Analog dimming circuit, analog dimming method and LED driving circuit

Abstract

The present invention proposes an analog dimming circuit, an analog dimming method and an LED driving circuit. The analog dimming circuit is used to generate a dimming signal to control the operation of the LED driving circuit, and the analog dimming circuit includes an analog signal processing circuit and a chopping circuit. The input end of the analog signal processing circuit is used to receive a first analog signal, and the analog signal processing circuit is used to generate a digital signal according to the first analog signal. The first input end of the chopping circuit is coupled to the output end of the analog signal processing circuit, the second input end of the chopping circuit is used to receive a second analog signal, and the chopping circuit is used to chop the second analog signal according to the digital signal to output a dimming signal. The analog dimming circuit, the analog dimming method and the LED driving circuit proposed by the present invention can realize the combined dimming function of dual analog signal input in the LED driving scheme, ensure the dimming accuracy of the LED driving circuit, and the circuit structure is relatively simple and the implementation cost is low.

Description

Technical Field

[0001] The invention belongs to the field of power electronics, and relates to an LED dimming technology, and in particular to an analog dimming circuit, an analog dimming method and an LED driving circuit. Background Art

[0002] In the LED driving circuit, the working state of the system can usually be adjusted by analog signal or PWM signal. The existing LED dimming methods include analog signal input dimming, PWM signal input dimming and analog signal combined with PWM signal input dimming. In a specific application scenario, two control signals are required to control the same adjustment amount. For example, both control signals are analog signals, one of which is used to control the maximum amplitude of the dimming signal, and the other control signal is used to control the size of the dimming signal. The dimming signal is controlled by adjusting the two control signals to achieve dimming control of the LED driving circuit. In the scenario where both control signals are analog signals, the most direct way is to use a multiplier solution to achieve the modulation of dual analog signals, but the implementation cost of this solution is high, and it is difficult to implement inside the chip, and it also leads to relatively poor control accuracy.

[0003] In view of this, it is necessary to provide a new structure or control method to solve at least part of the above technical problems. Summary of the invention

[0004] In response to one or more problems in the prior art, the present invention proposes an analog dimming circuit, an analog dimming method and an LED driving circuit, which can realize the combined dimming function of dual analog signal inputs, ensure the dimming accuracy of the LED driving circuit, and have a relatively simple circuit structure and low implementation cost.

[0005] According to one aspect of the present invention, an analog dimming circuit is used to generate a dimming signal to control the operation of an LED driving circuit, and the analog dimming circuit includes:

[0006] an analog signal processing circuit, whose input terminal is used to receive a first analog signal and to generate a digital signal according to the first analog signal; and

[0007] The chopping circuit has a first input terminal coupled to the output terminal of the analog signal processing circuit and a second input terminal for receiving a second analog signal, and is used for performing chopping processing on the second analog signal according to the digital signal to output a dimming signal.

[0008] As a preferred embodiment of the present invention, the chopper circuit comprises:

[0009] A first switch device, a first end of which is used to receive a second analog signal, a second end of which outputs a dimming signal, and a control end of which is coupled to an output end of the analog signal processing circuit; and

[0010] A second switch device, a first end of which is coupled to the second end of the first switch device, and a second end of which is coupled to the ground; wherein,

[0011] The signal received by the control end of the first switch device is a first control signal, and the signal received by the control end of the second switch device is a second control signal. The first control signal and the second control signal are complementary.

[0012] As a preferred embodiment of the present invention, the analog signal processing circuit is used to generate a digital signal according to the periodic fundamental wave signal and the first analog signal.

[0013] As a preferred embodiment of the present invention, the analog dimming circuit also includes: an operation circuit, whose first input terminal is coupled to the second analog signal terminal to receive the second analog signal, and whose second input terminal is coupled to the adjustment signal terminal to receive the adjustment signal, and is used to perform operation processing based on the second analog signal and the adjustment signal to obtain a bias signal.

[0014] As a preferred embodiment of the present invention, both the first switch device and the second switch device are switch tubes.

[0015] As a preferred embodiment of the present invention, the periodic fundamental wave signal is a sawtooth wave or a triangle wave.

[0016] As a preferred embodiment of the present invention, the operation circuit is an adder or a subtractor.

[0017] According to another aspect of the present invention, an LED driving circuit is provided, the LED driving circuit comprising the analog dimming circuit as described in any one of the above items, the analog dimming circuit being used to output a dimming signal to control the switching state of a main switch tube in the LED driving circuit.

[0018] According to another aspect of the present invention, an analog dimming method is used for dimming control of an analog dimming circuit, and the analog dimming method includes:

[0019] receiving a first analog signal, and generating a digital signal according to the first analog signal; and

[0020] A second analog signal is received, and the second analog signal is chopped according to the digital signal, thereby outputting a dimming signal to control the operation of the LED driving circuit.

[0021] As a preferred embodiment of the present invention, the step of chopping the second analog signal according to the digital signal specifically includes: controlling the switching states of the first switching device and the second switching device respectively according to the digital signal to achieve chopping of the second analog signal.

[0022] The present invention proposes an analog dimming circuit, an analog dimming method and an LED driving circuit. The analog dimming circuit is used to generate a dimming signal to control the operation of the LED driving circuit, and the analog dimming circuit includes an analog signal processing circuit and a chopping circuit. The input end of the analog signal processing circuit is used to receive a first analog signal, and the analog signal processing circuit is used to generate a digital signal according to the first analog signal. The first input end of the chopping circuit is coupled to the output end of the analog signal processing circuit, the second input end of the chopping circuit is used to receive a second analog signal, and the chopping circuit is used to chop the second analog signal according to the digital signal to output a dimming signal. The analog dimming circuit, the analog dimming method and the LED driving circuit proposed by the present invention can realize the combined dimming function of dual analog signal input in the LED driving scheme, ensure the dimming accuracy of the LED driving circuit, and the circuit structure is relatively simple and the implementation cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide a further understanding of the present invention and are used together with the description to explain the embodiments of the present invention, but do not constitute a limitation of the present invention. In the accompanying drawings:

[0024] Figure 1 A schematic diagram of the circuit structure of an analog dimming circuit according to an embodiment of the present invention is shown;

[0025] Figure 2 A circuit structure schematic diagram of an analog dimming circuit according to another embodiment of the present invention is shown;

[0026] Figure 3 A schematic diagram showing waveforms of signals in an analog dimming circuit according to an embodiment of the present invention is shown;

[0027] Figure 4 A schematic diagram showing the steps of an analog dimming method according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0028] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0029] The description in this section is only for several typical embodiments, and the present invention is not limited to the scope of the embodiments. The combination of different embodiments, the mutual replacement of some technical features in different embodiments, and the mutual replacement of the same or similar prior art means with some technical features in the embodiments are also within the scope of the description and protection of the present invention.

[0030] "Coupled" or "connected" in the specification includes both direct connection and indirect connection. Indirect connection is a connection through an intermediate medium, such as a connection through an electrically conductive medium such as a conductor, wherein the electrically conductive medium may contain parasitic inductance or parasitic capacitance, or a connection through an intermediate circuit or component described in the embodiments in the specification; an indirect connection may also include a connection through other active or passive devices on the basis of achieving the same or similar functions, such as a connection through circuits or components such as switches, signal amplification circuits, and follower circuits. "Multiple" or "many" means two or more. In addition, in the present invention, words such as first and second are mainly used to distinguish one technical feature from another technical feature, and do not necessarily require or imply that there is a certain actual relationship or order between these technical features.

[0031] An embodiment of the present invention discloses an analog dimming circuit for generating a dimming signal to control the operation of an LED driving circuit, and the analog dimming circuit includes an analog signal processing circuit and a chopping circuit. In the analog dimming circuit, dimming control of the LED driving circuit is achieved through two analog signals. Specifically, the dimming signal is adjusted by two analog signals, and the dimming signal can be used to control the switching state of the main switch tube in the LED driving circuit, thereby controlling the output of the LED driving circuit. The input end of the analog signal processing circuit receives a first analog signal, and the analog signal processing circuit is used to generate a digital signal according to the first analog signal. The first input end of the chopping circuit is coupled to the output end of the analog signal processing circuit, and the second input end of the chopping circuit receives a second analog signal. The chopping circuit is used to chop the second analog signal according to the digital signal to output a dimming signal.

[0032] In one embodiment of the present invention, Figure 1As shown, the analog dimming circuit 10 includes an analog signal processing circuit 11 and a chopping circuit 12. The input end of the analog signal processing circuit 11 is coupled to the first analog signal end to receive the first analog signal ADIM1, and the analog signal processing circuit 11 is used to generate a digital signal PWM1 according to the first analog signal ADIM1. The first input end of the chopping circuit 12 is coupled to the output end of the analog signal processing circuit 11, and the second input end of the chopping circuit 12 is coupled to the second analog signal end to receive the second analog signal ADIM2. The chopping circuit 12 performs chopping processing on the second analog signal according to the digital signal PWM1 to obtain a dimming signal Vdim, and the output end of the chopping circuit 12 outputs the dimming signal Vdim. In one embodiment, the chopping circuit 12 includes a first switching device Q1 and a second switching device Q2. The signal received by the control end of the first switching device Q1 is a first control signal, and the signal received by the control end of the second switching device Q2 is a second control signal, and the first control signal and the second control signal are complementary. Exemplarily, when the first control signal is at a first level (e.g., a high level), the second control signal is at a second level (e.g., a low level); when the first control signal is at a second level (e.g., a low level), the second control signal is at a first level (e.g., a high level). In a specific embodiment, the chopping circuit 12 includes a first switching device Q1, a second switching device Q2, and a NOT gate. The first end of the first switching device Q1 is coupled to the second analog signal end to receive the second analog signal ADIM2, the second end of the first switching device Q1 is used to output the dimming signal Vdim, and the control end of the first switching device Q1 is coupled to the output end of the analog signal processing circuit 11. The first end of the second switching device Q2 is coupled to the second end of the first switching device Q1, and the second end of the second switching device Q2 is coupled to the ground. The output end of the analog signal processing circuit is also coupled to the input end of the NOT gate, and the output end of the NOT gate is coupled to the control end of the second switching device Q2.

[0033] In another embodiment, the chopper circuit includes a first switch device Q1, a second switch device Q2, and a NOT gate. The first end of the first switch device Q1 is coupled to the second analog signal end to receive the second analog signal ADIM2, the second end of the first switch device Q1 is used to output the dimming signal Vdim, and the control end of the first switch device Q1 is coupled to the output end of the analog signal processing circuit. The first end of the second switch device Q2 is coupled to the second end of the first switch device Q1, and the second end of the second switch device Q2 is coupled to the ground. The output end of the analog signal processing circuit is also coupled to the input end of the NOT gate, and the output end of the NOT gate is coupled to the control end of the first switch device Q1.

[0034] In one embodiment of the present invention, Figure 1 and Figure 3 As shown, the analog signal processing circuit is used to generate a digital signal PWM1 according to the periodic fundamental wave signal and the first analog signal ADIM1. Figure 3In the illustrated embodiment, the periodic fundamental wave signal is a triangular wave signal. The triangular wave signal varies back and forth within the range of voltage VDIM_0 and voltage VDIM_full. When the first dimming signal is voltage VDIM_0, the duty cycle of the digital signal PWM1 is zero, and at this time the dimming signal Vdim is zero. When the first dimming signal is voltage VDIM_full, the duty cycle of the digital signal PWM1 is 1, and at this time the dimming signal Vdim is the second analog signal ADIM2. When the first dimming signal is a certain value between voltage VDIM_0 and voltage VDIM_full, the duty cycle of the digital signal PWM1 is k, where 0 < k < 1. At this time, the dimming signal Vdim is ADIM2*k, where ADIM2 can be the voltage value of the second analog signal. In an embodiment such as Figure 3 In the embodiment, when the first analog signal ADIM1 is greater than the triangular wave signal, the digital signal is in the first level state (for example, high level); when the first analog signal ADIM1 is less than the triangular wave signal, the digital signal is in the second level state (for example, low level). The second analog signal is chopped by the digital signal PWM1 to obtain the dimming signal Vdim. In another embodiment, the periodic fundamental wave signal is a sawtooth wave signal.

[0035] In an embodiment of the present invention, the dimming accuracy of the first analog signal is lower than that of the second analog signal. By converting the first analog signal with a lower dimming accuracy requirement into the digital signal PWM1, and then using the digital signal PWM1 to chop the second analog signal with a higher dimming accuracy requirement to obtain the dimming signal Vdim, the combined dimming control of the two-channel analog signal is realized. In a specific embodiment, the first analog signal adjusts the output current of the LED driving circuit to vary between 0-100% within the range of voltage VDIM_0 to voltage VDIM_full. When the output current is 100%, the LED driving circuit ensures the operation of the LED lamp with the maximum output current. Similarly, the second analog signal adjusts the output current of the LED driving circuit to vary between 0-100% within the range of voltage VDIM_0' to voltage VDIM_full'. Among them, the dimming accuracy of the first analog signal is different from that of the second analog signal.

[0036] In an embodiment of the present invention, such as Figure 2As shown, the analog dimming circuit 20 includes an analog signal processing circuit 21, a chopping circuit and an operation circuit 23. The input end of the analog signal processing circuit 21 is coupled to the first analog signal end to receive the first analog signal ADIM1, and the analog signal processing circuit 21 is used to generate a digital signal PWM1 according to the first analog signal ADIM1. The first input end of the operation circuit 23 is coupled to the second analog signal end to receive the second analog signal ADIM2, and the second input end of the operation circuit 23 is coupled to the adjustment signal end to receive the adjustment signal VDIM2. The operation circuit 23 is used to perform operation processing according to the second analog signal ADIM2 and the adjustment signal VDIM2 to obtain a bias signal to achieve bias adjustment of the second analog signal ADIM2. In one embodiment, the operation circuit 23 is an adder, and the bias signal is obtained by performing an addition operation processing on the second analog signal and the adjustment signal. In another embodiment, the operation circuit 23 is a subtractor, and the bias signal is obtained by performing a subtraction operation processing on the second analog signal and the adjustment signal. As shown in FIG. Figure 2 As shown, the chopping circuit includes a first switching device Q1, a second switching device Q2 and a NOT gate. The first end of the first switching device Q1 is coupled to the output end of the operation circuit 23, and the control end of the first switching device Q1 is coupled to the output end of the analog signal processing circuit 21. The first end of the second switching device Q2 is coupled to the second end of the first switching device Q1, the input end of the NOT gate is coupled to the output end of the analog signal processing circuit 21, the output end of the NOT gate is coupled to the control end of the second switching device Q2, and the second end of the second switching device Q2 is coupled to the ground. The switching states of the first switching device Q1 and the second switching device Q2 in the chopping circuit are controlled by the digital signal PWM1 to realize the chopping processing of the second analog signal, and the dimming signal Vdim is output at the second end of the first switching device Q1.

[0037] In one embodiment of the present invention, the same adjustment amount in the LED driving circuit is controlled by two analog signals, namely, a first analog signal and a second analog signal. The first analog signal is used to control the magnitude of the dimming signal, and the second analog signal is used to control the maximum amplitude of the dimming signal. The dimming signal is adjusted and controlled by the coordinated adjustment of the two analog signals to achieve dimming control of the LED driving circuit. Specifically, the first analog signal is converted into a digital signal PWM1, and the second analog signal is chopped according to the digital signal PWM1 to obtain a dimming signal.

[0038] In one embodiment of the present invention, the first switch device and the second switch device are both switch tubes. In a specific embodiment, the first switch device and the second switch device are respectively one of a metal oxide semiconductor field effect transistor (MOSFET), a junction field effect transistor (JFET), and an insulated gate bipolar transistor (IGBT). In one embodiment, the first switch device and the second switch device are both metal oxide semiconductor field effect transistors, the drain of the first switch device is coupled to the second analog signal terminal to receive the second analog signal, and the gate of the first switch device is coupled to the output terminal of the analog signal processing circuit. The drain of the second switch device is coupled to the source of the first switch device, the gate of the second switch device is coupled to the output terminal of the analog signal processing circuit, and the source of the second switch device is coupled to the ground.

[0039] An embodiment of the present invention further discloses an LED driving circuit, the LED driving circuit includes an analog dimming circuit as described in any of the above items, the analog dimming circuit is used to output a dimming signal to control the switching state of the main switch tube in the LED driving circuit. The output current of the LED driving circuit can be controlled by adjusting the dimming signal. Specifically, the switching state of the main switch tube in the LED driving circuit is controlled according to the dimming signal and the current sampling signal to achieve control of the output current. The current sampling signal can characterize the magnitude of the output current of the LED driving circuit, and can be obtained by sampling the current flowing through the main switch tube. In a specific embodiment, the current sampling signal is a sampled voltage signal characterizing the output current of the LED driving circuit.

[0040] An embodiment of the present invention further discloses an analog dimming method, which is used for dimming control of an analog dimming circuit. Figure 4 As shown, the analog dimming methods include:

[0041] Step S100, receiving a first analog signal, and generating a digital signal according to the first analog signal;

[0042] Step S200: receiving a second analog signal, and chopping the second analog signal according to the digital signal, thereby outputting a dimming signal to control the operation of the LED driving circuit.

[0043] In one embodiment of the present invention, the analog signal processing circuit receives a first analog signal and generates a digital signal according to the first analog signal. The chopping circuit receives a second analog signal and a digital signal and performs chopping processing on the second analog signal according to the digital signal, thereby outputting a dimming signal to control the operation of the LED driving circuit. The analog signal processing circuit generates a digital signal according to a periodic fundamental wave signal and the first analog signal. Specifically, the periodic fundamental wave signal is a triangular wave signal or a sawtooth wave signal.

[0044] In another embodiment of the present invention, the step of chopping the second analog signal according to the digital signal specifically includes: the chopping circuit controls the switching states of the first switching device and the second switching device respectively according to the digital signal to achieve chopping of the second analog signal.

[0045] In one embodiment of the present invention, the dimming accuracy of the first analog signal is lower than the dimming accuracy of the second analog signal.

[0046] An analog dimming circuit, an analog dimming method and an LED driving circuit proposed in the present invention can realize a combined dimming function of dual analog signal inputs in an LED driving scheme, thereby ensuring the dimming accuracy of the LED driving circuit, and the circuit structure is relatively simple and the implementation cost is low.

[0047] Those skilled in the art should know that the logic controls such as "high level" and "low level", "set" and "reset", "AND gate" and "OR gate", "non-inverting input terminal" and "inverting input terminal" in the logic controls involved in the specification or drawings can be interchanged or changed with each other, and the same function or purpose as the above embodiment can be achieved by adjusting the subsequent logic controls.

[0048] The description and application of the present invention here are illustrative, and it is not intended to limit the scope of the present invention to the above-mentioned embodiments. The effects or advantages involved in the specification may not be reflected in the actual experimental examples due to the uncertainty of specific condition parameters or other factors, and the effects or advantages are not used to limit the scope of the invention. The deformation and change of the embodiments disclosed here are possible, and the replacement of the embodiments and the various equivalent parts are well known to those of ordinary skill in the art. It should be clear to those skilled in the art that the present invention can be implemented in other forms, structures, arrangements, proportions, and with other components, materials and parts without departing from the spirit or essential features of the present invention. Other deformations and changes can be made to the embodiments disclosed here without departing from the scope and spirit of the present invention.

Claims

1. An analog dimming circuit for generating a dimming signal to control the operation of an LED driving circuit, characterized in that: The analog dimming circuit comprises: an analog signal processing circuit, whose input terminal is used to receive a first analog signal and to generate a digital signal according to the first analog signal; and A chopper circuit, wherein a first input terminal is coupled to an output terminal of the analog signal processing circuit, and a second input terminal is used to receive a second analog signal, and is used to chop the second analog signal according to the digital signal to output a dimming signal; the chopper circuit comprises: A first switch device, a first end of which is used to receive a second analog signal, a second end of which outputs a dimming signal, and a control end of which is coupled to an output end of the analog signal processing circuit; and A second switch device, a first end of which is coupled to the second end of the first switch device, and a second end of which is coupled to the ground; wherein, The signal received by the control end of the first switch device is a first control signal, and the signal received by the control end of the second switch device is a second control signal. The first control signal and the second control signal are complementary.

2. The analog dimming circuit according to claim 1, characterized in that: The analog signal processing circuit is used to generate a digital signal according to the periodic fundamental wave signal and the first analog signal.

3. The analog dimming circuit according to claim 1, characterized in that: The analog dimming circuit also includes: The operation circuit has a first input terminal coupled to the second analog signal terminal to receive the second analog signal, and a second input terminal coupled to the adjustment signal terminal to receive the adjustment signal, and is used to perform operation processing according to the second analog signal and the adjustment signal to obtain a bias signal.

4. The analog dimming circuit according to claim 1, characterized in that: The first switch device and the second switch device are both switch tubes.

5. The analog dimming circuit according to claim 2, characterized in that: The periodic fundamental wave signal is a sawtooth wave or a triangle wave.

6. The analog dimming circuit according to claim 3, characterized in that: The operation circuit is an adder or a subtractor.

7. An LED driving circuit, characterized in that: The LED driving circuit comprises the analog dimming circuit as described in any one of claims 1 to 6, and the analog dimming circuit is used to output a dimming signal to control the switching state of a main switch tube in the LED driving circuit.

8. An analog dimming method for dimming control of an analog dimming circuit, characterized in that: The analog dimming method comprises: receiving a first analog signal, generating a digital signal according to the first analog signal; and A second analog signal is received, and the second analog signal is chopped according to the digital signal, thereby outputting a dimming signal to control the operation of the LED driving circuit; the step of chopping the second analog signal according to the digital signal specifically includes: controlling the switching states of the first switching device and the second switching device respectively according to the digital signal to realize the chopping processing of the second analog signal.

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