One-to-multipath Class2 circuit

Abstract

The invention discloses a one-to-multiple Class2 circuit, which comprises a power supply input end, a power supply circuit and at least two mutually independent output channels, and is characterized in that each output channel comprises a sampling circuit, an amplifying circuit, a comparison circuit, a signal control circuit, a switching circuit and a power supply output end; the power supply output end is electrically connected with the power supply input end and the switching circuit, and the input end of the sampling circuit is electrically connected with the power supply output end so as to sample a current signal of a load. The output end of the sampling circuit is electrically connected with the input end of the amplification circuit so as to amplify the sampled current signal to obtain an amplified signal, and the amplification circuit is electrically connected with the comparison circuit so as to compare the amplified signal with a reference signal to obtain a comparison signal. And the signal control circuit is electrically connected with the comparison circuit so as to control the on-off state of the switching circuit according to the comparison signal.

Description

Technical Field

[0001] The invention relates to the technical field of LED drive power supply, in particular to a one-to-multiple Class 2 circuit. Background Art

[0002] The power supply for LED lighting can be a power supply evaluated by standards such as UL1310 (Class 2 power unit), UL60950-1 (Power Supply), and UL1012 (non Class 2 power unit). Among them, Class 2 considers current and energy. If it is confirmed as a Class 2 circuit, some accessories connected to this circuit can be reduced, such as reducing the fireproof shell in the lamp, the insulation of the LED wiring, etc., thereby reducing the requirements for lamp design and reducing the cost of lamp design. For LED driver power supplies defined as Class 2 output certification, the following basic electrical performance must be met: the output voltage meets UL8750, and the output current and its power limits under normal or abnormal conditions must meet UL1310. The power energy output of existing high-power LED driver power supplies is greater than 100W and the current is greater than 5A, which poses a safety hazard in application. In order to improve safety and reliability, multiple power supplies less than 100W can be selected for application, or a power supply with multiple outputs and meeting Class 2 can be selected for application. The former uses more power supplies, which makes wiring more complicated and the cost also rises year-on-year; the latter’s power supply itself is very expensive and not universal, which is equivalent to professional customization and cannot meet the application requirements of LEDs. Summary of the invention

[0003] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art and to provide a low-cost one-to-multiple Class 2 circuit that can transform a conventional power supply that does not meet Class 2 into a Class 2-compliant one.

[0004] According to an embodiment of the present invention, a Class 2 circuit that converts one channel into multiple channels includes a power input terminal, a power supply circuit and at least two independent output channels, wherein the output channel includes a sampling circuit, an amplifying circuit, a comparing circuit, a delay circuit, a signal control circuit, a switching circuit and a power output terminal, wherein the power supply circuit is electrically connected to the power input terminal to convert an input voltage into a working voltage to respectively power the sampling circuit, the amplifying circuit, the comparing circuit, the signal control circuit and the switching circuit; the output power of each output channel is ≤100W and the current is ≤5A; the power output terminal is electrically connected to the power input terminal and the switching circuit respectively, the input terminal of the sampling circuit is electrically connected to the power output terminal to sample a current signal of a load, the output terminal of the sampling circuit is electrically connected to the input terminal of the amplifying circuit to amplify the sampled current signal to obtain an amplified signal, the amplifying circuit is electrically connected to the comparing circuit to compare the amplified signal with a reference signal to obtain a comparison signal, the comparison signal enters the signal control circuit after being delayed by the delay circuit, and the signal control circuit controls the on-off state of the switching circuit according to the comparison signal to achieve overload and short-circuit protection.

[0005] According to the one-to-multiple Class 2 circuit of the embodiment of the present invention, at least the following beneficial effects are achieved: the present invention divides a high-power conventional power supply into multiple independent output channels that meet Class 2 (output power of each channel ≤ 100W, current ≤ 5A), and the output power of each output channel can be independently set by changing the parameters of the sampling module, without interfering with each other, and a conventional power supply that does not meet Class 2 is turned into a multi-channel output power supply that meets Class 2, and a delay circuit is provided in each output channel, which is a delay buffer for overload protection, to avoid the phenomenon of immediate shutdown when overloaded, and then immediately turning on high-speed strobe, and protecting the circuit. For example, a 300W 24V power supply is turned into 4 independent output channels such as 1 100W, 1 30W, 1 80W, and 1 90W, and each output channel works independently. If 30W of them is overloaded, the 30W output channel will be overload protected according to the comparison signal, and the other 3 channels will work normally, which is equivalent to obtaining 4 or even more independent power supplies that meet Class 2 with overload or short circuit protection, which will make the application of LED more convenient. Even if this 300W conventional power supply does not have overload or short-circuit protection, the independent protection of each output channel can be met through such circuit transformation. This is equivalent to the 300W conventional power supply also having overload protection function, which improves the safety of the application and is more convenient and lower-cost in LED drive applications.

[0006] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings; Figure 1 This is the principle block diagram of a one-to-many Class2 circuit; Figure 2 This is the circuit schematic of a one-to-multiple Class2 circuit; Figure 3 This is the circuit schematic of the thyristor dimming module. DETAILED DESCRIPTION

[0008] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it cannot be understood as a limitation on the scope of protection of the present invention.

[0009] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0010] In the description of the present invention, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood as not including the number itself, and "above", "below", "within" etc. are understood as including the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0011] Reference Figures 1 to 3The present invention discloses a one-to-many Class 2 circuit, comprising a power input terminal, a power supply circuit 20 and at least two independent output channels 10, wherein the output channel 10 comprises a sampling circuit 11, an amplifying circuit 12, a comparing circuit 13, a delay circuit 14, a signal control circuit 15, a switching circuit 16 and a power output terminal, and the power supply circuit 20 is electrically connected to the power input terminal to convert the input voltage into a working voltage to respectively power the sampling circuit 11, the amplifying circuit 12, the comparing circuit 13, the signal control circuit 15 and the switching circuit 16; the output power of each output channel 10 is ≤100W and the current is ≤5A The power output end is electrically connected to the power input end and the switch circuit 16 respectively, the input end of the sampling circuit 11 is electrically connected to the power output end to sample the current signal of the load, the output end of the sampling circuit 11 is electrically connected to the input end of the amplifier circuit 12 to amplify the sampled current signal to obtain an amplified signal, the amplifier circuit 12 is electrically connected to the comparison circuit 13 to compare the amplified signal with the reference signal to obtain a comparison signal, the comparison signal enters the signal control circuit 15 after being delayed by the delay circuit 14, and the signal control circuit 15 controls the on-off state of the switch circuit 16 according to the comparison signal to achieve overload and short-circuit protection.

[0012] The present invention divides a high-power conventional power supply into multiple independent output channels 10 that meet Class2 (output power of each channel ≤100W, current ≤5A). The output power of each output channel 10 can be set independently by changing the parameters of the sampling module without interfering with each other. A conventional power supply that does not meet Class2 is turned into a multi-channel output power supply that meets Class2, and each output channel 10 is provided with a delay circuit 14, which is a delay buffer for overload protection to avoid the phenomenon of immediate shutdown when overloaded, and then immediately turning on high-speed strobe to protect the circuit. For example, a 300W 24V power supply is turned into 4 independent output channels 10 such as 100W, 1 30W, 1 80W, and 1 90W. Each output channel 10 works independently. If 30W of them is overloaded, the 30W output channel 10 will be overloaded according to the comparison signal, and the other 3 channels will work normally, which is equivalent to obtaining 4 or even more independent power supplies that meet Class2 with overload or short-circuit protection, which will make the application of LED more convenient. Even if this 300W conventional power supply does not have overload or short-circuit protection, the independent protection of each output channel 10 can be met after such circuit transformation. This is equivalent to the 300W conventional power supply also having an overload protection function, which improves the safety of the application, is more convenient in LED drive applications, and has lower costs.

[0013] like Figure 1As shown, in a specific application, four output channels 10 are included, and the power output ends of the four output channels 10 correspond to power output 1, power output 2, power output 3, and power output 4 respectively; Figure 2 As shown, the power output end of each output channel 10 includes a positive output end and a negative output end, the power input end includes a positive input end and a negative input end, the power input end can be a constant voltage or a constant current, the positive input end is electrically connected to the four positive output ends respectively, the four negative input ends are grounded, and the power supply circuit 20 can be a DC-DC topology structure, such as Figure 2 A linear LDO is used to output the working voltage VCC to power each circuit. The circuit structures of the four output channels 10 are the same, but the specific parameters in the circuits are different according to the power of each. Taking the specific circuit of one of the output channels 10 as an example: the switch circuit 16 includes a MOS tube Q1, a resistor R1 and a resistor R2. The D pole of the MOS tube Q1 is electrically connected to the negative output end, the G pole of the MOS tube Q1 is electrically connected to one end of the resistor R2, the other end of the resistor R2 is electrically connected to one end of the resistor R1 and the signal control circuit 15 respectively, the other end of the resistor R1 is electrically connected to the power supply circuit 20 to input the working voltage VCC, and the S pole of the MOS tube Q1 is electrically connected to the sampling circuit 11. The sampling circuit 11 includes a resistor R6, one end of the resistor R6 is electrically connected to the S pole of the MOS tube Q1 and the input end of the amplifier circuit 12 respectively, and the other end of the resistor R6 is grounded. The amplifier circuit 12 includes an operational amplifier U1, a resistor R8, a resistor R10 and a capacitor C4. The positive input terminal of the operational amplifier U1 is electrically connected to the sampling circuit 11R6, the negative input terminal of the operational amplifier U1 is electrically connected to one end of the resistor R8, one end of the resistor R10 and one end of the capacitor C4 respectively, the other end of the resistor R8 and the other end of the capacitor C4 are electrically connected to the output terminal of the operational amplifier U1 respectively, the output terminal of the operational amplifier U1 is electrically connected to the comparison circuit 13, and the other end of the resistor R10 is grounded. The comparison circuit 13 includes a comparator U2, a resistor R5, a capacitor C1 and a reference circuit 131. The output terminal of the amplifier circuit 12 is electrically connected to the positive input terminal of the comparator U2 and one end of the capacitor C1 respectively through the series resistor R5, the other end of the capacitor C1 is electrically connected to the output terminal of the comparator U2, the reference circuit 131 is electrically connected to the negative input and output terminal of the comparator U2, and the output terminal of the comparator U2 is electrically connected to the delay circuit 14.

[0014] The reference circuit 131 includes a resistor R9, a resistor R11 and a capacitor C5, one end of the resistor R9 is electrically connected to the power supply circuit 20 to input the working voltage VCC, the other end of the resistor R9 is electrically connected to one end of the resistor R11, one end of the capacitor C5 and the negative input end of the comparator U2, and the other end of the resistor R11 and the other end of the capacitor C5 are grounded. The signal control circuit 15 includes a MOS transistor Q2. Further, it also includes a delay circuit 14, which includes a diode D1, a resistor R7 and a capacitor C3. The anode of the diode D1 is electrically connected to the output end of the comparison circuit 13, the cathode of the diode D1 is electrically connected to one end of the resistor R7, one end of the capacitor C3 and the G pole of the MOS transistor Q2, the other end of the resistor R7, the other end of the capacitor C3 and the S pole of the MOS transistor Q2 are grounded, and the D pole of the MOS transistor Q2 is electrically connected to the switch circuit 16.

[0015] When the power output terminal is working normally, the MOS tube Q1 is turned on by power-on, and a voltage is generated on the resistor R6, which is the sampling signal (load current signal). The larger the value of the resistor R6, the smaller the corresponding load current and the output power. That is, by adjusting the value of the resistor R6, the output power of the output channel 10 can be adjusted to make the output power not greater than 100W and the output current not greater than 5A to meet Class 2. The sampling signal is sent to the operational amplifier U1 through the resistor R4 for signal amplification. The amplification factor is determined by the parameters of the operational amplifier U1, the resistor R8, the resistor R10 and the capacitor C4. The amplified signal is sent to the voltage comparator U2 through the resistor R5. The reference of U2 is determined by the resistor R9, the resistor R11 and the capacitor C5 in the reference circuit 131. When working normally, the amplified signal is less than the reference of U2, and the 7th pin of U2 outputs a low level. At this time, the MOS tube Q2 is turned off, and the working voltage VCC passes through the resistor R1 and the resistor R2 to drive the MOS tube Q1 to turn on normally, and the load works normally.

[0016] When the power output is overloaded, the sampling signal generated on the resistor R6 is sent to the operational amplifier U1 through the resistor R4, and then to the voltage comparator U2 through the resistor R5. At this time, the amplified signal is greater than the reference voltage, and the 7th pin of U2 outputs a high level. At this time, the high level charges the capacitor C3 through the diode D1. When the voltage of the capacitor C3 reaches the turn-on voltage of the MOS tube Q2, the MOS tube Q2 is turned on, which will lower the driving voltage of the MOS tube Q1, so that the MOS tube Q1 is turned off and the output is turned off, thereby protecting the LED. When the MOS tube Q1 is turned off, the sampling signal generated on the resistor R6 is zero, and after being amplified and sent to the voltage comparator, it is still zero. At this time, the comparator U2 outputs a low level, the diode D1 is in reverse cut-off, and the capacitor C3 and the resistor R7 form a discharge circuit. The discharge time is determined by the parameters of the capacitor C3 and the resistor R7. When the voltage of the capacitor C3 drops to the cut-off voltage of the MOS tube Q2, the MOS tube Q2 is turned off, and the MOS tube Q1 is turned on again, and the LED is re-lit. Similarly, if overload and overcurrent occur again, the above steps will be repeated. The time interval between the opening and closing of the LED will be determined by the capacitor C3 and the resistor R7. The flashing of the LED will indicate that it is in an overload state and needs to be checked and troubleshooted. The LED is always in the process of closing-lighting-overload-closing, which effectively protects the LED from overheating caused by overload, overheating damage to the driver, and a series of other problems. If the output end of the power supply is in a short-circuit state, Q1 will be turned off again at the moment Q1 is turned on, and it will be in an intermittent test conduction. The LED will not light up (the conduction time is too short and the brightness cannot be observed by the naked eye) until the short circuit is restored and the LED resumes lighting. While the above process is occurring, other channels may also be overloaded or short-circuited at the same time, with the same phenomenon as above. When the fault is eliminated and normal is restored, each channel will interfere with each other independently and complementary.

[0017] The present invention lowers the threshold for CLASS2 applications, combines ordinary power supplies with CLASS2 principles to achieve applications that meet CLASS2, effectively protects LEDs from overload applications, increases the service life of LEDs, reduces the risk of overheating due to overload, increases the application versatility of the driver, and makes production and replacement more convenient.

[0018] like Figure 3In some embodiments, a dimming circuit is also included, which includes a thyristor dimming module. The thyristor dimming module includes a thyristor dimmer, a thyristor freewheeling module 31, a thyristor sampling module 32, an isolation module 33 and a dimming control module 34. In actual applications, the power input end can be connected to the live wire and the neutral wire, the thyristor dimmer is electrically connected to the input end of the thyristor freewheeling module 31, the output end of the thyristor freewheeling module 31 is electrically connected to the input end of the thyristor sampling module 32, the output end of the thyristor sampling module 32 is electrically connected to one end of the isolation module 33, the other end of the isolation module 33 is electrically connected to the input end of the dimming control module 34, and the output end of the dimming control module 34 is electrically connected to the switch circuit to output a PWM signal; the dimming signal of the thyristor dimmer is transmitted to the thyristor sampling module 32 via the thyristor freewheeling module 31, and the thyristor sampling module 32 can convert the dimming signal into a square wave signal to control the dimming control module to output a PWM signal. The thyristor freewheeling module 31 includes a diode D2, a constant current IC U3, a resistor R50 and a MOS tube Q3. The anode of the diode D2 is electrically connected to the thyristor dimmer, the cathode of the diode D2 is electrically connected to one end of the constant current IC U3, the other end of the constant current IC U3 is electrically connected to the drain of the MOS tube Q3 via the series voltage-dividing resistor R50, the source of the MOS tube Q3 is grounded, and the gate of the MOS tube Q3 is electrically connected to the thyristor sampling module 32. The thyristor sampling module 32 includes a MOS tube Q4, a resistor R100, and a resistor R30. One end of the resistor R100 is electrically connected to the gate of the MOS tube Q4, the other end of the resistor R100 is electrically connected to the cathode of the diode D2, the source of the MOS tube Q4 is grounded, one end of the resistor R30 is connected to the VCC voltage, and the drain of the MOS tube Q4 is electrically connected to the other end of the resistor R30 and the isolation module 33. The isolation module 33 uses an optocoupler U4. The dimming control module 34 includes an integration circuit and a main control chip U5. The integration circuit includes a MOS tube Q5, a resistor R20, a resistor R40 and a capacitor C10. One output end of the isolation circuit is electrically connected to the drain of the MOS tube Q3 and one end of the resistor R20 respectively through the series resistor R40. The other end of the resistor R20 is electrically connected to one end of the capacitor C10 and the input end of the main control chip U5 respectively. The other end of the capacitor C10 and the source of the MOS tube Q5 are grounded respectively. The other output end of the isolation module 33 is electrically connected to the gate of the MOS tube Q5 through the series resistor.Among them, U3 is a linear constant current IC, and its constant current is slightly larger than the thyristor freewheeling value, generally greater than about 20mA. The current is determined by the constant current ICU3. ZD1 is a voltage regulator to protect the MOS driver. Generally, a 12V voltage regulator is used. Resistor R100 provides a bias voltage for the MOS tube to turn on. When the thyristor dimmer is turned on, MOS tube Q3 is turned on, and MOS tube Q4 is also turned on. At this time, the optocoupler U4 is cut off, and the emitter of the optocoupler U4 outputs a high level through the resistor R90 to control the MOS tube Q5 to turn on, and outputs a low level through the resistor R20. When the thyristor dimmer is not turned on, it is connected with the resistor The VIN node connected to one end of R100 has no voltage, MOS tube Q4 is cut off, optocoupler U4 is turned on, and the emitter of optocoupler U4 outputs a low level through resistor R90 to control the MOS tube Q5 to be cut off. At this time, the 5V voltage charges capacitor C10 through resistors R40 and R20 to form an integration circuit 0. By adjusting the parameters, a smooth voltage value can be obtained on capacitor C10, and the voltage value is controlled by the conduction angle of the thyristor. The main control chip U5 outputs a PWM signal from pin 3 to drive MOS tube Q1 according to the voltage value on capacitor C10, thereby realizing the brightness adjustment of the LED.

[0019] That is, by sampling the dimming signal of the thyristor dimmer, the thyristor freewheeling module maintains the thyristor conduction state, and then the thyristor sampling module obtains the conduction angle signal of the dimming signal, and then the signal isolation processing of the isolation module is sent to the dimming control module to control the output PWM. In this way, changing the conduction angle of the thyristor is equivalent to changing the brightness of the LED. Since the thyristor dimming part is not connected to the live wire, whether it is 100% load or 10% load, the power supply can input a complete AC signal through the neutral wire and the live wire, and is not affected by the thyristor dimming part. Its harmonics and PF values ​​are well controlled and can meet the EMC standards of the power supply. In any state of the thyristor dimming, the power can be output linearly without being limited by the thyristor conduction angle. During dimming, the dimming signal comes from the thyristor freewheeling module and the sampling module, and is not affected by the power size of the power supply. Regardless of the conduction angle of the thyristor dimmer, the dimming signal is stable, avoiding the difficulty of low-brightness flickering of traditional thyristor dimming. In addition, the dimming response speed is fast and the dimming can be linear, because in the entire dimming range, the power supply is in normal working condition, only the weight of the load changes.

[0020] In some embodiments, the dimming circuit includes at least one of a PWM dimming module, a DALI dimming module and a 0-10V dimming module, and is compatible with multiple dimming modes for easy application.

[0021] It is easy for those skilled in the art to understand that the above preferred embodiments can be freely combined and superimposed without conflict.

[0022] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or directly or indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A one-to-many Class 2 circuit, characterized in that: include: A power input terminal, a power supply circuit (20) and at least two mutually independent output channels (10), wherein the output channel (10) comprises a sampling circuit (11), an amplifying circuit (12), a comparing circuit (13), a delay circuit (14), a signal control circuit (15), a switch circuit (16) and a power output terminal, wherein the power supply circuit (20) is electrically connected to the power input terminal to convert an input voltage into an operating voltage to respectively supply power to the sampling circuit (11), the amplifying circuit (12), the comparing circuit (13), the signal control circuit (15) and the switch circuit (16); the output power of each output channel (10) is ≤100 W and the current is ≤5 A; the power output terminal is respectively connected to the sampling circuit (11), the amplifying circuit (12), the comparing circuit (13), the signal control circuit (15) and the switch circuit (16). The power input terminal is electrically connected to the switch circuit (16); the input terminal of the sampling circuit (11) is electrically connected to the power output terminal to sample the current signal of the load; the output terminal of the sampling circuit (11) is electrically connected to the input terminal of the amplifier circuit (12) to amplify the sampled current signal to obtain an amplified signal; the amplifier circuit (12) is electrically connected to the comparison circuit (13) to compare the amplified signal with a reference signal to obtain a comparison signal; the comparison signal enters the signal control circuit (15) after being delayed by the delay circuit (14); the signal control circuit (15) controls the on / off state of the switch circuit (16) according to the comparison signal to achieve overload and short circuit protection.

2. The one-to-many Class 2 circuit according to claim 1, characterized in that: The power supply output end comprises a positive output end and a negative output end, the power supply input end comprises a positive input end and a negative input end, the positive input end is electrically connected to the positive output end, the negative input end is grounded, the switch circuit (16) comprises a MOS tube Q1, a resistor R1 and a resistor R2, the D pole of the MOS tube Q1 is electrically connected to the negative output end, the G pole of the MOS tube Q1 is electrically connected to one end of the resistor R2, the other end of the resistor R2 is electrically connected to one end of the resistor R1 and the signal control circuit (15), the other end of the resistor R1 is electrically connected to the power supply circuit (20) to input the working voltage VCC, and the S pole of the MOS tube Q1 is electrically connected to the sampling circuit (11).

3. The one-to-many Class 2 circuit according to claim 2, characterized in that: The sampling circuit (11) comprises a resistor R6, one end of the resistor R6 is electrically connected to the S pole of the MOS tube Q1 and the input end of the amplifier circuit (12), and the other end of the resistor R6 is grounded.

4. The one-to-many Class 2 circuit according to claim 3, characterized in that: The amplifier circuit (12) comprises an operational amplifier U1, a resistor R8, a resistor R10 and a capacitor C4. The positive input terminal of the operational amplifier U1 is electrically connected to the sampling circuit (11) R6. The negative input terminal of the operational amplifier U1 is electrically connected to one end of the resistor R8, one end of the resistor R10 and one end of the capacitor C4 respectively. The other end of the resistor R8 and the other end of the capacitor C4 are electrically connected to the output terminal of the operational amplifier U1 respectively. The output terminal of the operational amplifier U1 is electrically connected to the comparison circuit (13). The other end of the resistor R10 is grounded.

5. The one-to-many Class 2 circuit according to claim 1, characterized in that: The comparison circuit (13) comprises a comparator U2, a resistor R5, a capacitor C1 and a reference circuit (131); the output end of the amplifier circuit (12) is electrically connected to the positive input end of the comparator U2 and one end of the capacitor C1 respectively via the series resistor R5; the other end of the capacitor C1 is electrically connected to the output end of the comparator U2; the reference circuit (131) is electrically connected to the negative input and output end of the comparator U2; and the output end of the comparator U2 is electrically connected to the delay circuit (14).

6. The one-to-many Class 2 circuit according to claim 5, characterized in that: The reference circuit (131) comprises a resistor R9, a resistor R11 and a capacitor C5, one end of the resistor R9 is electrically connected to the power supply circuit (20) to input a working voltage VCC, the other end of the resistor R9 is electrically connected to one end of the resistor R11, one end of the capacitor C5 and a negative input end of the comparator U2 respectively, and the other end of the resistor R11 and the other end of the capacitor C5 are grounded respectively.

7. The one-to-many Class 2 circuit according to claim 1, characterized in that: The signal control circuit (15) comprises a MOS tube Q2, and the delay circuit (14) comprises a diode D1, a resistor R7 and a capacitor C3, the anode of the diode D1 is electrically connected to the output end of the comparison circuit (13), the cathode of the diode D1 is electrically connected to one end of the resistor R7, one end of the capacitor C3 and the G pole of the MOS tube Q2 respectively, the other end of the resistor R7, the other end of the capacitor C3 and the S pole of the MOS tube Q2 are grounded respectively, and the D pole of the MOS tube Q2 is electrically connected to the switch circuit (16).

8. The one-to-many Class 2 circuit according to claim 1, characterized in that: The invention also comprises a dimming circuit electrically connected to the switch circuit, the dimming circuit comprising a thyristor dimming module, the thyristor dimming module comprising a thyristor dimmer, a thyristor freewheeling module (31), a thyristor sampling module (32), an isolation module (33) and a dimming control module (34), the power input terminal being connected to a live wire and a neutral wire, the thyristor dimmer being electrically connected to the input terminal of the thyristor freewheeling module (31), the output terminal of the thyristor freewheeling module (31) being electrically connected to the input terminal of the thyristor sampling module (32), and the thyristor sampling module (32) being electrically connected to the input terminal of the thyristor sampling module (32). The output end of the control module (32) is electrically connected to one end of the isolation module (33), the other end of the isolation module (33) is electrically connected to the input end of the dimming control module (34), and the output end of the dimming control module (34) is electrically connected to the switch circuit to output a PWM signal; the dimming signal of the thyristor dimmer is transmitted to the thyristor sampling module (32) via the thyristor freewheeling module (31), and the thyristor sampling module (32) is capable of converting the dimming signal into a square wave signal to control the dimming control module to output a PWM signal.

9. The one-to-many Class 2 circuit according to claim 8, characterized in that: The dimming circuit includes at least one of a PWM dimming module, a DALI dimming module and a 0-10V dimming module.

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