LED color temperature brightness adjustment circuit

Abstract

This utility model relates to the field of LED control technology, specifically to an LED color temperature and brightness adjustment circuit, comprising: a filter and rectifier circuit, a step-down constant current circuit, a color temperature adjustment circuit, an auxiliary power supply circuit, and an MCU circuit; the filter and rectifier circuit is used to convert AC mains power into constant voltage DC power and to power the step-down constant current circuit and the auxiliary power supply circuit; the MCU circuit is used to provide a first pulse control signal and a second pulse control signal; the step-down constant current circuit is used to generate a constant drive current to the color temperature adjustment circuit according to the first pulse control signal issued by the MCU circuit; the color temperature adjustment circuit is used to control two NMOS transistors to alternately conduct to generate different potential signals to drive two LED strings with different color temperatures according to the constant drive current provided by the step-down constant current circuit and the second pulse control signal issued by the MCU circuit; the auxiliary power supply circuit is used to generate a constant voltage to the MCU circuit according to the constant voltage DC power provided by the filter and rectifier circuit.

Description

Technical Field

[0001] This utility model relates to the field of LED control technology, specifically to an LED color temperature and brightness adjustment circuit. Background Technology

[0002] Lighting fixtures are everyday necessities. With the gradual development of LED lighting technology, LED lights are developing at a very fast pace and gradually replacing other lighting fixtures due to their unparalleled advantages. They have been widely used in various lighting fields.

[0003] Traditional LED color temperature adjustment circuits use an MCU circuit to send three independent control signals to control three sets of constant current IC circuits to adjust the color temperature and brightness of two LED strings with different color temperatures. Because three sets of constant current IC circuits are needed to adjust the color temperature and brightness of two LED strings with different color temperatures, the circuit has many components, large space, and high cost. Utility Model Content

[0004] To address the shortcomings of existing technologies, this utility model provides an LED color temperature and brightness adjustment circuit, aiming to solve the problems of existing LED color temperature adjustment circuits requiring three sets of constant current IC circuits to adjust the color temperature and brightness of two LED light strings with different color temperatures, resulting in numerous circuit components, large space requirements, and high costs.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] An LED color temperature and brightness adjustment circuit includes: a filter rectifier circuit, a step-down constant current circuit, a color temperature adjustment circuit, an auxiliary power supply circuit, and an MCU circuit;

[0007] The filter rectifier circuit is connected to the step-down constant current circuit and the auxiliary power supply circuit, and is used to convert AC mains power into constant voltage DC power and to supply power to the step-down constant current circuit and the auxiliary power supply circuit;

[0008] The MCU circuit connects the step-down constant current circuit and the color temperature adjustment circuit, and is used to provide a first pulse control signal and a second pulse control signal. The first pulse control signal is used to control the current output by the step-down constant current circuit, and the second pulse control signal is used to control the two MOS transistors of the color temperature adjustment circuit to alternately conduct to generate different potential signals.

[0009] The step-down constant current circuit is connected to the color temperature adjustment circuit. The step-down constant current circuit generates a constant drive current to the color temperature adjustment circuit based on the first pulse control signal issued by the MCU circuit. The color temperature adjustment circuit generates a drive signal through the gate drive level conversion circuit based on the constant drive current provided by the step-down constant current circuit and the second pulse control signal issued by the MCU circuit to control the MOS transistor to alternately conduct, thereby driving two LED strings with different color temperatures to achieve continuous color temperature adjustment from 2700K to 6500K with current ripple <5%.

[0010] The auxiliary power supply circuit is connected to the MCU circuit and is used to generate a constant voltage for the MCU circuit based on the constant voltage DC power provided by the filter and rectifier circuit.

[0011] In some embodiments, the filter rectifier circuit includes: a thermal relay FR1, a common-mode inductor LF1, a common-mode inductor LF2, capacitors CY1 and CY2, a varistor MOV1, resistors R1, R2, and R3, capacitor CX1, a rectifier bridge DB1, capacitors C1 and C2, and inductor L1. One end of the thermal relay FR1 is connected to the live wire of the mains power supply, and the other end of the thermal relay is connected to one end of capacitor CY1 and the first pin of the common-mode inductor LF1. The other end of capacitor CY1 is grounded and connected to one end of capacitor CY2. The other end of capacitor CY2 is connected to the neutral wire of the mains power supply and the second pin of the common-mode inductor LF1. The third pin of the common-mode inductor LF1 is connected to the varistor MOV1, the resistor R1, and the inductor L1. One end of capacitor CX1 is connected to the first pin of common-mode inductor LF2. The other end of resistor R1 is connected to one end of resistor R2. The fourth pin of common-mode inductor LF1 is connected to varistor MOV1, resistor R2, the other end of capacitor CX1, and the second pin of common-mode inductor LF2. The third pin of common-mode inductor LF2 is connected to the first pin of rectifier bridge. The fourth pin of inductor LF2 is connected to the third pin of rectifier bridge. The second pin of rectifier bridge is connected to one end of capacitor C1, resistor R3, and inductor L1. The other end of resistor R3 and inductor L1 is connected to one end of capacitor C2 as high-voltage output terminal HV1. The fourth pin of rectifier bridge is grounded and connected to the other end of capacitor C1 and capacitor C2.

[0012] In some embodiments, the step-down constant current circuit includes: an LED constant current controller U1, resistors R4~R12, resistor R15, resistor R16, capacitor C4, capacitor C5, capacitor EC2, capacitor EC3, diode D1, diode D6, NMOS transistor Q1, transformer T1, and common-mode inductor LF3. The VDD pin of the LED constant current controller U1 is connected to the high-voltage output terminal HV1, the GND pin of the LED constant current controller U1 is grounded and connected to one end of resistor R10, and the other end of resistor R10 is connected to the ROVP pin of the LED constant current controller U1. The Dim pin of the LED constant current controller U1 is connected to one end of capacitor C5 and resistor R15. The other end of capacitor C5 and resistor R15 is connected to one end of resistor R16. The other end of resistor R16 is connected to the first pulse control signal output terminal of the MCU circuit. The CS pin of the LED constant current controller U1 is connected to one end of resistors R4, R5, and R6 and the source of NMOS transistor Q1. The other end of resistors R4, R5, and R6 is connected to the GND pin of the LED constant current controller U1 and ground. The GATE pin of controller U1 is connected to one end of resistor R7. The other end of resistor R7 is connected to one end of resistor R8 and the reverse terminal of diode D1. The other end of resistor R8 and the forward terminal of diode D1 are connected to the gate of NMOS transistor Q1. The drain of NMOS transistor Q1 is connected to transformer T1, one end of resistor R9, and the forward terminal of diode D6. The reverse terminal of diode D6 is connected to the high-voltage output terminal HV1. The other end of resistor R9 is connected to one end of capacitor C4. The other end of capacitor C4 is connected to the high-voltage output terminal HV1. The other end of transformer T1 is connected to one end of capacitor EC2, capacitor EC3, resistor R11, resistor R12 and the second pin of common mode inductor LF3. The other end of capacitor EC2, capacitor EC3, resistor R11, resistor R12 is connected to the high voltage output terminal HV1 and the first pin of common mode inductor LF3. The third pin of common mode inductor LF3 serves as the positive current output terminal LED+ and is connected to the positive input terminal of the color temperature adjustment circuit. The fourth pin of common mode inductor LF3 serves as the negative current output terminal V- and is connected to the negative input terminal of the color temperature adjustment circuit.

[0013] In some embodiments, the auxiliary power supply circuit includes: an LED buck controller U2, resistors R13, R26, and R27, capacitors EC1 and EC4, diodes D2 and D7, a Zener diode ZD1, a transformer L2, and a socket COM1. The drain pin of the LED buck controller U2 is connected to capacitor EC1, one end of resistor R27, and the reverse terminal of diode D7. The forward terminal of diode D7 is connected to the high-voltage output terminal HV1. The other end of resistor R27 is connected to one end of resistor R26. Resistor R26 and the other end of capacitor EC1 are connected to the GND pin of the LED buck controller U2 and grounded. The VDD pin of the LED buck controller U2 is connected to one end of capacitor C6 and the forward terminal of Zener diode ZD1. The other end of capacitor C6 is connected to... The LED buck controller U2 has its ICG pin connected to one end of the transformer L2. The other end of the transformer L2 is connected to the forward terminal of the diode D2 and the first pin of the socket COM1, as well as one end of the resistor R13 and the capacitor EC4. The other ends of the resistor R13 and the capacitor EC4 are connected to the GND pin of the LED buck controller U2 and grounded. The reverse terminal of the Zener diode ZD1 is connected to the reverse terminal of the diode D2. The first pin of the socket COM1 serves as the voltage output terminal V+, the second pin of the socket COM1 serves as the ground terminal, the third pin of the socket COM1 serves as the first pulse control signal connection terminal for connecting the buck constant current circuit and the MCU circuit, and the fourth pin of the socket COM1 serves as the second pulse control signal connection terminal for connecting the color temperature adjustment circuit and the MCU circuit.

[0014] In some embodiments, the color temperature adjustment circuit includes: transistors Q3, Q4, Q5, NMOS transistors Q6 and Q7, resistors R17-R22, resistor R24, resistor R25, capacitors C8 and C10, Zener diode ZD2, diode D5, Zener diode ZD3, a string of cool LEDs, and a string of warm LEDs. One end of resistor R18 is connected to the fourth pin of socket COM1, and the other end of resistor R18 is connected to one end of resistor R17 and the base of transistor Q3. The emitter of transistor Q3 is grounded and connected to the resistor. At the other end of R17, the collector of transistor Q3 is connected to one end of resistor R19. The other end of resistor R19 is connected to the base of transistor Q4 and one end of resistor R20. The emitter of transistor Q4 is connected to the other end of resistor R20 and the positive current output terminal LED+. The collector of transistor Q4 is connected to one end of resistor R21. The other end of resistor R21 is connected to the base of transistor Q5 and one end of resistor R22. The other end of resistor R22 is connected to the negative current output terminal V- and transistor Q5. The transistor is connected to the emitter of the diode, the positive terminal of the Zener diode ZD2, the source of the NMOS transistor Q6, the positive terminal of the Zener diode ZD3, the source of the NMOS transistor Q7, the collector of the transistor Q5 is connected to the reverse terminal of the Zener diode ZD2, the gate of the NMOS transistor Q6, one end of the resistor R24, the other end of the resistor R24 ​​is connected to the positive current output terminal LED+, the drain of the NMOS transistor Q6 is connected to the negative terminal of the LED string, the reverse terminal of the diode D5, one end of the capacitor C8, and the other end of the capacitor C8 is connected to the positive current output terminal LED+. The positive terminal of the cold light string is connected to the positive current output terminal LED+. The forward terminal of the diode D5 is connected to the reverse terminal of the Zener diode ZD3, the gate of the NMOS transistor Q7, and one end of the resistor R25. The other end of the resistor R25 is connected to the positive current output terminal LED+. The drain of the NMOS transistor Q7 is connected to the negative terminal of the warm light string and one end of the capacitor C10. The other end of the capacitor C10 is connected to the positive current output terminal LED+. The positive terminal of the warm light string is connected to the positive current output terminal LED+.

[0015] In some embodiments, the cold light string includes cold light lamps LEDC1~LEDCx connected in series, the positive terminal of the cold light lamp LEDC1 is connected to the positive current output terminal LED+, and the cold light lamp LEDCx is connected to the negative current output terminal V-; the warm light string includes warm light lamps LEDW1~LEDWx connected in series, the positive terminal of the warm light lamp LEDW1 is connected to the positive current output terminal LED+, and the warm light lamp LEDWx is connected to the negative current output terminal V-; where x is a positive integer.

[0016] In some embodiments, the MCU circuit includes: a processor U3, capacitors C11~C15, an oscillator Y1, an antenna ANT, and an inductor L3. The second and third pins of the processor U3 are respectively connected to the two ends of the oscillator Y1 and are grounded through capacitors C11 and C12 respectively. The fourth pin of the processor U3 is connected to one end of the inductor L3. The other end of the inductor L3 is connected to the antenna ANT and one end of the capacitor C13. The other end of the capacitor C13 is grounded to the fifth pin of the processor U3. The ninth pin of the processor U3 outputs the first pulse control signal. The tenth pin of the processor U3 is connected to the auxiliary power supply circuit and is grounded through the parallel capacitors C14 and C15. The fifteenth pin of the processor U3 outputs the second pulse control signal.

[0017] The LED color temperature and brightness adjustment circuit described in this utility model has the following advantages:

[0018] The LED color temperature and brightness adjustment circuit integrates a three-stage architecture: filtering and rectification → buck constant current → color temperature adjustment. The filtering and rectification circuit converts AC mains power into constant voltage DC power and supplies power to the buck constant current circuit and auxiliary power supply circuit. The buck constant current circuit provides a constant drive current to the color temperature adjustment circuit and can control the output current according to the first pulse control signal of the MCU circuit, thereby controlling the brightness change of the two LED strings with different color temperatures. The MCU circuit controls the constant drive current of a set of buck constant current circuits through a pulse control signal to control the brightness. In addition, the color temperature adjustment circuit generates a drive signal through the gate drive level conversion circuit according to the second pulse control signal issued by the MCU circuit to control the MOS transistor to alternately conduct to drive the two LED strings with different color temperatures to achieve continuous color temperature adjustment from 2700K to 6500K, instead of the traditional current shunting scheme. This reduces the number of constant current IC circuits required to achieve LED color temperature adjustment. Compared to the traditional three-channel constant current IC circuit for controlling LED brightness and dual color temperature, this application only requires one step-down constant current circuit to achieve brightness control, while the color temperature does not require a separate step-down constant current circuit. The dual color temperature can be achieved simply by alternating the conduction of MOSFETs, which reduces the number of circuit components, thereby reducing circuit space occupation and circuit cost. Attached Figure Description

[0019] Figure 1 This is a connection block diagram of the LED color temperature and brightness adjustment circuit according to an embodiment of the present invention;

[0020] Figure 2 This is a circuit diagram of the filter and rectifier circuit according to an embodiment of the present invention;

[0021] Figure 3This is a circuit diagram of the step-down constant current circuit according to an embodiment of the present invention;

[0022] Figure 4 This is a circuit diagram of the color temperature adjustment circuit according to an embodiment of the present invention;

[0023] Figure 5 This is a circuit diagram of the auxiliary power supply circuit according to an embodiment of the present invention;

[0024] Figure 6 This is a circuit diagram of the MCU circuit according to an embodiment of the present invention. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0026] like Figure 1 As shown, this utility model discloses an LED color temperature and brightness adjustment circuit, including: a filter rectifier circuit, a step-down constant current circuit, a color temperature adjustment circuit, an auxiliary power supply circuit, and an MCU circuit;

[0027] The filter rectifier circuit connects the step-down constant current circuit and the auxiliary power supply circuit, and is used to convert AC mains power into constant voltage DC power and to supply power to the step-down constant current circuit and the auxiliary power supply circuit.

[0028] The MCU circuit connects the buck constant current circuit and the color temperature adjustment circuit, and is used to provide a first pulse control signal and a second pulse control signal. The first pulse control signal is used to control the current output of the buck constant current circuit, and the second pulse control signal is used to control the two MOS transistors of the color temperature adjustment circuit to alternately conduct to generate different potential signals.

[0029] A step-down constant current circuit is connected to a color temperature adjustment circuit. The step-down constant current circuit generates a constant drive current for the color temperature adjustment circuit based on the first pulse control signal from the MCU circuit. The color temperature adjustment circuit generates a drive signal through a gate drive level conversion circuit based on the constant drive current provided by the step-down constant current circuit and the second pulse control signal from the MCU circuit. This signal controls the MOS transistors to alternately conduct, thereby driving two LED strings with different color temperatures to achieve continuous color temperature adjustment from 2700K to 6500K, with current ripple <5%.

[0030] The auxiliary power supply circuit is connected to the MCU circuit and is used to generate a constant voltage for the MCU circuit based on the constant voltage DC power provided by the filter and rectifier circuit.

[0031] The LED color temperature and brightness adjustment circuit integrates a three-stage architecture: filtering and rectification → buck constant current → color temperature adjustment. The filtering and rectification circuit converts AC mains power into constant voltage DC power and supplies power to the buck constant current circuit and auxiliary power supply circuit. The buck constant current circuit provides a constant drive current to the color temperature adjustment circuit and can control the output current according to the first pulse control signal of the MCU circuit, thereby controlling the brightness change of the two LED strings with different color temperatures. The MCU circuit controls the constant drive current of a set of buck constant current circuits through a pulse control signal to control the brightness. In addition, the color temperature adjustment circuit generates a drive signal through the gate drive level conversion circuit according to the second pulse control signal issued by the MCU circuit to control the MOS transistor to alternately conduct to drive the two LED strings with different color temperatures to achieve continuous color temperature adjustment from 2700K to 6500K, instead of the traditional current shunting scheme. This reduces the number of constant current IC circuits required to achieve LED color temperature adjustment. Compared to the traditional three-channel constant current IC circuit for controlling LED brightness and dual color temperature, this application only requires one step-down constant current circuit to achieve brightness control, while the color temperature does not require a separate step-down constant current circuit. The dual color temperature can be achieved simply by alternating the conduction of MOSFETs, which reduces the number of circuit components, thereby reducing circuit space occupation and circuit cost.

[0032] like Figure 2 As shown, in some embodiments, the filter rectifier circuit includes: a thermal relay FR1, common-mode inductors LF1 and LF2, capacitors CY1 and CY2, a varistor MOV1, resistors R1, R2, and R3, capacitor CX1, a rectifier bridge DB1, capacitors C1 and C2, and inductor L1. One end of the thermal relay FR1 is connected to the live wire of the mains power supply, and the other end of the thermal relay is connected to one end of capacitor CY1 and the first pin of common-mode inductor LF1. The other end of capacitor CY1 is grounded and connected to one end of capacitor CY2. The other end of capacitor CY2 is connected to the neutral wire of the mains power supply and the second pin of common-mode inductor LF1. The third pin of common-mode inductor LF1 is connected to the varistor MOV1. V1, resistor R1, capacitor CX1, and the first pin of common mode inductor LF2 are connected. The other end of resistor R1 is connected to one end of resistor R2. The fourth pin of common mode inductor LF1 is connected to the other end of varistor MOV1, resistor R2, capacitor CX1, and the second pin of common mode inductor LF2. The third pin of common mode inductor LF2 is connected to the first pin of rectifier bridge. The fourth pin of inductor LF2 is connected to the third pin of rectifier bridge. The second pin of rectifier bridge is connected to one end of capacitor C1, resistor R3, and inductor L1. The other end of resistor R3 and inductor L1 is connected to one end of capacitor C2 as the high voltage output terminal HV1. The fourth pin of rectifier bridge is grounded and connected to the other end of capacitor C1 and capacitor C2.

[0033] Two common-mode inductors (LF1 / LF2) and Y capacitors (CY1 / CY2) constitute a π-type filter, meeting the EN55015 conducted emission standard. A varistor MOV1 (specification must be 14D471K) works with a thermal relay FR1 to provide dual overvoltage / overtemperature protection. Capacitors CY1 / CY2 are Y2 safety capacitors with a capacitance of 2.2nF ± 10%. The AC input terminal of the rectifier bridge DB1 and the common-mode inductor LF2 are connected using a Kelvin connection to reduce high-frequency impedance. The thermal relay FR1 and NTC resistor R3 provide dual over-temperature protection, cutting off the main circuit when the PCB temperature exceeds 85℃. Combined with software overcurrent detection, a three-level protection mechanism is implemented.

[0034] like Figure 3 As shown, in some embodiments, the step-down constant current circuit includes: an LED constant current controller U1, resistors R4~R12, resistor R15, resistor R16, capacitors C4, C5, EC2, EC3, diode D1, diode D6, NMOS transistor Q1, transformer T1, and common-mode inductor LF3. The VDD pin of the LED constant current controller U1 is connected to the high-voltage output terminal HV1, and the GND pin of the LED constant current controller U1 is grounded and connected to one end of resistor R10. The other end of resistor R10 is connected to the LED constant current... The ROVP pin of controller U1 and the Dim pin of LED constant current controller U1 are connected to one end of capacitor C5 and resistor R15. The other end of capacitor C5 and resistor R15 is connected to one end of resistor R16. The other end of resistor R16 is connected to the first pulse control signal output terminal of MCU circuit. The CS pin of LED constant current controller U1 is connected to one end of resistors R4, R5, and R6 and the source of NMOS transistor Q1. The other end of resistors R4, R5, and R6 is connected to the GND pin of LED constant current controller U1. And grounding, the GATE pin of the LED constant current controller U1 is connected to one end of resistor R7. The other end of resistor R7 is connected to one end of resistor R8 and the reverse terminal of diode D1. The other end of resistor R8 and the forward terminal of diode D1 are connected to the gate of NMOS transistor Q1. The drain of NMOS transistor Q1 is connected to transformer T1, one end of resistor R9 and the forward terminal of diode D6. The reverse terminal of diode D6 is connected to the high-voltage output terminal HV1. The other end of resistor R9 is connected to one end of capacitor C4. The other end of capacitor C4 is connected to the high-voltage output terminal HV1. 1. The other end of transformer T1 is connected to one end of capacitor EC2, capacitor EC3, resistor R11, resistor R12 and the second pin of common mode inductor LF3. The other ends of capacitor EC2, capacitor EC3, resistor R11, resistor R12 are connected to the high voltage output terminal HV1 and the first pin of common mode inductor LF3. The third pin of common mode inductor LF3 serves as the positive current output terminal LED+ and is connected to the positive input terminal of the color temperature adjustment circuit. The fourth pin of common mode inductor LF3 serves as the negative current output terminal V- and is connected to the negative input terminal of the color temperature adjustment circuit.

[0035] Using a dedicated LED constant current controller U1 (such as KP1466), a reference current is set through a current sampling network composed of resistors R4-R6. This, along with MOSFET Q1 and transformer T1, implements an isolated Buck topology. The PWM dimming signal from the MCU circuit is introduced through the Dim pin. After voltage division by resistors R15 / R16 and filtering by capacitor C5, 0-100% flicker-free dimming is achieved, meeting IEEE standards. The 1789 standard uses a common-mode inductor LF3 to isolate the constant current drive circuit from the color temperature adjustment circuit at high frequencies, and a transformer T1 to provide input / output electrical isolation (withstand voltage 4kV / 1min). The VDD pin is directly taken from the high-voltage bus (HV1). A current sampling network is formed using resistors R4-R6 (0.1Ω×3 in parallel). The PWM dimming signal (0-3.3V) output by the MCU circuit is conditioned by a precision resistor divider network (resistors R15 / R16) combined with a π-type filter network (capacitor C5), converting it into a controllable pulse width signal with a power density of 0.1-10kHz. An integrated slope compensation circuit (resistor R7 / diode D1 / NMOS transistor Q1) maintains loop stability when the duty cycle is >50%, avoiding subharmonic oscillations. The synchronous rectification design (diode D6) reduces freewheeling loss by 62%, and the measured efficiency across the entire load range is >92% (Vin=220VAC).

[0036] like Figure 5As shown, in some embodiments, the auxiliary power supply circuit includes: an LED buck controller U2, resistors R13, R26, and R27, capacitors EC1 and EC4, diodes D2 and D7, a Zener diode ZD1, a transformer L2, and a socket COM1. The drain pin of the LED buck controller U2 is connected to one end of capacitor EC1 and resistor R27, and the reverse terminal of diode D7. The forward terminal of diode D7 is connected to the high-voltage output terminal HV1. The other end of resistor R27 is connected to one end of resistor R26. Resistor R26 and the other end of capacitor EC1 are connected to the GND pin of the LED buck controller U2 and grounded. The VDD pin of the LED buck controller U2 is connected to one end of capacitor C6 and the forward terminal of Zener diode ZD1. The other end of capacitor C6... One end is connected to the ICG pin of the LED buck controller U2 and one end of the transformer L2. The other end of the transformer L2 is connected to the forward terminal of the diode D2, the first pin of the socket COM1, and one end of the resistor R13 and capacitor EC4. The other end of the resistor R13 and capacitor EC4 is connected to the GND pin of the LED buck controller U2 and grounded. The reverse terminal of the Zener diode ZD1 is connected to the reverse terminal of the diode D2. The first pin of the socket COM1 serves as the voltage output terminal V+. The second pin of the socket COM1 serves as the ground terminal. The third pin of the socket COM1 serves as the first pulse control signal connection terminal for connecting the buck constant current circuit and the MCU circuit. The fourth pin of the socket COM1 serves as the second pulse control signal connection terminal for connecting the color temperature adjustment circuit and the MCU circuit.

[0037] The auxiliary power supply circuit adopts a flyback topology using an LED step-down controller U2 (model KP3501A) + transformer L2. It provides a stable output of 5V / 500mA under a wide input voltage range (85-305VAC), with a conversion efficiency >80% and standby power consumption <0.5W. A wireless module (such as Bluetooth / BLE) can be integrated into the MCU circuit to enable remote color temperature adjustment via an app. A combination of Zener diode ZD1 (5.6V) and capacitor EC4 (220μF) ensures an output voltage ripple of <50mV. The flyback topology (U2+L2) achieves a conversion efficiency >82% at a 220VAC input. Transformer L2 can use an EE13 core, with a 60T primary winding and a 3T secondary winding. The PWM signal line of socket COM1 can be connected in parallel with a TVS diode, providing 8kV ESD protection.

[0038] like Figure 4As shown, in some embodiments, the color temperature adjustment circuit includes: transistors Q3, Q4, Q5, NMOS transistors Q6 and Q7, resistors R17-R22, resistor R24, resistor R25, capacitors C8 and C10, Zener diode ZD2, diode D5, Zener diode ZD3, a string of cool LEDs, and a string of warm LEDs. One end of resistor R18 is connected to the fourth pin of socket COM1, and the other end of resistor R18 is connected to one end of resistor R17 and the base of transistor Q3. The emitter of transistor Q3 is grounded and connected to the other end of resistor R17. The collector of transistor Q3 is connected to one end of resistor R19. The other end of resistor R19 is connected to the base of transistor Q4 and one end of resistor R20. The emitter of transistor Q4 is connected to the other end of resistor R20 and the positive current output terminal LED+. The collector of transistor Q4 is connected to one end of resistor R21. The other end of resistor R21 is connected to the base of transistor Q5 and one end of resistor R22. The other end of resistor R22 is connected to the negative current output terminal V-. The transistor Q5's emitter, Zener diode ZD2's forward terminal, NMOS transistor Q6's source, Zener diode ZD3's forward terminal, and NMOS transistor Q7's source are connected to the following terminals: the collector of transistor Q5 is connected to the Zener diode ZD2's reverse terminal, the gate of NMOS transistor Q6, one end of resistor R24, and the other end of resistor R24 ​​is connected to the positive output terminal LED+; the drain of NMOS transistor Q6 is connected to the negative terminal of the LED string; the diode D5's reverse terminal is connected to the following terminals: one end of capacitor C8, and the other end of capacitor C8 is connected to the following terminal. The positive output terminal LED+ is connected to the positive terminal of the cold light string. The forward terminal of diode D5 is connected to the reverse terminal of Zener diode ZD3, the gate of NMOS transistor Q7, and one end of resistor R25. The other end of resistor R25 is connected to the current positive output terminal LED+. The drain of NMOS transistor Q7 is connected to the negative terminal of the warm light string and one end of capacitor C10. The other end of capacitor C10 is connected to the current positive output terminal LED+. The positive terminal of the warm light string is connected to the current positive output terminal LED+.

[0039] A complementary MOS drive structure (transistor Q6 / transistor Q7) is adopted. A three-stage Darlington structure is formed by a level shifting circuit composed of transistors Q3-Q5 to boost the 3.3V MCU circuit signal to 12V to drive the MOS gate, ensuring full-cycle conduction. The cool / warm light LED strings adopt a common anode layout, with the cathodes controlled by NMOS transistors Q6 / Q7 respectively. The two PWM signals have a 180° phase difference to avoid cross-conduction. Zener diodes ZD2 / ZD3 (e.g., 12V) protect the MOS gate, and capacitors C8 / C10 absorb voltage spikes. The Zener diodes ZD2 / ZD3 (12V) are gate clamped, and a spike absorption network consisting of capacitor C8 and resistor R24 ​​is used. The turn-on delay times of the MOSFETs Q6 / Q7 differ by 1.2μs, set by the resistance ratio of resistor R21 / R22. The NMOS transistors Q6 / Q7 are mounted on the same heatsink, with a thermal coupling coefficient >0.9. In the color temperature adjustment circuit, the current ratio of the cool-light LED string to the warm-light LED string is dynamically adjusted by the PWM duty cycle. Thermal balance design: The MOSFETs are arranged in a thermally symmetrical distribution, combined with a 2oz copper-thick PCB, ensuring a dual-path temperature difference of <5℃ (@full load).

[0040] In some embodiments, the cold light string includes cold light lamps LEDC1~LEDCx connected in series, with the positive terminal of cold light lamp LEDC1 connected to the positive current output terminal LED+, and the cold light lamp LEDCx connected to the negative current output terminal V-; the warm light string includes warm light lamps LEDW1~LEDWx connected in series, with the positive terminal of warm light lamp LEDW1 connected to the positive current output terminal LED+, and the warm light lamp LEDWx connected to the negative current output terminal V-; where x is a positive integer.

[0041] like Figure 6 As shown, in some embodiments, the MCU circuit includes: processor U3, capacitors C11~C15, oscillator Y1, antenna ANT, and inductor L3. The second and third pins of processor U3 are respectively connected to the two ends of oscillator Y1 and grounded through capacitors C11 and C12 respectively. The fourth pin of processor U3 is connected to one end of inductor L3. The other end of inductor L3 is connected to antenna ANT and one end of capacitor C13. The other end of capacitor C13 is grounded to the fifth pin of processor U3. The ninth pin of processor U3 outputs a first pulse control signal. The tenth pin of processor U3 is connected to the auxiliary power supply circuit and grounded through parallel capacitors C14 and C15. The fifteenth pin of processor U3 outputs a second pulse control signal.

[0042] Processor U3 is the main control unit, responsible for generating pulse signals for dimming (brightness) and color temperature adjustment (dual-channel LED control). Oscillator Y1 and processor U3 together form a clock circuit, providing a stable clock source. Antenna ANT is used for signal transmission and reception of wireless communication modules (such as Bluetooth / Wi-Fi). Inductor L3 and capacitor C13 form an LC matching circuit to optimize antenna impedance characteristics. Capacitors C11~C15 are used for clock circuit filtering (C11, C12), antenna matching (C13), and power supply decoupling (C14, C15), respectively.

[0043] Clock circuit: Processor U3 pins 2 and 3: connected to the two ends of oscillator Y1 respectively, forming an oscillation circuit. Capacitors C11 and C12: grounded from pins 2 and 3 respectively, used to eliminate high-frequency noise and ensure stable clock signal.

[0044] Wireless communication module: Processor U3 pin 4: Connects to one end of inductor L3, and the other end of inductor L3 is connected to antenna ANT and capacitor C13. Capacitor C13: One end is grounded, forming an antenna matching network with inductor L3 to improve signal transmission efficiency. Wireless communication modules (such as Bluetooth / Wi-Fi) are directly integrated through antenna ANT and LC matching circuit (L3, C13), eliminating the need for external RF chips and reducing system complexity.

[0045] Dimming and Color Temperature Adjustment Signal Output: Processor U3 pin 9: Outputs the first pulse control signal (e.g., PWM-C) to adjust the brightness of LED module 1. Processor U3 pin 15: Outputs the second pulse control signal (e.g., PWM-M) to adjust the brightness of LED module 2, achieving gradual color temperature change through dual-channel independent control. Processor U3 pins 9 and 15 output PWM signals in a time-division manner, driving the two LED modules respectively. Continuous color temperature change (e.g., 2700K~6500K) is achieved through brightness ratio adjustment, avoiding the color temperature jump problem of traditional single-channel control.

[0046] Power Management: Processor U3 pin 10: Connects to the auxiliary power supply circuit (e.g., 3.3V or 5V), and grounded through parallel capacitors C14 and C15 to filter power supply noise and ensure stable MCU operation. The combination of parallel capacitors C14 (e.g., a 10μF electrolytic capacitor) and C15 (e.g., a 0.1μF ceramic capacitor) on pin 10 provides wide-band noise filtering, ensuring the stability of the MCU under high-frequency PWM signals. The processor U3 can be an ESP32-C3.

[0047] The above description is merely a preferred embodiment of the present utility model and does not constitute any limitation on the technical scope of the present utility model. Therefore, any minor modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present utility model shall still fall within the scope of the technical solution of the present utility model.

Claims

1. An LED color temperature brightness adjustment circuit, characterized by, include: Filtering and rectifying circuit, step-down constant current circuit, color temperature adjustment circuit, auxiliary power supply circuit and MCU circuit; The filter rectifier circuit is connected to the step-down constant current circuit and the auxiliary power supply circuit, and is used to convert AC mains power into constant voltage DC power and to supply power to the step-down constant current circuit and the auxiliary power supply circuit; The MCU circuit connects the step-down constant current circuit and the color temperature adjustment circuit, and is used to provide a first pulse control signal and a second pulse control signal. The first pulse control signal is used to control the current output by the step-down constant current circuit, and the second pulse control signal is used to control the two MOS transistors of the color temperature adjustment circuit to alternately conduct to generate different potential signals. The step-down constant current circuit is connected to the color temperature adjustment circuit. The step-down constant current circuit generates a constant drive current to the color temperature adjustment circuit based on the first pulse control signal issued by the MCU circuit. The color temperature adjustment circuit generates a drive signal through the gate drive level conversion circuit based on the constant drive current provided by the step-down constant current circuit and the second pulse control signal issued by the MCU circuit to control the MOS transistor to alternately conduct, thereby driving two LED strings with different color temperatures to achieve continuous color temperature adjustment from 2700K to 6500K with current ripple <5%. The auxiliary power supply circuit is connected to the MCU circuit and is used to generate a constant voltage for the MCU circuit based on the constant voltage DC power provided by the filter and rectifier circuit.

2. The LED color temperature and brightness adjustment circuit according to claim 1, characterized in that, The filtering and rectifier circuit includes: a thermal relay FR1, common-mode inductors LF1 and LF2, capacitors CY1 and CY2, a varistor MOV1, resistors R1, R2, and R3, capacitor CX1, a rectifier bridge DB1, capacitors C1 and C2, and inductor L1. One end of the thermal relay FR1 is connected to the live wire of the mains power supply. The other end of the thermal relay is connected to one end of capacitor CY1 and the first pin of the common-mode inductor LF1. The other end of capacitor CY1 is grounded and connected to one end of capacitor CY2. The other end of capacitor CY2 is connected to the neutral wire of the mains power supply and the second pin of the common-mode inductor LF1. The third pin of the common-mode inductor LF1 is connected to the varistor MOV1, the resistor R1, and the capacitor CX1. One end of the common-mode inductor LF2 is connected to the first pin of the common-mode inductor 1. The other end of the resistor R1 is connected to one end of the resistor R2. The fourth pin of the common-mode inductor LF1 is connected to the other end of the varistor MOV1, the resistor R2, the capacitor CX1, and the second pin of the common-mode inductor LF2. The third pin of the common-mode inductor LF2 is connected to the first pin of the rectifier bridge. The fourth pin of the inductor LF2 is connected to the third pin of the rectifier bridge. The second pin of the rectifier bridge is connected to one end of the capacitor C1, the resistor R3, and the inductor L1. The other end of the resistor R3 and the inductor L1 is connected to one end of the capacitor C2 as the high-voltage output terminal HV1. The fourth pin of the rectifier bridge is grounded and connected to the other end of the capacitor C1 and the capacitor C2.

3. The LED color temperature and brightness adjustment circuit according to claim 2, characterized in that, The step-down constant current circuit includes: an LED constant current controller U1, resistors R4~R12, resistor R15, resistor R16, capacitors C4, C5, EC2, and EC3, diode D1, diode D6, NMOS transistor Q1, transformer T1, and common-mode inductor LF3. The VDD pin of the LED constant current controller U1 is connected to the high-voltage output terminal HV1. The GND pin of the LED constant current controller U1 is grounded and connected to one end of resistor R10. The other end of resistor R10 is connected to the ROVP pin of the LED constant current controller U1. The Dim pin of U1 is connected to one end of capacitor C5 and resistor R15. The other end of capacitor C5 and resistor R15 is connected to one end of resistor R16. The other end of resistor R16 is connected to the first pulse control signal output terminal of the MCU circuit. The CS pin of the LED constant current controller U1 is connected to one end of resistors R4, R5, and R6 and the source of NMOS transistor Q1. The other end of resistors R4, R5, and R6 is connected to the GND pin of the LED constant current controller U1 and ground. The GATE pin is connected to one end of resistor R7. The other end of resistor R7 is connected to one end of resistor R8 and the reverse terminal of diode D1. The other end of resistor R8 and the forward terminal of diode D1 are connected to the gate of NMOS transistor Q1. The drain of NMOS transistor Q1 is connected to transformer T1, one end of resistor R9, and the forward terminal of diode D6. The reverse terminal of diode D6 is connected to the high-voltage output terminal HV1. The other end of resistor R9 is connected to one end of capacitor C4. The other end of capacitor C4 is connected to the high-voltage output terminal HV1. The other end of device T1 is connected to one end of capacitor EC2, capacitor EC3, resistor R11, resistor R12 and the second pin of common mode inductor LF3. The other ends of capacitor EC2, capacitor EC3, resistor R11, resistor R12 are connected to the high voltage output terminal HV1 and the first pin of common mode inductor LF3. The third pin of common mode inductor LF3 serves as the positive current output terminal LED+ and is connected to the positive input terminal of the color temperature adjustment circuit. The fourth pin of common mode inductor LF3 serves as the negative current output terminal V- and is connected to the negative input terminal of the color temperature adjustment circuit.

4. The LED color temperature and brightness adjustment circuit according to claim 2, characterized in that, The auxiliary power supply circuit includes: an LED step-down controller U2, resistors R13, R26, and R27, capacitors EC1 and EC4, diode D2 and D7, a Zener diode ZD1, a transformer L2, and a socket COM1. The drain pin of the LED step-down controller U2 is connected to capacitor EC1, one end of resistor R27, and the reverse terminal of diode D7. The forward terminal of diode D7 is connected to the high-voltage output terminal HV1. The other end of resistor R27 is connected to one end of resistor R26. The other end of resistor R26 and capacitor EC1 are connected to the gate pin of the LED step-down controller U2. The LED buck controller U2's VDD pin is grounded. One end of capacitor C6 and the positive terminal of Zener diode ZD1 are connected. The other end of capacitor C6 is connected to the LED buck controller U2's ICG pin and one end of transformer L2. The other end of transformer L2 is connected to the positive terminal of diode D2, the first pin of socket COM1, and one end of resistor R13 and capacitor EC4. The other ends of resistor R13 and capacitor EC4 are connected to the LED buck controller U2's GND pin and grounded. The negative terminal of Zener diode ZD1 is connected to the negative terminal of diode D2. The first pin of the socket COM1 serves as the voltage output terminal V+, the second pin of the socket COM1 serves as the ground terminal, the third pin of the socket COM1 serves as the first pulse control signal connection terminal for connecting the step-down constant current circuit and the MCU circuit, and the fourth pin of the socket COM1 serves as the second pulse control signal connection terminal for connecting the color temperature adjustment circuit and the MCU circuit.

5. The LED color temperature and brightness adjustment circuit according to claim 4, characterized in that, The color temperature adjustment circuit includes: transistors Q3, Q4, Q5, NMOS transistors Q6 and Q7, resistors R17-R22, resistor R24, resistor R25, capacitors C8 and C10, Zener diode ZD2, diode D5, Zener diode ZD3, a string of cool LEDs, and a string of warm LEDs. One end of resistor R18 is connected to the fourth pin of socket COM1, and the other end of resistor R18 is connected to one end of resistor R17 and the base of transistor Q3. The emitter of transistor Q3 is grounded and connected to the other end of resistor R17. The collector of transistor Q3 is connected to one end of resistor R19. The other end of resistor R19 is connected to the base of transistor Q4 and one end of resistor R20. The emitter of transistor Q4 is connected to the other end of resistor R20 and the positive current output terminal LED+. The collector of transistor Q4 is connected to one end of resistor R21. The other end of resistor R21 is connected to the base of transistor Q5 and one end of resistor R22. The other end of resistor R22 is connected to the negative current output terminal V- and the emitter of transistor Q5. The circuit consists of: the positive terminal of Zener diode ZD2, the source of NMOS transistor Q6, the positive terminal of Zener diode ZD3, the source of NMOS transistor Q7, the collector of transistor Q5 connected to the reverse terminal of Zener diode ZD2, the gate of NMOS transistor Q6, one end of resistor R24, the other end of resistor R24 ​​connected to the positive current output terminal LED+, the drain of NMOS transistor Q6 connected to the negative terminal of the LED string, the reverse terminal of diode D5, one end of capacitor C8, and the other end of capacitor C8 connected to the positive current output terminal L. ED+, the positive terminal of the cold light string is connected to the positive current output terminal LED+, the forward terminal of the diode D5 is connected to the reverse terminal of the Zener diode ZD3, the gate of the NMOS transistor Q7, one end of the resistor R25, the other end of the resistor R25 is connected to the positive current output terminal LED+, the drain of the NMOS transistor Q7 is connected to the negative terminal of the warm light string and one end of the capacitor C10, the other end of the capacitor C10 is connected to the positive current output terminal LED+, and the positive terminal of the warm light string is connected to the positive current output terminal LED+.

6. The LED color temperature and brightness adjustment circuit according to claim 5, characterized in that, The cold light string includes cold light lamps LEDC1~LEDCx connected in series. The positive terminal of the cold light lamp LEDC1 is connected to the positive current output terminal LED+, and the cold light lamp LEDCx is connected to the negative current output terminal V-. The warm light string includes warm light lamps LEDW1~LEDWx connected in series. The positive terminal of the warm light lamp LEDW1 is connected to the positive current output terminal LED+, and the warm light lamp LEDWx is connected to the negative current output terminal V-. Where x is a positive integer.

7. The LED color temperature and brightness adjustment circuit according to claim 1, characterized in that, The MCU circuit includes: processor U3, capacitors C11~C15, oscillator Y1, antenna ANT, and inductor L3. The second and third pins of processor U3 are respectively connected to the two ends of oscillator Y1 and are grounded through capacitors C11 and C12 respectively. The fourth pin of processor U3 is connected to one end of inductor L3. The other end of inductor L3 is connected to antenna ANT and one end of capacitor C13. The other end of capacitor C13 is grounded to the fifth pin of processor U3. The ninth pin of processor U3 outputs the first pulse control signal. The tenth pin of processor U3 is connected to the auxiliary power supply circuit and is grounded through capacitors C14 and C15 connected in parallel. The fifteenth pin of processor U3 outputs the second pulse control signal.

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