Multipath output dimming circuit based on DMX512 protocol

Abstract

The utility model provides a multiplexed output dimming circuit based on a DMX512 protocol. A DMX512 interface unit is connected with a dimming processing unit; the digital isolation unit is respectively connected with the dimming processing unit and the dimming voltage reduction unit; the dimming step-down unit is connected with the power supply assembly; the power supply assembly is connected with a lamp panel to be dimmed; a dimming signal of the DMX512 interface unit is transmitted to the dimming processing unit; a plurality of paths of PWM signals of the dimming processing unit are transmitted to the digital isolation unit; a plurality of paths of PWM signals of the digital isolation unit are transmitted to the dimming step-down unit; a plurality of paths of PWM signals of the dimming step-down unit are transmitted to the power supply assembly; an output signal of the power supply assembly is transmitted to the lamp panel to be dimmed. The digital isolation unit is used for isolation, so that the transmission speed requirement of the high-frequency PWM signal can be met, and delay and offset are reduced.

Description

Technical Field

[0001] This application relates to the field of LED dimming lighting, and in particular to a multi-output dimming circuit based on the DMX512 protocol. Background Technology

[0002] The DMX512 protocol is a digital transmission protocol used to control lighting, enabling precise control of lighting equipment, including adjusting brightness and color. For enhanced safety and compliance with CE and UL certification requirements, the power control input circuitry based on the DMX512 protocol typically requires isolation.

[0003] However, the isolation portion of existing dimming circuits suffers from significant transmission delays and offsets. Utility Model Content

[0004] In view of the above problems, this application is made in order to provide a multi-output dimming circuit based on the DMX512 protocol that overcomes or at least partially solves the above problems.

[0005] This application discloses a multi-output dimming circuit based on the DMX512 protocol, including a power supply component and a dimming component; the dimming component includes: a dimming processing unit, a digital isolation unit, and a dimming buck unit;

[0006] The DMX512 interface unit is connected to the dimming processing unit; the digital isolation unit is connected to both the dimming processing unit and the dimming step-down unit; the dimming step-down unit is connected to the power supply assembly; and the power supply assembly is connected to the lamp board to be dimmed.

[0007] The dimming signal of the DMX512 interface unit is transmitted to the dimming processing unit; the multiple PWM signals of the dimming processing unit are transmitted to the digital isolation unit; the multiple PWM signals of the digital isolation unit are transmitted to the dimming buck unit; the multiple PWM signals of the dimming buck unit are transmitted to the power supply component; and the output signal of the power supply component is transmitted to the lamp board to be dimmed.

[0008] Furthermore, the power supply assembly includes: an input unit, a PFC boost unit, an input voltage detection unit, an LLC resonant unit, a power processing unit, and an output unit;

[0009] The input unit is connected to the PFC boost unit and the input voltage detection unit respectively; the power processing unit is connected to the PFC boost unit, the input voltage detection unit and the LLC resonant unit respectively; the LLC resonant unit is connected to the PFC boost unit and the output unit respectively; the dimming buck unit is connected to the output unit; the output unit is connected to the lamp board to be dimmed;

[0010] The current from the input unit is transmitted to the PFC boost unit and the input voltage detection unit, respectively; the current from the PFC boost unit is transmitted to the LLC resonant unit; the current from the input voltage detection unit is transmitted to the power processing unit; the control signal from the power processing unit is transmitted to the PFC boost unit and the LLC resonant unit, respectively; the current from the LLC resonant unit is transmitted to the output unit; the multi-channel PWM signal from the dimming buck unit is transmitted to the output unit; and the output signal from the output unit is transmitted to the lamp board to be dimmed.

[0011] Furthermore, the dimming processing unit includes: a driver chip U2;

[0012] The first output terminal of the DMX512 interface unit is connected to the first input terminal of the inductor LF5, and the second output terminal of the DMX512 interface unit is connected to the second input terminal of the inductor LF5.

[0013] The first output terminal of inductor LF5 is connected to one end of diode TVS2, one end of diode TVS1, and one end of resistor R59; the second output terminal of inductor LF5 is connected to one end of diode TVS3, the other end of diode TVS1, and one end of resistor R58; the other end of diode TVS3 is connected to the other end of diode TVS2 and ground GS; the DA pin of driver chip U2 is connected to the other end of resistor R58; the DB pin of driver chip U2 is connected to the other end of resistor R59.

[0014] The anode of diode D13 is connected to the 12V-SVCC power supply; the cathode of diode D13 is connected to one end of resistor RF1, one end of resistor RF2, and one end of capacitor CE9; the VDD pin of the driver chip U2 is connected to the other end of resistor RF1, the other end of resistor RF2, one end of capacitor CE10, one end of capacitor CE11, one end of capacitor C1, one end of resistor R61, one end of resistor R62, one end of resistor R63, and one end of resistor R64; the other end of capacitor CE9 is connected to the other ends of capacitor CE10 and capacitor CE11, and to ground GS.

[0015] The R pin of the driver chip U2 is connected to the other end of resistor R61; the G pin of the driver chip U2 is connected to the other end of resistor R62; the B pin of the driver chip U2 is connected to the other end of resistor R63; and the W pin of the driver chip U2 is connected to the other end of resistor R64.

[0016] Furthermore, the digital isolation unit includes digital isolator U8 and digital isolator U9;

[0017] The R pin of the driver chip U2 is connected to one end of the resistor R68; the G pin of the driver chip U2 is connected to one end of the resistor R69; the B pin of the driver chip U2 is connected to one end of the resistor R70; and the W pin of the driver chip U2 is connected to one end of the resistor R71.

[0018] The VIB pin of the digital isolator U8 is connected to the other end of resistor R68; the VIA pin of the digital isolator U8 is connected to the other end of resistor R69; the VIA pin of the digital isolator U9 is connected to the other end of resistor R70; and the VIB pin of the digital isolator U9 is connected to the other end of resistor R71.

[0019] The VCC1 pin of the digital isolator U8 is connected to the 5V-S power supply and one end of the capacitor C35; the GND1 pin of the digital isolator U8 is connected to the other end of the capacitor C35 and ground GS; the VCC2 pin of the digital isolator U8 is connected to the 5V power supply and one end of the capacitor C17; the other end of the capacitor C17 is connected to ground SGND; the GND2 pin of the digital isolator U8 is connected to ground SGND.

[0020] The VCC1 pin of the digital isolator U9 is connected to the 5V-S power supply and one end of the capacitor C36; the GND1 pin of the digital isolator U9 is connected to the other end of the capacitor C36 and ground GS; the VCC2 pin of the digital isolator U9 is connected to the 5V power supply and one end of the capacitor C37; the other end of the capacitor C37 is connected to ground SGND; and the GND2 pin of the digital isolator U9 is connected to ground SGND.

[0021] Furthermore, the dimming step-down unit includes step-down transformers DC1, DC2, DC3, and DC4;

[0022] The PWM pin of the step-down transformer DC1 is connected to the VOB pin of the digital isolator U8 and one end of the resistor R72; the other end of the resistor R72 is connected to ground SGND.

[0023] The PWM pin of the step-down transformer DC2 is connected to the VOA pin of the digital isolator U8 and one end of the resistor R73; the other end of the resistor R73 is connected to ground SGND.

[0024] The PWM pin of the step-down transformer DC3 is connected to the VOA pin of the digital isolator U9 and one end of the resistor R74; the other end of the resistor R74 is connected to ground SGND.

[0025] The PWM pin of the step-down transformer DC4 is connected to the VOB pin of the digital isolator U9 and one end of the resistor R75; the other end of the resistor R75 is connected to ground SGND.

[0026] Furthermore, the power supply component includes an inductor LF3;

[0027] The first input terminal of the inductor LF3 is connected to the VIN pin of the step-down transformer DC1, the VIN pin of the step-down transformer DC2, the VIN pin of the step-down transformer DC3, and the VIN pin of the step-down transformer DC4.

[0028] The OUT pin of the step-down transformer DC1 is connected to the second input terminal of the inductor LF3; the OUT pin of the step-down transformer DC2 is connected to the third input terminal of the inductor LF3; the OUT pin of the step-down transformer DC3 is connected to the fourth input terminal of the inductor LF3; the OUT pin of the step-down transformer DC4 is connected to the fifth input terminal of the inductor LF3.

[0029] The first output terminal of the inductor LF3 is connected to the positive terminals of the red LED, green LED, blue LED, and yellow LED of the dimming lamp board.

[0030] The negative terminal of the red LED of the dimming lamp board is connected to the second output terminal of the inductor LF3; the negative terminal of the green LED of the dimming lamp board is connected to the third output terminal of the inductor LF3; the negative terminal of the blue LED of the dimming lamp board is connected to the fourth output terminal of the inductor LF3; and the negative terminal of the yellow LED of the dimming lamp board is connected to the fifth output terminal of the inductor LF3.

[0031] Furthermore, the power processing unit includes a controller U1; the PFC boost unit includes a switching transistor Q1, an inductor T1B, and a capacitor CE1.

[0032] The gate of the switch Q1 is connected to one end of resistor R11, one end of resistor R19, and the negative terminal of diode D4; the source of the switch Q1 is connected to the other end of resistor R11, the collector of transistor U5, and ground GND; the emitter of transistor U5 is connected to the other end of resistor R19.

[0033] The GATEB pin of the controller U1 is connected to the base of the transistor U5 and one end of the resistor R9; the other end of the resistor R9 is connected to the anode of the diode D4; the drain of the switching transistor Q1 is connected to the output terminal of the inductor T1B, one end of the resistor R12, and the anode of the diode D5; the input terminal of the inductor T1B is connected to the anode of the diode D3 and the output terminal of the input unit.

[0034] The power supply HV+ is connected to the positive terminal of capacitor CE1, one end of resistor R14, the negative terminals of diode D5 and diode D3; the negative terminal of capacitor CE1 is connected to ground GND.

[0035] The HV pin of the controller U1 is connected to one end of the resistor R13; the other end of the resistor R13 is connected to the other end of the resistor R12.

[0036] The FBB pin of the controller U1 is connected to one end of resistor R16; the other end of resistor R16 is connected to one end of resistor R15; and the other end of resistor R15 is connected to the other end of resistor R14.

[0037] Furthermore, the power processing unit includes a controller U1; the LLC resonant unit includes: a switching transistor Q2, a switching transistor Q3, a transformer T2, a capacitor C12, and an inductor L3;

[0038] The GATEH pin of the controller U1 is connected to one end of the resistor R22 and the base of the transistor U6; the other end of the resistor R22 is connected to the positive terminal of the diode D7.

[0039] The gate of the switching transistor Q2 is connected to the cathode of the diode D7, one end of the resistor R30, and one end of the resistor R25; the power supply HV+ is connected to the drain of the switching transistor Q2 and one end of the capacitor C13; the emitter of the transistor U6 is connected to the other end of the resistor R30.

[0040] The source of the switching transistor Q2 is connected to the drain of the switching transistor Q3, one end of the capacitor C14, one end of the inductor L3, the collector of the transistor U6, the other end of the resistor R25, and the other end of the capacitor C13.

[0041] The first input terminal of transformer T2 is connected to the other end of inductor L3; the second input terminal of transformer T2 is connected to one end of capacitor C12; the other end of capacitor C12 is connected to ground GND.

[0042] The GATEL pin of the controller U1 is connected to one end of the resistor R23 and the base of the transistor U7; the other end of the resistor R23 is connected to the positive terminal of the diode D8.

[0043] The gate of the switch Q3 is connected to one end of resistor R26, one end of resistor R53, and the negative terminal of diode D8.

[0044] The source of the switching transistor Q3 is connected to the collector of the transistor U7, the other end of the resistor R26, the other end of the capacitor C14, and ground GND.

[0045] Furthermore, the input unit includes: a lightning surge absorption subunit, an EMC filtering subunit, and an input rectification filtering subunit;

[0046] The input terminal of the lightning surge absorption subunit is connected to the AC power supply; the output terminal of the lightning surge absorption subunit is connected to the input terminal of the EMC filter subunit; the output terminal of the EMC filter subunit is connected to the input terminal of the input rectifier filter subunit and the input terminal of the input voltage detection unit; the output terminal of the input rectifier filter subunit is connected to the input terminal of the PFC boost unit.

[0047] Furthermore, it also includes: a first isolator power supply unit and a second isolator power supply unit;

[0048] The output terminal of the first isolator power supply unit is connected to the input terminal of the digital isolation unit; the output terminal of the second isolator power supply unit is connected to the output terminal of the digital isolation unit.

[0049] This application has the following advantages:

[0050] In the embodiments of this application, addressing the significant transmission delay and offset issues inherent in the isolation sections of existing dimming circuits, this application provides a solution of "achieving isolation processing of the dimming circuit through digital isolation technology." Specifically: a DMX512 interface unit is connected to a dimming processing unit; a digital isolation unit is connected to both the dimming processing unit and a dimming step-down unit; the dimming step-down unit is connected to a power supply component; the power supply component is connected to the lamp board to be dimmed; the dimming signal from the DMX512 interface unit is transmitted to the dimming processing unit; multiple PWM signals from the dimming processing unit are transmitted to the digital isolation unit; multiple PWM signals from the digital isolation unit are transmitted to the dimming step-down unit; multiple PWM signals from the dimming step-down unit are transmitted to the power supply component; and the output signal from the power supply component is transmitted to the lamp board to be dimmed. This application, through isolation using a digital isolation unit, can meet the transmission speed requirements of high-frequency PWM signals, thereby reducing delay and offset. Attached Figure Description

[0051] To more clearly illustrate the technical solution of this application, the drawings used in the description of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0052] Figure 1 This is a first structural block diagram of a multi-output dimming circuit based on the DMX512 protocol provided in an embodiment of this application;

[0053] Figure 2This is a second structural block diagram of a multi-output dimming circuit based on the DMX512 protocol provided in one embodiment of this application;

[0054] Figure 3 This is a schematic diagram of the circuit structure of the DMX512 interface unit, the dimming processing unit, and the digital isolation unit in one embodiment of this application;

[0055] Figure 4 This is a schematic diagram of the circuit structure of the output unit, the dimming and step-down unit, the first isolator power supply unit, and the second isolator power supply unit in one embodiment of this application;

[0056] Figure 5 This is a schematic diagram of the circuit structure of the power processing unit, the PFC boost unit, and the LLC resonant unit in one embodiment of this application;

[0057] Figure 6 This is a schematic diagram of the circuit structure of the input unit and the input voltage detection unit in one embodiment of this application;

[0058] Figure 7 This is a schematic diagram of the circuit structure of the feedback unit in a specific embodiment of this application;

[0059] Figure 8 This is a schematic diagram of the circuit structure of the primary-side VCC unit in a specific embodiment of this application. Detailed Implementation

[0060] To make the objectives, features, and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0061] The inventors, through analysis of existing technologies, discovered that the significant transmission delay and offset in the isolation section of existing dimming circuits are fundamentally due to the fact that current isolation circuit designs typically rely on optocouplers for isolation. However, optocouplers have slow signal transmission speeds and low data transmission rates. Furthermore, when the PWM signal frequency is high, the optocouplers generate substantial delays and distortions, leading to duty cycle misalignment, waveform distortion, and impacting signal accuracy and real-time performance. This also results in a series of problems such as light flicker, degraded dimming light characteristics, and premature light shutdown. Simultaneously, the relatively slow switching speed of optocouplers causes significant delays on the rising and falling edges of the PWM signal, affecting control precision. Moreover, the junction capacitance within the optocoupler causes substantial distortion in the PWM signal, resulting in large linear errors when the duty cycle's start and end points are converted into current.

[0062] Since digital isolators are based on the principle of capacitance, their signal transmission speed is much faster than that of optocouplers, and they can transmit the high-frequency components of PWM signals more accurately to reduce signal distortion. Therefore, one of the core technical concepts of this application is to achieve the isolation of the dimming circuit through digital isolation technology.

[0063] Reference Figure 1 This illustration shows a multi-output dimming circuit based on the DMX512 protocol according to an embodiment of this application, including a power supply component and a dimming component; the dimming component includes: a dimming processing unit, a digital isolation unit and a dimming buck unit;

[0064] The DMX512 interface unit is connected to the dimming processing unit; the digital isolation unit is connected to both the dimming processing unit and the dimming step-down unit; the dimming step-down unit is connected to the power supply assembly; and the power supply assembly is connected to the lamp board to be dimmed.

[0065] The dimming signal of the DMX512 interface unit is transmitted to the dimming processing unit; the multiple PWM signals of the dimming processing unit are transmitted to the digital isolation unit; the multiple PWM signals of the digital isolation unit are transmitted to the dimming buck unit; the multiple PWM signals of the dimming buck unit are transmitted to the power supply component; and the output signal of the power supply component is transmitted to the lamp board to be dimmed.

[0066] In the embodiments of this application, addressing the significant transmission delay and offset issues inherent in the isolation sections of existing dimming circuits, this application provides a solution of "achieving isolation processing of the dimming circuit through digital isolation technology." Specifically: a DMX512 interface unit is connected to a dimming processing unit; a digital isolation unit is connected to both the dimming processing unit and a dimming step-down unit; the dimming step-down unit is connected to a power supply component; the power supply component is connected to the lamp board to be dimmed; the dimming signal from the DMX512 interface unit is transmitted to the dimming processing unit; multiple PWM signals from the dimming processing unit are transmitted to the digital isolation unit; multiple PWM signals from the digital isolation unit are transmitted to the dimming step-down unit; multiple PWM signals from the dimming step-down unit are transmitted to the power supply component; and the output signal from the power supply component is transmitted to the lamp board to be dimmed. This application, through isolation using a digital isolation unit, can meet the transmission speed requirements of high-frequency PWM signals, thereby reducing delay and offset.

[0067] Meanwhile, the digital isolation circuit of this application features fast data transmission speed, meeting the transmission requirements of high-frequency PWM signals and achieving high-precision duty cycle control; it has accurate timing characteristics, with small transmission delay and offset, ensuring the synchronization and accuracy of the PWM signal; it enables precise transmission of voltage signals across the isolation medium, with the input and output PWM waveforms being very close to 1:1, greatly improving the dimming depth to 1 / 1000. Furthermore, it has low power consumption, which helps reduce system energy consumption and improve energy efficiency.

[0068] The following will further describe a multi-output dimming circuit based on the DMX512 protocol in this exemplary embodiment.

[0069] It should be noted that the DMX512 interface unit is used to output DMX512 dimming signals to the dimming processing unit; the power supply component is used to provide power to the lamp board to be dimmed; the multi-channel PWM signal can specifically be four channels, including: PWM-R red light signal, PWM-G green light signal, PWM-B blue light signal, and PWM-W white light signal; the digital isolation unit can isolate the four PWM signals respectively; the digital isolation unit may include isolation capacitors.

[0070] The internal IC of the digital isolation unit can couple the PWM signal to the output terminal of the IC by utilizing the principle that capacitors pass AC and block DC, have low capacitive reactance at high frequencies and high capacitive reactance at low frequencies. Since the amplitude of the PWM signal decreases due to the capacitive reactance of the isolation capacitor after passing through the IC, the specific change is determined by the frequency of the PWM signal and the capacitive reactance of the isolation capacitor.

[0071] Reference Figure 2 In one embodiment of this application, the power supply component includes: an input unit, a PFC boost unit, an input voltage detection unit, an LLC resonant unit, a power processing unit, and an output unit;

[0072] The input unit is connected to the PFC boost unit and the input voltage detection unit respectively; the power processing unit is connected to the PFC boost unit, the input voltage detection unit and the LLC resonant unit respectively; the LLC resonant unit is connected to the PFC boost unit and the output unit respectively; the dimming buck unit is connected to the output unit; the output unit is connected to the lamp board to be dimmed;

[0073] The current from the input unit is transmitted to the PFC boost unit and the input voltage detection unit, respectively; the current from the PFC boost unit is transmitted to the LLC resonant unit; the current from the input voltage detection unit is transmitted to the power processing unit; the control signal from the power processing unit is transmitted to the PFC boost unit and the LLC resonant unit, respectively; the current from the LLC resonant unit is transmitted to the output unit; the multi-channel PWM signal from the dimming buck unit is transmitted to the output unit; and the output signal from the output unit is transmitted to the lamp board to be dimmed.

[0074] It should be noted that the PFC boost unit can achieve a constant output voltage by precisely controlling the on and off times of the switching transistor; the LLC resonant unit can utilize the reactance voltage division principle, with its resonant cavity operating in the inductive region, achieving zero-voltage turn-on (ZVS) and zero-current turn-off (ZCS) at most operating frequencies, reducing switching losses, improving efficiency, and enabling the power supply to operate at high frequencies, thereby reducing the size of magnetic components and electrolytic capacitors, and achieving high power in a small size.

[0075] Reference Figure 3 In one embodiment of this application, the dimming processing unit includes: a driver chip U2;

[0076] The first output terminal of the DMX512 interface unit is connected to the first input terminal of the inductor LF5, and the second output terminal of the DMX512 interface unit is connected to the second input terminal of the inductor LF5.

[0077] The first output terminal of inductor LF5 is connected to one end of diode TVS2, one end of diode TVS1, and one end of resistor R59; the second output terminal of inductor LF5 is connected to one end of diode TVS3, the other end of diode TVS1, and one end of resistor R58; the other end of diode TVS3 is connected to the other end of diode TVS2 and ground GS; the DA pin of driver chip U2 is connected to the other end of resistor R58; the DB pin of driver chip U2 is connected to the other end of resistor R59.

[0078] The anode of diode D13 is connected to the 12V-SVCC power supply; the cathode of diode D13 is connected to one end of resistor RF1, one end of resistor RF2, and one end of capacitor CE9; the VDD pin of the driver chip U2 is connected to the other end of resistor RF1, the other end of resistor RF2, one end of capacitor CE10, one end of capacitor CE11, one end of capacitor C1, one end of resistor R61, one end of resistor R62, one end of resistor R63, and one end of resistor R64; the other end of capacitor CE9 is connected to the other ends of capacitor CE10 and capacitor CE11, and to ground GS.

[0079] The R pin of the driver chip U2 is connected to the other end of resistor R61; the G pin of the driver chip U2 is connected to the other end of resistor R62; the B pin of the driver chip U2 is connected to the other end of resistor R63; and the W pin of the driver chip U2 is connected to the other end of resistor R64.

[0080] It should be noted that the driver chip U2 may be a Hi512E4.

[0081] In one specific implementation, the DMX512 control bus signal is decoded by the driver chip U2, and then the driver chip U2 outputs 4 PWM signals.

[0082] Reference Figure 3 In one embodiment of this application, the digital isolation unit includes a digital isolator U8 and a digital isolator U9;

[0083] The R pin of the driver chip U2 is connected to one end of the resistor R68; the G pin of the driver chip U2 is connected to one end of the resistor R69; the B pin of the driver chip U2 is connected to one end of the resistor R70; and the W pin of the driver chip U2 is connected to one end of the resistor R71.

[0084] The VIB pin of the digital isolator U8 is connected to the other end of resistor R68; the VIA pin of the digital isolator U8 is connected to the other end of resistor R69; the VIA pin of the digital isolator U9 is connected to the other end of resistor R70; and the VIB pin of the digital isolator U9 is connected to the other end of resistor R71.

[0085] The VCC1 pin of the digital isolator U8 is connected to the 5V-S power supply and one end of the capacitor C35; the GND1 pin of the digital isolator U8 is connected to the other end of the capacitor C35 and ground GS; the VCC2 pin of the digital isolator U8 is connected to the 5V power supply and one end of the capacitor C17; the other end of the capacitor C17 is connected to ground SGND; the GND2 pin of the digital isolator U8 is connected to ground SGND.

[0086] The VCC1 pin of the digital isolator U9 is connected to the 5V-S power supply and one end of the capacitor C36; the GND1 pin of the digital isolator U9 is connected to the other end of the capacitor C36 and ground GS; the VCC2 pin of the digital isolator U9 is connected to the 5V power supply and one end of the capacitor C37; the other end of the capacitor C37 is connected to ground SGND; and the GND2 pin of the digital isolator U9 is connected to ground SGND.

[0087] It should be noted that the model number of the digital isolator U8 and the model number of the digital isolator U9 can be π122X3.

[0088] After the DMX512 control bus signal is decoded by the driver chip U2, the driver chip U2 outputs four PWM signals. These signals pass through the signal input pins of digital isolators U8 and U9, and then through the internal RC coupling of digital isolators U8 and U9 to the output pins. The PWM signals can be restored to the same amplitude as when they were input using a compensation and shaping circuit before being transmitted to the outputs (VOA and VOB pins) of digital isolators U8 and U9.

[0089] Reference Figure 4 In one embodiment of this application, the dimming step-down unit includes step-down transformers DC1, DC2, DC3, and DC4.

[0090] The PWM pin of the step-down transformer DC1 is connected to the VOB pin of the digital isolator U8 and one end of the resistor R72; the other end of the resistor R72 is connected to ground SGND.

[0091] The PWM pin of the step-down transformer DC2 is connected to the VOA pin of the digital isolator U8 and one end of the resistor R73; the other end of the resistor R73 is connected to ground SGND.

[0092] The PWM pin of the step-down transformer DC3 is connected to the VOA pin of the digital isolator U9 and one end of the resistor R74; the other end of the resistor R74 is connected to ground SGND.

[0093] The PWM pin of the step-down transformer DC4 is connected to the VOB pin of the digital isolator U9 and one end of the resistor R75; the other end of the resistor R75 is connected to ground SGND.

[0094] It should be noted that step-down transformers DC1, DC2, DC3, and DC4 are all equipped with PWM dimming output pins for switching and dimming control.

[0095] Reference Figure 4 In one embodiment of this application, the power supply component includes an inductor LF3;

[0096] The first input terminal of the inductor LF3 is connected to the VIN pin of the step-down transformer DC1, the VIN pin of the step-down transformer DC2, the VIN pin of the step-down transformer DC3, and the VIN pin of the step-down transformer DC4.

[0097] The OUT pin of the step-down transformer DC1 is connected to the second input terminal of the inductor LF3; the OUT pin of the step-down transformer DC2 is connected to the third input terminal of the inductor LF3; the OUT pin of the step-down transformer DC3 is connected to the fourth input terminal of the inductor LF3; the OUT pin of the step-down transformer DC4 is connected to the fifth input terminal of the inductor LF3.

[0098] The first output terminal of the inductor LF3 is connected to the positive terminals of the red LED, green LED, blue LED, and yellow LED of the dimming lamp board.

[0099] The negative terminal of the red LED of the dimming lamp board is connected to the second output terminal of the inductor LF3; the negative terminal of the green LED of the dimming lamp board is connected to the third output terminal of the inductor LF3; the negative terminal of the blue LED of the dimming lamp board is connected to the fourth output terminal of the inductor LF3; and the negative terminal of the yellow LED of the dimming lamp board is connected to the fifth output terminal of the inductor LF3.

[0100] Reference Figure 5 In one embodiment of this application, the power processing unit includes a controller U1; the PFC boost unit includes a switching transistor Q1, an inductor T1B, and a capacitor CE1.

[0101] The gate of the switch Q1 is connected to one end of resistor R11, one end of resistor R19, and the negative terminal of diode D4; the source of the switch Q1 is connected to the other end of resistor R11, the collector of transistor U5, and ground GND; the emitter of transistor U5 is connected to the other end of resistor R19.

[0102] The GATEB pin of the controller U1 is connected to the base of the transistor U5 and one end of the resistor R9; the other end of the resistor R9 is connected to the anode of the diode D4; the drain of the switching transistor Q1 is connected to the output terminal of the inductor T1B, one end of the resistor R12, and the anode of the diode D5; the input terminal of the inductor T1B is connected to the anode of the diode D3 and the output terminal of the input unit.

[0103] The power supply HV+ is connected to the positive terminal of capacitor CE1, one end of resistor R14, the negative terminals of diode D5 and diode D3; the negative terminal of capacitor CE1 is connected to ground GND.

[0104] The HV pin of the controller U1 is connected to one end of the resistor R13; the other end of the resistor R13 is connected to the other end of the resistor R12.

[0105] The FBB pin of the controller U1 is connected to one end of resistor R16; the other end of resistor R16 is connected to one end of resistor R15; and the other end of resistor R15 is connected to the other end of resistor R14.

[0106] It should be noted that the controller U1 may be model SY5055; the controller U1 is used to control the on and off of the switching transistor Q1.

[0107] The PFC boost process includes a turn-on phase and a turn-off phase for switch Q1, and the specific principle is as follows:

[0108] When the switch Q1 is turned on, the current flows through the inductor T1B. Before the inductor T1B is saturated, the current in the inductor T1B increases linearly. The electrical energy is stored in the inductor T1B in the form of magnetic energy. At this time, the capacitor CE1 discharges to provide energy to the load.

[0109] When the switching transistor Q1 is off, a self-induced electromotive force VL is generated across the inductor T1B to maintain the current direction. This self-induced electromotive force VL is connected in series with the power supply HV+ to supply power to capacitor CE1 and the load, thereby increasing the output voltage to a value greater than the input voltage. Simultaneously, the FBB pin of the controller U1 detects the voltage across capacitor CE1 through several resistors and capacitors. When the voltage across capacitor CE1 reaches a set value, the controller U1 decreases the duty cycle of the GATEB pin; when the voltage across capacitor CE1 is less than the set value, the controller U1 increases the duty cycle of the GATEB pin, thus precisely controlling the on and off times of the switching transistor to achieve a constant output voltage.

[0110] Reference Figure 5 In one embodiment of this application, the power processing unit includes a controller U1; the LLC resonant unit includes: a switching transistor Q2, a switching transistor Q3, a transformer T2, a capacitor C12, and an inductor L3;

[0111] The GATEH pin of the controller U1 is connected to one end of the resistor R22 and the base of the transistor U6; the other end of the resistor R22 is connected to the positive terminal of the diode D7.

[0112] The gate of the switching transistor Q2 is connected to the cathode of the diode D7, one end of the resistor R30, and one end of the resistor R25; the power supply HV+ is connected to the drain of the switching transistor Q2 and one end of the capacitor C13; the emitter of the transistor U6 is connected to the other end of the resistor R30.

[0113] The source of the switching transistor Q2 is connected to the drain of the switching transistor Q3, one end of the capacitor C14, one end of the inductor L3, the collector of the transistor U6, the other end of the resistor R25, and the other end of the capacitor C13.

[0114] The first input terminal of transformer T2 is connected to the other end of inductor L3; the second input terminal of transformer T2 is connected to one end of capacitor C12; the other end of capacitor C12 is connected to ground GND.

[0115] The GATEL pin of the controller U1 is connected to one end of the resistor R23 and the base of the transistor U7; the other end of the resistor R23 is connected to the positive terminal of the diode D8.

[0116] The gate of the switch Q3 is connected to one end of resistor R26, one end of resistor R53, and the negative terminal of diode D8.

[0117] The source of the switching transistor Q3 is connected to the collector of the transistor U7, the other end of the resistor R26, the other end of the capacitor C14, and ground GND.

[0118] It should be noted that the controller U1 is used to control the conduction and cutoff of the switching transistors Q2 and Q3.

[0119] The LLC resonant process includes an energy storage stage, an energy transfer stage, and a repetitive energy storage stage. The specific principle is as follows:

[0120] Energy storage stage: When switch Q2 is turned on and switch Q3 is turned off, the input current flows into the resonant circuit through the input inductor Lin. Inductor Lin stores energy, and resonant capacitor C12 and resonant inductor L3 are charged. At this time, the primary winding current of the transformer increases, and the secondary winding current is zero.

[0121] Energy transfer stage: When switch Q2 is off and switch Q3 is on, the inductor's stored energy is released, and the current is transferred to the secondary winding through the transformer. The primary winding current decreases and the secondary winding current increases, thus realizing the transfer and conversion of electrical energy.

[0122] Repeated energy storage stage: When switch Q2 turns on again and switch Q3 turns off again, the circuit returns to the energy storage stage, inductor Lin stores energy again, and resonant capacitor C12 and resonant inductor L3 discharge, and so on.

[0123] Reference Figure 6 In one embodiment of this application, the input unit includes: a lightning surge absorption subunit, an EMC filtering subunit, and an input rectification filtering subunit;

[0124] The input terminal of the lightning surge absorption subunit is connected to the AC power supply; the output terminal of the lightning surge absorption subunit is connected to the input terminal of the EMC filter subunit; the output terminal of the EMC filter subunit is connected to the input terminal of the input rectifier filter subunit and the input terminal of the input voltage detection unit; the output terminal of the input rectifier filter subunit is connected to the input terminal of the PFC boost unit.

[0125] Reference Figure 4 In one embodiment of this application, it further includes: a first isolator power supply unit and a second isolator power supply unit;

[0126] The output terminal of the first isolator power supply unit is connected to the input terminal of the digital isolation unit; the output terminal of the second isolator power supply unit is connected to the output terminal of the digital isolation unit.

[0127] It should be noted that the first isolator power supply unit and the second isolator power supply unit can be used to power the digital isolation unit.

[0128] Reference Figure 4 In one specific embodiment of this application, the output component includes a controller U6, and the controller U6 is model MP6925;

[0129] The first isolator power supply unit includes U12; the vin pin of U12 is connected to the PPA pin of the controller U6; the O pin of U12 is connected to the 5V power supply; and the G pin of U12 is connected to ground SGND.

[0130] The second isolator power supply unit includes U13; the vin pin of U13 is connected to the 12V-SVCC power supply; the O pin of U13 is connected to the 5V-S power supply; and the G pin of U13 is connected to ground SG.

[0131] It should be noted that the first isolator power supply unit is the VCC power supply circuit at the output terminals of digital isolators U8 and U9; the second isolator power supply unit is the VCC power supply circuit at the input terminals of digital isolators U8 and U9, and is also the power supply circuit for the 512 decoder U2.

[0132] Reference Figure 7 In one specific embodiment of this application, the power supply component further includes a feedback unit; the feedback unit includes an optocoupler PC1; the feedback unit is connected to the FBL pin of the controller U1 and the output unit respectively.

[0133] Reference Figure 8 In one specific embodiment of this application, the power supply component further includes a primary-side VCC unit; the primary-side VCC unit is connected to the VCC pin of the controller U1 and the input terminal of the transformer T2, respectively. The primary-side VCC unit is used for powering the IC and for voltage detection.

[0134] Although preferred embodiments of the present application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present application.

[0135] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0136] The above provides a detailed description of a multi-output dimming circuit based on the DMX512 protocol provided in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A multi-output dimming circuit based on DMX512 protocol, characterized in that, The power supply assembly and the dimming assembly are included; the dimming assembly includes a dimming processing unit, a digital isolation unit and a dimming step-down unit; The DMX512 interface unit is connected with the dimming processing unit; the digital isolation unit is connected with the dimming processing unit and the dimming step-down unit respectively; the dimming step-down unit is connected with the power supply assembly; the power supply assembly is connected with the lamp panel to be dimmed; The dimming signal of the DMX512 interface unit is transmitted to the dimming processing unit; the multi-channel PWM signal of the dimming processing unit is transmitted to the digital isolation unit; the multi-channel PWM signal of the digital isolation unit is transmitted to the dimming step-down unit; the multi-channel PWM signal of the dimming step-down unit is transmitted to the power supply assembly; the output signal of the power supply assembly is transmitted to the lamp panel to be dimmed.

2. The circuit of claim 1, wherein, The power supply assembly includes an input unit, a PFC step-up unit, an input voltage detection unit, an LLC resonance unit, a power supply processing unit and an output unit; The input unit is connected with the PFC step-up unit and the input voltage detection unit respectively; the power supply processing unit is connected with the PFC step-up unit, the input voltage detection unit and the LLC resonance unit respectively; the LLC resonance unit is connected with the PFC step-up unit and the output unit respectively; the dimming step-down unit is connected with the output unit; the output unit is connected with the lamp panel to be dimmed; The current of the input unit is transmitted to the PFC step-up unit and the input voltage detection unit respectively; the current of the PFC step-up unit is transmitted to the LLC resonance unit; the current of the input voltage detection unit is transmitted to the power supply processing unit; the control signal of the power supply processing unit is transmitted to the PFC step-up unit and the LLC resonance unit respectively; the current of the LLC resonance unit is transmitted to the output unit; the multi-channel PWM signal of the dimming step-down unit is transmitted to the output unit; the output signal of the output unit is transmitted to the lamp panel to be dimmed.

3. The circuit of claim 1, wherein, The dimming processing unit includes a driving chip U2; The first output end of the DMX512 interface unit is connected with the first input end of an inductor LF5, and the second output end of the DMX512 interface unit is connected with the second input end of the inductor LF5; The first output end of the inductor LF5 is connected with one end of a diode TVS2, one end of a diode TVS1 and one end of a resistor R59; the second output end of the inductor LF5 is connected with one end of a diode TVS3, the other end of the diode TVS1 and one end of a resistor R58; the other end of the diode TVS3 is connected with the other end of the diode TVS2 and a ground G-S; the DA pin of the driving chip U2 is connected with the other end of the resistor R58; the DB pin of the driving chip U2 is connected with the other end of the resistor R59; The positive electrode of diode D13 is connected with power supply 12V-SVCC; the negative electrode of diode D13 is connected with one end of resistor RF1, one end of resistor RF2 and one end of capacitor CE9; the VDD pin of driving chip U2 is connected with the other end of resistor RF1, the other end of resistor RF2, one end of capacitor CE10, one end of capacitor CE11, one end of capacitor C1, one end of resistor R61, one end of resistor R62, one end of resistor R63 and one end of resistor R64; the other end of capacitor CE9 is connected with the other end of capacitor CE10, the other end of capacitor CE11 and ground G-S; The R pin of driving chip U2 is connected with the other end of resistor R61; the G pin of driving chip U2 is connected with the other end of resistor R62; the B pin of driving chip U2 is connected with the other end of resistor R63; the W pin of driving chip U2 is connected with the other end of resistor R64.

4. The circuit of claim 3, wherein, The digital isolation unit comprises digital isolator U8 and digital isolator U9; The R pin of driving chip U2 is connected with one end of resistor R68; the G pin of driving chip U2 is connected with one end of resistor R69; the B pin of driving chip U2 is connected with one end of resistor R70; the W pin of driving chip U2 is connected with one end of resistor R71; The VIB pin of digital isolator U8 is connected with the other end of resistor R68; the VIA pin of digital isolator U8 is connected with the other end of resistor R69; the VIA pin of digital isolator U9 is connected with the other end of resistor R70; the VIB pin of digital isolator U9 is connected with the other end of resistor R71; The vcc1 pin of digital isolator U8 is connected with power supply 5V-S and one end of capacitor C35, and the gnd1 pin of digital isolator U8 is connected with the other end of capacitor C35 and ground G-S; the vcc2 pin of digital isolator U8 is connected with power supply 5V and one end of capacitor C17, and the other end of capacitor C17 is connected with ground SGND; the gnd2 pin of digital isolator U8 is connected with ground SGND; The vcc1 pin of digital isolator U9 is connected with power supply 5V-S and one end of capacitor C36, and the gnd1 pin of digital isolator U9 is connected with the other end of capacitor C36 and ground G-S; the vcc2 pin of digital isolator U9 is connected with power supply 5V and one end of capacitor C37, and the other end of capacitor C37 is connected with ground SGND; the gnd2 pin of digital isolator U9 is connected with ground SGND.

5. The circuit of claim 4, wherein, The dimming step-down unit comprises step-down DC1, step-down DC2, step-down DC3 and step-down DC4; The PWM pin of step-down DC1 is connected with the VOB pin of digital isolator U8 and one end of resistor R72; the other end of resistor R72 is connected with ground SGND; The PWM pin of step-down DC2 is connected with the VOA pin of digital isolator U8 and one end of resistor R73; the other end of resistor R73 is connected with ground SGND; The PWM pin of step-down DC3 is connected with the VOB pin of digital isolator U9 and one end of resistor R74; the other end of resistor R74 is connected with ground SGND; The PWM pin of step-down DC4 is connected with the VOA pin of digital isolator U9 and one end of resistor R75; the other end of resistor R75 is connected with ground SGND. The PWM pin of the voltage reducer DC3 is connected with the VOA pin of the digital isolator U9 and one end of the resistor R74; the other end of the resistor R74 is connected with the ground SGND; The PWM pin of the voltage reducer DC4 is connected with the VOB pin of the digital isolator U9 and one end of the resistor R75; the other end of the resistor R75 is connected with the ground SGND.

6. The circuit of claim 5, wherein, The power supply component comprises an inductor LF3; The first input end of the inductor LF3 is connected with the VIN pin of the voltage reducer DC1, the VIN pin of the voltage reducer DC2, the VIN pin of the voltage reducer DC3 and the VIN pin of the voltage reducer DC4; The OUT pin of the voltage reducer DC1 is connected with the second input end of the inductor LF3; the OUT pin of the voltage reducer DC2 is connected with the third input end of the inductor LF3; the OUT pin of the voltage reducer DC3 is connected with the fourth input end of the inductor LF3; the OUT pin of the voltage reducer DC4 is connected with the fifth input end of the inductor LF3; The first output end of the inductor LF3 is connected with the positive pole of the red LED of the light panel to be adjusted, the positive pole of the green LED of the light panel to be adjusted, the positive pole of the blue LED of the light panel to be adjusted and the positive pole of the yellow LED of the light panel to be adjusted; The negative pole of the red LED of the light panel to be adjusted is connected with the second output end of the inductor LF3; the negative pole of the green LED of the light panel to be adjusted is connected with the third output end of the inductor LF3; the negative pole of the blue LED of the light panel to be adjusted is connected with the fourth output end of the inductor LF3; the negative pole of the yellow LED of the light panel to be adjusted is connected with the fifth output end of the inductor LF3.

7. The circuit of claim 2, wherein, The power supply processing unit comprises a controller U1; the PFC voltage boosting unit comprises a switching tube Q1, an inductor coil T1B and a capacitor CE1; The gate of the switching tube Q1 is connected with one end of the resistor R11, one end of the resistor R19 and the negative pole of the diode D4; the source of the switching tube Q1 is connected with the other end of the resistor R11, the collector of the triode U5 and the ground GND; the emitter of the triode U5 is connected with the other end of the resistor R19; The GATEB pin of the controller U1 is connected with the base of the triode U5 and one end of the resistor R9; the other end of the resistor R9 is connected with the positive pole of the diode D4; the drain of the switching tube Q1 is connected with the output end of the inductor coil T1B, one end of the resistor R12 and the positive pole of the diode D5; the input end of the inductor coil T1B is connected with the positive pole of the diode D3 and the output end of the input unit; The power supply HV+ is connected with the positive pole of the capacitor CE1, one end of the resistor R14, the negative pole of the diode D5 and the negative pole of the diode D3; the negative pole of the capacitor CE1 is connected with the ground GND; The HV pin of the controller U1 is connected with one end of the resistor R13; the other end of the resistor R13 is connected with the other end of the resistor R12; The FBB pin of the controller U1 is connected with one end of the resistor R16; the other end of the resistor R16 is connected with one end of the resistor R15; the other end of the resistor R15 is connected with the other end of the resistor R14.

8. The circuit of claim 2, wherein, The power supply processing unit comprises a controller U1; the LLC resonance unit comprises a switch tube Q2, a switch tube Q3, a transformer T2, a capacitor C12 and an inductor L3; The GATEH pin of the controller U1 is connected with one end of the resistor R22 and the base of the triode U6; the other end of the resistor R22 is connected with the positive electrode of the diode D7; The gate of the switch tube Q2 is connected with the negative electrode of the diode D7, one end of the resistor R30 and one end of the resistor R25; the power supply HV+ is connected with the drain of the switch tube Q2 and one end of the capacitor C13; the emitter of the triode U6 is connected with the other end of the resistor R30; The source of the switch tube Q2 is connected with the drain of the switch tube Q3, one end of the capacitor C14, one end of the inductor L3, the collector of the triode U6, the other end of the resistor R25 and the other end of the capacitor C13; The first input end of the transformer T2 is connected with the other end of the inductor L3; the second input end of the transformer T2 is connected with one end of the capacitor C12; the other end of the capacitor C12 is connected with the ground GND; The GATEL pin of the controller U1 is connected with one end of the resistor R23 and the base of the triode U7; the other end of the resistor R23 is connected with the positive electrode of the diode D8; The gate of the switch tube Q3 is connected with one end of the resistor R26, one end of the resistor R53 and the negative electrode of the diode D8; The source of the switch tube Q3 is connected with the collector of the triode U7, the other end of the resistor R26, the other end of the capacitor C14 and the ground GND.

9. The circuit of claim 2, wherein, The input unit comprises a lightning surge absorption subunit, an EMC filtering subunit and an input rectification filtering subunit; The input end of the lightning surge absorption subunit is connected with the alternating current power supply; the output end of the lightning surge absorption subunit is connected with the input end of the EMC filtering subunit; the output end of the EMC filtering subunit is connected with the input end of the input rectification filtering subunit and the input end of the input voltage detection unit; the output end of the input rectification filtering subunit is connected with the input end of the PFC voltage boosting unit.

10. The circuit of claim 1, wherein, Further comprising: A first isolator power supply unit and a second isolator power supply unit; The output end of the first isolator power supply unit is connected with the input end of the digital isolation unit; The output end of the second isolator power supply unit is connected with the output end of the digital isolation unit.

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