An LED lighting drive circuit for stepless dimming double-end input T-tube lamp

Abstract

The present invention discloses an LED lighting drive circuit for a stepless dimming double-end input T-tube lamp, which relates to the field of lighting drive circuits, including an input module, a rectifier and filter module, a main control PWM constant voltage module, a DC-DC constant current module, a dimming and anti-leakage module; wherein an AC signal is connected to a load through the input module, the rectifier and filter module, the main control PWM constant voltage module, and the DC-DC constant current module in sequence; a dimming signal is connected to the input end of the dimming and anti-leakage module, and the output end of the dimming and anti-leakage module is connected to the DC-DC constant current module, and the dimming and anti-leakage module limits the loop current of the dimming signal and the AC signal. On the basis of stepless dimming, the present invention adds flicker-free output and anti-leakage protection, as well as dimming signal interface misconnection to mains protection and whole lamp misconnection to electronic ballast protection, which greatly improves the safety performance of the product.

Description

Technical Field

[0001] The present invention relates to the field of lighting drive circuits, and more particularly to an LED lighting drive circuit for a stepless dimming double-end input T-tube lamp. Background Art

[0002] With the development of the smart lighting market, more and more dimmable T-tube lamps are used in various office and commercial places. The main dimming methods are thyristor dimming, wireless dimming, 0-10V dimming, and resistor dimming.

[0003] For 0-10V dimming and resistor dimming, the lamp has 4 pins, two of which are connected to the AC power at one end and two of which are connected to the dimming signal at the other end. There is a current path at both ends of the lamp, and there is a possibility that the dimming interface is mistakenly connected to the AC power and the lamp is mistakenly connected to the electronic ballast. Without special circuit processing, it will cause electric shock and burn out the lamp.

[0004] Existing 0-10V dimming and resistor dimming lamps cannot meet the requirements of leakage current testing, dimming terminal misconnection to mains protection, and misconnection to electronic ballast protection. In addition, most of them use a single-stage driving solution, which has a large flicker.

[0005] How to provide an LED driving circuit for stepless dimming T-tube lamp application that is free of flicker, prevents leakage, and prevents misconnection is an urgent problem to be solved by those skilled in the art. Summary of the invention

[0006] In view of this, the present invention provides an LED lighting drive circuit for a stepless dimming double-end input T-tube lamp. On the basis of stepless dimming, it adds flicker-free output and anti-leakage protection as well as protection against misconnection of the dimming signal interface to the mains and protection against misconnection of the entire lamp to the electronic ballast, thereby greatly improving the safety performance of the product.

[0007] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: an LED lighting driving circuit of a stepless dimming double-end input T-tube lamp, comprising an input module, a rectifier and filter module, a main control PWM constant voltage module, a DC-DC constant current module, a dimming and leakage prevention module; wherein, an AC signal is connected to the input end of the input module, the input module is connected to the rectifier and filter module, the rectifier and filter module outputs a constant voltage signal to the DC-DC constant current module through the main control PWM constant voltage module, the dimming and leakage prevention module is connected to both ends of the DC-DC constant current module, the dimming signal is connected to the input end of the dimming and leakage prevention module, and the DC-DC constant current module is connected to a load.

[0008] Preferably, the rectifier and filter module includes a rectifier bridge DB1, a varistor RV1, a capacitor C1, a capacitor C2, an inductor L1, and a resistor R1; the varistor RV1 and the capacitor C1 are connected in parallel between the L line and the N line, and are connected to the rectifier bridge DB1 through the resistor R1 and the inductor L1, and a temperature-controlled fuse F1 is connected in series between the L line and the rectifier bridge DB1.

[0009] Preferably, the main control PWM constant voltage module includes a switch chip U1 and its peripheral circuits; the rectifier bridge DB1 outputs a bus voltage, a capacitor C2 is connected in parallel between the bus voltage and the ground, the bus voltage is connected to the VIN pin of the switch chip U1 through resistors R2 and R3, the VIN pin of the switch chip U1 is connected to the cathode of the diode D2 and one end of the capacitor C5, the other end of the capacitor C5 is connected to the GND pin of the switch chip U1, the anode of the diode D2 is connected to one end of the resistor R6, the other end of the resistor R6 is connected to one end of the resistor R9 and the first end of the winding T1, the other end of the resistor R9 is connected to one end of the resistor R4, the other end of the resistor R4 is connected to one end of the resistor R5 and is connected to the ZCS pin of the switch chip U1, the other end of the resistor R5 is connected to the GND pin of the switch chip U1, and the COMP pin of the switch chip U1 is connected to the GND pin of the switch chip U1 through the resistor R8 and the capacitor C4. The ND pin of the switch chip U1 is connected to the ND pin, and the COMP pin of the switch chip U1 is connected to the GND pin of the switch chip U1 through the capacitor C3. The DRV pin of the switch chip U1 is connected to the gate of the switch tube Q1 through the series resistor R24, and is connected to the source of the switch tube Q1 and the CS pin of the switch chip U1 through the resistor R23. The CS pin of the switch chip U1 is connected to one end of the resistor RS1 and the resistor RS2, and the other ends of the resistor RS1 and the resistor RS2 are connected to the GND pin of the switch chip U1. The CS pin of the switch chip U1 is connected to the source of the switch tube Q1, and the GND pin of the switch chip U1 is connected to the second end of the winding T1. The bus voltage is connected to one end of the capacitor C10, and the other end of the capacitor C10 is connected to the third end of the winding T1. The third end of the winding T1 is simultaneously connected to one end of the capacitor C7, and is connected to one end of the resistor R14, one end of the capacitor C9, and the cathode of the voltage regulator ZD4.

[0010] By adopting the above technical solution, the following beneficial technical effects are achieved: the main control PWM constant current module realizes power factor correction and constant voltage loop control, and the input module and the rectifier filter module convert the AC input signal into a DC signal.

[0011] Preferably, the DC-DC constant current module includes a switch chip U2 and its peripheral circuit; the other end of the capacitor C9 is connected to the GND pin of the switch chip U2, the anode of the voltage regulator ZD4 is connected to one end of the resistor R12, the other end of the resistor R12 is connected to one end of the resistor R30 and the EN pin of the switch chip U2, the other end of the resistor R30 is connected to the GND pin of the switch chip U2, the cathode of the voltage regulator ZD4 is connected to the SEN pin of the switch chip U2 and the VIN pin of the switch chip U2, and is connected to the cathode of the freewheeling diode D5 and one end of the capacitor C12, and is connected to the One end of the resistor RS3, the resistor RS4, and the resistor RS5 are connected, and the resistor RS3, the resistor RS4, and the resistor RS5 are connected in parallel. The other ends of the resistor RS3, the resistor RS4, and the resistor RS5 are connected to the SENN pin of the switch chip U2 and to the positive electrode of the load. One end of the inductor L2 is connected to the other end of the capacitor C12, the negative electrode of the load, and one end of the capacitor C11. The other end of the inductor L2 is connected to the anode of the freewheeling diode D5 and to the SW pin of the switch chip U2. The other end of the capacitor C11 is connected to the GND pin of the switch chip U2.

[0012] By adopting the above technical solution, the following beneficial technical effects are achieved: the DC-DC constant current module mainly converts the constant voltage signal into a constant current signal without low-frequency ripple and outputs it to the load, realizing constant current output, flicker-free output and dimmable light output functions.

[0013] Preferably, the dimming and leakage prevention module includes a resistor R14, a resistor R15, a resistor R16, a resistor R17, a resistor R18, a resistor R29, a fuse F2, a fuse F3, a capacitor C13, a capacitor C14, a capacitor C15, a capacitor C16, a diode D6, a diode D9, a diode D10, a voltage regulator ZD2, a voltage regulator ZD3, and a MOS tube Q2; the other end of the resistor R14 is connected to the anodes of the diode D9 and the diode D10 through the resistor R15, the cathode of the diode D10 is connected to one end of the fuse F2 and one end of the capacitor C15, the other end of the fuse F2 receives a Dim+ input signal, the other end of the capacitor C15 is connected to one end of the fuse F3, the anode of the diode D6 and one end of the capacitor C16, the other end of the fuse F3 receives a Dim- signal, and the cathode of the diode D6 is connected to the leakage of the MOS tube Q2. The source of the MOS tube Q2 is connected to one end of the resistor R29, the other end of the resistor R29 is connected to the gate of the MOS tube Q2, and is connected to the GND pin of the switch chip U2. The cathode of the diode D9 is connected to one end of the resistor R16 and one end of the capacitor C13. The other end of the resistor R16 is connected to the cathode of the voltage regulator tube ZD2. The anode of the voltage regulator tube ZD2 is connected to the cathode of the voltage regulator tube ZD3 and one end of the resistor R17. The other end of the resistor R17 is connected to one end of the resistor R18 and one end of the capacitor C14, and is connected to the CF pin of the switch chip U2. The other end of the resistor R18 is connected to the GND pin of the switch chip U2. The other end of the capacitor C13 and the other end of the capacitor C14 are connected to the GND pin of the switch chip U2.

[0014] By adopting the above technical solution, the following beneficial technical effects are achieved: the dimming module realizes the function of converting the dimming signal into a dimming signal recognizable by the DC-DC constant current module, the anti-leakage module limits the current of the loop between the AC signal Vac and the dimming signal, and also limits the current of the dimming signal interface.

[0015] It can be seen from the above technical solutions that the present invention discloses a stepless dimming double-end input T-tube lamp LED lighting drive circuit, which has the following beneficial technical effects compared with the prior art:

[0016] 1) The present invention adopts stepless dimming driving technology to achieve flicker-free output;

[0017] 2) The present invention adopts stepless dimming driving technology, which can meet the leakage current test standard;

[0018] 3) The present invention adopts stepless dimming driving technology, which can support dimming signal interface anti-misconnection protection;

[0019] 4) The present invention adopts stepless dimming driving technology, which can support the protection of the entire lamp from being misconnected to the electronic ballast. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0021] Figure 1 The accompanying drawing is a schematic diagram of the structure of the LED lighting drive circuit of the present invention;

[0022] Figure 2 The accompanying drawing is a schematic diagram of the LED lighting drive circuit of the present invention. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] The embodiment of the present invention discloses an LED lighting drive circuit of a stepless dimming double-end input T-tube lamp, comprising an input module, a rectifier and filter module, a main control PWM constant voltage module, a DC-DC constant current module, a dimming and leakage prevention module.

[0025] The connection relationship between each module is as follows: Figure 1 As shown, the AC signal is connected to the input end of the input module, the input module is connected to the rectifier and filter module, the rectifier and filter module outputs the constant voltage signal to the DC-DC constant current module through the main control PWM constant voltage module, the dimming and leakage protection module is connected to both ends of the DC-DC constant current module, the dimming signal is connected to the input end of the dimming and leakage protection module, and the DC-DC constant current module is connected to the load.

[0026] The embodiment of the present invention proposes an LED lighting driving circuit for a stepless dimming double-end input T-tube lamp, and the specific circuit schematic diagram is as follows: Figure 2 shown.

[0027] The main working principle of the present invention is as follows: the input module and the rectifier and filter module convert the AC input signal into a DC signal, the main control PWM constant voltage module converts the DC signal after rectification and filtering into a constant voltage signal and provides it to the DC-DC constant current module and the dimming and leakage protection module, the DC-DC constant current module mainly converts the constant voltage signal into a constant current signal without low-frequency ripple and outputs it to the load, the dimming circuit in the dimming and leakage protection module mainly provides power supply current by resistors R14 and R15, so that a bias voltage greater than 10V is generated between Vdim+ and Vdim-, resistors R16, R17, R18, capacitor C14, voltage regulator tube ZD2, and voltage regulator tube ZD3 forms a voltage divider network, which mainly divides the voltage between Vdim+Vdim- in proportion to both ends of the voltage regulator ZD3. The voltage regulator ZD3 provides an upper clamping mechanism, and then further divides the voltage to both ends of the capacitor C14 through resistors R17 and R18. When the voltage of Vdim+Vdim- increases, the voltage regulator ZD3 and the capacitor C14 also increase. When the voltage of Vdim+Vdim- continues to increase, making the voltage divider ZD3 greater than the voltage regulator ZD3 voltage regulator value, the voltage regulator ZD3 and the capacitor C14 no longer change with Vdim+Vdim-, and the same is true when the voltage of Vdim+Vdim- decreases. The voltage across the capacitor C14 is directly provided to the DC-DC constant current module, and the DC-DC constant current module adjusts the output current by the voltage value of the capacitor C14, thereby realizing the dimming function. The anti-leakage circuit in the dimming and anti-leakage module is mainly composed of resistor R14, resistor R15, resistor R19, MOS tube Q2, diode D6, diode D9, and diode D10. Resistors R14 and R15 limit the current from the AC input signal to the Vdim+ loop, diode D6 blocks the AC signal to the Vdim- loop, MOS tube Q2 and resistor R19 limit the current from Vdim- to the AC signal loop, diode D10 blocks the Vdim+ to the AC signal loop, and diodes D9, D6, and D10 block the currents of Vdim- and Vdim+. The above settings constitute leakage current protection, protection against the dimming interface being misconnected to the AC power supply, and protection against the entire lamp being misconnected to the electronic ballast.

[0028] Specifically, the circuit structure of the embodiment of the present invention is described as follows:

[0029] The rectifier and filter module includes a rectifier bridge DB1, a varistor RV1, a capacitor C1, a capacitor C2, an inductor L1, and a resistor R1; the varistor RV1 and the capacitor C1 are connected in parallel between the L line and the N line, and are connected to the rectifier bridge DB1 through the resistor R1 and the inductor L1. A temperature-controlled fuse F1 is connected in series between the L line and the rectifier bridge DB1.

[0030] The main control PWM constant voltage module includes a switch chip U1 and its peripheral circuits; the rectifier bridge DB1 outputs a bus voltage, a capacitor C2 is connected in parallel between the bus voltage and the ground, the bus voltage is connected to the VIN pin of the switch chip U1 through resistors R2 and R3, the VIN pin of the switch chip U1 is connected to the cathode of the diode D2 and one end of the capacitor C5, the other end of the capacitor C5 is connected to the GND pin of the switch chip U1, the anode of the diode D2 is connected to one end of the resistor R6, the other end of the resistor R6 is connected to one end of the resistor R9 and the first end of the winding T1, the other end of the resistor R9 is connected to one end of the resistor R4, the other end of the resistor R4 is connected to one end of the resistor R5, and is connected to the ZCS pin of the switch chip U1, the other end of the resistor R5 is connected to the GND pin of the switch chip U1, and the COMP pin of the switch chip U1 is connected to the GND pin of the switch chip U1 through the resistor R8 and the capacitor C4. The COMP pin of the switch chip U1 is connected to the GND pin of the switch chip U1 through the capacitor C3, the DRV pin of the switch chip U1 is connected to the gate of the switch tube Q1 through the series resistor R24, and is connected to the source of the switch tube Q1 and the CS pin of the switch chip U1 through the resistor R23, the CS pin of the switch chip U1 is connected to one end of the resistor RS1 and the resistor RS2, the other ends of the resistor RS1 and the resistor RS2 are connected to the GND pin of the switch chip U1, the CS pin of the switch chip U1 is connected to the source of the switch tube Q1, the GND pin of the switch chip U1 is connected to the second end of the winding T1, the bus voltage is connected to one end of the capacitor C10, the other end of the capacitor C10 is connected to the third end of the winding T1, the third end of the winding T1 is simultaneously connected to one end of the capacitor C7, and is connected to one end of the resistor R14, one end of the capacitor C9, and the cathode of the voltage regulator ZD4.

[0031] The DC-DC constant current module includes a switch chip U2 and its peripheral circuits; the other end of the capacitor C9 is connected to the GND pin of the switch chip U2, the anode of the voltage regulator ZD4 is connected to one end of the resistor R12, the other end of the resistor R12 is connected to one end of the resistor R30 and the EN pin of the switch chip U2, the other end of the resistor R30 is connected to the GND pin of the switch chip U2, the cathode of the voltage regulator ZD4 is connected to the SEN pin of the switch chip U2, the VIN pin of the switch chip U2, and the cathode of the freewheeling diode D5 and one end of the capacitor C12, and at the same time connected to One end of the resistor RS3, the resistor RS4, and the resistor RS5 are connected, and the resistor RS3, the resistor RS4, and the resistor RS5 are connected in parallel. The other ends of the resistor RS3, the resistor RS4, and the resistor RS5 are connected to the SENN pin of the switch chip U2 and to the positive electrode of the load. One end of the inductor L2 is connected to the other end of the capacitor C12, the negative electrode of the load, and one end of the capacitor C11. The other end of the inductor L2 is connected to the anode of the freewheeling diode D5 and to the SW pin of the switch chip U2. The other end of the capacitor C11 is connected to the GND pin of the switch chip U2.

[0032] The dimming and leakage prevention module includes a resistor R14, a resistor R15, a resistor R16, a resistor R17, a resistor R18, a resistor R29, a fuse F2, a fuse F3, a capacitor C13, a capacitor C14, a capacitor C15, a capacitor C16, a diode D6, a diode D9, a diode D10, a voltage regulator ZD2, a voltage regulator ZD3, and a MOS tube Q2; the other end of the resistor R14 is connected to the anodes of the diode D9 and the diode D10 through the resistor R15, the cathode of the diode D10 is connected to one end of the fuse F2 and one end of the capacitor C15, the other end of the fuse F2 receives a Dim+ input signal, the other end of the capacitor C15 is connected to one end of the fuse F3, the anode of the diode D6 and one end of the capacitor C16, the other end of the fuse F3 receives a Dim- signal, and the cathode of the diode D6 is connected to the MO The drain of the S tube Q2 is connected, the other end of the capacitor C16 is connected to the gate of the MOS tube Q2, the source of the MOS tube Q2 is connected to one end of the resistor R29, the other end of the resistor R29 is connected to the gate of the MOS tube Q2, and is connected to the GND pin of the switch chip U2, the cathode of the diode D9 is connected to one end of the resistor R16 and one end of the capacitor C13, the other end of the resistor R16 is connected to the cathode of the voltage regulator tube ZD2, the anode of the voltage regulator tube ZD2 is connected to the cathode of the voltage regulator tube ZD3 and one end of the resistor R17, the other end of the resistor R17 is connected to one end of the resistor R18 and one end of the capacitor C14, and is connected to the CF pin of the switch chip U2, the other end of the resistor R18 is connected to the GND pin of the switch chip U2, the other end of the capacitor C13 and the other end of the capacitor C14 are connected to the GND pin of the switch chip U2.

[0033] The AC signal VAC is connected to the input end of the input module, and the input module is connected to the rectifier and filter module. The rectifier and filter module outputs the constant voltage signal to the DC-DC constant current module and the dimming and leakage protection module through the main control PWM constant voltage module. The dimming signal is transmitted to the DC-DC constant current module through the dimming and leakage protection module. The DC-DC constant current module converts the constant voltage signal into an adjustable current without low-frequency ripple through the control of the dimming signal and outputs it to the load. When the dimming signal changes, the output current also changes accordingly, realizing a stepless dimming system without flicker.

[0034] On the other hand, the AC signal VAC and the dimming signal form a loop through the dimming and anti-leakage module. In the embodiment of the present invention, the anti-leakage mechanism is placed at this node, which internally limits the current of the AC signal VAC and the dimming signal loop, and also limits the current of the dimming signal, so that the system meets the leakage current test standard. At the same time, it also protects the dimming signal interface from being mistakenly connected to the AC power and the whole lamp from being mistakenly connected to the electronic ballast.

[0035] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0036] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An LED lighting drive circuit for a stepless dimming double-end input T-tube lamp, characterized in that: It includes a rectifier and filter module, a main control PWM constant voltage module, a DC-DC constant current module, a dimming and leakage prevention module; wherein the AC signal is connected to the load through the rectifier and filter module, the main control PWM constant voltage module, and the DC-DC constant current module in sequence; the dimming signal is connected to the input end of the dimming and leakage prevention module, the output end of the dimming and leakage prevention module is connected to the DC-DC constant current module, and the dimming and leakage prevention module limits the loop current of the dimming signal and the AC signal; The rectifier and filter module includes a rectifier bridge DB1, a varistor RV1, a capacitor C1, a capacitor C2, an inductor L1, and a resistor R1; the varistor RV1 and the capacitor C1 are connected in parallel between the L line and the N line, and are connected to the rectifier bridge DB1 through the resistor R1 and the inductor L1, and a temperature-controlled fuse F1 is connected in series between the L line and the rectifier bridge DB1; The main control PWM constant voltage module includes a switch chip U1 and its peripheral circuits; the rectifier bridge DB1 outputs a bus voltage, a capacitor C2 is connected in parallel between the bus voltage and the ground, the bus voltage is connected to the VIN pin of the switch chip U1 through resistors R2 and R3, the VIN pin of the switch chip U1 is connected to the cathode of the diode D2 and one end of the capacitor C5, the other end of the capacitor C5 is connected to the GND pin of the switch chip U1, the anode of the diode D2 is connected to one end of the resistor R6, the other end of the resistor R6 is connected to one end of the resistor R9 and the first end of the winding T1, the other end of the resistor R9 is connected to one end of the resistor R4, the other end of the resistor R4 is connected to one end of the resistor R5 and is connected to the ZCS pin of the switch chip U1, the other end of the resistor R5 is connected to the GND pin of the switch chip U1, and the COMP pin of the switch chip U1 is connected to the GND pin of the switch chip U1 through the resistor R8 and the capacitor C4. pin is connected, and at the same time, the COMP pin of the switch chip U1 is connected to the GND pin of the switch chip U1 through the capacitor C3, the DRV pin of the switch chip U1 is connected to the gate of the switch tube Q1 through the series resistor R24, and is connected to the source of the switch tube Q1 and the CS pin of the switch chip U1 through the resistor R23, the CS pin of the switch chip U1 is connected to one end of the resistor RS1 and the resistor RS2, the other end of the resistor RS1 and the resistor RS2 is connected to the GND pin of the switch chip U1, the CS pin of the switch chip U1 is connected to the source of the switch tube Q1, the GND pin of the switch chip U1 is connected to the second end of the winding T1, the bus voltage is connected to one end of the capacitor C10, the other end of the capacitor C10 is connected to the third end of the winding T1, the third end of the winding T1 is simultaneously connected to one end of the capacitor C7, and is connected to one end of the resistor R14, one end of the capacitor C9, and the cathode of the voltage regulator ZD4; The DC-DC constant current module includes a switch chip U2 and its peripheral circuit; the other end of the capacitor C9 is connected to the GND pin of the switch chip U2, the anode of the voltage regulator ZD4 is connected to one end of the resistor R12, the other end of the resistor R12 is connected to one end of the resistor R30 and the EN pin of the switch chip U2, the other end of the resistor R30 is connected to the GND pin of the switch chip U2, the cathode of the voltage regulator ZD4 is connected to the SEN pin of the switch chip U2 and the VIN pin of the switch chip U2, and is connected to the cathode of the freewheeling diode D5 and one end of the capacitor C12, and is also connected to the resistor R S3, resistor RS4, and one end of resistor RS5 are connected, the resistors RS3, RS4, and RS5 are connected in parallel, the other ends of the resistors RS3, RS4, and RS5 are connected to the SENN pin of the switch chip U2, and to the positive electrode of the load, one end of the inductor L2 is connected to the other end of the capacitor C12, the negative electrode of the load, and one end of the capacitor C11, the other end of the inductor L2 is connected to the anode of the freewheeling diode D5, and to the SW pin of the switch chip U2, and the other end of the capacitor C11 is connected to the GND pin of the switch chip U2; The dimming and leakage prevention module includes a resistor R14, a resistor R15, a resistor R16, a resistor R17, a resistor R18, a resistor R29, a fuse F2, a fuse F3, a capacitor C13, a capacitor C14, a capacitor C15, a capacitor C16, a diode D6, a diode D9, a diode D10, a voltage regulator ZD2, a voltage regulator ZD3, and a MOS tube Q2; the other end of the resistor R14 is connected to the anodes of the diode D9 and the diode D10 through the resistor R15, the cathode of the diode D10 is connected to one end of the fuse F2 and one end of the capacitor C15, the other end of the fuse F2 receives a Dim+ input signal, the other end of the capacitor C15 is connected to one end of the fuse F3, the anode of the diode D6 and one end of the capacitor C16, the other end of the fuse F3 receives a Dim- signal, and the cathode of the diode D6 is connected to the drain of the MOS tube Q2. The other end of the capacitor C16 is connected to the gate of the MOS tube Q2, the source of the MOS tube Q2 is connected to one end of the resistor R29, the other end of the resistor R29 is connected to the gate of the MOS tube Q2, and is connected to the GND pin of the switch chip U2, the cathode of the diode D9 is connected to one end of the resistor R16 and one end of the capacitor C13, the other end of the resistor R16 is connected to the cathode of the voltage regulator tube ZD2, the anode of the voltage regulator tube ZD2 is connected to the cathode of the voltage regulator tube ZD3 and one end of the resistor R17, the other end of the resistor R17 is connected to one end of the resistor R18, one end of the capacitor C14, and is connected to the CF pin of the switch chip U2, the other end of the resistor R18 is connected to the GND pin of the switch chip U2, the other end of the capacitor C13 and the other end of the capacitor C14 are connected to the GND pin of the switch chip U2.

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