LED driving device with adjustable dimming depth

Abstract

An LED driving device with adjustable dimming depth, comprising: an LED driver, including: a dimming control circuit that generates a first PWM signal according to a first brightness indication signal; and a driving circuit that drives a first light source to emit light through a first driving current and adjusts the brightness of the first light source according to the first PWM signal, wherein the duty cycle of the first PWM signal has a first corresponding relationship with the first driving current, and the first light source is connected to a first current sampling terminal; and a dimming depth control circuit, including: a first variable resistance circuit connected between the first current sampling terminal and the ground terminal, and the first variable resistance circuit controls the magnitude of a first variable resistance value between the first current sampling terminal and the ground terminal according to a first depth control signal. The first corresponding relationship is used to define a first dimming depth of the first light source, and the first dimming depth varies with the first variable resistance value. Through the foregoing technical means, the LED driving device can break through the limitation of the minimum dimming depth and avoid the problem of flicker during dimming.

Description

Technical Field

[0001] The present application relates to an LED driving device, and particularly to an LED driving device capable of adjusting the dimming depth. Background Art

[0002] First, in existing dimming circuits, the dimming depth of most of them is limited, especially limited by the parsing ability of the driving circuit for the pulse width modulation signal. For example, the minimum dimming depth is usually limited to 1% to 5%. If the overall dimming depth is to be increased to make the minimum dimming depth lower, problems such as inaccurate recognition of the input signal or failure to recognize will occur, and these problems will cause the LED light source to flicker or go out. Summary of the Invention

[0003] The technical problem to be solved by the present application is to provide an LED driving device capable of adjusting the dimming depth in view of the deficiencies of the prior art, which can break through the limitation of the minimum dimming depth of 1% and solve the problem of dimming flicker.

[0004] To solve the above technical problem, one of the technical solutions adopted by the present application is to provide an LED driving device capable of adjusting the dimming depth. The LED driving device for adjusting the dimming depth includes: an LED driver, including: a dimming control circuit configured to generate a first PWM signal according to a first brightness indication signal; and a driving circuit configured to drive a first light source to emit light through a first driving current and adjust the brightness of the first light source according to the first PWM signal, wherein the duty cycle of the first PWM signal has a first corresponding relationship with the first driving current, and the first light source is connected to a first current sampling terminal; and a dimming depth control circuit, including: a first variable resistance circuit connected between the first current sampling terminal and the ground terminal, the first variable resistance circuit being configured to control the magnitude of a first variable resistance value between the first current sampling terminal and the ground terminal according to a first depth control signal, wherein the first corresponding relationship is used to define a first dimming depth of the first light source, and the first dimming depth changes with the first variable resistance value.

[0005] One of the beneficial effects of the present application is that the LED driving device capable of adjusting the dimming depth provided by the present application can break through the limitation of the minimum dimming depth, and can meet the requirements for the dimming depth without increasing the parsing ability of the PWM signal, and can avoid the problem of dimming flicker. Moreover, due to the increase in the dimming depth, an energy-saving effect can be achieved. The present application can also extend the application to most bulb lamps and luminaires with a deep dimming function requirement.

[0006] To enable a further understanding of the features and technical content of the present application, please refer to the following detailed description and drawings of the present application. However, the provided drawings are only for reference and illustration, and are not intended to limit the present application. Description of the Drawings

[0007] Figure 1 It is a schematic circuit diagram of the LED driving device according to the first embodiment of the present application.

[0008] Figure 2 It is a schematic circuit diagram of the driving circuit according to the first embodiment of the present application.

[0009] Figure 3 It is the linear constant current control architecture according to the first embodiment of the present application.

[0010] Figure 4 It is a schematic circuit diagram of the first variable resistor circuit according to the first embodiment of the present application.

[0011] Figure 5 It is a graph of the dimming brightness versus the duty ratio of the first PWM signal according to the first embodiment of the present application.

[0012] Figures 6 to 8 They are respectively other schematic circuit diagrams of the first variable resistor circuit according to the first embodiment of the present application.

[0013] Figure 9 It is a schematic circuit diagram of the LED driving device according to the second embodiment of the present application. Detailed Description of the Embodiments

[0014] The following are specific embodiments to illustrate the implementation manners of the present application regarding the "LED driving device with adjustable dimming depth" disclosed in the present application. Those skilled in the art can understand the advantages and effects of the present application from the content disclosed in this specification. The present application can be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of the present application. Additionally, the drawings of the present application are only simple schematic illustrations and are not drawn according to actual sizes, hereby declared in advance. The following embodiments will further detail the related technical content of the present application, but the disclosed content is not intended to limit the protection scope of the present application. In addition, the term "or" used herein should, depending on the actual situation, may include any one or a combination of more of the related listed items.

[0015] First Embodiment

[0016] Figure 1 It is a schematic circuit diagram of the LED driving device according to the first embodiment of the present application, Figure 2 It is a schematic circuit diagram of the driving circuit according to the first embodiment of the present application. Refer to Figure 1As shown, the first embodiment of the present application provides an LED driving device 1 with adjustable dimming depth. The LED driving device 1 can be, for example, an LED driving circuit operating in a boost mode, and can be applied to a DC-DC boost converter 2 connected to an LED light source. The boost converter 2 at least includes an input capacitor Cin connected to the input voltage Vin, an inductor L0, a rectifying diode D0, an output capacitor Cout connected to the output voltage Vout, and a resistor R0. Among them, the input capacitor Cin and the output capacitor Cout are used for filtering. The boost converter 2 achieves the purpose of boost output by charging the capacitor through the internal transistor Q0 of the LED driving device 1. When the transistor Q0 is turned off, the inductor L0 discharges through rectification at the load end to drive the first light source L1 to emit light. In some embodiments, the positive end of the first light source L1 is connected to the output voltage Vout, and may include one or more light-emitting diodes. For example, the light-emitting diodes LD11 to LD1n. However, the present application does not limit the number of light-emitting diodes in the first light source L1. It should be noted that the LED driving device 1 is not limited to an LED driving circuit operating in a boost mode. In other embodiments, the LED driving device 1 can also be an LED driving circuit operating in a buck mode, and can be applied to a DC-DC buck converter connected to an LED light source. Similar to the boost type, the buck converter also relies on an inductor, a diode, a capacitor, and the internal transistor Q0 of the LED driving device 1 to adjust the output voltage, but the configuration method is different from that of the boost type, and its purpose is to reduce the DC input voltage to achieve a stable low output voltage.

[0017] As Figure 1 shown, the LED driving device 1 includes an LED driver 10 and a dimming depth control circuit 12. The LED driver 10 includes a driving circuit 100 and a dimming control circuit 102. Among them, the dimming control circuit 102 can be used to generate a first PWM signal Spwm1 according to the first brightness indication signal Si1, and the driving circuit 100 can drive the first light source L1 to emit light through the first driving current Id1, and adjust the magnitude of the first driving current Id1 according to the first PWM signal Spwm1, thereby controlling the brightness of the first light source L1. The first brightness indication signal Si1 can be input by the user or triggered by an environmental detection mechanism. The present application does not limit the generation and input method of the first brightness indication signal Si1.

[0018] As Figure 1 and Figure 2As shown, in this embodiment, from the outside of the driving circuit 100, the driving circuit 100 has a switch input terminal SW, a voltage input terminal VIN, a first PWM signal receiving terminal PWM1, a first current sampling terminal CS1, a ground terminal GND, an overvoltage protection terminal OVP, and a first LED output terminal D1. Among them, the switch input terminal SW is connected to the node N2 between the inductor L0 and the rectifier diode D0, the voltage input terminal VIN is connected to the input voltage Vin, the first PWM signal receiving terminal PWM1 is used to receive the first PWM signal Spwm1, the first current sampling terminal CS1 is connected to the first variable resistor circuit 120 of the dimming depth control circuit 12, and is electrically connected to the negative terminal of the first light source L1. The ground terminal GND is connected to the output capacitor Cout, the overvoltage protection terminal OVP is connected to the output voltage Vout through the resistor R0, and the first LED output terminal D1 is connected to the negative terminal of the first light source L1.

[0019] Looking at the inside of the driving circuit 100, the driving circuit 100 further includes a transistor Q0, a control logic 101, a dimming module 102, a reference voltage generation module 103, a linear control module 104, an overvoltage protection module 105, and a comparator CP1.

[0020] Among them, the first end of the transistor Q0 is connected to the switch input terminal SW, the second end of the transistor Q0 is connected to the chip ground terminal PGND, and the control end of the transistor Q0 is connected to the control logic 101. The control logic 101 can, according to the aforementioned boost control method, determine whether to turn on or off the transistor Q0 based on the magnitude of the obtained output voltage Vout and the magnitude of the first driving current Id1.

[0021] On the other hand, the first input terminal of the comparator CP1 is connected to the reference voltage generation module 103 for receiving the first reference voltage Vref1. The second input terminal of the comparator CP1 is connected to the first current sampling terminal CS1, and the output terminal of the comparator CP1 is connected to the control logic 101. The reference voltage generation module 103 is also connected to the voltage input terminal VIN for providing the first reference voltage Vref1, and the linear control module 104 is connected to the first LED output terminal D1.

[0022] It should be noted that the reference voltage generation module 103, the linear control module 104, and the comparator CP1 can be jointly used to implement the linear constant current control scheme of the driving circuit 100. Refer to Figure 3 , Figure 3 for the linear constant current control architecture of the first embodiment of this application. As Figure 3As shown, the linear control module 104 may include a transistor Q1, whose first end is connected to the first LED output terminal D1, whose second end is connected to the first current sampling terminal CS1, and whose control end is connected to the output terminal of a comparator CP1. Among them, the voltage at the second end of the transistor Q1 is fed back to the comparator CP1 for comparison, so that the voltage at the first current sampling terminal CS1 is kept constant at a first reference voltage Vref1, so as to make the first driving current Id1 passing through the first LED output terminal D1 a constant current.

[0023] In addition, in Figure 3 , the first variable resistance circuit 120 connected between the first current sampling terminal CS1 and the ground terminal GND is equivalent to a variable first variable resistance Rs1, and the magnitude of the first driving current Id1 can be set by adjusting the resistance value of the first variable resistance Rs1, as shown in the following formula (1):

[0024]

[0025] Wherein, I LED is the output average current.

[0026] In addition, the overvoltage protection module 105 is connected to the overvoltage protection terminal OVP. When the output voltage Vout rises beyond the voltage threshold, open-circuit protection can be triggered to disconnect the conductive path between the overvoltage protection terminal OVP and the control logic 101.

[0027] The dimming module 102 is connected to the first PWM signal receiving terminal PWM1, and is used to receive the first PWM signal Spwm1 and perform analog dimming. In some embodiments, the dimming module 102 may include a Delta-Sigma (ΔΣ) modulator circuit, a reversible counter, and a digital-to-analog converter to adjust the brightness of the first light source L1 according to the duty cycle of the first PWM signal Spwm1. More specifically, the duty cycle of the first PWM signal Spwm1 has a first corresponding relationship with the first driving current Id1.

[0028] In the existing LED driving circuit, although the output current of the LED can be correspondingly adjusted by adjusting the duty cycle of the PWM signal (for example, 1% - 100%), however, the dimming depth will change correspondingly with the change of the duty cycle, and the minimum dimming depth is usually 1%. The reason is that when the duty cycle is less than 1%, such as 0.5%, the driving circuit has insufficient parsing ability for the PWM signal, so it cannot accurately identify the input signal. At this time, the driving circuit will continuously cycle between the state of turning off the output current or turning on the output current, resulting in the LED light flickering. And when the duty cycle of the PWM signal is less than 0.5%, such as 0.1%, it is even more difficult for the driving circuit to identify the input signal, and the output current will be turned off to turn off the LED light.

[0029] For this reason, asFigure 1 As shown, in the embodiment of the present application, a dimming depth control circuit 12 that can be adjusted according to the dimming depth requirement is further provided. Among them, the dimming depth control circuit 12 includes a first variable resistance circuit 120, which is connected between the first current sampling terminal CS1 and the ground terminal GND. The first variable resistance circuit 120 is configured to control the resistance value of the first variable resistance Rs1 between the first current sampling terminal CS1 and the ground terminal GND according to the first depth control signal Sdd1.

[0030] It should be noted again that the duty cycle of the first PWM signal Spwm1 has a first corresponding relationship with the first driving current Id1. For example, a duty cycle of 1% to 100% corresponds to 1% to 100% of the first driving current Id1, and this first corresponding relationship will be used to limit the first dimming depth of the first light source L1, that is, to limit the first dimming depth to 1% to 100%.

[0031] However, when the resistance value of the first variable resistance Rs1 changes, the first dimming depth will change.

[0032] Please refer to Figure 4 , which is a circuit schematic diagram of the first variable resistance circuit of the first embodiment of the present application.

[0033] As Figure 4 shown, the first variable resistance circuit may include a first resistor R1, a second resistor R2, and a first switch circuit S1. The first resistor R1 is connected between the first current sampling terminal CS1 and the ground terminal GND. One end of the second resistor R2 is connected to the first current sampling terminal CS1. The first switch circuit S1 is connected between the other end of the second resistor R2 and the ground terminal GND, and is controlled by the first depth control signal Sdd1 to switch between conduction and cutoff. In this embodiment, the first switch circuit S1 may be, for example, a relay.

[0034] For example, it can be designed that the resistance value of the first resistor R1 is greater than the resistance value of the second resistor R2. When the first switch circuit S1 is off, the resistance value of the first variable resistance Rs1 is the first sampling resistance value. When the first switch circuit S1 is on, the resistance value of the first variable resistance Rs1 is the second sampling resistance value.

[0035] First, discuss the dimming depth when the first switch circuit S1 is off. When the first driving current Ids1 is 100%, the first driving current Ids1 is equal to the first sampling voltage Vcs divided by the first resistor R1 and then multiplied by 100%. At this time, the duty cycle of the corresponding first PWM signal Spwm1 is 100%.

[0036] Similarly, when the first drive current Ids1 is 50%, the first drive current Ids1 is equal to the first sampling voltage Vcs divided by the first resistor R1 and then multiplied by 50%. At this time, the duty cycle of the corresponding first PWM signal Spwm1 is 50%.

[0037] When the first drive current Ids1 is 1%, the first drive current Ids1 is equal to the first sampling voltage Vcs divided by the first resistor R1 and then multiplied by 1%. At this time, the duty cycle of the corresponding first PWM signal Spwm1 is 1%.

[0038] However, the PWM duty cycle of 1% is the bottom limit, and the corresponding first dimming depth is 1% to 100%.

[0039] Next, consider the situation when the first switch circuit S1 is turned on. Assume that in this embodiment, the resistance ratio of the first resistor R1 to the second resistor R2 is 1:0.01. When the first switch circuit S1 is turned on, the parallel resistance value of the first resistor R1 and the second resistor R2 is approximately 0.01 times the resistance value of the first resistor R1.

[0040] Therefore, when the first switch circuit S1 is turned on, the first drive current Ids1 is equal to the first sampling voltage Vcs divided by 0.01 times the first resistor R1. At this time, compared with when the first switch circuit S1 is turned off, the first drive current Ids1 is 100 times that of the original when the duty cycle is 100%. In other words, when the first switch circuit S1 is turned off, the brightness corresponding to the duty cycle of 1% to 100% will be 0.01% to 1% of the brightness when the first switch circuit S1 is turned on.

[0041] Reference can be made to Figure 5 , Figure 5 which is a graph of the dimming brightness of the first embodiment of the present application against the duty cycle of the first PWM signal. It can be inferred from the above that when the first switch circuit S1 is turned on, the maximum first drive current Ids1 will be obtained when the duty cycle of the first PWM signal Spwm1 is 100%, so it can correspond to the maximum brightness of 100%. Similarly, when the first switch circuit S1 remains on, when the duty cycle of the first PWM signal Spwm1 is adjusted to 1%, 1% of the maximum brightness will be obtained. Then, after the first switch circuit S1 is turned off, the resistance value of the first variable resistor Rs1 returns to twice the resistance value of the first resistor R1. If the first drive current Ids at the maximum brightness of 1% is to be obtained, the duty cycle needs to be increased to 100%. Therefore, after the first switch circuit S1 is turned off, when the duty cycle is 1%, 0.01% of the maximum brightness can be obtained.

[0042] That is to say, compared with the prior art without a variable resistor design, the LED driving device with adjustable dimming depth of the present application can break through the limitation of the minimum dimming depth, and can meet the requirement for dimming depth without increasing the ability to analyze PWM signals. Moreover, due to the increase in dimming depth, an energy-saving effect can be achieved.

[0043] It should be noted that in this embodiment, the first resistor R1 and the second resistor R2 can also be variable resistors. Based on the above inference, it can be known that the first dimming depth changes with the resistance value ratio of the first resistor R1 and the second resistor R2. However, what actually mainly affects the dimming depth is the resistance value of the first variable resistor circuit 120. That is to say, it is necessary to control the first variable resistance value of the first variable resistor circuit 120 to switch between different resistance values through the first depth control signal Sdd1. For example, switch between the first sampled resistance value and the second sampled resistance value, and the first sampled resistance value can be greater than the second sampled resistance value. Furthermore, the first sampled resistance value and the second sampled resistance value can also be designed according to requirements.

[0044] Optionally, the resistance value ratio range of the first sampled resistance value and the second sampled resistance value is from 1:0.5 to 1:0.01. Therefore, when the resistance value ratio of the first sampled resistance value and the second sampled resistance value is 1:0.5, the corresponding first dimming depth is 0.5% to 100%, and when the resistance value ratio of the first sampled resistance value and the second sampled resistance value is 1:0.01, the corresponding first dimming depth is 0.01% to 100%.

[0045] It should be noted that the present application is not limited to Figure 4 the variable resistor circuit design. Please refer to Figures 6 to 8 , Figures 6 to 8 which are other circuit schematic diagrams of the first variable resistor circuit of the first embodiment of the present application respectively.

[0046] As Figure 6 shown, in other embodiments, the first variable resistor circuit 120 may include a third resistor R3, a fourth resistor R4, and a second switch circuit S2. One end of the third resistor R3 is connected to the first current sampling terminal CS1, and one end of the fourth resistor R4 is connected to the first current sampling terminal CS1. The second switch circuit S2 has a first end, a second end, and a third end. The first end is connected to the other end of the third resistor R3, the second end is connected to the other end of the fourth resistor R4, and the third end is connected to the ground terminal GND. The second switch circuit S2 is controlled by the first depth control signal Sdd1 to selectively connect the third end to the first end or the second end. The first switch circuit S1 can be, for example, a single-pole double-throw switch.

[0047] Among them, the resistance value of the third resistor R3 is greater than that of the fourth resistor R4. When the third terminal is connected to the first terminal, the resistance value of the first variable resistor Rs1 can be, for example, the aforementioned first sampling resistance value. When the third terminal is connected to the second terminal, the resistance value of the first variable resistor Rs1 can be, for example, the aforementioned second sampling resistance value. That is to say, the resistance values of the third resistor R3 and the fourth resistor R4 can be equal to the first sampling resistance value and the second sampling resistance value respectively. Therefore, optionally, the range of the resistance value ratio of the third resistor R3 and the fourth resistor R4 is from 1:0.5 to 1:0.01. Therefore, when the resistance value ratio of the third resistor R3 and the fourth resistor R4 is 1:0.5, the corresponding first dimming depth is from 0.5% to 100%. When the resistance value ratio of the third resistor R3 and the fourth resistor R4 is 1:0.01, the corresponding first dimming depth is from 0.01% to 100%.

[0048] In addition, as Figure 7 shown, in other embodiments, the first variable resistance circuit 120 may include a fifth resistor R5, a sixth resistor R6, and a third switch circuit S3. One end of the fifth resistor R5 is connected to the first current sampling terminal CS1, and the sixth resistor R6 is connected between the other end of the fifth resistor R5 and the ground terminal GND. The third switch circuit S3 is connected between the first current sampling terminal CS1 and the other end of the fifth resistor R5, and the third switch circuit S3 is controlled by the first depth control signal Sdd1 to switch between conduction and cutoff. In this embodiment, the third switch circuit S3 can be, for example, a relay.

[0049] When the third switch circuit S3 is conductive, the first variable resistance value (i.e., the resistance value of the sixth resistor R6) is the second sampling resistance value. When the third switch circuit S3 is cutoff, the first variable resistance value (i.e., the resistance value after the fifth resistor R5 and the sixth resistor R6 are connected in series) is the first sampling resistance value.

[0050] Therefore, optionally, since the range of the resistance value ratio of the first sampling resistance value and the second sampling resistance value is from 1:0.5 to 1:0.01, the range of the resistance value ratio of the fifth resistor R5 and the sixth resistor R6 can be from 1:1 to 99:1. When the resistance value ratio of the fifth resistor R5 and the sixth resistor R6 is 1:1, the corresponding first dimming depth is from 0.5% to 100%. When the resistance value ratio of the fifth resistor R5 and the sixth resistor R6 is 99:1, the corresponding first dimming depth is from 0.01% to 100%.

[0051] In addition, in other embodiments, the fifth resistor R5 and the sixth resistor R6 can also be variable resistors, and the first dimming depth will change with the resistance value ratio of the first resistor and the second resistor.

[0052] Please refer to Figure 8, in other embodiments, the first variable resistance circuit 120 may include a seventh resistor R7, an eighth resistor R8, and a fourth switch circuit S4. One end of the seventh resistor R7 is connected to the first current sampling terminal CS1, and the eighth resistor R8 is connected between the other end of the seventh resistor R7 and the ground terminal GND. One end of the fourth switch circuit S4 is connected between the seventh resistor R7 and the eighth resistor R8, and the other end of the fourth switch circuit S4 is connected between the eighth resistor R8 and the ground terminal GND, and the fourth switch circuit S4 is controlled by the first depth control signal Sdd1 to switch between conduction and cutoff. In this embodiment, the fourth switch circuit S4 may be, for example, a relay.

[0053] When the fourth switch circuit S4 is conducting, the first variable resistance value (i.e., the resistance value of the seventh resistor R7) is the second sampling resistance value, and when the third switch circuit S3 is cutoff, the first variable resistance value (i.e., the resistance value of the seventh resistor R7 and the eighth resistor R8 in series) is the first sampling resistance value.

[0054] Therefore, optionally, since the resistance value ratio range of the first sampling resistance value and the second sampling resistance value is from 1:0.5 to 1:0.01, the resistance value ratio range of the seventh resistor R7 and the eighth resistor R8 can be from 1:1 to 1:99. When the resistance value ratio of the seventh resistor R7 and the eighth resistor R8 is 1:1, the corresponding first dimming depth is 0.5% to 100%, and when the resistance value ratio of the seventh resistor R7 and the eighth resistor R8 is 1:99, the corresponding first dimming depth is 0.01% to 100%.

[0055] Therefore, the first variable resistance circuit of the embodiments of the present application can have different implementation manners, and can all achieve the purpose of improving the dimming depth through the combination of different resistance values.

[0056] Second Embodiment

[0057] Please refer to Figure 9 , Figure 9 is a circuit schematic diagram of the LED driving device according to the second embodiment of the present application. It should be noted that Figure 9 A kind of LED driving device 1 capable of adjusting the dimming depth is provided, which is based on Figure 1 the embodiments, and similar components are described with similar component symbols, so the repeated description is omitted.

[0058] The difference from the first embodiment is that the LED driving device 1 of this embodiment is applied in the context of multiple light sources, and the multiple light sources can respectively represent light sources of different color temperatures or colors, and the dimming depths of the multiple light sources can be independently controlled. Therefore, taking three light sources as an example, but the present application is not limited thereto.

[0059] Specifically, the dimming control circuit 102 further generates a second PWM signal Spwm2 and a third PWM signal Spwm3 according to the second brightness indication signal Si2 and the third brightness indication signal Si3 respectively. The driving circuit 100 also drives the second light source L2 and the third light source L3 to emit light through the second driving current Id2 and the third driving current Id3 respectively, and adjusts the brightness of the second light source L2 and the third light source L3 according to the duty cycles of the second PWM signal Spwm2 and the third PWM signal Spwm3 respectively. Similarly, the duty cycle of the second PWM signal has a second corresponding relationship with the second driving current, and the negative terminal of the second light source L2 is connected to the second current sampling terminal CS2. The duty cycle of the third PWM signal Spwm3 has a third corresponding relationship with the third driving current Id3.

[0060] Similarly, the second brightness indication signal Si2 and the third brightness indication signal Si3 can be input by the user or triggered by an environmental detection mechanism. The present application does not limit the generation and input methods of the second brightness indication signal Si2 and the third brightness indication signal Si3.

[0061] In this embodiment, the dimming depth control circuit 12 further includes a second variable resistance circuit 121 and a third variable resistance circuit 122.

[0062] The second variable resistance circuit 121 is connected between the second current sampling terminal CS2 and the ground terminal GND. The second variable resistance circuit 121 has a second variable resistance value, which can be configured to control the magnitude of the second variable resistance value between the second current sampling terminal CS2 and the ground terminal GND according to the second depth control signal Sdd2. Among them, the second corresponding relationship is used to define the second dimming depth of the second light source L2, and the second dimming depth changes with the second variable resistance value.

[0063] Similarly, the third variable resistance circuit 122 is connected between the third current sampling terminal and the ground terminal. The third variable resistance circuit 122 has a third variable resistance value, and is configured to control the magnitude of the third variable resistance value between the third current sampling terminal CS3 and the ground terminal GND according to the third depth control signal Sdd3. Among them, the third corresponding relationship is used to define the third dimming depth of the third light source L3, and the third dimming depth can change with the third variable resistance value.

[0064] It should be noted that, in this embodiment, one or more of the first variable resistance circuit 120, the second variable resistance circuit 121, and the third variable resistance circuit 122 may be adopted Figure 4 、 6The circuit architecture of the first variable resistor circuit 120 shown in FIGS. 7 and 8, and the corresponding variable resistance value also adopts the aforementioned resistance value ratio range to individually adjust the dimming depth of the first light source L1, the second light source L2, and the third light source L3 according to requirements. Since the principle of adjusting the dimming depth in this application has been described in detail above, it will not be elaborated here.

[0065] Advantages of the embodiment

[0066] One of the advantages of the present invention and this application is that the LED driving device capable of adjusting the dimming depth provided by the present invention and this application can break through the limitation of the minimum dimming depth, achieve the requirements for the dimming depth without increasing the ability to analyze the PWM signal, and can avoid the problem of flickering during dimming. Moreover, due to the increase in the dimming depth, an energy-saving effect can be achieved. The present invention and this application can also extend the application to most bulb lamps and lighting fixtures with a demand for deep dimming functions.

[0067] The content disclosed above is only an optional and feasible embodiment of this application, and does not limit the protection scope of the claims of this application. Therefore, all equivalent technical changes made by using the content of the specification and drawings of this application are included in the protection scope of the claims of this application.

Claims

1. An LED driving device with adjustable dimming depth, characterized in that, The adjustable dimming depth LED driving device includes: An LED driver, including: A dimming control circuit configured to generate a first PWM signal according to a first brightness indication signal; and A driving circuit configured to drive a first light source to emit light through a first driving current and adjust the brightness of the first light source according to the first PWM signal, wherein a duty cycle of the first PWM signal has a first corresponding relationship with the first driving current, and the first light source is connected to a first current sampling terminal; and A dimming depth control circuit, including: A first variable resistance circuit connected between the first current sampling terminal and the ground terminal, the first variable resistance circuit being configured to control a magnitude of a first variable resistance value between the first current sampling terminal and the ground terminal according to a first depth control signal, wherein the first corresponding relationship is used to define a first dimming depth of the first light source, and the first dimming depth varies with the first variable resistance value; Wherein, the first variable resistance circuit controls the first variable resistance value to be a first sampling resistance value or a second sampling resistance value according to the first depth control signal; a resistance value ratio range of the first sampling resistance value and the second sampling resistance value is from 1:0.5 to 1:0.

01.

2. The LED driving device with adjustable dimming depth according to claim 1, wherein Wherein, When the resistance value ratio range of the first sampling resistance value and the second sampling resistance value is 1:0.5, the first dimming depth is from 0.5% to 100%, and when the resistance value ratio range of the first sampling resistance value and the second sampling resistance value is 1:0.01, the first dimming depth is from 0.01% to 100%.

3. The LED driving device with adjustable dimming depth according to claim 1, characterized in that, The first variable resistance circuit includes: A first resistor connected between the first current sampling terminal and the ground terminal; A second resistor, one end of which is connected to the first current sampling terminal; and A first switch circuit connected between the other end of the second resistor and the ground terminal, and switched between conduction and non-conduction under the control of the first depth control signal.

4. The LED driving device with adjustable dimming depth according to claim 3, characterized in that The resistance value of the first resistor is greater than the resistance value of the second resistor. When the first switch circuit is conductive, the first variable resistance value is the second sampling resistance value, and when the first switch circuit is non-conductive, the first variable resistance value is the first sampling resistance value.

5. The LED driving device with adjustable dimming depth according to claim 3, wherein, The first resistor and the second resistor are variable resistors, and the first dimming depth varies with a resistance value ratio of the first resistor and the second resistor.

6. The LED driving device with adjustable dimming depth according to claim 1, characterized in that, The first variable resistance circuit includes: A third resistor, one end of which is connected to the first current sampling terminal; A fourth resistor, one end of which is connected to the first current sampling terminal; and A second switch circuit having a first end, a second end and a third end, the first end being connected to the other end of the third resistor, the second end being connected to the other end of the fourth resistor, the third end being connected to the ground terminal, and the second switch circuit selectively connecting the third end to the first end or the second end under the control of the first depth control signal; Among them, the resistance value of the third resistor is greater than that of the fourth resistor. When the third terminal is connected to the first terminal, the first variable resistance value is the first sampling resistance value; when the third terminal is connected to the second terminal, the first variable resistance value is the second sampling resistance value.

7. The LED driving device with adjustable dimming depth according to claim 1, wherein The first variable resistance circuit includes: a fifth resistor, one end of which is connected to the first current sampling terminal; a sixth resistor, connected between the other end of the fifth resistor and the ground terminal; and a third switch circuit, connected between the first current sampling terminal and the other end of the fifth resistor, and the third switch circuit is controlled by the first depth control signal to switch between conduction and cutoff; wherein, when the third switch circuit is cutoff, the first variable resistance value is the first sampling resistance value; when the third switch circuit is conductive, the first variable resistance value is the second sampling resistance value.

8. The LED driving device with adjustable dimming depth according to claim 7, wherein The fifth resistor and the sixth resistor are variable resistors, and the first dimming depth changes with the resistance value ratio of the fifth resistor and the sixth resistor.

9. The LED driving device with adjustable dimming depth according to claim 6, characterized in that, The dimming control circuit further generates a second PWM signal according to a second brightness indication signal. The driving circuit further drives a second light source to emit light through a second driving current, and adjusts the brightness of the second light source according to the second PWM signal. The duty cycle of the second PWM signal has a second corresponding relationship with the second driving current, and the second light source is connected to a second current sampling terminal; Among them, the dimming depth control circuit further includes: a second variable resistance circuit, connected between the second current sampling terminal and the ground terminal. The second variable resistance circuit is configured to control the magnitude of the second variable resistance value between the second current sampling terminal and the ground terminal according to a second depth control signal. Among them, the second corresponding relationship is used to define a second dimming depth of the second light source, and the second dimming depth changes with the second variable resistance value.

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