CN110913530A

CN110913530A - Dimming LED driver

Info

Publication number: CN110913530A
Application number: CN201911044390.1A
Authority: CN
Inventors: 毛昭祺; 王纪周; 柯乃泉
Original assignee: Hangzhou Youte Power Co Ltd
Current assignee: Hangzhou Youte Power Co Ltd
Priority date: 2019-10-30
Filing date: 2019-10-30
Publication date: 2020-03-24
Anticipated expiration: 2039-10-30
Also published as: CN110913530B

Abstract

The invention discloses a dimming LED driver, comprising: the DC-DC circuit, the DC control circuit, the Boost main circuit, the Boost control circuit, the auxiliary power supply circuit, the second winding N2 and the feedback switching circuit, wherein the Boost main circuit is connected with the input end of the DC-DC circuit and comprises an inductor N1 and a switching tube S1, the second winding N2 is coupled with the inductor N1, the second winding N2 obtains energy from the Boost main circuit by being coupled with the inductor N1, and the auxiliary power supply circuit rectifies the alternating current obtained by the second winding N2 and outputs voltage Vcc; the output end of the DC control circuit is connected with the control end of the DC-DC circuit, the input end of the DC control circuit is connected with a dimming signal Vdim, the input end of the Boost control circuit is connected with the feedback switching circuit, and the output end of the Boost control circuit is connected with a switching tube S1 of the Boost main circuit. The auxiliary power supply circuit obtains energy from the inductor of the Boost main circuit, an independent auxiliary power supply circuit is not needed, the circuit is simple and low in cost, and a feedback switching circuit is arranged to maintain the normal work of the LED driver in a Dim-off state.

Description

Dimming LED driver

Technical Field

The invention relates to the technical field of lighting equipment, in particular to a dimming LED driver.

Background

The LED lamp has the advantages of energy conservation, environmental protection, long service life, high conversion efficiency and the like, and is widely applied to the field of illumination. In some lighting applications, in order to meet energy saving or lighting requirements, it is necessary that the brightness of the LED lamp can be adjusted. The LED lamp needs an LED driver to supply direct current, so that adjusting the brightness of the LED lamp can be achieved by adjusting the output current of the LED driver.

The dimmable LED driver receives the dimming signal Vdim and changes the magnitude of the output current according to the change of the Vdim signal. Also, in some dimming situations, it is desirable that the LED lamp is dimmable, i.e. that the LED driver is capable of outputting zero, which state is called Dim-off state, which indicates a state during dimming, and after Dim-off it is also desirable that the LED driver is capable of adjusting from output zero to a state in which the output current is restored. In order to meet the Dim-off function, the existing LED driver adopts a scheme of an independent auxiliary source, and the problems of high circuit cost and complex circuit exist.

Fig. 4 is a circuit diagram of a conventional dimmable LED driver, as shown in fig. 4, a main PFC circuit 12 is respectively connected to a PFC control circuit 16, a DC-DC main circuit 13, and an independent auxiliary power circuit 14, the PFC control circuit 16 is respectively connected to a DC-DC control circuit 15 and an independent auxiliary power circuit 14, the independent auxiliary power circuit 14 is connected to the DC-DC control circuit 15, the DC-DC control circuit 15 is connected to the main DC-DC circuit 13, the main DC-DC circuit 13 is connected to an LED lamp, the independent auxiliary power source obtains energy from an input terminal Vin of the LED driver, and generates an auxiliary power Vcc after conversion, and supplies the auxiliary power Vcc to each control circuit. The dimming signal Vdim is input to a control circuit of the LED driver, and the driver adjusts the current output to the LED lamp according to the dimming signal. When the dimming signal Vdim is a Dim-off signal, the DC control circuit controls the DC-DC circuit to stop working; furthermore, because the DC-DC circuit of the rear stage stops working, the load of the front stage PFC main circuit becomes very light and approximately no load, and the energy converted by the PFC main circuit is also extremely low. And the independent auxiliary power supply circuit is not influenced by the Vdim signal, so that the independent auxiliary power supply continuously works in a Dim-off state, and when the dimming signal is switched from the Dim-off signal to other dimming signals, each control circuit can quickly recover to work, thereby realizing the Dim-off function. But the independent auxiliary power supply realizes the Dim-off function, and the circuit is complex and high in cost.

Disclosure of Invention

The invention mainly solves the problems of complex circuit and high cost when the LED driver realizes the Dim-off function in the prior art; provided is a dimming LED driver, which realizes a Dim-off function without using a complicated independent auxiliary source, and simultaneously maintains the normal operation of the LED driver.

The technical problem of the invention is mainly solved by the following technical scheme: a dimming LED driver comprises a DC-DC circuit, a DC control circuit, a Boost main circuit, a Boost control circuit, an auxiliary power circuit, a second winding N2 and a feedback switching circuit, wherein the input end of the Boost main circuit is connected with a power supply, the Boost main circuit outputs a bus voltage Vbus, the output end of the Boost main circuit is connected with the input end of the DC-DC circuit, the output end of the DC-DC circuit is connected with an LED lamp, the Boost control circuit and the DC control circuit are both provided with power supply access ends, and the Boost main circuit comprises an inductor N1 and a switching tube S1; the second winding N2 is coupled with an inductor N1, the second winding N2 obtains energy from the Boost main circuit through coupling with an inductor N1, and the auxiliary power supply circuit rectifies alternating current obtained by the second winding N2 and outputs a voltage Vcc; the output end of the auxiliary power supply circuit is connected with the power supply access end of the Boost control circuit and the power supply access end of the DC control circuit; the feedback switching circuit is used for sampling the bus voltage Vbus, sampling the voltage Vcc of the output end of the auxiliary power supply circuit and receiving a dimming signal Vdiim, the feedback switching circuit outputs the sampling signal of the voltage Vcc of the output end of the auxiliary power supply circuit to the Boost control circuit when the dimming signal Vdiim is a dimming signal Vdiim-off, and the feedback switching circuit outputs the bus voltage Vbus sampling signal to the Boost control circuit when the dimming signal Vdiim is a non-dimming signal; the output end of the DC control circuit is connected with the control end of the DC-DC circuit, the input end of the DC control circuit is connected with a dimming signal Vlim, and the DC control circuit responds to the dimming signal Vlim and controls the output of the DC-DC circuit; the output end of the Boost control circuit is connected with the control end of a switching tube S1 of the Boost main circuit, the input end of the Boost control circuit is connected with the output end of the feedback switching circuit, and the Boost control circuit is used for generating a driving signal for outputting the switching tube S1 according to a signal output by the feedback switching circuit. The auxiliary power circuit obtains energy through the coupling of a second winding N2 and an inductor N1 when the auxiliary power circuit is connected with a power supply through a Boost main circuit to output voltage Vbus, the function of the auxiliary power supply is realized, a feedback switching circuit transmits a voltage Vcc sampling signal output by the auxiliary power circuit to the Boost control circuit when a turn-off signal Vdeim-off is adjusted, the output power of the Boost main circuit is controlled by the Boost control circuit according to the change of Vcc, the normal work of the auxiliary power circuit in a Dim-off state is maintained, meanwhile, the output voltage Vbus of the Boost main circuit is used as an input signal of the Boost control circuit through the feedback switching circuit when the turn-off signal is not adjusted, the output of the Boost main circuit is adjusted by the Boost control circuit according to the change of Vbus, and the normal work of an LED driver is maintained.

Preferably, the Boost main circuit further includes a diode D1 and an output capacitor C1, one end of the inductor N1 is connected to the first end of the switching tube S1 and the anode of the diode D1, the other end of the inductor N1 is used as the positive input end of the Boost main circuit, the second end of the switching tube S1 is used as the negative input end of the Boost main circuit, the output capacitor C1 is connected between the cathode of the diode D1 and the second end of the switching tube S1, and two ends of the output capacitor C1 are used as the output end of the Boost main circuit. The current is transmitted to the capacitor C1 through the inductor N1 of the Boost main circuit, so that the output capacitor C1 is used as an energy storage element to store energy and output the energy, the output voltage is Vbus, and the diode D1 prevents the current from reversely flowing into the inductor N1. And enabling the current to flow out of the output end of the Boost main circuit.

Preferably, the Boost control circuit includes a voltage feedback unit and a driving control unit, the voltage feedback unit compares the received sampling signal with a set voltage reference signal, amplifies the difference value after comparison, and outputs a feedback signal to the driving control unit, and the driving control unit generates a driving signal according to the received feedback signal and outputs the driving signal to the control end of the switching tube S1. The voltage feedback unit receives a voltage signal output by the auxiliary power supply circuit and a sampling signal output by the feedback switching circuit, and compares the received voltage signal and the sampling signal with a voltage reference signal respectively to enable an output signal of the Boost main circuit and an output voltage of the auxiliary power supply circuit to change along with the change of the feedback signal.

Preferably, the feedback switching circuit includes a first sampling circuit, a second sampling circuit, a switch SW and a switch control circuit, the first sampling circuit samples the bus voltage Vbus, the second sampling circuit samples the voltage Vcc at the output terminal of the auxiliary power supply circuit, a first end of the switch SW is connected to the Boost control circuit, a second end of the switch SW is provided with two contacts, the two contacts are respectively connected to the output terminal of the first sampling circuit and the output terminal of the second sampling circuit, a control end of the switch SW is connected to the output terminal of the switch control circuit, and an input terminal of the switch control circuit receives the dimming signal Vdim. When the dimming signal Vdim is a dimming signal Vdim-off, the switch SW is controlled to be connected with the contact of the first end and the second sampling circuit, and when the Vdim is a non-dimming signal, the switch SW is controlled to be connected with the contact of the first end and the first sampling circuit, so that the normal work of the LED driver in the dimming signal Vdim-off state or the non-dimming signal is guaranteed.

Preferably, the auxiliary power supply circuit includes a capacitor C2, a capacitor C3, a diode D2 and a diode D3, a first end of the capacitor C2 is connected to one end of the second winding N2, a second end of the capacitor C2 is connected to an anode of the diode D2 and a cathode of the diode D3, an anode of the diode D3 is connected to the other end of the second winding N2 and a first end of the capacitor C3, a cathode of the diode D2 is connected to a second end of the capacitor C3, and both ends of the capacitor C3 are used as the output terminal output voltage Vcc of the auxiliary power supply circuit. The capacitor C2, the capacitor C3, the diode D2 and the diode D3 are connected to form a voltage doubling rectifying circuit, the amplitude of Vcc is made to be proportional to Vbus, and if the input voltage of the main circuit of the Boost circuit is Vin and the output voltage is Vbus, the voltage of the inductor N1 of the Boost circuit is positive and negative two voltages, wherein one voltage is Vin and the other voltage is Vbus-Vin, meanwhile, the voltage of the second winding N2 is also the same as the voltage, and has positive voltage and negative voltage, and the amplitudes are Vin and Vbus-Vin respectively. After the second winding N2 is subjected to voltage doubling rectification, the voltage doubling rectification circuit superposes two voltages, and the rectified output voltage Vcc is proportional to the sum of the two voltages, namely Vin + (Vbus-Vin), namely Vbus. Therefore, the output voltage Vcc of the voltage-doubler rectification circuit is proportional to the output voltage Vbus of the Boost circuit.

Preferably, the auxiliary power supply circuit includes a capacitor C22, a capacitor C33, a diode D22 and a diode D33, an anode of the diode D22 is connected to a cathode of the diode D33 and one end of the second winding N2, a cathode of the diode D22 is connected to a first end of the capacitor C22, a second end of the capacitor C22 is connected to the other end of the second winding N2 and a first end of the capacitor C33, a second end of the capacitor C33 is connected to an anode of the diode D33, and the first end of the capacitor C22 and the second end of the capacitor C33 serve as the output terminal output voltage Vcc of the auxiliary power supply circuit.

Preferably, the first sampling circuit comprises a sampling resistor R1 and a sampling resistor R2, one end of the sampling resistor R1 is used as the positive input end of the first sampling circuit and connected with the positive electrode of the output end of the main Boost circuit, the other end of the sampling resistor R1 is connected with one end of the sampling resistor R2, the connection end of the sampling resistor R1 and the sampling resistor R2 is used as the output end of the first sampling circuit, the output end of the first sampling circuit is connected with the contact of the changeover switch SW, and the other end of the sampling resistor R2 is used as the negative input end of the first sampling circuit and connected with the negative electrode of the output end of the main Boost circuit. By adopting the resistor R1 and the sampling resistor R2 to sample the output voltage Vbus of the Boost main circuit, the circuit is simple, and the cost is saved.

Preferably, the second sampling circuit includes a sampling resistor R11 and a sampling resistor R22, one end of the sampling resistor R11 is connected to the positive terminal of the output terminal of the auxiliary power supply circuit as the positive input terminal of the second sampling circuit, the other end of the sampling resistor R11 is connected to one end of the sampling resistor R22, the connection end of the sampling resistor R11 and the sampling resistor R22 is connected to the output terminal of the second sampling circuit, the output terminal of the second sampling circuit is connected to the contact of the switch SW, and the other end of the sampling resistor R22 is connected to the negative terminal of the output terminal of the auxiliary power supply circuit as the negative input terminal of the second sampling circuit. The resistor R11 and the sampling resistor R22 are used for sampling the output power supply voltage Vcc of the auxiliary power supply circuit, so that the cost is saved.

The invention has the beneficial effects that: (1) an input end winding of the auxiliary power supply circuit is coupled with an inductor of the Boost main circuit, energy is obtained from the Boost main circuit, an independent auxiliary power supply circuit is not required to be arranged, and the circuit is simple and low in cost; (2) and a feedback switching circuit is arranged, and outputs the output voltage Vcc sampling signal of the auxiliary power supply circuit to a Boost control circuit by switching the sampling signal when the dimming signal is a dimming signal Vdim-off, so as to control a Boost main circuit to maintain the work of the auxiliary power supply circuit in a Dim-off state.

Drawings

Fig. 1 is a schematic diagram of an LED driver circuit according to a first embodiment.

Fig. 2 is a schematic diagram of an auxiliary power supply circuit according to the first embodiment.

Fig. 3 is a schematic diagram of an auxiliary power supply circuit according to a second embodiment.

Fig. 4 is a circuit diagram of a prior dimmable LED driver.

In the figure, 1, an auxiliary power circuit, 2, a drive control unit, 3, a voltage feedback unit, 4, a DC-DC circuit, 5, a DC control circuit, 6, a switch control circuit, 7, an LED lamp, 8, a Boost main circuit, 9, a first sampling circuit, 10, a Boost control circuit, 11, a second sampling circuit, 12, a PFC main circuit, 13, a DC-DC main circuit, 14, an independent power circuit, 15, a DC-DC control circuit and 16, the PFC control circuit.

Detailed Description

The technical scheme of the invention is further specifically described by the following embodiments and the accompanying drawings.

The first embodiment is as follows: a dimming LED driver comprises a DC-DC circuit 4, a DC control circuit 5, a Boost main circuit 8, a Boost control circuit 10, an auxiliary power circuit 1, a second winding N2 and a feedback switching circuit, wherein the input end of the Boost main circuit 8 is connected with a power supply, the Boost main circuit 8 outputs a bus voltage Vbus, the output end of the Boost main circuit 8 is connected with the input end of the DC-DC circuit 4, the output end of the DC-DC circuit 4 is connected with an LED lamp 7, the Boost control circuit 10 and the DC control circuit 5 are both provided with power supply access ends, the Boost main circuit 8 comprises an inductor N1 and a switching tube S1, the second winding N2 is coupled with an inductor N1, the second winding N2 obtains energy from the Boost main circuit 8 by being coupled with an inductor N1, and the auxiliary power circuit 1 rectifies alternating current obtained by the second winding N2 and outputs voltage Vcc; the output end of the auxiliary power circuit 1 is connected with the power supply access end of the Boost control circuit 10 and the power supply access end of the DC control circuit 5; the feedback switching circuit is used for sampling bus voltage Vbus, sampling voltage Vcc at the output end of the auxiliary power supply circuit 1 and receiving a dimming signal Vdim, the feedback switching circuit outputs the sampling signal of the voltage Vcc at the output end of the auxiliary power supply circuit 1 to the Boost control circuit 10 when the dimming signal Vdim is a dimming signal Vdim-off, and the feedback switching circuit outputs the bus voltage Vbus sampling signal to the Boost control circuit 10 when the dimming signal Vdim is a non-dimming signal; the output end of the DC control circuit 5 is connected with the control end of the DC-DC circuit 4, the input end of the DC control circuit 5 is connected with the dimming signal Vlim, and the DC control circuit 5 responds to the dimming signal Vlim and controls the output of the DC-DC circuit 4; the output end of the Boost control circuit 10 is connected with the control end of a switching tube S1 of the Boost main circuit 8, the input end of the Boost control circuit 10 is connected with the output end of the feedback switching circuit, and the Boost control circuit 10 is used for generating a driving signal output to the switching tube S1 according to a signal output by the feedback switching circuit.

The Boost main circuit 8 further comprises a diode D1 and an output capacitor C1, one end of an inductor N1 is connected with the first end of the switching tube S1 and the anode of the diode D1, the other end of the inductor N1 serves as the positive input end of the Boost main circuit 8, the second end of the switching tube S1 serves as the negative input end of the Boost main circuit 8, the output capacitor C1 is connected between the cathode of the diode D1 and the second end of the switching tube S1, and two ends of the output capacitor C1 serve as the output end of the Boost main circuit 8.

The Boost control circuit 10 includes a voltage feedback unit 3 and a driving control unit 2, the voltage feedback unit 3 compares the received sampling signal with a set voltage reference signal, amplifies the difference value after comparison, and outputs a feedback signal to the driving control unit 2, and the driving control unit 2 generates a driving signal according to the received feedback signal and outputs the driving signal to a control end of the switching tube S1.

The feedback switching circuit comprises a first sampling circuit 9, a second sampling circuit 11, a switch SW and a switch control circuit 6, wherein the first sampling circuit 9 samples bus voltage Vbus, the second sampling circuit 11 samples voltage Vcc of the output end of the auxiliary power supply circuit 1, the first end of the switch SW is connected with a Boost control circuit 10, the second end of the switch SW is provided with two contacts which are respectively connected with the output end of the first sampling circuit 9 and the output end of the second sampling circuit 11, the control end of the switch SW is connected with the output end of the switch control circuit 6, and the input end of the switch control circuit 6 receives a dimming signal Vdim.

The first sampling circuit 9 comprises a sampling resistor R1 and a sampling resistor R2, one end of the sampling resistor R1 is used as the positive input end of the first sampling circuit 9 and is connected with the positive output end of the Boost main circuit 8, the other end of the sampling resistor R1 is connected with one end of the sampling resistor R2, the connecting end of the sampling resistor R1 and the sampling resistor R2 is used as the output end of the first sampling circuit 9, the output end of the first sampling circuit 9 is connected with the contact of the change-over switch SW, and the other end of the sampling resistor R2 is used as the negative input end of the first sampling circuit 9 and is connected with the negative output end of the Boost main circuit 8.

The second sampling circuit 11 comprises a sampling resistor R11 and a sampling resistor R22, one end of the sampling resistor R11 is used as the positive input end of the second sampling circuit 11 and is connected with the positive output end of the auxiliary power supply circuit 1, the other end of the sampling resistor R11 is connected with one end of the sampling resistor R22, the connection end of the sampling resistor R11 and the sampling resistor R22 is used as the output end of the second sampling circuit 11, the output end of the second sampling circuit 11 is connected with the contact of the change-over switch SW, and the other end of the sampling resistor R22 is used as the negative input end of the second sampling circuit 11 and is connected with the negative output end of the auxiliary power supply circuit 1.

As shown in fig. 2, the auxiliary power supply circuit 1 includes a capacitor C2, a capacitor C3, a diode D2, and a diode D3, wherein a first end of the capacitor C2 is connected to one end of the second winding N2, a second end of the capacitor C2 is connected to an anode of the diode D2 and a cathode of the diode D3, an anode of the diode D3 is connected to the other end of the second winding N2 and a first end of the capacitor C3, a cathode of the diode D2 is connected to a second end of the capacitor C3, and both ends of the capacitor C3 are used as an output terminal output voltage Vcc of the auxiliary power supply circuit 1.

In the specific application, a power supply is input from one end of an inductor L of a main Boost circuit 8, the power supply is transmitted to an output capacitor C1 through a diode D1 to be charged, the output capacitor C1 stores energy firstly, then, two ends of the output capacitor C are used as output ends of the main Boost circuit 8 to output voltage, bus voltage Vbus is output, the voltage Vbus is adjusted through a DC-DC circuit 4 and is supplied to an LED lamp 7 to enable the LED lamp 7 to be lightened, a second winding N2 is coupled with the inductor N1 to transmit the energy to an auxiliary power circuit 1, the auxiliary power circuit 1 outputs voltage Vcc, the auxiliary power circuit 1 is a double-voltage rectification circuit, the amplitude of Vcc is proportional to the Vbus, and assuming that the input voltage of the main Boost circuit 8 is Vin and the output voltage is Vbus, the voltage of the inductor N1 of the main Boost circuit 8 is positive and negative, one of the positive and negative voltages is Vin, and the other is Vbus-Vin, similarly, the voltage of the second winding N2 is also the same, has positive and negative voltages, and has magnitudes of Vin and Vbus-Vin, respectively. After the second winding N2 is subjected to voltage doubling rectification, the voltage doubling rectification circuit superposes two voltages, and the rectified output voltage Vcc is proportional to the sum of the two voltages, namely Vin + (Vbus-Vin), namely Vbus. When the dimming signal Vdim is a dimming signal Vdim-off, the light-on control circuit 6 controls the switch SW to connect the first end with the contact of the second sampling circuit, the output voltage Vcc of the auxiliary power circuit 1 is fed back to the voltage feedback unit 3, the voltage feedback unit 3 is compared and amplified and then transmitted to the driving control unit 2, the driving control unit 2 outputs a driving signal to the switch tube S1, the output voltage Vbus of the Boost main circuit 8 is adjusted by controlling the on/off of the switch tube S1, the output power of the Boost main circuit 8 is controlled, the power of the auxiliary power circuit 1 is controlled by the inductive coupling of the inductor N1 and the second winding N2, the normal operation of the auxiliary power circuit 1 in a Dim-off state is maintained, the situation that the switching power is low due to the stop operation of each stage of main circuits under the control of the control circuit is prevented from occurring, and the problem that each control circuit cannot normally operate due to the insufficient energy of the auxiliary power Vcc is also prevented, the normal work of the LED driver in a Dim-off state is ensured; when Vdim is a non-dimming signal, the control switch circuit controls the switch SW to connect the first end and a contact of the first sampling circuit 9, samples the output voltage Vbus of the Boost main circuit 8, feeds the output voltage Vbus back to the voltage feedback unit 3, transmits the sampled output voltage to the drive control unit 2 after comparison and amplification, and the drive control unit 2 outputs a drive signal, controls the switching of the switch tube S1, controls the output power of the Boost main circuit 8, and maintains the normal operation of the LED driver in a non-Dim-off state.

In a second embodiment, as shown in fig. 3, the auxiliary power circuit 1 includes a capacitor C22, a capacitor C33, a diode D22, and a diode D33, an anode of the diode D22 is connected to a cathode of the diode D33 and one end of the second winding N2, a cathode of the diode D22 is connected to a first end of the capacitor C22, a second end of the capacitor C22 is connected to the other end of the second winding N2 and a first end of the capacitor C33, a second end of the capacitor C33 is connected to an anode of the diode D33, and a first end of the capacitor C22 and a second end of the capacitor C33 serve as the output terminal output voltage Vcc of the auxiliary power circuit 1. The rest circuits are the same as the first embodiment. In this embodiment, the capacitor C22, the capacitor C33, the diode D22, and the diode D33 are connected to form a voltage-doubler rectifier circuit, and the voltage of the secondary winding N2 is stored and then the power supply voltage Vcc is output.

The above-described embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention in any way, and other variations and modifications may be made without departing from the spirit of the invention as set forth in the claims.

Claims

1. A dimming LED driver comprises a DC-DC circuit, a DC control circuit, a Boost main circuit and a Boost control circuit, wherein the input end of the Boost main circuit is connected with a power supply, the Boost main circuit outputs a bus voltage Vbus, the output end of the Boost main circuit is connected with the input end of the DC-DC circuit, the output end of the DC-DC circuit is connected with an LED lamp, the Boost control circuit and the DC control circuit are both provided with power supply access ends, the Boost main circuit comprises an inductor N1 and a switching tube S1, and the dimming LED driver is characterized in that,

further comprising: an auxiliary power supply circuit, a second winding N2 and a feedback switching circuit;

the second winding N2 is coupled with an inductor N1, the second winding N2 obtains energy from the Boost main circuit through coupling with an inductor N1, and the auxiliary power supply circuit rectifies alternating current obtained by the second winding N2 and outputs a voltage Vcc; the output end of the auxiliary power supply circuit is connected with the power supply access end of the Boost control circuit and the power supply access end of the DC control circuit;

the feedback switching circuit is used for sampling the bus voltage Vbus, sampling the voltage Vcc of the output end of the auxiliary power supply circuit and receiving a dimming signal Vdiim, the feedback switching circuit outputs the sampling signal of the voltage Vcc of the output end of the auxiliary power supply circuit to the Boost control circuit when the dimming signal Vdiim is a dimming signal Vdiim-off, and the feedback switching circuit outputs the bus voltage Vbus sampling signal to the Boost control circuit when the dimming signal Vdiim is a non-dimming signal;

the output end of the DC control circuit is connected with the control end of the DC-DC circuit, the input end of the DC control circuit is connected with a dimming signal Vlim, and the DC control circuit responds to the dimming signal Vlim and controls the output of the DC-DC circuit;

the output end of the Boost control circuit is connected with the control end of a switching tube S1 of the Boost main circuit, the input end of the Boost control circuit is connected with the output end of the feedback switching circuit, and the Boost control circuit is used for generating a driving signal output to the switching tube S1 according to a signal output by the feedback switching circuit.

2. The dimming LED driver of claim 1,

the Boost main circuit further comprises a diode D1 and an output capacitor C1, one end of the inductor N1 is connected with the first end of the switch tube S1 and the anode of the diode D1, the other end of the inductor N1 serves as the input positive end of the Boost main circuit, the second end of the switch tube S1 serves as the input negative end of the Boost main circuit, the output capacitor C1 is connected between the cathode of the diode D1 and the second end of the switch tube S1, and two ends of the output capacitor C1 serve as the output end of the Boost main circuit.

3. The dimming LED driver of claim 1, wherein the Boost control circuit comprises a voltage feedback unit and a driving control unit, the voltage feedback unit compares the received sampling signal with a set voltage reference signal, amplifies the difference after comparison, and outputs a feedback signal to the driving control unit, and the driving control unit generates a driving signal according to the received feedback signal and outputs the driving signal to the control terminal of the switching tube S1.

4. The dimming LED driver of claim 1, wherein the feedback switching circuit comprises a first sampling circuit, a second sampling circuit, a switch SW and a switch control circuit, the first sampling circuit samples the bus voltage Vbus, the second sampling circuit samples the voltage Vcc at the output terminal of the auxiliary power circuit, the first terminal of the switch SW is connected to the Boost control circuit, the second terminal of the switch SW is provided with two contacts, the two contacts are respectively connected to the output terminal of the first sampling circuit and the output terminal of the second sampling circuit, the control terminal of the switch SW is connected to the output terminal of the switch control circuit, and the input terminal of the switch control circuit receives the dimming signal Vdim.

5. The dimming LED driver of claim 2, wherein the auxiliary power circuit comprises a capacitor C2, a capacitor C3, a diode D2 and a diode D3, wherein a first end of the capacitor C2 is connected to one end of the second winding N2, a second end of the capacitor C2 is connected to an anode of the diode D2 and a cathode of the diode D3, an anode of the diode D3 is connected to the other end of the second winding N2 and a first end of the capacitor C3, a cathode of the diode D2 is connected to a second end of the capacitor C3, and two ends of the capacitor C3 are used as the output terminal of the auxiliary power circuit to output the voltage Vcc.

6. The dimming LED driver of claim 2, wherein the auxiliary power circuit comprises a capacitor C22, a capacitor C33, a diode D22 and a diode D33, wherein an anode of the diode D22 is connected to a cathode of the diode D33 and one end of the second winding N2, a cathode of the diode D22 is connected to a first end of the capacitor C22, a second end of the capacitor C22 is connected to the other end of the second winding N2 and a first end of the capacitor C33, a second end of the capacitor C33 is connected to an anode of the diode D33, and the first end of the capacitor C22 and the second end of the capacitor C33 are used as the output voltage Vcc of the auxiliary power circuit.

7. The dimming LED driver of claim 4, wherein the first sampling circuit comprises a sampling resistor R1 and a sampling resistor R2, one end of the sampling resistor R1 serves as the positive input terminal of the first sampling circuit and is connected to the positive output terminal of the main Boost circuit, the other end of the sampling resistor R1 is connected to one end of the sampling resistor R2, the connection end of the sampling resistor R1 and the sampling resistor R2 serves as the output terminal of the first sampling circuit, the output terminal of the first sampling circuit is connected to the contact of the changeover switch SW, and the other end of the sampling resistor R2 serves as the negative input terminal of the first sampling circuit and is connected to the negative output terminal of the main Boost circuit.

8. The dimming LED driver of claim 4, wherein the second sampling circuit comprises a sampling resistor R11 and a sampling resistor R22, one end of the sampling resistor R11 serves as the positive input terminal of the second sampling circuit and is connected to the positive output terminal of the auxiliary power circuit, the other end of the sampling resistor R11 is connected to one end of the sampling resistor R22, the connection end of the sampling resistor R11 and the sampling resistor R22 serves as the output terminal of the second sampling circuit, the output terminal of the second sampling circuit is connected to the contact of the switch SW, and the other end of the sampling resistor R22 serves as the negative input terminal of the second sampling circuit and is connected to the negative output terminal of the auxiliary power circuit.