LED driving circuit, driving device, and lighting device

Abstract

The present application relates to an LED driving circuit, a driving device, and a lighting device. The LED driving circuit comprises a rectifying module, a first constant current source, and a second constant current source. The first constant current source is configured to adjust a turn-on impedance of the first constant current source on the basis of a first reference voltage and a voltage of a first voltage feedback point in the first constant current source, so as to generate and output a first driving current; the second constant current source is configured to adjust a turn-on impedance of the second constant current source on the basis of a second reference voltage and a voltage of a second voltage feedback point in the second constant current source when a second driving voltage is greater than a turn-on threshold of the second constant current source, so as to generate and output a second driving current; the second driving current is configured to drive, together with the first driving current, a first load to work and configured to raise the voltage of the first voltage feedback point, so as to reduce the first driving current. By means of the first constant current source and the second constant current source, the effect of constant current can be achieved, and when the first load is an LED light emitting device, the stroboscopic problem of the LED light emitting device can be eliminated.

Description

LED drive circuit, drive device and lighting equipment

[0001] This application claims priority to the Chinese patent application filed on September 20, 2023 with the Patent Office of the State Intellectual Property Office of the People's Republic of China, with application number 202311215863.6 and application name “LED drive circuit, drive device and lighting equipment”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application belongs to the field of LED lighting technology, and in particular relates to an LED driving circuit, a driving device, and a lighting device. Background Art

[0003] At present, LED lighting is an energy-saving and environmentally friendly lighting method, and has become the mainstream lighting method. At the same time, flicker, low cost, and the requirements of various environmental certifications for subharmonics have become important indicators of concern for LED lighting.

[0004] Because the LED loads used in LED lighting require DC current to drive, and the current flowing through the LED load determines the LED's brightness, the LED drive control process often introduces low-frequency ripple from the input AC mains into the LED load, causing light fluctuations in the LED load, which in turn leads to flicker. Furthermore, various environmental certifications require subharmonics, making existing circuits ineffective in addressing flicker. Technical issues

[0005] The purpose of this application is to provide an LED driving circuit, a driving device and a lighting device, aiming to solve the problem of flickering in traditional LED lighting devices that work based on alternating current. Technical Solutions

[0006] To achieve the above-mentioned objectives, the first aspect of the present application provides an LED driving circuit, comprising: a rectifier module, the rectifier module being used to generate a first driving voltage and a second driving voltage based on an input alternating current; a first constant current source, the input end of the first constant current source being connected to the rectifier module, the output end of the first constant current source and the reference ground of the first constant current source being used to be connected to a first load, the first constant current source being configured to adjust the on-resistance of the first constant current source according to a first reference voltage and a voltage at a first voltage feedback point in the first constant current source, so as to generate and output a first driving current based on the first driving voltage; wherein the first constant current source comprises a first sampling resistor, the first sampling resistor being connected between the first voltage feedback point and the output end of the first constant current source; a second constant current source, the input end of the first constant current source being connected to the rectifier module, the output end of the first constant current source and the reference ground of the first constant current source being used to be connected to a first load, the first constant current source being configured to adjust the on-resistance of the first constant current source according to a first reference voltage and a voltage at a first voltage feedback point in the first constant current source, so as to generate and output a first driving current based on the first driving voltage; wherein the first constant current source comprises a first sampling resistor, the first sampling resistor being connected between the first voltage feedback point and the output end of the first constant current source; The input end of the second constant current source is connected to the rectifier module, and the output end of the second constant current source and the reference ground of the second constant current source are both connected to the first voltage feedback point. The second constant current source is configured to adjust the on-impedance of the second constant current source according to the second reference voltage and the voltage of the second voltage feedback point in the second constant current source when the second drive voltage is greater than the turn-on threshold of the second constant current source, so as to generate and output a second drive current based on the second drive voltage; the second drive current is used to drive the first load together with the first drive current and to increase the voltage of the first voltage feedback point through the first sampling resistor, so that the first constant current source generates a third drive current, and the sum of the second drive current and the third drive current is equal to the first drive current.

[0007] In one embodiment, the first constant current source includes a first switching tube and a first operational amplifier unit; the first end of the first switching tube is the input end of the first constant current source, the second end of the first switching tube is connected to the first end of the first sampling resistor, the first end of the first sampling resistor is the first voltage feedback point of the first constant current source, and the second end of the first sampling resistor is the output end of the first constant current source and the reference ground of the first constant current source; the first operational amplifier unit is configured to adjust the on-resistance of the first switching tube based on the voltage of the first voltage feedback point of the first constant current source and the voltage of the reference ground of the first constant current source, so that the voltage on the first sampling resistor is equal to the first reference voltage.

[0008] In one embodiment, the first operational amplifier unit includes a first operational amplifier, a non-inverting input terminal of the first operational amplifier is used to receive the first reference voltage, an inverting input terminal of the first operational amplifier is connected to the first end of the first sampling resistor, a ground terminal of the first operational amplifier is connected to the second end of the first sampling resistor, and an output terminal of the first operational amplifier is connected to the controlled end of the first switching tube.

[0009] In one embodiment, the second constant current source includes a second switching tube, a second sampling resistor, and a second operational amplifier unit; the first end of the second switching tube is the input end of the second constant current source, the second end of the second switching tube is connected to the first end of the second sampling resistor, the first end of the second sampling resistor is the second voltage feedback point of the second constant current source, and the second end of the second sampling resistor is the output end of the second constant current source and the reference ground of the second constant current source; the second operational amplifier unit is configured to adjust the on-resistance of the second switching tube based on the voltage of the second voltage feedback point of the second constant current source and the voltage of the reference ground of the second constant current source, so that the voltage on the second sampling resistor is equal to the second reference voltage.

[0010] In one embodiment, the second operational amplifier unit includes a second operational amplifier, a non-inverting input terminal of the second operational amplifier is used to receive the second reference voltage, an inverting input terminal of the second operational amplifier is connected to the first terminal of the second sampling resistor, a ground terminal of the second operational amplifier is connected to the second terminal of the second sampling resistor, and an output terminal of the second operational amplifier is connected to the controlled terminal of the second switch tube.

[0011] In one embodiment, the first reference voltage is greater than the second reference voltage, and the resistance values ​​of the first sampling resistor and the second sampling resistor are equal; or, the first reference voltage is not greater than the second reference voltage, and the resistance ratio of the first sampling resistor to the second sampling resistor is equal to the ratio of the first reference voltage to the second reference voltage.

[0012] In one embodiment, a third constant current source is further included, wherein the input end of the third constant current source is connected to the rectifier module, and the output end of the third constant current source is used to be connected to the second load. The third constant current source is configured to adjust the impedance of the third constant current source according to a third reference voltage and the voltage of a third voltage feedback point in the third constant current source to generate a fourth drive current based on the first drive voltage; the third voltage feedback point in the third constant current source is also connected to the ground end of the first load.

[0013] In one embodiment, the rectifier module includes a rectifier unit, a unidirectional conductor and an energy storage capacitor; the input end of the rectifier unit is used to connect the input alternating current, and the rectifier unit is used to generate the second driving voltage based on the input alternating current; the positive pole of the unidirectional conductor is connected to the output end of the rectifier unit, and the negative pole of the unidirectional conductor is used to output the first driving voltage; the first end of the energy storage capacitor is connected to the negative pole of the unidirectional conductor, and the second end of the energy storage capacitor is grounded.

[0014] A second aspect of the present application provides a driving device, comprising: a main control device and an LED driving circuit as described above, wherein the main control device and the LED driving circuit are used to control the operation of the LED driving circuit.

[0015] A third aspect of the present application provides a lighting device, comprising: a first load and the LED driving circuit as described above, wherein the LED driving circuit is connected to the first load and is used to drive the first load to operate. Beneficial effects

[0016] The beneficial effects of the LED drive circuit, drive device and lighting device provided by the present application are: when the second drive voltage is less than the conduction threshold, the first constant current source drives the first load to work with a fixed first drive current. When the second drive voltage is greater than the conduction threshold, the second drive current generated by the second constant current source can affect the operation of the first constant current source. Since the second drive current needs to be transmitted to the first voltage feedback point of the first constant current source and transmitted to the first load through the first sampling resistor, the second drive current will increase the voltage of the first voltage feedback point. Finally, the first constant current source can output a third drive current based on the increased voltage at the first voltage feedback point, thereby achieving the effect of providing a constant current to the first load. When the first load is an LED light-emitting device, the flicker problem of the LED light-emitting device can be eliminated. At the same time, compared with using only a single constant current source, the second constant current source can also optimize the harmonics of the input current of the LED drive circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] FIG1 is a schematic structural diagram of an LED driving circuit provided in one embodiment of the present application;

[0019] FIG2 is a schematic diagram of a waveform of a second driving voltage;

[0020] FIG3 is a schematic diagram of a specific circuit of an LED driving circuit provided in one embodiment of the present application;

[0021] FIG4 is a schematic diagram of a waveform of a driving current when the first reference voltage is not less than the second reference voltage;

[0022] FIG5 is a schematic diagram of a waveform of a driving current when the first reference voltage is lower than the second reference voltage;

[0023] FIG6 is a schematic diagram of the waveforms of the input voltage and input current;

[0024] FIG7 is another specific circuit diagram of an LED driving circuit provided in an embodiment of the present application;

[0025] FIG8 is a schematic structural diagram of a driving device provided in one embodiment of the present application;

[0026] FIG9 is a schematic structural diagram of a lighting device provided in an embodiment of the present application. Modes for Carrying Out the Invention

[0027] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, this application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0028] It should be noted that when an element is referred to as being “connected to” another element, it can be directly connected to the another element or indirectly connected to the another element.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0030] FIG1 shows a schematic diagram of the structure of an LED driving circuit provided in an embodiment of the present application. For ease of illustration, only the parts related to this embodiment are shown, which are described in detail as follows:

[0031] An LED driving circuit 10 includes a rectifier module 100 , a first constant current source 200 , and a second constant current source 300 .

[0032] The rectifier module 100 is configured to generate a first driving voltage and a second driving voltage based on input AC power.

[0033] It should be noted that, as shown in Figure 2, after the input AC power VAC is rectified by the rectifier module 100, a second driving voltage V2 can be obtained. The rectifier module 100 can obtain the first driving voltage based on the second driving voltage V2. The waveform of the second driving voltage V2 is a steamed bun wave as shown in Figure 2.

[0034] The input end of the first constant current source 200 is connected to the rectifier module 100, and the output end of the first constant current source 200 and the reference ground of the first constant current source 200 are both used to connect to the first load 20. The output end of the first constant current source 200 is also the reference ground of the first constant current source 200. The first constant current source 200 is configured to adjust the on-resistance of the first constant current source 200 according to the first reference voltage and the voltage of the first voltage feedback point in the first constant current source 200 to generate and output a first driving current based on the first driving voltage. Wherein, the first load 20 can be an LED lamp group composed of light-emitting diodes. The output end of the first constant current source 200 is connected to the positive electrode of the first load 20, and the negative electrode of the first load 20 is grounded. Wherein, the first constant current source 200 includes a first sampling resistor, and the first sampling resistor is connected between the first voltage feedback point and the output end of the first constant current source.

[0035] It is understood that the voltage of the reference ground of the first constant current source 200 can be used as a reference voltage. By collecting the voltage at the first voltage feedback point, the voltage difference between the first voltage feedback point and the reference ground of the first constant current source 200 can be obtained. In other words, the voltage difference between the first voltage feedback point and the output terminal of the first constant current source 200 can be obtained. The first constant current source 200 can adjust its own on-resistance based on the obtained voltage difference between the first voltage feedback point and the output terminal of the first constant current source 200 so that the voltage difference between the first voltage feedback point and the output terminal of the first constant current source 200 is equal to the first reference voltage. By controlling the voltage applied to the first sampling resistor to be stable, the stable output of the first drive current is ensured. The first drive current is the current input from the input terminal of the first constant current source 200 and output from the output terminal of the first constant current source 200. When only the first constant current source 200 is operating, the first drive current is the actual current transmitted to the first load 20. Therefore, the first reference voltage and the first sampling resistor can be adjusted according to actual needs to control the actual current transmitted to the first load.

[0036] The input end of the second constant current source 300 is connected to the rectifier module 100, and the output end of the second constant current source 300 and the reference ground of the second constant current source 300 are both connected to the first voltage feedback point. The second constant current source 300 is configured to adjust the on-resistance of the second constant current source 300 according to the second reference voltage and the voltage of the second voltage feedback point in the second constant current source 300 when the second driving voltage V2 is greater than the on-threshold of the second constant current source 300, so as to generate and output a second driving current based on the second driving voltage V2. In some embodiments, the on-threshold of the first constant current source 200 is equal to the on-threshold of the second constant current source 300, and the on-threshold is less than the minimum value of the first driving voltage, and the on-threshold is greater than the minimum value of the second driving voltage V2.

[0037] It can be understood that the voltage of the reference ground of the second constant current source 300 can be used as a reference, and the voltage difference between the second voltage feedback point and the reference ground of the second constant current source 300 can be obtained by collecting the voltage of the second voltage feedback point, that is, the voltage difference between the second voltage feedback point and the output end of the second constant current source 300 can be obtained. The second constant current source 300 can adjust its own on-resistance according to the obtained voltage difference between the first voltage feedback point and the output end of the second constant current source 300, so that the voltage difference between the second voltage feedback point and the output end of the second constant current source 300 is equal to the second reference voltage, thereby ensuring the stable output of the second drive current. The second drive current is the current input by the input end of the second constant current source 300 and output from the output end of the second constant current source 300.

[0038] The second drive current is used to be transmitted to the first load 20 through the first sampling resistor to work and increase the voltage of the first voltage feedback point, so that the first constant current source 200 generates a third drive current based on the voltage of the first voltage feedback point after the second drive current is increased, and the sum of the second drive current and the third drive current is equal to the first drive current.

[0039] It should be noted that when the second driving voltage V2 is less than the turn-on threshold of the second constant current source 300, only the first constant current source 200 is used to power the first load 20. The first constant current source 200 can adjust the on-impedance of the first constant current source 200 according to the voltage of the first voltage feedback point, so that the voltage of the first voltage feedback point is equal to the first reference voltage. Finally, a stable first driving current can be provided to the first load 20 based on the stable voltage of the first voltage feedback point.

[0040] When the second driving voltage V2 is greater than the conduction threshold of the second constant current source 300, causing the second constant current source 300 to output the second driving current, the second driving current will increase the voltage at the first voltage feedback point. The first constant current source 200 can increase the on-resistance of the first constant current source 200 according to the increased voltage at the first voltage feedback point, ultimately maintaining the voltage at the first voltage feedback point stable, thereby providing a stable third driving current to the first load 20 based on the first reference voltage. At this time, the first load 20 is driven by the second driving current and the third driving current. When the first load 20 is an LED lamp, flickering of the LED lamp can be eliminated.

[0041] For example, assuming the first reference voltage is 1V and the first sampling resistor is 10Ω, when the second drive voltage V2 is less than the on-threshold of the second constant current source 300, the first drive current is 0.1A. When the second drive voltage V2 is greater than the on-threshold of the second constant current source 300, so that the second constant current source 300 outputs a second drive current of 0.08A, the second drive current causes the voltage at the first voltage feedback point to rise by 0.8V. The first constant current source 200 then adjusts its own impedance accordingly to generate and output a third drive current of 0.02A to replace the first drive current, so that the voltage at the first voltage feedback point reaches 1V. At this point, the sum of the second drive current and the third drive current is still equal to the first drive current, and the current received by the first load 20 remains constant.

[0042] In one embodiment, as shown in FIG3 , the first constant current source 200 further includes a first switch tube Q1 and a first operational amplifier unit 210. The first switch tube Q1 may be a MOS tube (Power MOSFET, power field effect transistor) or an IGBT tube (Insulate-Gate Bipolar Transistor, insulated gate bipolar transistor), and may be configured according to actual needs.

[0043] The first end of the first switching transistor Q1 serves as the input end of the first constant current source 200. The second end of the first switching transistor Q1 is connected to the first end of the first sampling resistor R1. The first end of the first sampling resistor R1 serves as the first voltage feedback point of the first constant current source 200. The second end of the first sampling resistor R1 serves as the output end of the first constant current source 200 and the reference ground GND1 of the first constant current source 200. The first operational amplifier unit 210 is configured to adjust the on-resistance of the first switching transistor Q1 (i.e., adjust the on-resistance from the first end of the first switching transistor Q1 to the second end of the first switching transistor Q1) based on the voltage at the first voltage feedback point of the first constant current source 200 and the voltage at the reference ground GND1 of the first constant current source 200, so that the voltage across the first sampling resistor R1 is equal to the first reference voltage REF1.

[0044] It is understood that by controlling the voltage provided by the first operational amplifier unit 210 to the controlled terminal of the first switch tube Q1, the on-resistance of the first switch tube Q1 can be adjusted, thereby achieving the effect of adjusting the on-resistance of the first constant current source 200. When the first constant current source 200 is operating normally, the specific value of the first drive current I1 can be calculated using the first formula: ILED=I1=REF1 / R1, where ILED is the actual current actually transmitted to the first load 20.

[0045] In one embodiment, the first operational amplifier unit 210 includes a first operational amplifier U1. A non-inverting input terminal of the first operational amplifier U1 is used to receive a first reference voltage REF1. An inverting input terminal of the first operational amplifier U1 is connected to a first terminal of a first sampling resistor R1. A ground terminal GND1 of the first operational amplifier U1 is connected to a second terminal of the first sampling resistor R1. An output terminal of the first operational amplifier U1 is connected to a controlled terminal of a first switch tube Q1.

[0046] The first operational amplifier U1 can adjust the output voltage according to the voltage difference between the non-inverting input terminal and the inverting input terminal, thereby controlling the on-resistance of the first switch tube Q1.

[0047] In one embodiment, the second constant current source 300 includes a second switch tube Q2, a second sampling resistor R2, and a second operational amplifier unit 310. The second switch tube Q2 can be a MOS tube (Power MOSFET, power field effect transistor) or an IGBT tube (Insulate-Gate Bipolar Transistor, insulated gate bipolar transistor).

[0048] The first end of the second switch Q2 serves as the input end of the second constant current source 300. The second end of the second switch Q2 is connected to the first end of the second sampling resistor R2. The first end of the second sampling resistor R2 serves as the second voltage feedback point of the second constant current source 300. The second end of the second sampling resistor R2 serves as the output end of the second constant current source 300 and the reference ground GND2 of the second constant current source 300. The second operational amplifier unit 310 is configured to adjust the on-resistance of the second switch Q2 based on the voltage at the second voltage feedback point of the second constant current source 300 and the voltage at the reference ground GND2 of the second constant current source 300, so that the voltage across the second sampling resistor R2 is equal to the second reference voltage REF2.

[0049] It can be understood that by controlling the voltage provided to the controlled end of the second switch tube Q2, the on-resistance of the second switch tube Q2 can be adjusted to achieve the effect of adjusting the on-resistance of the second constant current source 300. When the second constant current source 300 is operating normally, the specific value of the second drive current I2 can be calculated by the second formula: I2=REF2 / R2. At the same time, when the second drive current I2 is transmitted to the first load 20 through the first sampling resistor R1, the voltage of the first voltage feedback point will be increased. Due to the constant current characteristic of the first constant current source 200, a third drive current I3 lower than the first drive current I1 will be generated. The reduced third drive current I3 can be obtained by the third formula: I3=(REF1-REF2) / R1. Finally, the actual current ILED output to the first load 20 can be obtained by the fourth formula: ILED=REF2 / R2+(REF1-REF2) / R1.

[0050] By adjusting the first reference voltage REF1, the second reference voltage REF2, the first sampling resistor R1 and the second sampling resistor R2, the sum of the second drive current I2 and the third drive current I3 can be made equal to the first drive current I1, thereby achieving constant current output.

[0051] In one embodiment, the second operational amplifier unit 310 includes a second operational amplifier U2, a non-inverting input terminal of the second operational amplifier U2 is used to receive the second reference voltage REF2, an inverting input terminal of the second operational amplifier U2 is connected to the first terminal of the second sampling resistor R2, a ground terminal GND2 of the second operational amplifier U2 is connected to the second terminal of the second sampling resistor R2, and an output terminal of the second operational amplifier U2 is connected to the controlled terminal of the second switch tube Q2.

[0052] The second operational amplifier U2 can adjust the output voltage according to the voltage difference between the non-inverting input terminal and the inverting input terminal, thereby controlling the on-resistance of the second switch tube Q2.

[0053] In one embodiment, the first reference voltage REF1 is greater than the second reference voltage REF2 , and the resistances of the first sampling resistor R1 and the second sampling resistor R2 are equal.

[0054] It can be understood that, as shown in FIG4 , when the resistance of the first sampling resistor R1 is equal to the resistance of the second sampling resistor R2, if the second driving voltage V2 is less than the conduction threshold of the second constant current source 300, only the first constant current source 200 supplies power to the first load 20, and the actual current ILED is equal to the first driving current I1. If the second driving voltage V2 is greater than the conduction threshold of the second constant current source 300, then since the resistances of the first sampling resistor R1 and the second sampling resistor R2 are equal, the fourth formula can be simplified to obtain the fifth formula: ILED = REF1 / R1. The fifth formula shows that the actual current ILED at this time is equal to the first driving current I1 before the second constant current source 300 is turned on. Therefore, the actual current ILED remains stable.

[0055] If the first reference voltage REF1 is equal to the second reference voltage REF2 , it can be seen from the third formula that the first driving current I1 is zero, and the first load 20 is driven only by the second constant current source 300 .

[0056] In one embodiment, the first reference voltage REF1 is not greater than the second reference voltage REF2 , and the resistance ratio of the first sampling resistor R1 to the second sampling resistor R2 is equal to the ratio of the first reference voltage REF1 to the second reference voltage REF2 .

[0057] It is understood that when the first reference voltage REF1 is less than the second reference voltage REF2, as shown in FIG5 , if the second drive voltage V2 is less than the conduction threshold of the second constant current source 300, the second drive current I2 is zero, and the actual current ILED is equal to the first drive current I1. If the second drive voltage V2 is greater than the conduction threshold of the second constant current source 300, since the ratio of the resistance values ​​of the first sampling resistor R1 to the second sampling resistor R2 is equal to the ratio of the first reference voltage REF1 to the second reference voltage REF2, the voltage drop generated by the second drive current I2 across the first sampling resistor R1 can be made equal to the first reference voltage REF1, ultimately making the third drive current I3 zero, and the actual current ILED remains constant.

[0058] In one embodiment, as shown in FIG3 , the rectifier module 100 includes a rectifier unit 110 , a unidirectional conductor D1 , and an energy storage capacitor C1 .

[0059] The input terminal of the rectifier unit 110 is used to receive the input AC power VAC. The rectifier unit 110 is configured to generate and output the second driving voltage V2 based on the input AC power VAC from the output terminal of the rectifier unit 110. The input terminal of the second constant current source 300 is connected to the output terminal of the rectifier unit 110. The rectifier unit 110 may include a full-bridge rectifier circuit composed of diodes, configured to rectify the input AC power VAC to output the second driving voltage V2.

[0060] The positive electrode of the unidirectional conductor D1 is connected to the output terminal of the rectifier unit 110, the first end of the energy storage capacitor C1 and the first constant current source 200 are both connected to the negative electrode of the unidirectional conductor D1, and the second end of the energy storage capacitor C1 is grounded. By charging and discharging the energy storage capacitor C1, a first driving voltage can be generated and output. At the same time, according to actual conditions, the parameters of the energy storage capacitor C1 can be configured so that the voltage on the energy storage capacitor C1 is always greater than the conduction threshold of the first constant current source 200, thereby keeping the first constant current source 200 in the on state. The unidirectional conductor D1 can be a diode.

[0061] It should be noted that when the second driving voltage V2 is greater than the voltage on the energy storage capacitor C1, the energy storage capacitor C1 can be charged through the unidirectional conductor D1. When the second driving voltage V2 is less than the conduction threshold of the first constant current source 200, the energy storage capacitor C1 can be discharged to provide the first driving voltage to power the first constant current source 200. At this time, the unidirectional conductor D1 is reversely turned off, and the electric energy output by the energy storage capacitor C1 cannot be transmitted to the second constant current source 300 through the unidirectional conductor D1, thereby turning off the second constant current source 300.

[0062] The waveforms of the input voltage Vin and input current Iin received by the rectifier module 100 are shown in FIG6 . It should be noted that, in the T0 to T1 time period, the second driving voltage V2 obtained after the input voltage Vin is rectified is greater than the conduction threshold of the second constant current source 300, and the second constant current source 300 outputs the second driving current I2. At the same time, the first driving voltage can be provided to the first constant current source 200 through the unidirectional conductor D1 and the third driving current I3 is generated. At this time, the input current Iin is equal to the sum of the second driving current I2 and the third driving current I3. In the T1 to T2 time period, the second driving voltage V2 is greater than the voltage on the energy storage capacitor C1. Therefore, the input current Iin needs to charge the energy storage capacitor C1 while providing current to the first constant current source 200 and the second constant current source 300, so that the input current Iin increases rapidly until it reaches the T2 moment. During the time period from T2 to T3, the input current Iin reaches a peak current because the voltage difference between the second driving voltage V2 and the energy storage capacitor C1 reaches a maximum value. Thereafter, the input current Iin begins to decrease until it reaches time T3, when the energy storage capacitor C1 is fully charged, and the voltage on the energy storage capacitor C1 (i.e., the first driving voltage) is equal to the second driving voltage V2. The energy storage capacitor C1 is no longer charged. At this time, the second constant current source 300 outputs a second driving current I2 based on the second driving voltage V2, and the first constant current source 200 outputs a third driving current I3 based on the first driving voltage, so that the input current Iin remains stable. At this time, the input current Iin is equal to the actual current ILED. The second constant current source 300 can ensure that the input current Iin is always no less than the second drive current I2 when the second drive voltage V2 is greater than the conduction threshold of the second constant current source 300. Furthermore, according to actual conditions, by adjusting the parameters of the energy storage capacitor C1 and the conduction threshold of the second constant current source 300, the input current Iin can be made ≥ 5% of the peak current before the voltage conduction angle is 60°; the input current Iin can be made to reach a maximum value before the voltage conduction angle is 65°; and the input current Iin can be made ≥ 5% of the peak current when the voltage conduction angle is 90°, so as to optimize the harmonics of the input current Iin and meet the requirements of certification standards such as CCC and CE.

[0063] In one embodiment, as shown in FIG7 , the LED driving circuit 10 further includes a third constant current source 400 . The input end of the third constant current source 400 is connected to the rectifier module 100 , and the output end of the third constant current source 400 is used to be connected to the second load 30 . The third constant current source 400 is configured to adjust the impedance of the third constant current source 400 based on the third reference voltage REF3 and the voltage of the third voltage feedback point in the third constant current source 400 to generate a fourth driving current based on the first driving voltage. The structure of the third constant current source 400 can be equal to that of the first current source 200 .

[0064] The third voltage feedback point in the third constant current source 400 is also connected to the ground terminal of the first load 20 .

[0065] The third constant current source 400 can realize a wide voltage input of the LED driving circuit 10. When the average input voltage is high, both the first constant current source 200 and the second constant current source 300 are turned on to drive the first load 20 and the second load 30 to operate simultaneously. When the average input voltage is low, only the third constant current source 400 can be turned on to drive only the second load 30 to operate.

[0066] The third constant current source 400 includes a third switch tube Q3, a third sampling resistor R3, and a third operational amplifier unit 410. The third switch tube Q3 may be a MOS tube (Power MOSFET, power field effect transistor) or an IGBT tube (Insulate-Gate Bipolar Transistor, insulated gate bipolar transistor).

[0067] A first end of the third switching transistor Q3 serves as an input end of the third constant current source 400. A second end of the third switching transistor Q3 is connected to a first end of a third sampling resistor R3. The first end of the third sampling resistor R3 serves as a first voltage feedback point of the third constant current source 400. A second end of the third sampling resistor R3 serves as an output end of the third constant current source 400 and a reference ground GND3 of the third constant current source 400. The third operational amplifier unit 410 is configured to adjust the on-resistance of the third switching transistor Q3 based on the voltage at the third voltage feedback point of the third constant current source 400 and the voltage at the reference ground GND3 of the third constant current source 400, so that the voltage across the third sampling resistor R3 is equal to the third reference voltage REF3.

[0068] It is understandable that the on-resistance of the third switch tube Q3 can be adjusted by controlling the voltage provided to the controlled terminal of the third switch tube Q3 by the third operational amplifier unit 410, thereby achieving the effect of adjusting the on-resistance of the third constant current source 400.

[0069] In one embodiment, the third operational amplifier unit 410 includes a third operational amplifier U3, a non-inverting input terminal of the third operational amplifier U3 is used to receive a third reference voltage REF3, an inverting input terminal of the third operational amplifier U3 is connected to a first terminal of a third sampling resistor R3, a ground terminal of the third operational amplifier U3 is connected to a second terminal of the third sampling resistor R3, and an output terminal of the third operational amplifier U3 is connected to a controlled terminal of a third switch tube Q3.

[0070] The third operational amplifier U3 can adjust the output voltage according to the voltage difference between the non-inverting input terminal and the inverting input terminal, thereby controlling the on-resistance of the third switch tube Q3.

[0071] FIG8 shows a schematic diagram of the structure of a driving device provided in an embodiment of the present application. For ease of explanation, only the parts related to this embodiment are shown, which are described in detail as follows:

[0072] The driving device 40 includes a main control device 50 and an LED driving circuit 10 as in any of the above embodiments. The main control device 50 and the LED driving circuit 10 are used to control the operation of the LED driving circuit 10. The main control device 50 can be an electronic device such as a single chip device or a microprocessor.

[0073] The main control device 50 can output the corresponding first reference voltage REF1 and second reference voltage REF2 to control the operation of the LED driving circuit 10 .

[0074] FIG9 shows a schematic structural diagram of a lighting device provided in an embodiment of the present application. For ease of illustration, only the parts related to this embodiment are shown, which are described in detail as follows:

[0075] The lighting device 60 includes a first load 20 and an LED driving circuit 10 according to any of the above embodiments, wherein the LED driving circuit 10 is connected to the first load 20 and is used to drive the first load 20. The first load 20 includes an LED lamp group composed of light-emitting diodes.

[0076] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0077] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0078] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. An LED driving circuit, characterized in that: include: A rectifier module, the rectifier module is used to generate a first driving voltage and a second driving voltage based on an input alternating current; A first constant current source, wherein an input end of the first constant current source is connected to the rectifier module, an output end of the first constant current source and a reference ground of the first constant current source are both used to be connected to a first load, and the first constant current source is configured to adjust an on-resistance of the first constant current source according to a first reference voltage and a voltage of a first voltage feedback point in the first constant current source, so as to generate and output a first driving current based on a first driving voltage; wherein the first constant current source comprises a first sampling resistor, and the first sampling resistor is connected between the first voltage feedback point and the output end of the first constant current source; a second constant current source, wherein the input end of the second constant current source is connected to the rectifier module, the output end of the second constant current source and the reference ground of the second constant current source are both connected to the first voltage feedback point, and the second constant current source is configured to adjust the on-resistance of the second constant current source according to the second reference voltage and the voltage of the second voltage feedback point in the second constant current source when the second driving voltage is greater than the on-threshold of the second constant current source, so as to generate and output a second driving current based on the second driving voltage; wherein the second constant current source comprises a second sampling resistor, and the second sampling resistor is connected between the second voltage feedback point and the output end of the second constant current source; The second drive current is used to be transmitted to the first load through the first sampling resistor to increase the voltage of the first voltage feedback point so that the first constant current source generates a third drive current, and the sum of the second drive current and the third drive current is equal to the first drive current.

2. The LED driving circuit according to claim 1, characterized in that: The first constant current source also includes a first switch tube and a first operational amplifier unit; The first end of the first switch tube is the input end of the first constant current source, the second end of the first switch tube is connected to the first end of the first sampling resistor, the first end of the first sampling resistor is the first voltage feedback point of the first constant current source, and the second end of the first sampling resistor is the output end of the first constant current source and the reference ground of the first constant current source; The first operational amplifier unit is configured to adjust the on-resistance of the first switch tube based on the voltage of the first voltage feedback point of the first constant current source and the voltage of the reference ground of the first constant current source so that the voltage on the first sampling resistor is equal to the first reference voltage.

3. The LED driving circuit according to claim 2, characterized in that: The first operational amplifier unit includes a first operational amplifier, a non-inverting input terminal of the first operational amplifier is used to receive the first reference voltage, an inverting input terminal of the first operational amplifier is connected to the first end of the first sampling resistor, a ground terminal of the first operational amplifier is connected to the second end of the first sampling resistor, and an output terminal of the first operational amplifier is connected to the controlled end of the first switch tube.

4. The LED driving circuit according to claim 2, characterized in that: The first switch tube includes a MOS tube or an IGBT tube.

5. The LED driving circuit according to claim 2, characterized in that: The second constant current source includes a second switch tube and a second operational amplifier unit; The first end of the second switch tube is the input end of the second constant current source, the second end of the second switch tube is connected to the first end of the second sampling resistor, the first end of the second sampling resistor is the second voltage feedback point of the second constant current source, and the second end of the second sampling resistor is the output end of the second constant current source and the reference ground of the second constant current source; The second operational amplifier unit is configured to adjust the on-resistance of the second switch tube based on the voltage of the second voltage feedback point of the second constant current source and the voltage of the reference ground of the second constant current source so that the voltage on the second sampling resistor is equal to the second reference voltage.

6. The LED driving circuit according to claim 5, characterized in that: The second operational amplifier unit includes a second operational amplifier, a non-inverting input terminal of the second operational amplifier is used to receive the second reference voltage, an inverting input terminal of the second operational amplifier is connected to the first terminal of the second sampling resistor, a ground terminal of the second operational amplifier is connected to the second terminal of the second sampling resistor, and an output terminal of the second operational amplifier is connected to the controlled terminal of the second switch tube.

7. The LED driving circuit according to claim 5, characterized in that: The second switch tube includes a MOS tube or an IGBT tube.

8. The LED driving circuit according to claim 5, characterized in that: The first reference voltage is greater than the second reference voltage, and the resistance values ​​of the first sampling resistor and the second sampling resistor are equal; Alternatively, the first reference voltage is not greater than the second reference voltage, and a resistance ratio of the first sampling resistor to that of the second sampling resistor is equal to a ratio of the first reference voltage to the second reference voltage.

9. The LED driving circuit according to claim 1, characterized in that: The rectifier module includes a rectifier unit, a unidirectional conductor and an energy storage capacitor; The input end of the rectifier unit is used to receive the input alternating current, and the rectifier unit is used to generate the second driving voltage based on the input alternating current; The positive electrode of the one-way conductor is connected to the output end of the rectifying unit, and the negative electrode of the one-way conductor is used to output the first driving voltage; The first end of the energy storage capacitor is connected to the negative electrode of the unidirectional conductor, and the second end of the energy storage capacitor is grounded.

10. The LED driving circuit according to claim 1, characterized in that: Also includes a third constant current source, the input end of the third constant current source is connected to the rectifier module, the output end of the third constant current source is used to be connected to the second load, and the third constant current source is configured to adjust the impedance of the third constant current source according to a third reference voltage and a voltage of a third voltage feedback point in the third constant current source, so as to generate a fourth driving current based on the first driving voltage; The third voltage feedback point in the third constant current source is also connected to the ground terminal of the first load.

11. The LED driving circuit according to claim 10, characterized in that: The third constant current source includes a third switch tube, a third sampling resistor and a third operational amplifier unit; The first end of the third switch tube is the input end of the third constant current source, the second end of the third switch tube is connected to the first end of the third sampling resistor, the first end of the third sampling resistor is the first voltage feedback point of the third constant current source, and the second end of the third sampling resistor is the output end of the third constant current source and the reference ground of the third constant current source; the third operational amplifier unit is configured to adjust the on-impedance of the third switch tube based on the voltage of the third voltage feedback point of the third constant current source and the voltage of the reference ground of the third constant current source, so that the voltage on the third sampling resistor is equal to the third reference voltage.

12. The LED driving circuit according to claim 11, characterized in that: The third operational amplifier unit includes a third operational amplifier, a non-inverting input terminal of the third operational amplifier is used to receive the third reference voltage, an inverting input terminal of the third operational amplifier is connected to the first terminal of the third sampling resistor, a ground terminal of the third operational amplifier is connected to the second terminal of the third sampling resistor, and an output terminal of the third operational amplifier is connected to the controlled terminal of the third switch tube.

13. A driving device, characterized in that: It comprises: a main control device and an LED driving circuit as described in any one of claims 1 to 11, wherein the main control device and the LED driving circuit are used to control the operation of the LED driving circuit.

14. A lighting device, characterized in that: include: A first load and an LED driving circuit as described in any one of claims 1 to 11, wherein the LED driving circuit is connected to the first load and is used to drive the first load to operate.

15. The lighting device according to claim 14, characterized in that The first load includes an LED lamp group.

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