor EC1 through the first diode D1. That is, unlike the startup state, the second electrolytic capacitor EC2 no longer supplies power to the first electrolytic capacitor EC1 through the second resistor R2; instead, the auxiliary winding of the first transformer T1 supplies power to the first electrolytic capacitor EC1 through the first diode D1. Furthermore, the auxiliary winding and output winding of the first transformer T1 have a turns ratio relationship. When the turns ratio of the two windings is N, the relationship between the voltage V_EC1 across the first electrolytic capacitor EC1 and the voltage V_EC3 across the third electrolytic capacitor EC3 is: V_EC1 = V_EC3 / N. At this time, the voltage across the first electrolytic capacitor EC1 is greater than the operating voltage of the second control chip U2, and the second control chip U2 is continuously powered and operates normally. The bias resistor of the first transistor Q1, i.e., the first resistor R1, is connected to the first terminal of the first electrolytic capacitor EC1, and current flows into the base of the first transistor Q1, so the first transistor Q1 is continuously turned on. The fourth capacitor C4 is continuously powered by the first electrolytic capacitor EC1, and the voltage at the terminal of the fourth capacitor C4 is always higher than the operating voltage of the first control chip U1, so the first control chip U1 continues to operate normally. Furthermore, the voltage across the first electrolytic capacitor EC1 is always lower than the voltage regulation voltage of the Zener diode ZD1. Therefore, the Zener diode ZD1 is not conducting. In other words, no current flows into the base of the second transistor Q2, i.e., the base current is zero. Consequently, the collector and emitter of the second transistor Q2 are not conducting, keeping the collector of the second transistor Q2 at a high potential. This does not affect the normal operation of the first transistor Q1, thus ensuring the continuous normal operation of the first control chip U1.

[0042] Furthermore, the open-circuit state of the LED driver circuit means that when the output LED load is not connected, that is, when the output terminal is in an unloaded state, the power module 200 continues to work, and the energy consumption without load causes the output voltage to rise continuously. When the output voltage rises, according to the relationship between the voltage V_EC1 across the first electrolytic capacitor EC1 and the voltage V_EC3 across the third electrolytic capacitor EC3: V_EC1=V_EC3 / N, it can be seen that the increase in output voltage causes the voltage across the first electrolytic capacitor EC1 to rise. When the voltage across the first electrolytic capacitor EC1 rises to the Zener voltage of the Zener diode ZD1, current flows from the Zener diode ZD1 to the base of the second transistor Q2, resulting in a base current greater than zero in the second transistor Q2. This causes the collector and emitter of the second transistor Q2 to conduct, pulling the collector of the second transistor Q2 low. Consequently, the base voltage of the first transistor Q1 is pulled low, and the first transistor Q1 disconnects, no longer providing the first operating voltage to the input rectifier module 100. As a result, the voltage received by the eighth pin VCC of the first control chip U1 drops below the operating voltage threshold of the first control chip U1, and the input rectifier module 100 stops working, reducing energy loss under no-load conditions. Simultaneously, since the first transistor Q1 is disconnected, the input rectifier module 100 stops working, causing the first boost unit to also stop working. This reduces the voltage of the second electrolytic capacitor EC2, thus lowering the voltage supplied by EC2 to the second resistor R2, and consequently reducing the power consumption of R2, further minimizing energy loss. Furthermore, since the input rectifier module 100 is not working, its power consumption is zero. Therefore, the standby power consumption of the entire power supply is only that of the power module 200, thereby reducing standby power consumption under no-load conditions. In one embodiment, the second control chip U2 may also be provided with an open-circuit protection point. This open-circuit protection point is 60V and can be set by dividing the voltage between the ninth resistor R9 and the tenth resistor R10 and then connecting it to the FB pin of the second control chip U2.

[0043] In another embodiment of this application, such as Figure 3As shown, the second control chip U2 can be a BP3337D from Shanghai Jingfeng Mingyuan Semiconductor Co., Ltd., which is a solution with a built-in MOS transistor. In this embodiment, the power module 200 includes a second control chip U2, a first step-down unit, and a first output rectifier unit, and further includes a sixth capacitor C6, a ninth resistor R9, a tenth resistor R10, and a twelfth resistor R12; the first pin GND of the second control chip U2 is grounded; the second pin COM of the second control chip U2 is connected to the first terminal of the sixth capacitor C6, and the second terminal of the sixth capacitor C6 is grounded; the third pin FB of the second control chip U2 is connected to the second terminal of the ninth resistor R9 and the first terminal of the tenth resistor R10, the first terminal of the ninth resistor R9 is connected to the power supply switching module 300 and the first step-down unit, and the second terminal of the tenth resistor R10 is grounded; the fourth pin CS of the second control chip U2 is connected to the first terminal of the twelfth resistor R12, and the second terminal of the twelfth resistor R12 is grounded; the fifth pin D and the sixth pin D of the second control chip U2 are connected to the first step-down unit; the eighth pin VCC of the second control chip is connected to the power supply switching module 300. In this embodiment, the structure of the input rectifier module 100 and the power supply switching module 300 is similar to... Figure 2 The implementation method shown is the same.

[0044] In another embodiment of this application, such as Figure 4 As shown, in Figure 3Based on the illustrated embodiment, the model of the first control chip U1 can be replaced with STMicroelectronics' L6562. In one embodiment, the input rectifier module 100 includes a first control chip U1, a first rectifier unit, and a first boost unit, and further includes a second diode D2, a second electrolytic capacitor EC2, a fifth resistor R5, a sixth resistor R6, an eighth resistor R8, a thirteenth resistor R13, a fourteenth resistor R14, a first MOSFET Q3, a third capacitor C3, and a fourth capacitor C4; the first pin INV of the first control chip U1 is connected to the first terminal of the third capacitor C3, the second terminal of the fifth resistor R5, and the first terminal of the sixth resistor R6; the first terminal of the fifth resistor R5 is connected to the cathode of the second diode D2 and the first terminal of the second electrolytic capacitor EC2; the anode of the second diode D2 is connected to the first boost unit and the drain of the first MOSFET Q3; the second terminal of the second electrolytic capacitor EC2 is grounded; the second pin COM of the first control chip U1 is connected to the third capacitor C3. The second terminal; the third pin MULT of the first control chip U1 is connected to the second terminal of the thirteenth resistor R13 and the first terminal of the fourteenth resistor R14. The first terminal of the thirteenth resistor R13 is connected to the first rectifier unit and the first boost unit, and the second terminal of the fourteenth resistor R14 is grounded; the fourth pin CS of the first control chip U1 is connected to the first terminal of the eighth resistor R8 and the source of the first MOSFET Q3, and the second terminal of the eighth resistor R8 is grounded; the fifth pin ZCD of the first control chip U1 is connected to the first boost unit; the sixth pin GND of the first control chip U1 is grounded; the seventh pin GATE of the first control chip U1 is connected to the gate of the first MOSFET Q3; the eighth pin VCC of the first control chip U1 is connected to the second terminal of the fourth capacitor C4 and the power supply switching module 300, and the first terminal of the fourth capacitor C4 is grounded. In this embodiment, the structure of the power supply module 200 and the power supply switching module 300 is similar to that of the first control chip U1. Figure 3 The implementation method shown is the same.

[0045] It should be noted that the above-mentioned chip is not intended to limit this application, but is only an example. Any equivalent replacement of this application with a control chip of the same function is included within the protection scope of this application.

[0046] In summary, this application provides an LED driver circuit, comprising: an input rectifier module for converting AC mains power into a first DC power; a power supply module connected to the input rectifier module for converting the first DC power into a second DC power with a voltage lower than the first DC power to supply the LED load; and a power supply switching module connected to the input rectifier module and the power supply module for supplying power to both the input rectifier module and the power supply module. The power supply switching module has two operating states: a first operating state and a second operating state. In the first operating state, the LED load is turned on, and the power supply switching module supplies power to both the input rectifier module and the power supply module simultaneously. In the second operating state, the LED load is open-circuited, and the power supply switching module stops supplying power to the input rectifier module and only supplies power to the power supply module. The LED driver circuit of this application, by automatically switching off power supply to the input rectifier module and supplying power only to the power supply module when the LED load is open-circuited, reduces standby power consumption under no-load conditions. Moreover, it can effectively save energy and reduce energy loss without the need for manual operation, making it more widely applicable and improving the user experience.

[0047] The above provides a detailed description of the chip power supply circuit, drive control chip, and power supply circuit provided in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An LED driving circuit, characterized in that, include: An input rectifier module is used to convert AC mains power into a first DC power. A power module, which is connected to the input rectifier module, is used to convert the first DC power into a second DC power with a voltage lower than the first DC power to supply the LED load. A power supply switching module is connected to the input rectifier module and the power supply module, and is used to supply power to the input rectifier module and the power supply module; The power supply switching module has two working states: a first working state and a second working state. In the first working state, the LED load is turned on, and the power supply switching module supplies power to both the input rectifier module and the power module simultaneously. In the second working state, the LED load is open, and the power supply switching module stops supplying power to the input rectifier module and supplies power only to the power module. The power supply switching module includes a first transistor, a second transistor, a first diode, a Zener diode, a first electrolytic capacitor, a first resistor, a second resistor, a third resistor, a fourth resistor, and a first capacitor. The emitter of the first transistor is connected to the eighth pin of the first control chip of the input rectifier module and the second terminal of the fourth capacitor to provide a first operating voltage to the input rectifier module. The collector of the first transistor is connected to the power supply module to provide a second operating voltage to the power supply module. The collector of the first transistor is also connected to the second terminal of the first resistor, the second terminal of the second resistor, the cathode of the first diode, the first terminal of the third resistor, and the first terminal of the first electrolytic capacitor. The base of the first transistor is connected to the... The first terminal of the first resistor is connected to the collector of the second transistor; the first terminal of the second resistor is connected to the cathode of the second diode of the input rectifier module, the first terminal of the second electrolytic capacitor, the first terminal of the eleventh resistor of the power supply module, the first terminal of the fifth capacitor, and the first pin of the first transformer; the anode of the first diode is connected to the fifth pin of the first transformer of the power supply module and the first terminal of the ninth resistor; the second terminal of the third resistor is connected to the cathode of the Zener diode, and the anode of the Zener diode is connected to the base of the second transistor, the first terminal of the first capacitor, and the first terminal of the fourth resistor; the emitter of the second transistor, the second terminal of the first capacitor, the second terminal of the fourth resistor, and the second terminal of the first electrolytic capacitor are grounded.

2. The LED driving circuit according to claim 1, characterized in that, The input rectifier module includes a first rectifier unit and a first boost unit, and further includes a second diode, a second electrolytic capacitor, a fifth resistor, a sixth resistor, an eighth resistor, a first MOSFET, a third capacitor, and a fourth capacitor. A first pin of the first control chip is connected to the second terminal of the fifth resistor and the first terminal of the sixth resistor. The first terminal of the fifth resistor is connected to the cathode of the second diode and the first terminal of the second electrolytic capacitor. The anode of the second diode is connected to the first boost unit and the drain of the first MOSFET. The second terminal of the second electrolytic capacitor is grounded. A second pin of the first control chip is connected to the first terminal of the third capacitor, and the second terminal of the third capacitor is grounded. A fourth pin of the first control chip is connected to the first terminal of the eighth resistor and the source of the first MOSFET. The second terminal of the eighth resistor is grounded. A fifth pin of the first control chip is connected to the first boost unit. A sixth pin of the first control chip is grounded. A seventh pin of the first control chip is connected to the gate of the first MOSFET. An eighth pin of the first control chip is also connected to the second terminal of the fourth capacitor, and the first terminal of the fourth capacitor is grounded.

3. The LED driving circuit according to claim 2, characterized in that, The first rectifier unit includes a rectifier bridge, a second capacitor, a first input terminal, and a second input terminal; the first input terminal is connected to the second terminal of the rectifier bridge, the second input terminal is connected to the third terminal of the rectifier bridge, the fourth terminal of the rectifier bridge is grounded, the first terminal of the rectifier bridge is connected to the first terminal of the second capacitor and the first boost unit, and the second terminal of the second capacitor is grounded.

4. The LED driving circuit according to claim 3, characterized in that, The first boost unit includes a second transformer and a seventh resistor. The first pin of the second transformer is connected to the positive terminal of the second diode and the drain of the first MOSFET. The fifth pin of the second transformer is connected to the first terminal of the second capacitor. The eighth pin of the second transformer is connected to the first terminal of the seventh resistor. The second terminal of the seventh resistor is connected to the fifth pin of the first control chip. The ninth pin of the second transformer is grounded.

5. The LED driving circuit according to claim 4, characterized in that, The power module includes a second control chip, a first buck unit, and a first output rectifier unit, and also includes a second MOSFET, a ninth resistor, a tenth resistor, and a twelfth resistor. The first pin of the second control chip is connected to the collector of the first transistor in the power supply switching module. The third pin of the second control chip is connected to the second terminal of the ninth resistor and the first terminal of the tenth resistor. The first terminal of the ninth resistor is also connected to the first buck unit, and the second terminal of the tenth resistor is grounded. The fifth pin of the second control chip is grounded. The sixth pin of the second control chip is connected to the first terminal of the twelfth resistor and the source of the second MOSFET, and the second terminal of the twelfth resistor is grounded. The seventh pin of the second control chip is connected to the gate of the second MOSFET.

6. The LED driving circuit according to claim 5, characterized in that, The first step-down unit includes a first transformer, a third diode, a fifth capacitor, and an eleventh resistor; the first end of the eleventh resistor is also connected to the first end of the fifth capacitor and the first pin of the first transformer; the second end of the eleventh resistor is connected to the second end of the fifth capacitor and the negative terminal of the third diode; the positive terminal of the third diode is connected to the third pin of the first transformer; the fifth pin of the first transformer is also connected to the first end of the ninth resistor; the sixth pin of the first transformer is grounded; the eighth and seventh pins of the first transformer are connected to the first output rectifier unit.

7. The LED driving circuit according to claim 6, characterized in that, The first output rectifier unit includes a fourth diode, a third electrolytic capacitor, a first output terminal, and a second output terminal; the positive terminal of the fourth diode is connected to the seventh pin of the first transformer, and the negative terminal of the fourth diode is connected to the second terminal of the third electrolytic capacitor and the first output terminal; the first terminal of the third electrolytic capacitor is connected to the eighth pin of the first transformer and the second output terminal.

8. The LED driving circuit according to claim 1, characterized in that, The power module includes a second control chip, a first buck unit, and a first output rectifier unit, and also includes a sixth capacitor, a ninth resistor, a tenth resistor, and a twelfth resistor. The first pin of the second control chip is grounded. The second pin of the second control chip is connected to the first terminal of the sixth capacitor, and the second terminal of the sixth capacitor is grounded. The third pin of the second control chip is connected to the second terminal of the ninth resistor and the first terminal of the tenth resistor. The first terminal of the ninth resistor is connected to the power supply switching module and the first buck unit, and the second terminal of the tenth resistor is grounded. The fourth pin of the second control chip is connected to the first terminal of the twelfth resistor, and the second terminal of the twelfth resistor is grounded. The fifth and sixth pins of the second control chip are connected to the first buck unit. The eighth pin of the second control chip is connected to the power supply switching module.

9. The LED driving circuit according to claim 8, characterized in that, The input rectification module includes a first control chip, a first rectification unit, and a first boost unit, and also includes a second diode, a second electrolytic capacitor, a fifth resistor, a sixth resistor, an eighth resistor, a thirteenth resistor, a fourteenth resistor, a first MOSFET, a third capacitor, and a fourth capacitor; the first pin of the first control chip is connected to the first terminal of the third capacitor, the second terminal of the fifth resistor, and the first terminal of the sixth resistor; the first terminal of the fifth resistor is connected to the cathode of the second diode and the first terminal of the second electrolytic capacitor; the anode of the second diode is connected to the drain of the first boost unit and the first MOSFET; the second terminal of the second electrolytic capacitor is grounded; the second pin of the first control chip is connected to the second terminal of the third capacitor. The third pin of the first control chip is connected to the second terminal of the thirteenth resistor and the first terminal of the fourteenth resistor. The first terminal of the thirteenth resistor is connected to the first rectifier unit and the first boost unit. The second terminal of the fourteenth resistor is grounded. The fourth pin of the first control chip is connected to the first terminal of the eighth resistor and the source of the first MOSFET. The second terminal of the eighth resistor is grounded. The fifth pin of the first control chip is connected to the first boost unit. The sixth pin of the first control chip is grounded. The seventh pin of the first control chip is connected to the gate of the first MOSFET. The eighth pin of the first control chip is connected to the second terminal of the fourth capacitor and the power supply switching module. The first terminal of the fourth capacitor is grounded.

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