A dimming circuit, a PCB board and a dimming power supply

Abstract

The present invention discloses a dimming circuit, a PCB board and a dimming power supply. The dimming circuit includes a dimming port, an input processing unit, a control unit, a dimming unit and an output processing unit. The output end of the input processing unit is connected to the input end of the control unit; the control unit includes a primary coil T2A of a second transformer, and the dimming unit includes a secondary coil T2B of the second transformer; the secondary coil T2B of the second transformer is connected to the dimming port, and the primary coil T2A of the second transformer is inductively connected to the secondary coil T2B of the second transformer; the output end of the control unit is connected to the input end of the output processing unit, and the control unit is used to adjust the output current according to the dimming signal. In the dimming circuit disclosed in this application, a second transformer is used to perform safety isolation on the dimming signal input by the dimming port, replacing the optocoupler isolation in the prior art, which can improve the signal transmission accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of dimming control circuits, and particularly to a dimming circuit, a PCB board, and a dimming power supply. Background Art

[0002] An optocoupler, also known as an opto-isolator or an optical coupler, is a device that transmits electrical signals through light. Usually, the light emitter and the light receiver are encapsulated in the same housing. When an electrical signal is applied to the input terminal, the light emitter emits light, and after the light receiver receives the light, a photocurrent flows out from the output terminal, thus realizing the conversion of "electricity - light - electricity"; the optocoupler has the advantages of small size, long life, no contacts, strong anti-interference ability, insulation between the output and the input, and unidirectional signal transmission, and is widely used in digital circuits.

[0003] For the 0 - 10V dimming power supply on the market, its dimming port needs to be isolated from the main circuit. Currently, optocouplers are used as intermediate devices in the market to achieve isolation between the dimming part and the main circuit. By inputting a PWM signal at the light-emitting end of the optocoupler, the same PWM signal or an analog signal is output at the light-receiving end to control the output current; however, during the operation of the dimming power supply, due to the slow switching speed of the optocoupler, there is a large delay between the leading edge and the trailing edge of the driving pulse, reducing the signal transmission accuracy. Moreover, the optocoupler is easily affected by the external ambient temperature. The higher the temperature, the worse the current transfer ratio of the optocoupler, which means that a larger operating current is required at the light-emitting end to ensure the normal signal received at the light-receiving end, reducing the stability during the operation of the dimming power supply.

[0004] It can be seen that the existing technology still needs to be improved. Summary of the Invention

[0005] In view of the deficiencies of the above-mentioned existing technology, the purpose of the present invention is to provide a dimming circuit that uses a second transformer for safety isolation to improve the signal transmission accuracy.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] A dimming circuit includes a dimming port, an input processing unit, a control unit, a dimming unit, and an output processing unit. The input processing unit is used to perform filtering and rectification processing on the input alternating current. The output end of the input processing unit is connected to the input end of the control unit. The control unit includes the primary coil T2A of a second transformer, and the dimming unit includes the secondary coil T2B of the second transformer. One end of the secondary coil T2B of the second transformer is connected to pin 1 of the dimming port, and the other end of the secondary coil T2B of the second transformer is connected to pin 2 of the dimming port. The primary coil T2A of the second transformer is inductively connected to the secondary coil T2B of the second transformer. The output end of the control unit is connected to the input end of the output processing unit, and the control unit is used to adjust the output current according to the dimming signal. The output processing unit is used to rectify the power supply.

[0008] In the dimming circuit described above, the input processing unit includes a filtering part and a first rectifying part. The input end of the filtering part is connected to the alternating current, the output end of the filtering part is connected to the input end of the first rectifying part, and the output end of the first rectifying part is connected to the input end of the control unit.

[0009] In the dimming circuit described above, the control unit includes a first control chip U1, a voltage dividing part, the secondary coil T1C of a first transformer, and a charging part. The input end of the voltage dividing part is connected to the output end of the input processing unit. The output end of the voltage dividing part is respectively connected to one end of the secondary coil T1C of the first transformer, pin 8 of the first control chip U1, and one end of the charging part. The other end of the charging part is connected to one end of the primary coil T2A of the second transformer. The other end of the secondary coil T1C of the first transformer and the other end of the primary coil T2A of the second transformer are respectively grounded.

[0010] In the dimming circuit described above, the charging part includes an eleventh capacitor C11 and a twenty-first resistor R21. One end of the eleventh capacitor C11 is connected to the output end of the voltage dividing part, the other end of the eleventh capacitor C11 is connected to one end of the twenty-first resistor R21, and the other end of the twenty-first resistor R21 is connected to one end of the primary coil T21 of the second transformer.

[0011] In the dimming circuit described above, the control unit further includes a second rectifying part and the primary coil T1B of a first transformer. One end of the primary coil T2A of the second transformer is further connected to the input end of the second rectifying part. The output end of the second rectifying part is connected to pin 4 of the first control chip U1. Pin 6 of the first control chip U1 is connected to one end of the primary coil T1B of the first transformer, and the other end of the primary coil T1B of the first transformer is connected to the output end of the input processing unit.

[0012] In the dimming circuit described above, the second rectifying section includes a ninth diode D9, a twenty-second resistor R22, and a third triode Q3. The anode of the ninth diode D9 is connected to one end of the primary coil T2A of the second transformer. The cathode of the ninth diode D9 is connected to one end of the twenty-second resistor R22. The other end of the twenty-second resistor R22 is connected to the base of the third triode Q3. The emitter of the third triode Q3 is grounded. The collector of the third triode Q3 is connected to pin 4 of the first control chip U1.

[0013] In the dimming circuit described above, the control unit further includes a sampling section and a second triode Q2. One end of the sampling section is connected to pin 6 of the first control chip U1. The other end of the sampling section is connected to the source of the second triode Q2. The gate of the second triode Q2 is connected to pin 7 of the first control chip U1. The drain of the second triode Q2 is connected to one end of the primary coil T1B of the first transformer.

[0014] In the dimming circuit described above, the output processing unit includes a third rectifying section, an energy storage section, and the secondary coil T1D of the first transformer. The secondary coil T1D of the first transformer is inductively connected to the primary coil T1B of the first transformer. One end of the secondary coil T1D of the first transformer is connected to the input end of the third rectifying section. The output end of the third rectifying section is connected to the output pin.

[0015] The present invention also correspondingly provides a PCB board, on which the dimming circuit described above is printed.

[0016] The present invention also correspondingly provides a dimming power supply, including a housing, and the PCB board described above is fixedly arranged inside the housing.

[0017] Beneficial effects:

[0018] The present invention provides a dimming circuit. The control unit includes the primary coil T2A of the second transformer. The dimming unit includes the secondary coil T2B of the second transformer. The primary coil T2A of the second transformer is inductively connected to the secondary coil T2B of the second transformer, which can achieve the safety isolation between the dimming signal and the control unit. The second transformer generates a small delay at the front and rear edges of the driving pulse, which can improve the signal transmission accuracy. And the second transformer is not affected by environmental temperature factors during operation, which can improve the stability of the dimming power supply during operation. Description of the drawings

[0019] Figure 1 It is the circuit structure diagram of the dimming circuit provided by the present invention;

[0020] Figure 2 The circuit structure diagram of the input processing unit provided by the present invention;

[0021] Figure 3 The circuit structure diagram of the control unit provided by the present invention;

[0022] Figure 4 The circuit structure diagram of the dimming unit provided by the present invention;

[0023] Figure 5 The circuit structure diagram of the output processing unit provided by the present invention. Specific embodiments

[0024] The present invention provides a dimming circuit, a PCB board and a dimming power supply. To make the objectives, technical solutions and effects of the present invention clearer and more definite, the following further describes the present invention in detail with reference to the accompanying drawings and by way of examples.

[0025] In the description of the present invention, it should be understood that terms such as "installation" and "connection" should be understood in a broad sense. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] Please refer to Figures 1 to 5 , the present invention provides a dimming circuit, including a dimming port, an input processing unit, a control unit, a dimming unit and an output processing unit. The input processing unit is used for filtering and rectifying the input alternating current. The output end of the input processing unit is connected to the input end of the control unit; the control unit includes the primary coil T2A of the second transformer, and the dimming unit includes the secondary coil T2B of the second transformer; one end of the secondary coil T2B of the second transformer is connected to pin 1 of the dimming port, and the other end of the secondary coil T2B of the second transformer is connected to pin 2 of the dimming port. The primary coil T2A of the second transformer is inductively connected to the secondary coil T2B of the second transformer; the output end of the control unit is connected to the input end of the output processing unit, and the control unit is used for adjusting the output current according to the dimming signal; the output processing unit is used for rectifying the power supply.

[0027] In the dimming circuit disclosed in this application, the control unit includes the primary coil T2A of the second transformer, the dimming unit includes the secondary coil T2B of the second transformer, and the primary coil T2A of the second transformer is inductively connected to the secondary coil T2B of the second transformer. The voltage signal input by the dimming port is fed back to the control unit through the second transformer, which can realize the safety isolation between the dimming signal and the control unit; the second transformer generates a small delay on the leading and trailing edges of the driving pulse, which can improve the signal transmission accuracy, and the second transformer is not affected by environmental temperature factors during operation, improving the stability of the dimming power supply during operation.

[0028] Further, please refer to Figure 1 and Figure 2 , the input processing unit includes a filtering section and a first rectifying section. The input end of the filtering section is connected to alternating current, the output end of the filtering section is connected to the input end of the first rectifying section, and the output end of the first rectifying section is connected to the input end of the control unit; in one embodiment, the filtering section includes an EMI filtering circuit, and the first rectifying section includes a bridge BR1 rectifying circuit.

[0029] Further, please refer to Figure 1 , Figure 2 and Figure 3 , the control unit includes a first control chip U1, a voltage dividing section, the secondary coil T1C of a first transformer, and a charging section. The input end of the voltage dividing section is connected to the output end of the input processing unit, and the output end of the voltage dividing section is respectively connected to one end of the secondary coil T1C of the first transformer, pin 8 of the first control chip U1, and one end of the charging section. The other end of the charging section is connected to one end of the primary coil T2A of a second transformer. The other end of the secondary coil T1C of the first transformer and the other end of the primary coil T2A of the second transformer are respectively grounded; in one embodiment, the model of the first control chip U1 is RT7306D.

[0030] The voltage rectified by the first rectifying section is divided by the voltage dividing section and then input to pin 8 of the first control chip U1 to provide a startup working voltage for the first control chip U1; when the secondary coil T1 of the first transformer is a positive voltage, the secondary coil T1C of the first transformer charges the charging section and the primary coil T2A of the second transformer respectively. At this time, the primary coil T2A of the second transformer is coupled with the secondary coil T2B of the second transformer, and the voltage of the primary coil T2A is clamped, and the clamped voltage is the port voltage of 0 - 10V; when the voltage of the secondary coil T1C of the first transformer is a reverse voltage, the secondary coil T1C charges the charging section and the primary coil T2A reversely, the primary coil T2A is demagnetized and induces a reverse voltage, the positive voltage of the charging section is neutralized to zero and charged to a negative voltage; when the secondary coil T1C of the first transformer becomes a positive voltage again, the charging section is recharged with a positive voltage, and due to the coupling effect of the coil, the voltage of the primary coil T2A of the second transformer is clamped again, thereby forming a driving pulse signal.

[0031] In one embodiment, please refer to Figure 3, the voltage dividing part includes a fifth resistor R5 and a sixth resistor R6. One end of the fifth resistor R5 is connected to the output end of the first rectifying part, the other end of the fifth resistor R5 is connected to one end of the sixth resistor R6, and the other end of the sixth resistor R6 is respectively connected to one end of the secondary side coil T1C of the first transformer, one end of the charging part, and pin 8 of the first control chip U1.

[0032] Further, please refer to Figure 1 , Figure 2 and Figure 3 , the charging part includes an eleventh capacitor C11 and a twenty - first resistor R21. One end of the eleventh capacitor C11 is connected to the output end of the voltage dividing part, the other end of the eleventh capacitor C11 is connected to one end of the twenty - first resistor R21, and the other end of the twenty - first resistor R21 is connected to one end of the primary side coil T21 of the second transformer; the eleventh capacitor C11 is used for storing electricity.

[0033] In one embodiment, the control unit further includes a ninth resistor R9, a tenth resistor R10, a seventh capacitor C7, an eleventh resistor R11, an eighth capacitor C8, a ninth capacitor C9, and a tenth capacitor C10; Pin 5 of the first control chip U1 is respectively connected to one end of the ninth resistor R9, one end of the tenth resistor R10, and one end of the seventh capacitor C7. The other end of the ninth resistor R9 is connected to the other end of the sixth resistor R6. The other end of the tenth resistor R10 and the other end of the seventh capacitor C7 are respectively grounded; Pin 1 of the first control chip U1 is connected to one end of the eleventh resistor R11, and the other end of the eleventh resistor R11 is grounded; Pin 3 of the first control chip U1 is connected to one end of the ninth capacitor C9, and the other end of the ninth capacitor C9 is grounded; Pin 6 of the first control chip U1 is further connected to one end of the tenth capacitor C10, and the other end of the tenth capacitor C10 is grounded; Pin 4 of the first control chip U1 is further connected to one end of the eighth capacitor C8, and the other end of the eighth capacitor C8 is grounded; Pin 2 of the first control chip U1 is grounded.

[0034] Further, please refer to Figure 1 , Figure 3 and Figure 4, the control unit further includes a second rectifying section and the primary coil T1B of the first transformer; one end of the primary coil T2A of the second transformer is also connected to the input end of the second rectifying section, the output end of the second rectifying section is connected to pin 4 of the first control chip U1, pin 6 of the first control chip U1 is connected to one end of the primary coil T1B of the first transformer, and the other end of the primary coil T1B of the first transformer is connected to the output end of the input processing unit; the voltage signal output from the dimming port is safely isolated by the second transformer and then rectified by the second rectifying section, and the rectified voltage signal is input to pin 4 of the first control chip U1, and pin 6 of the first control chip U1 outputs a control signal to adjust the output current of the dimming circuit.

[0035] Further, please refer to Figure 1 , Figure 3 and Figure 4 , the second rectifying section includes a ninth diode D9, a twenty-second resistor R22 and a third triode Q3. The positive electrode of the ninth diode D9 is connected to one end of the primary coil T2A of the second transformer, the negative electrode of the ninth diode D9 is connected to one end of the twenty-second resistor R22, the other end of the twenty-second resistor R22 is connected to the base of the third triode Q3, the emitter of the third triode Q3 is grounded, and the collector of the third triode Q3 is connected to pin 4 of the first control chip U1.

[0036] In one embodiment, please refer to Figure 3 , the second rectifying section further includes a twenty-fourth resistor R24, a thirteenth capacitor C13, a twelfth capacitor C12 and a twenty-third resistor R23. The negative electrode of the ninth diode D9 is respectively connected to one end of the twenty-fourth resistor R24, one end of the thirteenth capacitor C13 and one end of the twenty-second resistor R22. The other end of the twenty-second resistor R22 is respectively connected to one end of the twelfth capacitor C12 and the base of the third triode Q3. The emitter of the third triode Q3 is connected to one end of the twenty-third resistor R23. The other ends of the twenty-third resistor R23, the twelfth capacitor C12, the thirteenth capacitor C13 and the twenty-fourth resistor R24 are respectively grounded.

[0037] Further, please refer to Figure 1 and Figure 3 , the control unit further includes a sampling section and a second triode Q2. One end of the sampling section is connected to pin 6 of the first control chip U1, the other end of the sampling section is connected to the source of the second triode Q2, the gate of the second triode Q2 is connected to pin 7 of the first control chip U1, and the drain of the second triode Q2 is connected to one end of the primary coil T1B of the first transformer.

[0038] In one embodiment, refer to Figure 3 , the sampling unit includes a tenth capacitor C10, a fourteenth resistor R14, a sixteenth resistor R16, a seventeenth resistor R17, an eighteenth resistor R18, a nineteenth resistor R19, and a twentieth resistor R20. One end of the pin 6 of the first control chip U1 is connected to one end of the tenth capacitor 10 and one end of the fifteenth resistor R15. The other end of the fifteenth resistor R15 is respectively connected to one end of the sixteenth resistor R16, one end of the seventeenth resistor R17, one end of the eighteenth resistor R18, one end of the nineteenth resistor R19, one end of the twentieth resistor R20, and one end of the fourteenth resistor R14. The other end of the fourteenth resistor R14 is connected to the gate of the second triode Q2, and the source of the second triode Q2 is connected to one end of the twentieth resistor R20; the other ends of the sixteenth resistor R16, the seventeenth resistor R17, the eighteenth resistor R18, the nineteenth resistor R19, and the twentieth resistor R20 are respectively grounded.

[0039] Further, refer to Figure 1 , Figure 3 and Figure 5 , the output processing unit includes a third rectifying section, an energy storage section, and the secondary coil T1D of the first transformer; the secondary coil T1D of the first transformer is inductively connected to the primary coil T1B of the first transformer. One end of the secondary coil T1D of the first transformer is connected to the input end of the third rectifying section, and the output end of the third rectifying section is connected to the output pin; the primary coil T1B of the first transformer feeds back a voltage to the secondary coil T1D of the first transformer, and after rectification by the third rectifying section and energy storage by the energy storage section, an output is formed.

[0040] In one embodiment, refer to Figure 5, the third rectifying section includes a twelfth diode D12 and a thirteenth diode D13, and the energy storage section includes a seventeenth capacitor C17, an eighteenth capacitor C18, a nineteenth capacitor C19, and a twentieth capacitor C20; the positive electrodes of the twelfth diode D12 and the thirteenth diode D13 are respectively connected to one end of the secondary coil T1D of the first transformer; the negative electrode of the twelfth diode D12 is connected to the negative electrode of the thirteenth diode D13, and the negative electrode of the thirteenth diode D13 is also respectively connected to the positive electrode of the seventeenth capacitor C17, the positive electrode of the eighteenth capacitor C18, the positive electrode of the nineteenth capacitor C19, the positive electrode of the twentieth capacitor C20, and the output positive pin; the other end of the secondary coil T1D of the first transformer, the negative electrode of the seventeenth capacitor C17, the negative electrode of the eighteenth capacitor C18, the negative electrode of the nineteenth capacitor C19, the negative electrode of the twentieth capacitor C20, and the output negative pin are respectively grounded; the seventeenth capacitor C17, the eighteenth capacitor C18, the nineteenth capacitor C19, and the twentieth capacitor C20 are electrolytic capacitors.

[0041] The present invention also correspondingly provides a PCB board, on which the dimming circuit described in any one of the above is printed.

[0042] The present invention also correspondingly provides a dimming power supply, including a housing, and the PCB board described above is fixedly arranged in the housing; in one embodiment, the PCB board is screwed to the housing.

[0043] It can be understood that for those of ordinary skill in the art, equivalent replacements or changes can be made according to the technical solutions and inventive concepts of the present invention, and all such changes or replacements should fall within the protection scope of the present invention.

Claims

1. A dimming circuit, comprising a dimming port, characterized in that, It further includes an input processing unit, a control unit, a dimming unit, and an output processing unit. The input processing unit is used to filter and rectify the input alternating current. The output end of the input processing unit is connected to the input end of the control unit. The control unit includes the primary coil T2A of the second transformer. The dimming unit includes the secondary coil T2B of the second transformer. One end of the secondary coil T2B of the second transformer is connected to pin 1 of the dimming port, and the other end of the secondary coil T2B of the second transformer is connected to pin 2 of the dimming port. The primary coil T2A of the second transformer is inductively connected to the secondary coil T2B of the second transformer. The output end of the control unit is connected to the input end of the output processing unit. The control unit is used to adjust the output current according to the dimming signal. The output processing unit is used to rectify the power supply. The control unit includes a first control chip U1, a voltage dividing part, the secondary coil T1C of the first transformer, and a charging part. The model of the first control chip U1 is RT7306D. The input end of the voltage dividing part is connected to the output end of the input processing unit. The output end of the voltage dividing part is respectively connected to one end of the secondary coil T1C of the first transformer, pin 8 of the first control chip U1, and one end of the charging part. The other end of the charging part is connected to one end of the primary coil T2A of the second transformer. The other end of the secondary coil T1C of the first transformer and the other end of the primary coil T2A of the second transformer are respectively grounded. The charging part includes the eleventh capacitor C11 and the twenty-first resistor R21. One end of the eleventh capacitor C11 is connected to the output end of the voltage dividing part. The other end of the eleventh capacitor C11 is connected to one end of the twenty-first resistor R21. The other end of the twenty-first resistor R21 is connected to one end of the primary coil T21 of the second transformer. The control unit further includes a second rectifying part and the primary coil T1B of the first transformer. One end of the primary coil T2A of the second transformer is further connected to the input end of the second rectifying part. The output end of the second rectifying part is connected to pin 4 of the first control chip U1. Pin 6 of the first control chip U1 is connected to one end of the primary coil T1B of the first transformer. The other end of the primary coil T1B of the first transformer is connected to the output end of the input processing unit. The control unit further includes a sampling part and a second triode Q2. One end of the sampling part is connected to pin 6 of the first control chip U1. The other end of the sampling part is connected to the source electrode of the second triode Q2. The gate electrode of the second triode Q2 is connected to pin 7 of the first control chip U1. The drain electrode of the second triode Q2 is connected to one end of the primary coil T1B of the first transformer.

2. The dimming circuit according to claim 1, characterized in that, The input processing unit includes a filtering section and a first rectifying section. The input end of the filtering section is connected to an alternating current, the output end of the filtering section is connected to the input end of the first rectifying section, and the output end of the first rectifying section is connected to the input end of the control unit.

3. The dimming circuit according to claim 1, characterized in that, The second rectifying section includes a ninth diode D9, a twenty-second resistor R22, and a third triode Q3. The positive electrode of the ninth diode D9 is connected to one end of the primary coil T2A of the second transformer, the negative electrode of the ninth diode D9 is connected to one end of the twenty-second resistor R22, the other end of the twenty-second resistor R22 is connected to the base of the third triode Q3, the emitter of the third triode Q3 is grounded, and the collector of the third triode Q3 is connected to pin 4 of the first control chip U1.

4. The dimming circuit according to claim 1, characterized in that, The output processing unit includes a third rectifying section, an energy storage section, and the secondary coil T1D of the first transformer; the secondary coil T1D of the first transformer is inductively connected to the primary coil T1B of the first transformer, one end of the secondary coil T1D of the first transformer is connected to the input end of the third rectifying section, and the output end of the third rectifying section is connected to an output pin.

5. A PCB board, characterized in that, The dimming circuit according to any one of claims 1-4 is printed on the PCB board.

6. A dimming power supply, comprising a housing, characterized in that, The PCB board according to claim 5 is fixedly provided in the housing.

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