LED lamp driving circuit and LED lamp

Abstract

The invention provides an LED lamp driving circuit and an LED lamp, and the LED lamp driving circuit comprises a voltage stabilizing circuit which is used for converting commercial power into stable DC voltage and supplying power to the LED lamp driving circuit, a square wave generating circuit which comprises a rectifier bridge and an optocoupler, a PWM pulse width adjusting circuit which is used for generating pulse signals at a photosensitive semiconductor side of the optocoupler, and a power supply circuit which is used for supplying power to the LED lamp driving circuit, comprising a single-chip microcomputer controller, a photosensitive semiconductor is connected to a power-off detection terminal of the single-chip microcomputer controller, when it is detected that an LED lamp is powered on, the pulse width of an output PMM signal is gradually increased, when it is detected that the LED lamp is powered off, the pulse width of the output PMM signal is gradually reduced, the pulse width type driving circuit comprises a pulse width type LED driving chip, the input end of the pulse width type LED driving chip is connected with a PWM signal, and the output end of the pulse width type LED driving chip is connected with a power-off detection terminal of the single-chip microcomputer controller. The circuit is used for providing current with variable amplitude for the LED lamp, so that slow starting and slow extinguishing of the LED lamp are realized, the circuit safety is protected, and the LED lamp is prevented from flickering.

Description

Technical Field

[0001] The present invention relates to the technical field of LEDs, and in particular to an LED lamp driving circuit and an LED lamp. Background Art

[0002] There are three common existing LED lamp power drive solutions. The first is an AC-to-DC circuit plus a single-chip microcomputer or a DC-to-DC circuit. The second is an AC-to-DC circuit plus a destrober chip and an op amp conversion dimming circuit. The third is an AC-to-DC circuit plus an op amp conversion dimming circuit, in which a single-chip microcomputer is used for control.

[0003] The above methods all light up the LED lights directly after power-on, which causes all lights to light up immediately or light up very quickly. This sudden lighting effect will affect vision and may hurt the eyes. At the same time, there will be a surge current when powering on, and the power supply is unstable at this time. If the lights are lit directly after powering on, the lights may flicker, and in severe cases, some components may even be burned out. In addition, when turning off the LED lights, the LED driver is turned off instantly. Because the electrolytic capacitor inside the LED driver power supply cannot discharge the remaining power in a short time, it causes the LED lights to flash back and other phenomena. Summary of the invention

[0004] The present invention provides an LED lamp driving circuit and an LED lamp, which can realize the slow start and slow stop of the LED lamp, protect the circuit safety, and prevent the LED lamp from flickering.

[0005] In one aspect, the present invention provides an LED lamp driving circuit, comprising:

[0006] A voltage stabilizing circuit, used for converting the mains electricity into a stable direct current voltage to supply power to the LED lamp driving circuit;

[0007] A square wave generating circuit includes a rectifier bridge and an optical coupler, wherein the input end of the rectifier bridge is connected to the mains, and the output end is connected to the light-emitting diode of the optical coupler through a resistor. The mains is rectified by the rectifier bridge to obtain a fluctuating DC voltage, and the fluctuating DC voltage causes the light emission of the photosensitive diode to fluctuate, thereby generating a pulse signal on the photosensitive semiconductor side of the optical coupler;

[0008] A PWM pulse width modulation circuit, comprising a single-chip controller, wherein the photosensitive semiconductor is connected to a power-off detection terminal of the single-chip controller, and the single-chip controller is used to perform PWM modulation on the received pulse signal to obtain a PWM signal with a pulse width variation, wherein when it is detected that the LED lamp is powered on, the pulse width of the PMM signal is gradually increased, and when it is detected that the LED lamp is powered off, the pulse width of the PMM signal is gradually reduced;

[0009] A pulse width driving circuit comprises a pulse width LED driving chip, the input end of the pulse width LED driving chip is connected to the PWM signal, and the output end is connected to the LED lamp, so as to provide the LED lamp with a current with varying amplitude, thereby realizing slow start and slow stop of the LED lamp.

[0010] In one of the embodiments, a time dial is also included, including a plurality of selection switches, each selection switch is respectively connected to an input terminal of the single-chip controller, and different input codes are formed by turning the dial. Different codes correspond to the output of PWM signals with different time periods, which are used to adjust the delay time of the slow start and slow off of the LED lamp.

[0011] In one of the embodiments, a current dialer is also included, including a plurality of selection switches, each selection switch is connected to a resistor, and the plurality of resistors are connected in parallel. One end of the parallel resistor is connected to the current adjustment terminal of the pulse width LED driver chip, and the other end is grounded, and is used to adjust the maximum amplitude of the output current of the LED driver circuit according to the selection state of the dialer.

[0012] In one embodiment, the square wave generating circuit includes a rectifier bridge BD2, a resistor R32, a resistor R33 and an optocoupler U7, the input end of the rectifier bridge BD2 is connected to the AC power, the output end is connected to resistors R32 and R33 in sequence, the other end of resistor R33 is connected to the positive electrode of the light-emitting diode of the optocoupler U7, the negative electrode of the light-emitting diode is grounded, the photosensitive semiconductor of the optocoupler is a phototransistor, the collector of the phototransistor is connected to a 5V DC voltage, and the emitter is connected to the power-off detection terminal of the single-chip controller.

[0013] In one embodiment, the PWM pulse width modulation circuit includes a single-chip microcomputer controller U2, a resistor R26, a resistor R27 and a capacitor C2. The emitter of the phototransistor is connected to the power-off detection terminal AC of the single-chip microcomputer controller U2 through a voltage divider circuit. The voltage divider circuit includes resistors R26 and R27. One end of the resistor R26 is connected to the collector of the phototransistor, and the other end is connected to the resistor R27 and the power-off detection terminal of the single-chip microcomputer controller U2. The other end of the resistor R27 is grounded. The power supply terminal VCC of the single-chip microcomputer controller U2 is connected to a 5V DC voltage and is grounded after filtering by the capacitor C2.

[0014] In one embodiment, the time dialer K1 includes two parallel selection switches, one end of the two selection switches is respectively connected to the two input terminals S0 and S1 of the single-chip controller U2, and the other end of the two selection switches is grounded, forming four different input codes to achieve four different delay times for the slow start and slow stop of the LED light.

[0015] In one embodiment, the pulse width drive circuit includes a pulse width LED drive chip U3, a resistor R11, a resistor R12, a resistor R15, a resistor R19, a resistor R20, an electrolytic capacitor C5, a capacitor C6, a diode D4 and an inductor L1, the voltage stabilizing circuit outputs a stable DC voltage to power the pulse width drive circuit, the PWM terminal of the single chip controller is connected to the PWM terminal of the pulse width LED drive chip U3 through the resistor R12, the DC voltage is connected to the power supply terminal VDD and the LD terminal of the pulse width LED drive chip U3 through the resistor R15, and is connected to the power supply terminal VDD and the LD terminal of the pulse width LED drive chip U3 through the electrolytic capacitor C5. The other end of the resistor R15 is connected to the ground, the other end of the resistor R15 is connected to one end of the capacitor C6, the other end of the capacitor C6 is connected to one end of the resistor R11, the other end of the resistor R11 is connected to the PWM terminal of the pulse width LED driver chip U3, the resistor R19 and the resistor R20 are connected in parallel, one end is connected to the current adjustment terminal CS of the pulse width LED driver chip U3, and the other end is grounded, the drain terminal D of the pulse width LED driver chip U3 is connected to the anode of the diode D4 and one end of the inductor L1, the cathode of the diode D4 is connected to the positive power supply of the LED lamp, and the other end of the inductor L1 is connected to the negative power supply of the LED lamp.

[0016] In one embodiment, the current dialer K2 includes two selection switches, each selection switch is connected to a resistor R17 and a resistor R18, the resistor R17 and the resistor R18 are connected in parallel, one end of the parallel resistor is connected to the current adjustment terminal CS of the pulse width LED driver chip, and the other end is grounded, and is used to adjust the maximum amplitude of the output current of the pulse width LED driver chip according to the selection state of the dialer K2.

[0017] On the other hand, the present invention further provides an LED lamp, comprising an LED lamp, a lamp body and any one of the above-mentioned LED driving circuits.

[0018] In one of the embodiments, the lamp is provided with a selection switch for adjusting the delay time of the slow start and slow shut down of the LED lamp.

[0019] The present invention discloses an LED lamp driving circuit and an LED lamp, comprising a voltage stabilizing circuit for converting mains electricity into a stable direct current voltage to supply power to the LED lamp driving circuit, a square wave generating circuit comprising a rectifier bridge and an optocoupler, wherein the mains electricity is rectified by the rectifier bridge to obtain a fluctuating direct current voltage, and a pulse signal is generated on the photosensitive semiconductor side of the optocoupler, a PWM pulse width modulation circuit comprising a single-chip microcomputer controller, wherein the photosensitive semiconductor is connected to a power-off detection terminal of the single-chip microcomputer controller, wherein when it is detected that the LED lamp is powered on, the pulse width of the output PMM signal is gradually increased, and when it is detected that the LED lamp is powered off, the pulse width of the output PMM signal is gradually reduced, and a pulse width type driving circuit comprising a pulse width type LED driving chip, wherein the input end of the pulse width type LED driving chip is connected to a PWM signal to provide a current with a varying amplitude to the LED lamp; the driving circuit performs power-on and power-off detection on the LED lamp, generates a PWM signal with a varying pulse width according to the detection signal, controls the current of the LED lamp based on the varying PWM signal, thereby realizing slow start and slow stop of the LED lamp, protecting the circuit safety, and preventing the LED lamp from flickering. 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 following briefly introduces the drawings required for use in the embodiments. The drawings described below are only drawings corresponding to some embodiments of the present invention. For ordinary technicians in this field, drawings of other embodiments can be obtained based on these drawings without creative work.

[0021] Figure 1 This is a circuit module diagram of an LED lamp driving circuit in one embodiment of the present invention;

[0022] Figure 2 A circuit diagram of a square wave generating circuit, a PWM pulse width modulation circuit and a pulse width type driving circuit in one embodiment of the present invention;

[0023] Figure 3 FIG. 4 is a circuit diagram of a voltage stabilizing circuit in one embodiment of the present invention. DETAILED DESCRIPTION

[0024] 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 those skilled in the art without creative work are within the scope of protection of the present invention.

[0025] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0026] See also Figure 1 The present invention provides an LED lamp driving circuit, in one embodiment, comprising:

[0027] The voltage stabilizing circuit 10 is used to convert the mains electricity into a stable direct current voltage to supply power to the LED lamp driving circuit.

[0028] The square wave generating circuit 20 includes a rectifier bridge and an optocoupler. The input end of the rectifier bridge is connected to the mains, and the output end is connected to the light-emitting diode of the optocoupler through a resistor. The mains is rectified by the rectifier bridge to obtain a fluctuating DC voltage. The fluctuating DC voltage causes the light emission of the photosensitive diode to fluctuate, thereby generating a pulse signal on the photosensitive semiconductor side of the optocoupler.

[0029] The PWM pulse width modulation circuit 30 includes a single-chip microcomputer controller 31. The photosensitive semiconductor is connected to the power-off detection terminal of the single-chip microcomputer controller 31. The single-chip microcomputer controller 31 is used to perform PWM modulation on the received pulse signal to obtain a PWM signal with a varying pulse width. When it is detected that the LED lamp is powered on, the pulse width of the PMM signal gradually increases. When it is detected that the LED lamp is powered off, the pulse width of the PMM signal gradually decreases.

[0030] The pulse width driving circuit 40 includes a pulse width LED driving chip 41, the input end of the pulse width LED driving chip 41 is connected to the PWM signal, and the output end is connected to the LED lamp, which is used to provide the LED lamp with a current with varying amplitude to achieve slow start and slow stop of the LED lamp.

[0031] In the LED lamp driving circuit of the present embodiment, when the LED lamp is electrically turned on, the square wave generating circuit 20 outputs a square wave signal consistent with the frequency of the mains power, and the power-off detection terminal of the single-chip controller 31 detects a signal input, indicating that the LED lamp is powered on. The single-chip controller 31 performs PWM modulation on the pulse signal to obtain a PWM signal with a gradually increasing pulse width. After receiving the gradually increasing PWM signal, the pulse width type LED driver chip 41 outputs a current with a gradually increasing amplitude to slowly light up the LED lamp, which can effectively protect the LED driving circuit and the LED lamp from being burned by instantaneous high current, effectively protect the safety of the circuit, prevent the LED lamp from flickering, and improve the user experience.

[0032] When the power-off detection terminal of the single-chip controller 31 no longer detects signal input, it indicates that the power of the LED lamp is turned off. The single-chip controller 31 performs PWM modulation on the pulse signal received previously to obtain a PWM signal with a gradually decreasing pulse width. After the pulse width type LED driver chip 41 receives the gradually decreasing PWM signal, it outputs a current with a gradually decreasing amplitude to slowly turn off the LED lamp, thereby preventing the LED lamp from flickering and improving the user experience.

[0033] For details, see Figure 2 In one embodiment, the square wave generating circuit 20 includes a rectifier bridge BD2, a resistor R32, a resistor R33 and an optocoupler U7, the input end of the rectifier bridge BD2 is connected to the mains, the output end is connected to the resistor R32 and the resistor R33 in sequence, the other end of the resistor R33 is connected to the positive electrode of the light-emitting diode of the optocoupler U7, the negative electrode of the light-emitting diode is grounded, the photosensitive semiconductor of the optocoupler is a phototransistor, the collector of the phototransistor is connected to a 5V DC voltage, and the emitter is connected to the power-off detection terminal of the single-chip controller.

[0034] The voltage signal output by the AC mains after being processed by the rectifier bridge is a ripple signal. The ripple signal is connected to the light-emitting diode through a resistor, which can cause the light emission of the light-emitting diode to fluctuate and generate a pulse signal with the same frequency as the mains on the photosensitive semiconductor side of the optocoupler.

[0035] In one embodiment, the PWM pulse width modulation circuit 30 includes a single-chip microcomputer controller U2, a resistor R26, a resistor R27 and a capacitor C2. The emitter of the phototransistor is connected to the power-off detection terminal AC of the single-chip microcomputer controller U2 through a voltage divider circuit. The voltage divider circuit includes resistors R26 and R27. One end of the resistor R26 is connected to the collector of the phototransistor, and the other end is connected to the resistor R27 and the power-off detection terminal of the single-chip microcomputer controller U2. The other end of the resistor R27 is grounded. The power supply terminal VCC of the single-chip microcomputer controller U2 is connected to a 5V DC voltage and is grounded after filtering by the capacitor C2.

[0036] The square wave generating circuit 20 generates a pulse signal with the same frequency as the mains power, and then performs a voltage reduction process and connects to the power-off detection terminal AC of the single-chip controller U2. The single-chip controller U2 modulates the pulse signal connected to the AC terminal, so that the PWM terminal of the single-chip controller U2 outputs a pulse signal with a gradually increasing or decreasing pulse width. Specifically, for example, when the AC terminal detects a pulse signal, a pulse signal with a duty cycle gradually increasing from 0-100% is output based on the pulse signal received at the AC terminal. When the AC terminal no longer detects a pulse signal, a pulse signal with a duty cycle gradually decreasing from 100%-0 is output based on the pulse signal previously received at the AC terminal.

[0037] In one embodiment, the pulse width drive circuit 40 includes a pulse width LED drive chip U3, a resistor R11, a resistor R12, a resistor R15, a resistor R19, a resistor R20, an electrolytic capacitor C5, a capacitor C6, a diode D4 and an inductor L1, the voltage stabilizing circuit outputs a stable DC voltage to power the pulse width drive circuit, the PWM terminal of the single chip controller is connected to the PWM terminal of the pulse width LED drive chip U3 through the resistor R12, the DC voltage is connected to the power supply terminal VDD and the LD terminal of the pulse width LED drive chip U3 through the resistor R15, and is connected to the power supply terminal VDD and the LD terminal of the pulse width LED drive chip U3 through the electrolytic capacitor C 5 is connected to ground, the other end of the resistor R15 is connected to one end of the capacitor C6, the other end of the capacitor C6 is connected to one end of the resistor R11, the other end of the resistor R11 is connected to the PWM terminal of the pulse width LED driver chip U3, the resistor R19 and the resistor R20 are connected in parallel, one end is connected to the current adjustment terminal CS of the pulse width LED driver chip U3, and the other end is grounded, the drain terminal D of the pulse width LED driver chip U3 is connected to the anode of the diode D4 and one end of the inductor L1, the cathode of the diode D4 is connected to the positive electrode of the power supply of the LED lamp, and the other end of the inductor L1 is connected to the negative electrode of the power supply of the LED lamp.

[0038] The PWM terminal of the pulse width LED driver chip U3 receives the PWM signal output by the single chip controller U2, and adjusts the output current of the drain terminal D based on the PWM signal, thereby changing the driving current of the LED lamp and realizing the slow start and slow stop of the LED lamp.

[0039] In one embodiment, the LED driving circuit also includes a time dial, which includes a plurality of selection switches, each of which is respectively connected to an input terminal of the single-chip microcomputer controller. Different input codes are formed by turning the dial, and different codes correspond to output PWM signals with different time periods, which are used to adjust the delay time of the slow start and slow off of the LED lamp.

[0040] For details, see Figure 2 The time dialer K1 includes two parallel selection switches, one end of the two selection switches is respectively connected to the two input terminals S0 and S1 of the single-chip controller U2, and the other end of the two selection switches is grounded, forming four different input codes to achieve four different delay times for the slow start and slow stop of the LED light.

[0041] For example, if the four states of the switch correspond to four different codes: 00, 01, 10 and 11, the microcontroller controller U2 will output PWM signals with different time periods, and set the delay time of the LED light to 3S, 5S, 7S and 9S respectively for users to choose, thereby improving the user experience.

[0042] Specifically, the code dial K1 is a manual selection switch, which can be set on the operation panel of the LED lamp to facilitate user use.

[0043] In one embodiment, the LED driving circuit also includes a current dialer, including a plurality of selection switches, each selection switch is connected to a resistor, and the plurality of resistors are connected in parallel. One end of the parallel resistor is connected to the current adjustment terminal of the pulse width LED driving chip, and the other end is grounded, and is used to adjust the maximum amplitude of the output current of the LED driving circuit according to the selection state of the dialer.

[0044] For details, see Figure 2 The current encoder K2 includes two selection switches, each of which is connected to a resistor R17 and a resistor R18 respectively. The resistor R17 and the resistor R18 are connected in parallel. One end of the parallel resistor is connected to the current adjustment terminal CS of the pulse width LED driver chip, and the other end is grounded, which is used to adjust the maximum amplitude of the output current of the pulse width LED driver chip according to the selection state of the encoder K2.

[0045] Similarly, through the selection switch of the current encoder K2, four different input signals can be generated at the current adjustment terminal CS of the pulse width LED driver chip U3, thereby adjusting the pulse width LED driver chip U3 to output four currents with different upper amplitude limits, thereby achieving the adjustment of the maximum brightness of the LED lamp and further improving the user experience.

[0046] Specifically, the code dial K2 is a manual selection switch, which can be set on the operation panel of the LED lamp to facilitate user use.

[0047] In one embodiment, participating Figure 3 The voltage stabilizing circuit 10 includes a rectifier bridge BD1, a constant voltage chip U1 and a transformer TR1. The AC power is connected to the rectifier bridge BD1 through a fuse FR1, a thermistor NTC1, a variable resistor VR1 and a filter circuit to realize circuit protection. The CSD pin of the constant current chip U1 is connected to the parallel resistors RS1 and RS2. The other ends of the resistors RS1 and RS2 are connected in parallel and then the signals are grounded. The HV pin of the constant voltage chip U1 is connected to the resistor R8. The other end of the resistor R8 is connected to the positive electrode of the electrolytic capacitor EC2. The other end of the electrolytic capacitor EC2 is grounded. The D terminal of the constant current chip U1 is connected to the No. 4 pin of the primary inductor of the transformer TR1. The output voltage of the rectifier bridge BD1 is connected to the No. 1 pin of the primary inductor after being processed by the filter. The output voltage of the secondary inductor is output as a stable DC voltage after being filtered to supply power to the pulse width LED driver chip U3 and the LED lamp.

[0048] The embodiment of the present application further provides an LED lamp, comprising an LED lamp, a lamp body and the LED driving circuit described in any of the above embodiments.

[0049] In one of the embodiments, the lamp is provided with a selection switch for adjusting the delay time of the slow start and slow shut down of the LED lamp.

[0050] The LED lamp driving circuit and LED lamp of the embodiment of the present application perform power-on and power-off detection on the LED lamp, generate a PWM signal with a changed pulse width according to the detection signal, and control the current of the LED lamp based on the changed PWM signal, thereby realizing slow start and slow shutoff of the LED lamp, protecting the circuit safety and preventing the LED lamp from flickering. At the same time, a time dialer is set on the single-chip microcomputer controller to generate PWM signals with different time periods according to the switch selection state of the dialer, and adjust the delay time of the slow start and slow shutoff of the LED lamp. A current dialer is set on the pulse width type LED driver chip to generate currents with different amplitude upper limits according to the switch selection state of the dialer, thereby adjusting the maximum display brightness of the LED lamp and improving the user experience.

[0051] In the above embodiments provided by the present invention, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0052] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0053] In addition, each functional unit in each embodiment of the present application may be integrated into a processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of a software functional unit. If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it may be stored in a computer-readable storage medium.

[0054] Based on this understanding, the technical solution of the present application, or the part that makes the contribution, or all or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for enabling a computer device (which can be a mobile terminal, a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., various media that can store program codes.

[0055] To sum up, although the present invention has been disclosed as above in the form of preferred embodiments, the protection scope of the present invention is not limited thereto, and any technician familiar with the technical field can make equivalent substitutions or changes according to the concept of the technical solution of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

[0056] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. An LED lamp driving circuit, characterized in that: include: A voltage stabilizing circuit, used for converting the mains electricity into a stable direct current voltage to supply power to the LED lamp driving circuit; A square wave generating circuit includes a rectifier bridge and an optical coupler, wherein the input end of the rectifier bridge is connected to the mains, and the output end is connected to the light-emitting diode of the optical coupler through a resistor. The mains is rectified by the rectifier bridge to obtain a fluctuating DC voltage, and the fluctuating DC voltage causes the light emission of the photosensitive diode to fluctuate, thereby generating a pulse signal on the photosensitive semiconductor side of the optical coupler; A PWM pulse width modulation circuit, comprising a single-chip controller, wherein the photosensitive semiconductor is connected to a power-off detection terminal of the single-chip controller, and the single-chip controller is used to perform PWM modulation on the received pulse signal to obtain a PWM signal with a pulse width variation, wherein when it is detected that the LED lamp is powered on, the pulse width of the PMM signal is gradually increased, and when it is detected that the LED lamp is powered off, the pulse width of the PMM signal is gradually reduced; A pulse width driving circuit comprises a pulse width LED driving chip, the input end of the pulse width LED driving chip is connected to the PWM signal, and the output end is connected to the LED lamp, so as to provide the LED lamp with a current with varying amplitude, thereby realizing slow start and slow stop of the LED lamp.

2. The LED lamp driving circuit according to claim 1, characterized in that: It also includes a time dial, including several selection switches, each selection switch is connected to an input terminal of the single-chip controller, and different input codes are formed by turning the dial. Different codes correspond to the output of PWM signals with different time periods, which are used to adjust the delay time of the slow start and slow off of the LED lamp.

3. The LED lamp driving circuit according to claim 1, characterized in that: It also includes a current dialer, including several selection switches, each selection switch is connected to a resistor, and several resistors are connected in parallel. One end of the parallel resistor is connected to the current adjustment terminal of the pulse width LED driver chip, and the other end is grounded, which is used to adjust the maximum amplitude of the output current of the LED driver circuit according to the selection state of the dialer.

4. The LED lamp driving circuit according to claim 1, characterized in that: The square wave generating circuit comprises a rectifier bridge BD2, a resistor R32, a resistor R33 and an optocoupler U7, wherein the input end of the rectifier bridge BD2 is connected to the mains, and the output end is connected to resistors R32 and R33 in sequence, the other end of resistor R33 is connected to the positive electrode of the light-emitting diode of the optocoupler U7, the negative electrode of the light-emitting diode is grounded, the photosensitive semiconductor of the optocoupler is a phototransistor, the collector of the phototransistor is connected to a 5V DC voltage, and the emitter is connected to the power-off detection terminal of the single-chip controller.

5. The LED lamp driving circuit according to claim 1, characterized in that: The PWM pulse width modulation circuit includes a single-chip microcomputer controller U2, a resistor R26, a resistor R27 and a capacitor C2. The emitter of the phototransistor is connected to the power-off detection terminal AC of the single-chip microcomputer controller U2 through a voltage divider circuit. The voltage divider circuit includes resistors R26 and R27. One end of the resistor R26 is connected to the collector of the phototransistor, and the other end is connected to the resistor R27 and the power-off detection terminal of the single-chip microcomputer controller U2. The other end of the resistor R27 is grounded. The power supply terminal VCC of the single-chip microcomputer controller U2 is connected to a 5V DC voltage and is grounded after filtering by the capacitor C2.

6. The LED lamp driving circuit according to claim 2, characterized in that: The time dialer K1 includes two parallel selection switches, one end of the two selection switches is respectively connected to the two input terminals S0 and S1 of the single-chip controller U2, and the other end of the two selection switches is grounded, forming four different input codes to achieve four different delay times for the slow start and slow stop of the LED light.

7. The LED lamp driving circuit according to claim 1, characterized in that: The pulse width drive circuit includes a pulse width LED drive chip U3, a resistor R11, a resistor R12, a resistor R15, a resistor R19, a resistor R20, an electrolytic capacitor C5, a capacitor C6, a diode D4 and an inductor L1. The voltage stabilizing circuit outputs a stable DC voltage to power the pulse width drive circuit. The PWM terminal of the single chip controller is connected to the PWM terminal of the pulse width LED drive chip U3 through the resistor R12. The DC voltage is connected to the power supply terminal VDD and the LD terminal of the pulse width LED drive chip U3 through the resistor R15, and is connected to the ground through the electrolytic capacitor C5. The other end of the resistor R15 is connected to one end of the capacitor C6, the other end of the capacitor C6 is connected to one end of the resistor R11, the other end of the resistor R11 is connected to the PWM terminal of the pulse width LED driver chip U3, the resistor R19 and the resistor R20 are connected in parallel, one end is connected to the current adjustment terminal CS of the pulse width LED driver chip U3, and the other end is grounded, the drain terminal D of the pulse width LED driver chip U3 is connected to the anode of the diode D4 and one end of the inductor L1, the cathode of the diode D4 is connected to the positive power supply of the LED lamp, and the other end of the inductor L1 is connected to the negative power supply of the LED lamp.

8. The LED lamp driving circuit according to claim 3, characterized in that: The current dialer K2 includes two selection switches, each of which is connected to a resistor R17 and a resistor R18 respectively. The resistors R17 and R18 are connected in parallel, one end of the parallel resistors is connected to the current adjustment terminal CS of the pulse width LED driver chip, and the other end is grounded, and is used to adjust the maximum amplitude of the output current of the pulse width LED driver chip according to the selection state of the dialer K2.

9. An LED lamp, characterized in that: It comprises an LED lamp, a lamp body and an LED driving circuit as described in any one of claims 1 to 8.

10. The lamp according to claim 9, characterized in that: The lamp is provided with a selection switch for adjusting the delay time of the slow start and slow shut down of the LED lamp.

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