High-precision LED dimming control circuit and implementation method thereof

Abstract

A high-precision LED dimming control circuit disclosed by the present invention comprises a microprocessor, a PWM signal pin of the microprocessor is respectively connected with a dimming input end of a constant current driver and a time delay circuit, a dimming output end of the constant current driver is connected with one end of an inductor L1, and the other end of the inductor L1 is respectively connected with a switch circuit and a negative electrode end of a light source LED. The positive electrode of the constant-voltage direct-current source is connected with the positive electrode end of the light source LED and the switching circuit, and the switching circuit is connected with the delay circuit. The invention further discloses an implementation method of the high-precision LED dimming control circuit. Control of the time delay circuit and the switching circuit is added, the precision problem caused by sudden current change after the output of the constant-current driver passes through the inductor L1 is eliminated, and dimming can be more accurate and smoother in cooperation with deep dimming control.

Description

Technical Field

[0001] The present invention belongs to the technical field of dimming control circuits, and in particular relates to a high-precision LED dimming control circuit and an implementation method thereof. Background Art

[0002] As smart LEDs are widely accepted and recognized by the market, people's requirements for light quality and light health are getting higher and higher. Currently, smart LED lights on the market mainly use conventional constant current drive methods, and use multi-channel light mixing and gradient dimming control to achieve smooth dimming and color control effects. However, in actual application, the following problems will be faced:

[0003] 1. The human eye is sensitive to low-brightness dimming. The control accuracy of conventional constant current drive circuits is not high in the range below 10%. The dimming process is prone to jitter and flicker, resulting in a poor user experience.

[0004] 2. When dimming multiple channels, the insufficient precision of the constant current circuit leads to differences in the ratio of light sources, which can easily cause uneven light mixing and color difference. Summary of the invention

[0005] The purpose of the present invention is to provide a high-precision LED dimming control circuit to solve the problems raised in the above background technology. The present invention provides a high-precision LED dimming control circuit, which has the characteristics of improving the accuracy of the constant current output of the DC / DC dimming circuit.

[0006] Another object of the present invention is to provide a method for implementing a high-precision LED dimming control circuit.

[0007] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a high-precision LED dimming control circuit, comprising a microprocessor, wherein the PWM signal pins of the microprocessor are respectively connected to the dimming input terminal of the constant current driver and the delay circuit, the dimming output terminal of the constant current driver is connected to one end of the inductor L1, the other end of the inductor L1 is respectively connected to the switching circuit and the negative end of the light source LED, the positive pole of the constant voltage DC source is respectively connected to the positive end of the light source LED and the switching circuit, and the switching circuit is connected to the delay circuit.

[0008] Further in the present invention, the microprocessor includes a chip U2, and the model of the chip U2 is ESP32-C3H4.

[0009] Further in the present invention, the delay circuit includes a MOS tube Q1, the gate of the MOS tube Q1 is respectively connected to the resistor R1 and one end of the capacitor C1, the other end of the resistor R1 is connected to the PWM pin of the chip U2, the drain of the MOS tube Q1 is connected to the switching circuit, and the source of the MOS tube Q1 and the other end of the capacitor C1 are respectively connected to the negative end of the constant voltage DC source.

[0010] Further in the present invention, the switching circuit includes a MOS tube Q2, the gate of the MOS tube Q2 is respectively connected to one end of the resistor R3 and the drain of the MOS tube Q1, the other end of the resistor R3 and the drain of the MOS tube Q2 are both connected to the positive end of the constant voltage DC source, and the source of the MOS tube Q2 is connected to the negative end of the light source LED.

[0011] In order to be used for constant current output, further, the constant current driver includes a chip U1, the SW pin of the chip U1 is connected to one end of the inductor L1, the DIM pin of the chip U1 is connected to the PWM pin of the chip U2, the GND pin of the chip U1 is connected to the negative end of the constant voltage DC source, and the model of the chip U1 is OC5020B.

[0012] In order to set the output current of the constant current driver, further, the CS pin of the chip U1 is connected to one end of the resistor R5, and the other end of the resistor R5 is connected to the negative terminal of the constant voltage DC source.

[0013] For voltage stabilization protection, the SW pin of the chip U1 is further connected to the positive terminal of the voltage stabilizing diode D1 , and the negative terminal of the voltage stabilizing diode D1 is connected to the positive terminal of the constant voltage DC source.

[0014] In order to improve impedance matching, reduce signal reflection and oscillation, and thus ensure stable signal transmission, further, the VDD pin of the chip U1 is connected to one end of the resistor R4, and the other end of the resistor R4 is connected to the positive terminal of the constant voltage DC source.

[0015] For filtering, further, the VDD pin of the chip U1 is connected to one end of the capacitor C3, the TOFF pin of the chip U1 is connected to one end of the capacitor C4, and the other ends of the capacitors C3 and C4 are connected to the negative terminal of the constant voltage DC source.

[0016] In the present invention, the method for implementing a high-precision LED dimming control circuit comprises the following steps:

[0017] (1) Chip U2 outputs PWM dimming signal;

[0018] (ii) When the PWM dimming signal changes from low level to high level, this period is the delay period, MOS tube Q1 is turned off, and MOS tube Q2 is turned on. At this time, the constant current output of chip U1 after passing through inductor L1 is 0;

[0019] (III) When the PWM dimming signal changes from high level to low level, the delay period ends, MOS tube Q1 is turned on, and MOS tube Q2 is turned off. At this time, the mutation effect of the constant current output of chip U1 through inductor L1 has been completed, and a stable constant current output is output through inductor L1.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention adds the control of the delay circuit and the switch circuit, eliminates the accuracy problem caused by the sudden change of the current after the output of the constant current driver passes through the inductor L1, and cooperates with the deep dimming control to make the dimming more accurate and smooth;

[0022] 2. In the application of multi-channel light mixing, the present invention eliminates the problems of color difference and light mixing uniformity caused by output current accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a circuit connection block diagram of the present invention;

[0024] Figure 2 A circuit diagram of the present invention;

[0025] In the figure: 1. microprocessor; 2. constant voltage DC source; 3. light source LED; 4. switching circuit; 5. delay circuit; 6. constant current driver. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Example 1

[0028] See also Figure 1-2 The present invention provides the following technical solutions: a high-precision LED dimming control circuit, comprising a microprocessor 1, wherein the PWM signal pins of the microprocessor 1 are respectively connected to the dimming input end of the constant current driver 6 and the delay circuit 5, the dimming output end of the constant current driver 6 is connected to one end of the inductor L1, the other end of the inductor L1 is respectively connected to the switch circuit 4 and the negative end of the light source LED3, the positive pole of the constant voltage DC source 2 is respectively connected to the positive end of the light source LED3 and the switch circuit 4, and the switch circuit 4 is connected to the delay circuit 5.

[0029] By adopting the above technical solution, the present invention adds the control of the delay circuit 5 and the switch circuit 4, eliminates the accuracy problem caused by the sudden change of current after the output of the constant current driver 6 passes through the inductor L1, and cooperates with the deep dimming control to make the dimming more accurate and smooth; in the application of multi-channel light mixing, the present invention eliminates the color difference caused by the output current accuracy and the problem of light mixing uniformity.

[0030] Specifically, the microprocessor 1 includes a chip U2, and the model of the chip U2 is ESP32-C3H4.

[0031] The above technical solution is used to output a PWM dimming signal.

[0032] Specifically, the delay circuit 5 includes a MOS tube Q1, the gate of the MOS tube Q1 is connected to one end of the resistor R1 and the capacitor C1 respectively, the other end of the resistor R1 is connected to the PWM pin of the chip U2, the drain of the MOS tube Q1 is connected to the switch circuit 4, and the source of the MOS tube Q1 and the other end of the capacitor C1 are respectively connected to the negative end of the constant voltage DC source 2.

[0033] Specifically, the switching circuit 4 includes a MOS tube Q2, the gate of the MOS tube Q2 is respectively connected to one end of the resistor R3 and the drain of the MOS tube Q1, the other end of the resistor R3 and the drain of the MOS tube Q2 are both connected to the positive end of the constant voltage DC source 2, and the source of the MOS tube Q2 is connected to the negative end of the light source LED.

[0034] Specifically, the constant current driver 6 includes a chip U1, a SW pin of the chip U1 is connected to one end of the inductor L1, a DIM pin of the chip U1 is connected to a PWM pin of the chip U2, a GND pin of the chip U1 is connected to the negative terminal of the constant voltage DC source 2, and the model of the chip U1 is OC5020B.

[0035] By adopting the above technical solution, it is used for constant current output.

[0036] Specifically, the CS pin of the chip U1 is connected to one end of the resistor R5 , and the other end of the resistor R5 is connected to the negative terminal of the constant voltage DC source 2 .

[0037] The above technical solution is used to set the output current of the constant current driver 6.

[0038] Specifically, the VDD pin of the chip U1 is connected to one end of the capacitor C3 , the TOFF pin of the chip U1 is connected to one end of the capacitor C4 , and the other ends of the capacitors C3 and C4 are both connected to the negative terminal of the constant voltage DC source 2 .

[0039] The above technical solution is adopted for filtering.

[0040] Example 2

[0041] The present embodiment is different from the first embodiment in that: specifically, the SW pin of the chip U1 is also connected to the positive terminal of the voltage zener diode D1 , and the negative terminal of the voltage zener diode D1 is connected to the positive terminal of the constant voltage DC source 2 .

[0042] The above technical solution is adopted for voltage stabilization protection.

[0043] Example 3

[0044] The difference between this embodiment and the first embodiment is that: specifically, the VDD pin of the chip U1 is connected to one end of the resistor R4 , and the other end of the resistor R4 is connected to the positive terminal of the constant voltage DC source 2 .

[0045] By adopting the above technical solution, impedance matching is improved, signal reflection and oscillation are reduced, thereby ensuring stable signal transmission.

[0046] Example 4

[0047] Furthermore, a method for implementing a high-precision LED dimming control circuit according to the present invention comprises the following steps:

[0048] (1) Chip U2 outputs PWM dimming signal;

[0049] (ii) When the PWM dimming signal changes from low level to high level, this period is the delay period, MOS tube Q1 is turned off, and MOS tube Q2 is turned on. At this time, the constant current output of chip U1 after passing through inductor L1 is 0;

[0050] (III) When the PWM dimming signal changes from high level to low level, the delay period ends, MOS tube Q1 is turned on, and MOS tube Q2 is turned off. At this time, the mutation effect of the constant current output of chip U1 through inductor L1 has been completed, and a stable constant current output is output through inductor L1.

[0051] In summary, the present invention adds the control of the delay circuit 5 and the switch circuit 4, eliminates the accuracy problem caused by the sudden change of current after the output of the constant current driver 6 passes through the inductor L1, and cooperates with the deep dimming control to make the dimming more accurate and smooth; in the application of multi-channel light mixing, the present invention eliminates the color difference caused by the output current accuracy and the problem of light mixing uniformity.

[0052] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-precision LED dimming control circuit, characterized in that: It includes a microprocessor, the PWM signal pin of the microprocessor is respectively connected to the dimming input end of the constant current driver and the delay circuit, the dimming output end of the constant current driver is connected to one end of the inductor L1, the other end of the inductor L1 is respectively connected to the switching circuit and the negative end of the light source LED, the positive pole of the constant voltage DC source is respectively connected to the positive end of the light source LED and the switching circuit, and the switching circuit is connected to the delay circuit.

2. The high-precision LED dimming control circuit according to claim 1, characterized in that: The microprocessor includes a chip U2, and the model of the chip U2 is ESP32-C3H4.

3. The high-precision LED dimming control circuit according to claim 2, characterized in that: The delay circuit includes a MOS tube Q1, a gate of the MOS tube Q1 is connected to one end of a resistor R1 and a capacitor C1 respectively, the other end of the resistor R1 is connected to the PWM pin of the chip U2, the drain of the MOS tube Q1 is connected to the switch circuit, and the source of the MOS tube Q1 and the other end of the capacitor C1 are connected to the negative end of the constant voltage DC source respectively.

4. The high-precision LED dimming control circuit according to claim 3, characterized in that: The switch circuit includes a MOS tube Q2, the gate of the MOS tube Q2 is respectively connected to one end of the resistor R3 and the drain of the MOS tube Q1, the other end of the resistor R3 and the drain of the MOS tube Q2 are both connected to the positive end of the constant voltage DC source, and the source of the MOS tube Q2 is connected to the negative end of the light source LED.

5. The high-precision LED dimming control circuit according to claim 2, characterized in that: The constant current driver includes a chip U1, a SW pin of the chip U1 is connected to one end of the inductor L1, a DIM pin of the chip U1 is connected to a PWM pin of the chip U2, a GND pin of the chip U1 is connected to the negative terminal of the constant voltage DC source, and the model of the chip U1 is OC5020B.

6. The high-precision LED dimming control circuit according to claim 5, characterized in that: The CS pin of the chip U1 is connected to one end of the resistor R5, and the other end of the resistor R5 is connected to the negative terminal of the constant voltage DC source.

7. The high-precision LED dimming control circuit according to claim 5, characterized in that: The SW pin of the chip U1 is also connected to the positive terminal of the voltage stabilizing diode D1 , and the negative terminal of the voltage stabilizing diode D1 is connected to the positive terminal of the constant voltage DC source.

8. The high-precision LED dimming control circuit according to claim 5, characterized in that: The VDD pin of the chip U1 is connected to one end of the resistor R4, and the other end of the resistor R4 is connected to the positive terminal of the constant voltage DC source.

9. The high-precision LED dimming control circuit according to claim 5, characterized in that: The VDD pin of the chip U1 is connected to one end of the capacitor C3, the TOFF pin of the chip U1 is connected to one end of the capacitor C4, and the other ends of the capacitors C3 and C4 are both connected to the negative terminal of the constant voltage DC source.

10. A method for implementing a high-precision LED dimming control circuit according to any one of claims 1 to 9, characterized in that: The following steps are involved: (1) Chip U2 outputs PWM dimming signal; (ii) When the PWM dimming signal changes from low level to high level, this period is the delay period, MOS tube Q1 is turned off, and MOS tube Q2 is turned on. At this time, the constant current output of chip U1 after passing through inductor L1 is 0; (III) When the PWM dimming signal changes from high level to low level, the delay period ends, MOS tube Q1 is turned on, and MOS tube Q2 is turned off. At this time, the mutation effect of the constant current output of chip U1 through inductor L1 has been completed, and a stable constant current output is output through inductor L1.

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