Isolated dimming and color-adjusting LED drive circuit

Abstract

The invention discloses an isolation type dimming and color-adjusting LED drive circuit which comprises a pre-stage circuit, a post-stage circuit and an optocoupler A8. In a pre-stage circuit, an EMI and rectification filter circuit A1 processes commercial power, a direct current power supply circuit A2 supplies 3.3 V power to an intelligent control module circuit A5, and a primary side chip on-off control circuit A3 cuts off power supply to a primary side constant current dimming chip circuit A6 when the primary side chip on-off control circuit A3 is in a standby state so as to reduce power consumption; in the post-stage circuit, a double color temperature control and drive circuit A10 uses discrete components to adjust the current ratio of the cold / warm LED, and an output short circuit protection control circuit A11 detects the voltage of the negative electrode of the LED to realize protection. And the whole structure is simplified, the cost is reduced, the consumption is reduced, and the system is suitable for smart home illumination.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of LED lighting drive, in particular to an isolated dimming and color adjusting LED drive circuit. BACKGROUND

[0002] In the current lighting field, with the popularization of intelligent lighting, the application of isolated LED dimming and color adjusting drive equipment is becoming more and more widespread. The existing isolated LED dimming and color adjusting drive equipment has the following problems: 1. Many isolated LED dimming and color adjusting drive equipment often uses two-stage control mode of front-stage AC-DC isolation circuit combined with rear-stage DC-CC constant current dimming and color adjusting drive circuit. This architecture makes the number of components in the circuit numerous, for example, the front-stage AC-DC isolation circuit needs to be equipped with a series of rectification, filtering components and transformers, and the rear-stage DC-CC constant current dimming and color adjusting drive circuit contains various control chips, power devices, etc. The increase of the number of components not only increases the complexity of circuit design, but also leads to a substantial increase in cost, which is not conducive to the large-scale promotion and application of products in the market.

[0003] 2. In order to achieve the goal of low standby power consumption, the existing technology often uses MCU or other control means to cut off the power supply of the front-stage AC-DC main circuit, or the rear-stage DC-CC dimming power supply circuit. But this process needs to use high-power switching elements, like some schemes use high-voltage, high-current MOSFET tubes, which are relatively high in cost, and in the control process, in order to ensure its reliable on-off, additional drive circuit and protection circuit are also needed, which further increases the cost investment. At the same time, high-power switching elements may also produce electromagnetic interference and other problems in the switching process, affecting the stability of the circuit.

[0004] Secondly, Chinese patent publication No. CN208285597U discloses a silicon controlled rectifier dimming constant current power supply and LED system, which includes a separate AC controller with a 485 communication interface and at least one silicon controlled rectifier power supply. The AC controller performs MOS chopping on the mains, and changes the output power by adjusting the chopping conduction angle, thereby adjusting the brightness, color temperature and color of the LED. The silicon controlled rectifier power supply contains a fuse resistor, a voltage-dependent resistor, a rectifier bridge, a drive chip and a transformer, etc., supporting one controller to control multiple power supplies and one power supply to control multiple LED lamps, solving the problem of flexible dimming of traditional LEDs. However, the prior art still has limitations. The silicon controlled rectifier power supply in the system contains a fuse resistor, a voltage-dependent resistor, a rectifier bridge, a drive chip and a transformer, etc., and the overall circuit structure is not simple, and there is still room for improvement in terms of precision of dimming and color control and energy consumption control. When implementing complex dimming and color control functions, due to the inherent characteristics of the circuit design, it may not be possible to extremely accurately adjust the current of different color temperature LEDs, resulting in deviations in the mixed light effect from the expected, affecting the lighting quality. Moreover, in the standby state, part of the elements in the circuit may still be in the power-on or low-power running state, causing unnecessary power loss.

[0005] In addition, some traditional isolated driving circuits need to convert input energy into high-frequency alternating current, and then isolate and step down through a transformer, which results in large energy loss in this process, reduces the energy efficiency of the entire LED lighting system, and also leads to large equipment size and weight, limiting design flexibility. At the same time, some dimming technologies, such as the PWM modulation scheme, may have linear distortion due to the leakage inductance of the transformer and parasitic oscillation, affecting the dimming linearity. Some driving circuits have prominent losses in transformers, switching tubes and chip circuits in light load or standby state, and some methods used to reduce the starting resistance power consumption and solve the standby power consumption problem, such as increasing the secondary transformer coupling voltage feedback to the chip for power supply, increase the complexity of the circuit line, and cause new problems such as electromagnetic compatibility.

[0006] In summary, the existing isolated LED dimming and color control driving equipment has deficiencies in circuit structure, standby power consumption and dimming and color control performance, and a new design scheme is needed to overcome these defects to meet the market demand for high-efficiency, low-cost and high-performance lighting driving equipment. SUMMARY

[0007] The present application overcomes the above-mentioned technical deficiencies, and provides an isolated light and color adjusting LED driving circuit, which uses only two IC1 and IC2 integrated circuit chips in addition to the intelligent module control circuit, and uses low-cost discrete electronic components to build the rest of the driving circuit, so as to realize the light and color adjusting driving and control of LED lighting with extremely low-cost circuit components, and realize the functions of ultra-low standby power consumption and short-circuit protection, so that the circuit has extremely high cost performance and product competitiveness. An isolated light and color adjusting LED driving circuit, comprising: a front-stage circuit for controlling the brightness of an LED light source, a rear-stage circuit electrically isolated from the front-stage circuit and for controlling the color temperature of the LED light source, and an optocoupler A8 for realizing the signal isolated transmission of the front-stage circuit and the rear-stage circuit. The front-stage circuit comprises: an EMI and rectification filter circuit A1, a direct-current power supply circuit A2, a primary-side chip on-off control circuit A3, an intelligent control module circuit A5, a primary-side constant-current light adjusting chip circuit A6, and a primary-side winding of a transformer A7 connected with the primary-side constant-current light adjusting chip circuit A6; the EMI and rectification filter circuit A1 is connected with an external power supply, and is used for providing a rectified and filtered direct-current input for the front-stage circuit; the direct-current power supply circuit A2 is connected with the output end of the EMI and rectification filter circuit A1, and is used for supplying power for the intelligent control module circuit A5; the primary-side chip on-off control circuit A3 is connected between the output end of the EMI and rectification filter circuit A1 and the input end of the primary-side constant-current light adjusting chip circuit A6, and is used for cutting off the power supply for the primary-side constant-current light adjusting chip A6 circuit when the LED light source is turned off and in standby state; the intelligent control module circuit A5 is connected with the primary-side chip on-off control circuit A3, the primary-side constant-current light adjusting chip circuit A6, and the optocoupler A8, respectively, and is used for generating a light adjusting control signal and sending it to the primary-side constant-current light adjusting chip circuit A6, and generating a color temperature control signal and sending it to the optocoupler A8, and controlling the working state of the primary-side chip on-off control circuit A3; the primary-side constant-current light adjusting chip circuit A6 is used for receiving the light adjusting control signal and adjusting the output current to control the brightness of the LED light source. The rear-stage circuit comprises: a secondary-side winding of the transformer A7; a secondary-side rectification and filter circuit A9 connected with the secondary-side winding of the transformer A7; The double-color temperature control and driving circuit A10 is composed of discrete components, and is connected with the optocoupler A8 and the secondary-side rectification and filter circuit A9, respectively, and is used for receiving the color temperature control signal transmitted in isolation and adjusting the current proportion of the external cool color temperature LED and warm color temperature LED. In the standby state, the primary-side chip on-off control circuit A3 makes the standby power consumption of the front-stage circuit lower than a preset threshold.

[0008] Preferably, the EMI and rectification filter circuit A1 comprises: an AC input interface COM1, a voltage-dependent resistor VR1, a first capacitor CX1, a common mode inductor LF1, a rectifier bridge DB1, a fuse F1, and a pre-stage filter circuit A111; the voltage-dependent resistor VR1 and the first capacitor CX1 are connected in parallel between two output terminals of the AC input interface COM1, a zero line output terminal of the AC input interface COM1 is connected to a fourth pin of the common mode inductor LF1, and a live line output terminal is connected to a second pin of the common mode inductor LF1 through the fuse F1; a first pin of the common mode inductor LF1 is connected to a first pin of the rectifier bridge DB1, and a third pin is connected to a second pin of the rectifier bridge DB1, a fourth pin of the rectifier bridge DB1 is grounded, and a third pin as a preliminary direct current voltage output terminal is connected to the pre-stage filter circuit A111, and an output terminal of the pre-stage filter circuit A111 as a filtered direct current voltage output terminal outputs smooth and stable direct current for providing rectification filtered direct current input to the pre-stage circuit.

[0009] Preferably, the direct current power supply circuit A2 comprises: a first chip IC1, a first diode D1, a second diode D2, a third diode D3, a first resistor R7, a first polarity capacitor C1, a second polarity capacitor C6, a second capacitor (C3), a third capacitor (C8), and a first inductor L2; the first chip IC1 is a low-power Buck type DC-DC control chip; an anode of the first diode D1 as an input terminal of the direct current power supply circuit A2 is connected to a preliminary direct current voltage output terminal of the EMI and rectification filter circuit A1, and a cathode is connected to a first pin of the first chip IC1; the first polarity capacitor C1 is connected in parallel between the cathode of the first diode D1 and the ground, for filtering voltage ripple input to the first chip IC1; the second diode D2 is connected in forward direction between the ground and an output terminal of the first chip IC1; a third pin of the first chip IC1 is connected to a positive electrode of the second polarity capacitor C6, one end of the first resistor R7, and one end of the third capacitor (C8) through the first inductor L2, and a common connection point of the three is connected to the intelligent control module circuit A5 as a power supply output terminal; a negative electrode of the second polarity capacitor C6, the other end of the first resistor R7, and the other end of the third capacitor (C8) are grounded; the third diode D3 is connected in forward direction between the positive electrode of the second polarity capacitor C6 and a second pin of the first chip IC1; specifically, the anode of the third diode D3 is connected to the positive electrode of the second polarity capacitor C6, and the cathode is connected to the second pin of the first chip IC1, for feeding back output voltage to a feedback adjustment end of the IC1, to realize precise voltage stabilization of 3.3V output voltage in cooperation with the IC1.

[0010] Preferably, the primary side chip on-off control circuit A3 comprises: a first transistor Q2, a first NMOS tube Q3, a second resistor R15, a third resistor R16, a fourth resistor R17, a fifth resistor R12, and a bidirectional voltage stabilizing diode D4; the first transistor Q2 is a PNP type transistor, the emitter thereof is connected to the positive output end of the EMI and rectification filtering circuit A1, and the collector thereof is connected to the power supply input end of the primary side constant current dimming chip circuit A6; the second resistor R15 is connected between the collector and the emitter of the first transistor Q2, for realizing voltage isolation when the first transistor Q2 is cut off, and providing a current path when the first transistor Q2 is turned on; one end of the third resistor R16 is connected to the collector of the first transistor Q2, the other end is connected to the base of the first transistor Q2 and the drain of the first NMOS tube Q3 through the fourth resistor R17, the source of the first NMOS tube Q3 is grounded; one end of the fifth resistor R12 is connected to the intelligent control module circuit A5 as a control signal input end, and the other end is connected to the gate of the first NMOS tube Q3; the bidirectional voltage stabilizing diode D4 is connected between one end of the fifth resistor R12 and the ground.

[0011] Preferably, the front stage circuit further comprises: a high voltage on-off detection circuit A4 connected between the EMI and rectification filtering circuit A1 and the intelligent control module circuit A5, for detecting the high voltage input state; the input end of the high voltage on-off detection circuit A4 is connected to the positive output end of the EMI and rectification filtering circuit A1 as a high voltage on-off signal input end, and the output end transmits a detection signal to the intelligent control module circuit A5; the high voltage on-off detection circuit A4 comprises: a sixth resistor R2, a seventh resistor R3, an eighth resistor R4, a fourth capacitor C7, a second transistor Q1, and a ninth resistor R9; one end of the sixth resistor R2 is connected to the positive output end of the EMI and rectification filtering circuit A1 as the high voltage on-off signal input end, and the other end is connected to the first end of the eighth resistor R4, the first end of the fourth capacitor C7, and the base of the second transistor Q1 through the seventh resistor R3; the other end of the eighth resistor R4, the other end of the fourth capacitor C7, and the emitter of the second transistor Q1 are grounded; the second transistor Q1 is an NPN type transistor, and the collector thereof is connected to the intelligent control module circuit A5 as a detection signal output end; one end of the ninth resistor R9 is connected to the collector of the second transistor Q1, and the other end is connected to the DC power supply circuit A2 as a power supply input end.

[0012] Preferably, the intelligent control module circuit A5 is provided with a power supply input end connected to the voltage output end of the DC power supply circuit A2, a high voltage on-off signal detection input end connected to the output end of the high voltage on-off detection circuit A4, a dimming control signal output end connected to the input end of the primary side constant current dimming chip circuit A6, and a color temperature control signal output end connected to the input end of the double color temperature control and driving circuit A10 through the optical coupler A8.

[0013] Preferably, the primary side constant current dimming chip circuit A6 comprises: a primary side constant current dimming chip IC2 and its peripheral circuit; the primary side constant current dimming chip IC2 is provided with a power supply input end T1 connected with the output end of the primary side chip on-off control circuit A3, a ground end T2, a dimming control signal input end T3 connected with the dimming control signal output end of the intelligent control module circuit A5, a first power output end T4, and a second power output end T5; the primary side winding of the transformer A7 is composed of two primary coils, wherein: one end of the first primary coil is connected with the positive output end of the EMI and rectification filter circuit A1, and the other end is connected with the first power output end T4 of the primary side constant current dimming chip IC2; one end of the second primary coil is connected with the second power output end T5 of the primary side constant current dimming chip IC2, and the other end is grounded; the secondary side winding of the transformer A7 is a coil, and the two ends thereof are respectively connected with the input end of the rear-stage circuit.

[0014] Preferably, the secondary side rectification and filter circuit A9 comprises: a tenth resistor R23, a fifth capacitor C15, a fourth diode D7, and a third polarity capacitor C14; the positive electrode of the fourth diode D7 is connected with one end of the tenth resistor R23 as an input end and connected with one end of the secondary coil of the secondary side winding, the negative electrode of the fourth diode D7 is connected with the positive electrode of the third polarity capacitor C14, and the negative electrode of the third polarity capacitor C14 is connected with the other end of the secondary coil of the secondary side winding and connected with a digital ground; the other end of the tenth resistor R23 is connected with the positive electrode of the third polarity capacitor C14 through the fifth capacitor C15, and the connection point of the two is connected with the double-color-temperature control and driving circuit A10 as an output end.

[0015] Preferably, the double-color-temperature control and driving circuit A10 comprises: an eleventh resistor R25, a twelfth resistor R27, a thirteenth resistor R24, a fourteenth resistor R26, a fifth diode D10, a sixth diode D8, a seventh diode D9, an eighth diode D12, a ninth diode D11, a first voltage stabilizing diode DZ1, a second voltage stabilizing diode DZ2, a second NMOS tube Q5, a third NMOS tube Q6, a sixth capacitor C17, a seventh capacitor C18, and an output interface COM2 connected with an external LED. One end of the eleventh resistor R25 is connected to the output end of the secondary side rectification and filter circuit A9, and the other end is connected to the gate of the second NMOS Q5; one end of the twelfth resistor R27 is connected to the third end of the output interface COM2 as the positive connection end of the LED light source, so as to connect the positive pole of the external LED light source; the other end of the twelfth resistor R27 is connected back to the third end of the output interface COM2 through the forwardly connected fifth diode D10 and the ninth diode D11 in sequence; the drain of the second NMOS Q5 is connected to the second end of the output interface COM2 as the negative connection end of the warm color temperature LED lamp string; the source of the second NMOS Q5 is connected to the digital ground; the first voltage stabilizing diode DZ1 and the thirteenth resistor R24 are connected in parallel between the emitter end and the collector end of the triode of the optocoupler A8; the collector of the triode of the optocoupler A8 is connected to the gate of the second NMOS Q5, and the emitter of the triode is connected to the digital ground; The gate of the third NMOS Q6 is connected to the positive pole of the fifth diode D10, the positive pole of the seventh diode D9, one end of the fourteenth resistor R26 and the negative pole of the second voltage stabilizing diode DZ2 respectively; the other end of the fourteenth resistor R26, the positive pole of the second voltage stabilizing diode DZ2, the source of the third NMOS Q6 are all connected to the digital ground; the sixth capacitor C17 is connected between the drain of the second NMOS Q5 and the digital ground; the seventh capacitor C18 is connected between the drain of the third NMOS Q6 and the digital ground; the drain of the third NMOS Q6 is connected to the first end of the output interface COM2 as the negative connection end of the cold color temperature LED lamp string; the sixth diode D8 is connected in forward direction between the collector end of the triode of the optocoupler A8 and the negative pole of the seventh diode D9.

[0016] Preferably, the post-stage circuit further comprises: an output short-circuit protection control circuit A11 connected with the dual-color temperature control and driving circuit A10, for controlling the dual-color temperature control and driving circuit A10 to be turned off to realize protection when the output end is short-circuited; the output short-circuit protection control circuit A11 comprises: a fifteenth resistor R28, a sixteenth resistor R29, a twelfth diode D13, an eleventh diode D14, a third zener diode DZ3, a fourth zener diode DZ4, an eighth capacitor C16, a fourth NMOS tube Q4; the anode of the twelfth diode D13 is connected with the second end of the output interface COM2 as a warm color temperature LED voltage detection input end, the anode of the eleventh diode D14 is connected with the first end of the output interface COM2 as a cold color temperature LED voltage detection input end; the connection point of the cathode of the twelfth diode D13 and the cathode of the eleventh diode D14 is connected with the negative electrode of the fourth zener diode DZ4, the positive electrode of the fourth zener diode DZ4 is connected with the positive electrode of the third zener diode DZ3 and the other end of the sixteenth resistor R29 respectively, the one end of the sixteenth resistor R29 is connected with the one end of the sixteenth resistor R29, the one end of the eighth capacitor C16 and the gate of the fourth NMOS tube Q4 respectively, the other end of the sixteenth resistor R29, the other end of the eighth capacitor C16 and the source of the fourth NMOS tube Q4 are connected with the digital ground, and the drain of the fourth NMOS tube Q4 is connected with the negative electrode of the seventh diode D9.

[0017] Compared with the prior art, the application has the following beneficial effects: 1. The application adopts a front-stage brightness control, a post-stage color temperature control and an optical coupling signal isolation architecture, realizes electrical isolation of the front stage and the post stage, meets safety specifications, separates brightness control and color temperature control into independent circuits, simplifies control logic, avoids the problem of cross interference of elements in the traditional two-stage control front-stage AC-DC+post-stage DC-CC, directly realizes constant current and brightness control through the primary side constant current dimming chip circuit in the front stage, and does not need an additional DC-CC module; the post-stage adopts a discrete element to build a dual-color temperature driving circuit, does not need a special control chip, reduces the number of core elements compared with the prior art, and reduces circuit complexity and cost. The primary side chip on-off control circuit can cut off the power supply of the primary side chip in standby mode, avoids the problem that a large power switch is needed to cut off the main circuit in the traditional scheme, greatly reduces standby power consumption, and reduces electromagnetic interference risk.

[0018] 2, The original edge chip on-off control circuit A3 uses a small power PNP transistor Q2 and NMOS tube Q3 to cooperate, only through microampere level control current can cut off the VCC power supply of A6. When on standby, A6 is completely powered off, there is no no-load loss, and the standby power consumption is reduced from hundreds of milliwatts in the traditional scheme to less than tens of milliwatts; Without the need for high-power switching elements and additional drive circuits, not only does it reduce costs, but it also avoids electromagnetic interference caused by high-power element switching, improves circuit stability, meets the energy efficiency standard of ultra-low standby power consumption, and solves the problems of high cost and high standby power consumption of high-power switching elements.

[0019] 3, The output short circuit protection control circuit A11 is built with discrete components diode D13 / D14, NMOS tube Q4, and voltage regulator DZ3 / DZ4, which directly detects the voltage state of WLED- and CLED-. When short-circuited, the voltage anomaly can trigger protection in microseconds, and by pulling down the A10 key node potential through Q4, Q5 and Q6 are quickly turned off to prevent MOS tube from burning out. Compared with the comparator and dedicated chip scheme, not only does it reduce costs, but it also avoids the delay of the chip leading to untimely protection; At the same time, DZ3 / DZ4 clamps the voltage, and C16 filters to prevent voltage fluctuations from triggering falsely, balancing protection speed and reliability, and solving the defects of traditional protection circuits such as complexity, slow response, and false triggering. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is the circuit structure diagram of embodiment one of the present application.

[0021] Figure 2 is the circuit schematic diagram of embodiment two of the present application. DETAILED DESCRIPTION

[0022] The features of the present application and other related features are further described in detail below through embodiments to facilitate the understanding of those skilled in the art: As shown in Figure 1 and Figure 2 , an isolated dimming and color control LED driving circuit, the main architecture includes: a front-end circuit for controlling the brightness of the LED light source, a back-end circuit electrically isolated from the front-end circuit for controlling the color temperature of the LED light source, and an optocoupler A8 for realizing signal isolation transmission between the front-end circuit and the back-end circuit; The front-end circuit includes: The EMI and rectification filtering sub-circuit A1 is an input preprocessing module of the front-end circuit, which is used for electromagnetic interference EMI suppression, rectification of alternating current to direct current, and filtering to reduce voltage fluctuation, providing clean and stable direct current input for all subsequent front-end modules, avoiding the influence of power grid interference on circuit performance.

[0023] The direct current power supply circuit A2 adopts a high-efficiency low-power Buck DC-DC 3.3V circuit, which is used to provide independent and stable low-voltage power supply for the front-stage core control module, i.e., the LED intelligent control module circuit A5, to reduce the input voltage to 3.3V, to ensure the low-power operation of the intelligent control module circuit, and to avoid the power supply interference of other modules on the control circuit.

[0024] The primary side chip on-off control circuit A3 is used to cut off the power supply of the VCC pin of the primary side constant current dimming chip A6 when the LED light source is turned off and on standby, to realize ultra-low standby power consumption only through small current on-off control, to not need high-power elements, and to reduce the cost.

[0025] The high-voltage on-off detection circuit A4 is used to detect the on-off state of the high-voltage input in real time, to transmit the detection signal to the intelligent control module circuit A5, to provide the basis for the intelligent control module circuit A5 to judge the input power supply working state and action execution in advance (for example, when the 220V input end is powered off, the A5 circuit needs to save the current brightness and color temperature parameters immediately, so as to restore the working state before power failure when the power is turned on again.)

[0026] The intelligent control module circuit A5 is used as the control center of the front-stage circuit, to execute two core instructions after receiving the wireless or wired lighting control instruction signal: one is to send the dimming control signal to the primary side constant current dimming chip A6 to realize brightness adjustment, and to control the power supply on-off of the primary side constant current dimming chip A6 through the primary side chip on-off control circuit A3 to manage the standby state according to the judgment of whether the brightness value is 0; the other is to send the color temperature control signal to the rear stage through the optocoupler A8 after isolation. The primary side constant current dimming chip circuit A6 is the execution core of the front-stage brightness control, to receive the dimming control signal sent by the intelligent control module circuit A5, to directly control the brightness of the LED light source by adjusting the constant value of the output current, and to ensure the accurate and stable brightness adjustment.

[0027] The transformer A7 is used to transfer the energy of the front-stage circuit (the primary side, mainly the primary side constant current dimming chip circuit A6) to the rear-stage circuit through electromagnetic induction coupling, to provide the working power required by the rear-stage circuit including the modules A9, A10, etc., to ensure that the rear-stage double-color temperature control and driving circuit A10 can normally drive the cool color temperature LED (CLED) and the warm color temperature LED (WLED), and to realize the dimming and color adjusting functions. In this way, the transformer can effectively isolate the front-stage high-voltage circuit and the rear-stage low-voltage circuit, avoid the direct connection of the rear-stage circuit and the front-stage high-voltage part, reduce the risk of electric shock for the user, prevent the electrical interference in the front-stage circuit from affecting the rear-stage circuit, and ensure the stable and accurate work of the rear-stage circuit, such as making the color temperature control of the rear-stage more stable and accurate.

[0028] The primary winding of the transformer A7 is connected with the primary constant current dimming chip circuit A6 of the previous stage circuit as an energy input and control terminal, and is connected with the secondary winding of the transformer A7 through electromagnetic induction to realize energy transmission, and to ensure electrical isolation between the previous stage circuit and the subsequent stage circuit. The optocoupler A8 is used as a signal isolation bridge between the previous stage circuit and the subsequent stage circuit, and transmits the color temperature control signal generated by the intelligent control module circuit A5 to the double-color temperature control and driving circuit A10 after electrical isolation, so as to avoid signal interference between the previous stage high-voltage circuit and the subsequent stage low-voltage circuit, and to ensure circuit safety.

[0029] The subsequent stage circuit is mainly used for color temperature adjustment and short circuit protection, and specifically includes: The secondary winding of the transformer A7 is connected with the subsequent stage secondary rectification and filtering circuit A9 as an energy output and isolation terminal, and is used as a low-voltage side core of the isolation architecture of the application. The secondary rectification and filtering circuit A9 is connected with the secondary winding of the transformer A7, and is used to rectify and filter the alternating current output by the transformer to direct current, and to supply power to the double-color temperature control and driving circuit A10. The double-color temperature control and driving circuit A10 is used as a core execution module of the subsequent stage circuit, and is used to receive the color temperature PWM signal isolated by the optocoupler A8, to adjust the current ratio of the cold and warm LEDs by controlling the on / off time of the two MOS tubes (corresponding to the cold color temperature LED (CLED) and the warm color temperature LED (WLED)), and to finally realize precise switching of the color temperature (such as the transition from cold white light to warm yellow light); and the double-color temperature control and driving circuit A10 needs to respond to the protection signal of the output short circuit protection control circuit A11 to turn off the MOS tube when short circuit occurs.

[0030] The output short circuit protection control circuit A11 is used as a safety protection module of the subsequent stage circuit, and is composed of discrete components, and is used to determine whether short circuit occurs by detecting the voltage value of the WLED- (warm color temperature LED negative electrode) or the CLED- (cold color temperature LED negative electrode) in real time: when the output end is short-circuited, the WLED- or CLED- voltage will be pulled up instantaneously, and at this time, the output short circuit protection control circuit A11 immediately sends a control signal to the double-color temperature control and driving circuit A10 to turn off the two MOS tubes inside the double-color temperature control and driving circuit A10, so as to prevent the MOS tube from being burned out due to overcurrent and overheating, and to protect the subsequent stage circuit and the LED light source.

[0031] As described above, the isolated light-adjusting and color-adjusting LED driving circuit of the present case significantly reduces the circuit cost and standby power consumption through the electrical isolation architecture of the front-stage brightness control and the rear-stage color temperature control, the combination of the optocoupler A8 to achieve safe transmission of the color temperature control signal, and the design of the primary chip on-off control circuit A3. In the front-stage circuit, the EMI and rectification filter circuit A1 and the DC power supply circuit A2 work together to provide stable and independent power supply for the intelligent control module A5, and at the same time, the primary chip on-off control circuit A3 cuts off the VCC power supply of the primary constant current light-adjusting chip A6 in standby mode through the small current on-off design, thereby avoiding the use of high-power elements and achieving ultra-low standby power consumption; the intelligent control module A5 integrates the wired or wireless lighting control instructions and the high-voltage on-off detection signal to generate the brightness and color temperature control PWM signal output and the standby state control signal, wherein the color temperature control PWM signal is precisely controlled after the rear-stage circuit after being isolated by the optocoupler A8. The rear-stage circuit adopts discrete components to build the dual-color temperature control and driving circuit A10, which realizes smooth switching of the color temperature by adjusting the current ratio of the cool / warm color temperature LED, without the need for a dedicated control chip, thereby greatly reducing the hardware cost; the secondary rectification and filter circuit A9 converts the transformer secondary side alternating current into direct current to provide stable power supply for the rear-stage, in addition, the output short-circuit protection control circuit A11 monitors the LED negative voltage in real time, quickly turns off the MOS tube in the dual-color temperature driving circuit in the event of a short circuit, prevents overheating and burning, and improves the system reliability. The overall circuit, through the modular design and multiple protection mechanisms, takes into account low cost, high performance and high safety, and is particularly suitable for smart home and other scenarios that require frequent light and color adjustment.

[0032] As shown in Figure 2 As a specific embodiment, the EMI and rectification filter circuit A1 includes: an AC input interface COM1, a voltage-dependent resistor VR1, a first capacitor CX1, a common-mode inductor LF1, a rectifier bridge DB1, a fuse F1, and a front-stage filter circuit A111 composed of an inductor L1, a resistor R1, capacitors C2 and C4; the voltage-dependent resistor VR1 and the first capacitor CX1 are both connected in parallel between the two output terminals of the AC input interface COM1, the zero line output terminal of the AC input interface COM1 is connected with the fourth pin of the common-mode inductor LF1, and the live wire output terminal is connected with the second pin of the common-mode inductor LF1 through the fuse F1; the first pin of the common-mode inductor LF1 is connected with the first pin of the rectifier bridge DB1, and the third pin is connected with the second pin of the rectifier bridge DB1, the fourth pin of the rectifier bridge DB1 is grounded, the third pin is connected with the front-stage filter circuit A111 as a preliminary DC voltage output terminal, and the output terminal of the front-stage filter circuit A111 is a filtered DC voltage output terminal. Specifically, the 220V voltage is first rectified into a unidirectional pulsating DC, output at the preliminary DC voltage output terminal, and then output as a smooth and stable DC at the filtered DC voltage output terminal through the front-stage filter circuit A111.

[0033] As described above, the common mode inductance L2 of the EMI and rectification filter circuit A1 is used to suppress the common mode electromagnetic interference of the mains input, to avoid the interference signal affecting the subsequent circuit, and to solve the problem of light flicker and color temperature drift caused by insufficient EMI suppression in the traditional circuit. The voltage-dependent resistor VR1 is used to break down and conduct when the mains voltage is too high, to protect the subsequent circuit from overvoltage damage; the fuse F1 is used to melt and cut off the power supply loop when an overcurrent fault occurs in the circuit; the fuse F1 and the voltage-dependent resistor VR1 constitute an overcurrent and overvoltage protection, to avoid damage to the circuit caused by mains fluctuations such as lightning and voltage surges, and to improve the reliability of the equipment. The rectifier bridge DB1 is used to rectify the mains alternating current into unidirectional pulsating direct current; in the pre-stage filter circuit, the inductor and the capacitor form an LC filter network, which cooperates with the resistor to consume high-frequency ripple energy, to filter and process the pulsating direct current after rectification, and to output a smooth direct current voltage for power supply to the subsequent circuit.

[0034] As shown in Figure 2 As a specific embodiment, the direct current power supply circuit A2 includes: a first chip IC1, a first diode D1, a second diode D2, a third diode D3, a first resistor R7, a first polarity capacitor C1, a second polarity capacitor C6, a second capacitor (C3), a third capacitor (C8), and a first inductor L2. The first chip IC1 is a low-power Buck type DC-DC control chip. The anode of the first diode D1 is connected to the input end of the direct current power supply circuit A2, and is connected to the preliminary direct current voltage output end of the EMI and rectification filter circuit A1, and the cathode is connected to the first pin of the first chip IC1. The first polarity capacitor C1 is connected in parallel between the cathode of the diode D1 and the ground, to filter out the voltage ripple input to the first chip IC1. The second diode D2 is connected in forward direction between the ground and the output end of the first chip IC1. The third pin of the first chip IC1 is connected to the positive electrode of the second polarity capacitor C6, one end of the first resistor R7, and one end of the third capacitor C8 through the first inductor L2, and the common connection point of the three is connected to the intelligent control module circuit A5 as a power supply output end, to provide stable 3.3V power supply for the intelligent control module circuit A5. The negative electrode of the second polarity capacitor C6, the other end of the first resistor R7, and the other end of the third capacitor (C8) are grounded. The third diode D3 is connected in forward direction between the positive electrode of the second polarity capacitor C6 and the second pin of the first chip IC1. The first chip IC1 can use a synchronous buck DC-DC conversion chip with model number H4020, which is designed for applications requiring high efficiency, low power consumption, and precise voltage / current control. It has a built-in high-voltage MOSFET, supports a wide range of input voltages 5V-36V, and can provide a continuous output current of up to 1A. By adjusting the voltage dividing resistor of the FB feedback port, users can easily set the output voltage between 2.5V and 24V. The definitions of the pins of the first chip IC1 are as follows: Pin 1: Voltage input VIN; Pin 2: Feedback regulation FB; Pin 3: Switch output SW, connected to the drain or source of the internal switching transistor. By periodically switching the switching transistor on and off, it controls the transfer and release of energy to inductor L2 and serves as the power conversion node of the Buck circuit. The positive terminal of capacitor C6 (second polarity) serves as the output terminal of DC power supply circuit A2.

[0035] As mentioned above, the DC power supply circuit A2 in this case utilizes a low-power Buck DC-DC chip IC1, significantly improving conversion efficiency and significantly reducing power consumption in the power supply circuit compared to traditional linear voltage regulator circuits. In particular, during standby mode, only microampere-level current is required to be supplied to the intelligent control module, further reducing overall standby power consumption. The independent power supply design isolates the intelligent control module A5 from fluctuations in the preceding high-voltage circuit, eliminating control signal interference and improving the stability and accuracy of dimming and color temperature control.

[0036] like Figure 2 As shown, as a preferred embodiment, the primary chip on-off control circuit A3 includes: a first transistor Q2, a first NMOS transistor Q3, a second resistor R15, a third resistor R16, a fourth resistor R17, a fifth resistor R12, and a bidirectional voltage regulator diode D4; the first transistor Q2 is a PNP transistor, the emitter of which is connected to the filtered DC voltage output terminal of the EMI and rectifier filter circuit A1, and the collector is connected to the power supply input terminal of the primary constant current dimming chip circuit A6; the second resistor R15 is connected between the collector and emitter of the first transistor Q2, and is used to achieve voltage isolation when the first transistor Q2 is turned off, and provide power when it is turned on. flow path; one end of the third resistor R16 is connected to the collector of the first transistor Q2, and the other end is connected to the base of the first transistor Q2; the connection node between the base of the first transistor Q2 and the third resistor R16 is connected to the drain of the first NMOS transistor Q3 through the fourth resistor R17, and the source of the first NMOS transistor Q3 is grounded; one end of the fifth resistor R12 is connected to the control signal output end of the intelligent control module circuit A5 as a control signal input end, and the other end is connected to the gate of the first NMOS transistor Q3; the bidirectional voltage regulator diode D4 is connected between one end of the fifth resistor R12 and ground, and is used to clamp the gate voltage of the first NMOS transistor Q3 to prevent overvoltage damage.

[0037] As described above, by designing a simple and efficient small current on-off control circuit, the present case successfully realizes the precise control of the A6VCC pin power supply of the primary side constant current dimming chip circuit. The circuit utilizes the synergistic effect of the small power PNP type first transistor Q2 and the first NMOS tube Q3 to avoid the use of high-power elements, significantly reduce the cost and the size of the circuit, and improve the integration of the overall design. When the LED light source enters the off standby state, the intelligent control module circuit A5 outputs a control signal to make the NMOS tube Q3 cut off, and then pull down the base potential of the first transistor Q2 to make it cut off quickly, thereby cutting off the VCC power supply of the primary side constant current dimming chip A6, effectively reducing the standby power consumption. Conversely, when the power supply needs to be restored, the control module outputs a high-level signal to make the transistor and NMOS tube conductive, and the VCC power supply is restored. This process only requires a small control current, greatly improving the energy utilization efficiency, and further optimizing the low-power performance of the circuit. At the same time, the second resistor R15 provides voltage isolation when the transistor is cut off, ensuring the safety of the circuit; when it is turned on, it provides a stable current path to ensure the normal work of the chip. The introduction of the bidirectional voltage stabilizing diode D4 effectively clamps the gate voltage of the NMOS tube Q3, preventing overvoltage damage and improving the reliability and stability of the circuit. In this way, the overall design of the circuit is economical and efficient, not only meeting the energy-saving needs, but also ensuring the stability and safety of the circuit under various working conditions.

[0038] As Figure 2 shown, as a preferred embodiment, the front-end circuit further comprises a high-voltage on-off detection circuit A4 connected between the EMI and rectifier filter circuit A1 and the intelligent control module circuit A5 for detecting the high-voltage input state; the input end of the high-voltage on-off detection circuit A4 is connected with the positive output end of the EMI and rectifier filter circuit A1 as a high-voltage on-off signal input end, and the output end transmits the detection signal to the intelligent control module circuit A5, providing a basis for the intelligent control module circuit A5 to judge the circuit working state (such as whether to start the standby mode, whether to execute the brightness adjustment); The high-voltage on-off detection circuit A4 includes a sixth resistor R2, a seventh resistor R3, an eighth resistor R4, a fourth capacitor C7, a second triode Q1, and a ninth resistor R9. One end of the sixth resistor R2 is connected to the positive output end / filtration DC voltage output end of the EMI and rectification filtration circuit A1 as the high-voltage on-off signal input end, and the other end is connected to one end of the eighth resistor R4, one end of the fourth capacitor C7, and the base of the second triode Q1 through the seventh resistor R3. The other end of the eighth resistor R4, the other end of the fourth capacitor C7, and the emitter of the second triode Q1 are grounded. The second triode Q1 is an NPN triode, and the collector is connected to the intelligent control module circuit A5 as the detection signal output end. One end of the ninth resistor R9 is connected to the collector of the second triode Q1, and the other end is connected to the power supply output end of the DC power supply circuit A2 as the power supply input end.

[0039] As described above, the high-voltage on-off detection circuit A4 realizes real-time monitoring of the high-voltage state of the output end of the EMI and rectification filtration circuit A1 through a precise resistor-capacitor-triode voltage division network. When the input voltage exceeds the safety threshold, the voltage divider composed of the sixth resistor R2 and the seventh resistor R3 reduces the high-voltage signal to a range that the base of the second triode Q1 can withstand, triggering the second triode Q1 to conduct, and the low-level signal output by the collector is quickly transmitted to the intelligent control module circuit A5, providing an overvoltage warning for the system. Conversely, within the normal voltage range, the second triode Q1 remains in a cut-off state, outputting a high-level signal. This design effectively suppresses false triggering caused by voltage fluctuations through the filtering effect of the fourth capacitor C7, ensuring the stability of the detection signal. At the same time, the ninth resistor R9 provides a stable bias current for the second triode Q1, ensuring reliable operation of the circuit under low voltage difference conditions. This circuit not only provides accurate high-voltage on-off state information for the intelligent control module, supporting decisions such as standby mode switching or brightness adjustment, but also achieves high-precision detection through simple discrete components, avoiding the use of complex integrated circuits, significantly reducing costs and improving the anti-interference ability of the circuit.

[0040] As a specific embodiment, the intelligent control module circuit A5 is provided with a power supply input end connected with the voltage output end of the direct current power supply circuit A2, a high voltage on-off signal detection input end MS connected with the output end of the high voltage on-off detection circuit A4, a dimming control signal output end (CW / TX) connected with the input end of the primary side constant current dimming chip circuit A6, and a color temperature control signal output end (WW / RX) connected with the input end of the double color temperature control and driving circuit A10 through the optocoupler A8. The intelligent control module circuit A5 can be a single-chip microcomputer module with wireless communication function, such as an STM32 series chip. The intelligent control module circuit A5 is internally integrated with an MCU core module, a PWM signal generation module, and a signal detection module. The MCU core module is used for receiving the detection signal of the high voltage on-off detection circuit A4, judging the working state of the circuit, and issuing corresponding control instructions. The PWM signal generation module is used for generating dimming PWM control signals / dimming control signals and color temperature PWM control / color temperature control signals according to the instructions of the MCU core module. The signal detection module is used for filtering and level converting the input high voltage on-off detection signal, so as to ensure that the signal can be accurately recognized by the MCU core module. In this way, the pin functions and connection relationships of the intelligent control module A5 are further defined, so that the module becomes a unified control core, avoiding the logic confusion caused by the dispersion of dimming, color temperature, and standby control in different chips in the traditional circuit, and simplifying system integration. Through the settings of the independent power supply input end, signal detection end, and control output end, the separation of power supply, detection, and control is realized, and the anti-interference ability is improved. The color temperature control signal is isolated and output through the optocoupler A8, so as to meet the electrical isolation requirements of the front stage and the rear stage, and meet the safety standard. In specific implementation, the intelligent control module circuit A5 can select an STM32F030C8T6 single-chip microcomputer. The VCC pin 3.3V of the single-chip microcomputer is connected with the output end of the direct current power supply circuit A2 as the power supply input end, and the GND pin is grounded. The high voltage on-off signal detection input end MS is connected with the collector of Q1 in the high voltage on-off detection circuit A4, and receives the power on-off signal. The dimming control signal output end CW / TX is connected with the DIM pin of the primary side constant current dimming chip circuit A6, and outputs a PWM signal with a duty cycle of 0-100% to adjust the LED brightness. The color temperature control signal output end WW / RX is connected with the primary side anode of the optocoupler A8, and controls the double color temperature ratio of the rear stage through the PWM signal duty cycle change, such as 0% corresponding to full cold color and 100% corresponding to full warm color. Another IO pin OFF of the module is connected with the gate of Q3 in the primary side chip on-off control circuit A3, and outputs a high-low level to control the on-off of Q3, so as to cut off / resume the power supply of the primary side chip.

[0041] As Figure 2As shown, as a specific embodiment, the primary constant current dimming chip circuit A6 includes: a primary constant current dimming chip IC2 and its peripheral circuit; the primary constant current dimming chip IC2 is provided with a power input terminal T1 connected with the output terminal of the primary chip on-off control circuit A3, a ground terminal T2, a dimming control signal input terminal T3 connected with the dimming control signal output terminal of the intelligent control module circuit A5, a first power output terminal T4, and a second power output terminal T5; The primary winding of the transformer A7 is composed of two primary coils, wherein: one end of the first primary coil is connected with the positive output terminal of the EMI and rectification filter circuit A1, the other end is connected with the first power output terminal T4 of the primary constant current dimming chip IC2; one end of the second primary coil is connected with the second power output terminal T5 of the primary constant current dimming chip IC2, and the other end is grounded; the two primary coils are connected in series to form a complete primary winding and a main loop for energy conversion; The secondary winding of the transformer A7 is a coil, and its two ends are respectively connected with the input terminals of the subsequent circuit, so as to realize energy transmission from the primary to the secondary through electromagnetic induction, and realize constant current driving of the LED load in cooperation with the primary constant current dimming chip IC2.

[0042] Specifically, the primary constant current dimming chip IC2 can also be called a primary feedback chip or a primary feedback power supply chip, etc.; for example, a primary feedback power supply chip with a model number of GP8891CS. After receiving the dimming control signal, the primary constant current dimming chip IC2 adjusts the current size of the primary winding of the transformer through the first power output terminal T4 and the second power output terminal T5, and then controls the secondary output current, so as to finally realize brightness adjustment of the LED light source.

[0043] As mentioned above, primary-side constant-current dimming chip circuit A6, with primary-side constant-current dimming chip IC2 at its core, integrates constant-current control and power output functions, eliminating the need for a complex constant-current feedback loop and significantly simplifying the circuit architecture. Transformer A7's primary winding utilizes two primary coils, which reduces voltage stress on a single coil and reduces coil losses. Combined with the high-frequency switching control of the primary-side constant-current dimming chip, this effectively improves primary-side energy conversion efficiency, resolving the issues of high energy conversion losses and low efficiency associated with traditional isolated drive circuits. Furthermore, primary-side constant-current dimming chip IC2 directly controls the transformer's primary current, eliminating the need for feedback from a post-stage sampling resistor. This avoids feedback delays, speeds up brightness adjustment response, and improves the brightness jumps and linear distortion associated with traditional dimming, ensuring stable lighting quality. In addition, the transformer primary-side dual-coil series structure can adapt to different ranges of input voltage, improving the product's market adaptability. The primary-side constant-current dimming chip IC2 power supply end is directly connected to the primary-side chip on-off control circuit A3, which can quickly cut off the power supply when in standby mode to avoid no-load loss. The secondary single-coil design simplifies the wiring logic of the secondary-side rectifier filter circuit A9, reduces post-stage drive failures, and improves circuit reliability. Compared with traditional secondary-side constant-current drive solutions, the primary-side constant-current design eliminates multiple components and reduces costs. The high integration of the primary-side constant-current dimming chip reduces the size of the front-stage circuit, adapting to the installation requirements of miniaturized LED lighting products and improving design flexibility.

[0044] like Figure 2As shown, as a specific embodiment, the secondary side rectification and filtering circuit A9 includes: a tenth resistor R23, a fifth capacitor C15, a fourth diode D7, and a third polarity capacitor C14; the connection point between the positive electrode of the fourth diode D7 and one end of the tenth resistor R23 is connected to one end of the secondary coil of the secondary winding as an input end, the negative electrode of the fourth diode D7 is connected to the positive electrode of the third polarity capacitor C14, and the negative electrode of the third polarity capacitor C14 is connected to the other end of the secondary coil of the secondary winding and to the digital ground; the other end of the tenth resistor R23 is connected to the positive electrode of the third polarity capacitor C14 through the fifth capacitor C15, and the connection point between the two is connected to the dual color temperature control and drive circuit A10 as an output end. In this way, secondary-side rectification and filtering circuit A9 efficiently rectifys the AC power output from the transformer's secondary winding via fourth diode D7. Combined with the filtering effect of third-polarity capacitor C14, it converts the pulsating AC signal into a smooth and stable DC voltage, providing reliable power for the subsequent dual-color temperature control and driver circuit A10. This prevents problems such as brightness flicker and color temperature drift in the LED light source caused by voltage fluctuations, ensuring stable lighting. Furthermore, the RC snubber circuit formed by tenth resistor R23 and fifth capacitor C15 effectively suppresses voltage spikes and high-frequency interference generated during the rectification process, preventing damage to subsequent components such as MOS transistors due to overvoltage and improving overall circuit reliability. The entire circuit utilizes a simple combination of discrete components to achieve rectification, filtering, and interference suppression, eliminating the need for complex integrated circuits. This simplifies the circuit structure while reducing costs, facilitating subsequent maintenance and troubleshooting, and meeting the low-cost, high-stability design requirements of the driver circuit.

[0045] like Figure 2 As shown, as a preferred embodiment, the dual-color temperature control and driving circuit A10 includes: an eleventh resistor R25, a twelfth resistor R27, a thirteenth resistor R24, a fourteenth resistor R26, a fifth diode D10, a sixth diode D8, a seventh diode D9, an eighth diode D12, a ninth diode D11, a first voltage zener diode DZ1, a second voltage zener diode DZ2, a second NMOS transistor Q5, a third NMOS transistor Q6, a sixth capacitor C17, a seventh capacitor C18, and an output interface COM2 connected to an external LED; One end of the eleventh resistor R25 is connected to the output end of the secondary side rectification and filter circuit A9, and the other end is connected to the gate of the second NMOS tube Q5; one end of the twelfth resistor R27 is connected to the third end of the output interface COM2 as the positive electrode connection end of the LED light source, so as to connect the positive electrode of the external LED light source; the other end of the twelfth resistor R27 is connected back to the third end of the output interface COM2 through the forwardly connected fifth diode D10 and ninth diode D11 in sequence; the drain of the second NMOS tube Q5 is connected to the second end of the output interface COM2 as the negative electrode connection end of the warm color temperature LED lamp string; the source of the second NMOS tube Q5 is connected to the digital ground; the first voltage stabilizing diode DZ1 and the thirteenth resistor R24 are connected in parallel between the emitter end and the collector end of the triode of the optocoupler A8; the collector of the triode of the optocoupler A8 is connected to the gate of the second NMOS tube Q5, and the emitter of the triode is connected to the digital ground; The gate of the third NMOS tube Q6 is connected to the fifth diode D10, the positive electrode of the seventh diode D9, one end of the fourteenth resistor R26, and the negative electrode of the second voltage stabilizing diode DZ2, respectively; the other end of the fourteenth resistor R26, the positive electrode of the second voltage stabilizing diode DZ2, and the source of the third NMOS tube Q6 are all connected to the digital ground; the sixth capacitor C17 is connected between the drain of the second NMOS tube Q5 and the digital ground; the seventh capacitor C18 is connected between the drain of the third NMOS tube Q6 and the digital ground; the drain of the third NMOS tube Q6 is connected to the first end of the output interface COM2 as the negative electrode connection end of the cold color temperature LED lamp string; The sixth diode D8 is connected in forward direction between the collector end of the triode of the optocoupler A8 and the negative electrode of the seventh diode D9.

[0046] As described above, the dual-color temperature control and driving circuit A10 is built by combining discrete components, without relying on a dedicated control chip. The second NMOS tube Q5 and the third NMOS tube Q6 correspondingly control the current paths of the warm color temperature and the cold color temperature LED lamp strings, respectively, and cooperate with the isolated color temperature control signal transmitted by the optocoupler A8 to accurately adjust the current ratio of the two types of LED lamp strings, realize stable color temperature switching and control, meet the lighting needs in different scenes, and avoid the adaptability limitation caused by the fixed function of the dedicated chip. At the same time, the first voltage stabilizing diode DZ1 and the second voltage stabilizing diode DZ2 in the circuit can protect the gate of the MOS tube from being damaged by overvoltage, the sixth capacitor C17 and the seventh capacitor C18 can suppress current fluctuation, and the fifth diode D10, the sixth diode D8 and other components further optimize signal transmission and loop protection, ensuring reliable operation of the circuit. In addition, the selection of discrete components not only greatly reduces the cost of the circuit, avoids the additional expenses brought by the dedicated chip, but also simplifies the circuit structure, facilitates flexible adjustment of component parameters according to actual needs, improves the adaptability of the circuit, and at the same time, reduces the difficulty of later maintenance and troubleshooting, which meets the design goals of low cost, high reliability and flexible adaptation of the driving circuit.

[0047] As shown in Figure 2 The rear circuit further comprises: An output short circuit protection control circuit A11 connected with the dual-color temperature control and driving circuit A10, for controlling the dual-color temperature control and driving circuit A10 to be turned off to realize protection when the output end is short-circuited. The output short circuit protection control circuit A11 comprises a fifteenth resistor R28, a sixteenth resistor R29, a twelfth diode D13, an eleventh diode D14, a third voltage stabilizing diode DZ3, a fourth voltage stabilizing diode DZ4, an eighth capacitor C16, and a fourth NMOS tube Q4. The anode of the twelfth diode D13 is connected with the second end of the output interface COM2 as a warm color temperature LED voltage detection input end, and the anode of the eleventh diode D14 is connected with the first end of the output interface COM2 as a cold color temperature LED voltage detection input end. The connection point of the cathodes of the twelfth diode D13 and the eleventh diode D14 is connected with the negative electrode of the fourth voltage stabilizing diode DZ4, the positive electrode of the fourth voltage stabilizing diode DZ4 is connected with the positive electrode of the third voltage stabilizing diode DZ3 and the other end of the sixteenth resistor R29, respectively, one end of the sixteenth resistor R29 is connected with one end of the sixteenth resistor R29, one end of the eighth capacitor C16 and the gate of the fourth NMOS tube Q4, respectively, the other end of the sixteenth resistor R29, the other end of the eighth capacitor C16 and the source of the fourth NMOS tube Q4 are connected with the digital ground, and the drain of the fourth NMOS tube Q4 is connected with the negative electrode of the seventh diode D9.

[0048] As described above, the output short circuit protection control circuit A11 also uses simple discrete components to build, without relying on complex protection chip, greatly reducing the cost of the circuit, simplifying the overall structure, and facilitating later maintenance and troubleshooting. The circuit directly detects the voltage state of the negative electrode of the warm color temperature and cold color temperature LED through the twelfth diode D13 and the eleventh diode D14, which can quickly capture the voltage anomaly when the output end is short-circuited. Compared with the traditional indirect detection scheme, the response is more rapid, and the protection action can be triggered in time. When a short circuit is detected, the circuit acts on the key control node of the dual-color temperature control and driving circuit A10 through the fourth NMOS tube Q4, quickly turns off the MOS tube responsible for LED driving, effectively avoids the overheating and burning of the MOS tube due to the short-circuit current, and at the same time protects the LED light source and the subsequent circuit from damage, significantly improving the reliability and safety of the overall circuit. In addition, the combination of the third voltage stabilizing diode DZ3, the fourth voltage stabilizing diode DZ4 and the eighth capacitor C16 can suppress voltage fluctuations and interference signals, prevent false triggering of the protection action, and ensure the stability of the circuit in the normal working state, meeting the design requirements of high cost performance and high reliability of the driving circuit.

[0049] The specific working principle of the present application is as follows: 1. Brightness control: The LED intelligent control module circuit A5 sends a dimming PWM signal / dimming control signal to the primary side constant current dimming chip circuit (A6) by executing the brightness control instruction, realizing the brightness adjustment of the LED light source.

[0050] 2. Color temperature control: The LED intelligent control module circuit A5 outputs a color temperature PWM color control signal by executing the color temperature control instruction, which is sent to the dual-color temperature control and driving circuit (A10) for color temperature control after signal isolation by the optocoupler (A8).

[0051] 3. Low standby power consumption: When the LED light source is off and on standby, the LED intelligent control module circuit (A5) cuts off the power supply to the VCC pin of the primary side chip through the primary side chip on-off control circuit (A3), thereby greatly reducing the standby power consumption.

[0052] 4. Short circuit protection: The output short circuit protection control circuit A11 detects the voltage value of WLED- or CLED- and sends a control signal to the dual-color temperature control and driving circuit (A10) to turn off the two NMOS tubes when a short circuit occurs at the output end, preventing overheating and burning.

[0053] In this way, through the circuit design of the present application, a low-cost, high-performance LED intelligent dimming and color control driving circuit is realized, which also has ultra-low standby power consumption and output short circuit protection function.

[0054] In summary, the application discloses an isolated light-adjusting and color-adjusting LED driving circuit, which comprises a front-stage circuit, a rear-stage circuit and a photoelectric coupler A8.The front-stage circuit comprises an EMI and rectification filter circuit A1, a DC power supply circuit A2, a primary chip on-off control circuit A3, a high-voltage on-off detection circuit A4, an intelligent control module circuit A5, a primary constant-current light-adjusting chip circuit A6 and a transformer A7 primary winding, A1 processes the input of commercial power, A2 supplies 3.3V power for A5, A3 cuts off the power supply of A6 to reduce power consumption when on standby, and A5 generates a light-adjusting / color temperature signal; the rear-stage circuit comprises a secondary winding of A7, a secondary rectification and filter circuit A9, a dual-color temperature control and driving circuit A10 and an output short-circuit protection control circuit A11, A9 rectifies and filters to supply power, A10 adjusts the cold / warm LED current ratio by using discrete components, and A11 detects the negative voltage of the LED to realize short-circuit protection; A8 isolates the signals of the front-stage and the rear-stage, simplifies the overall structure and reduces cost and consumption, and is suitable for smart home lighting.

[0055] As described above, the application protects an isolated light-adjusting and color-adjusting LED driving circuit, and all technical solutions identical or similar to the application shall be shown to fall within the protection scope of the application.

Claims

1. An isolated dimming and color-adjusting LED drive circuit, characterized in that: include: A front-stage circuit for controlling the brightness of an LED light source, a rear-stage circuit electrically isolated from the front-stage circuit and for controlling the color temperature of the LED light source, and an optical coupler (A8) for achieving isolated signal transmission between the front-stage circuit and the rear-stage circuit; The front-stage circuit comprises: an EMI and rectifier filter circuit (A1), a DC power supply circuit (A2), a primary chip on-off control circuit (A3), an intelligent control module circuit (A5), a primary constant current dimming chip circuit (A6), and a primary winding of a transformer (A7) connected to the primary constant current dimming chip circuit (A6); the EMI and rectifier filter circuit (A1) is connected to an external mains power supply and is used to provide a rectified and filtered DC input to the front-stage circuit; the DC power supply circuit (A2) is used to power the intelligent control module circuit (A5); the primary chip on-off control circuit (A3) is connected between the output end of the EMI and rectifier filter circuit (A1) and the primary winding of the transformer (A7) connected to the primary constant current dimming chip circuit (A6); The primary side constant current dimming chip circuit (A6) is connected to the input end of the primary side constant current dimming chip circuit (A6), and is used to cut off the power supply to the primary side constant current dimming chip circuit (A6) when the LED light source is turned off and in standby mode; the intelligent control module circuit (A5) is connected to the primary side chip on-off control circuit (A3), the primary side constant current dimming chip circuit (A6) and the optical coupler (A8), respectively, and is used to generate a dimming control signal and send it to the primary side constant current dimming chip circuit (A6), as well as generate a color temperature control signal and send it to the optical coupler (A8), and control the working state of the primary side chip on-off control circuit (A3); the primary side constant current dimming chip circuit (A6) is used to receive the dimming control signal and adjust the output current to control the brightness of the LED light source; The post-stage circuit comprises: a secondary winding of a transformer (A7), a secondary rectification and filtering circuit (A9) connected to the secondary winding of the transformer (A7), and a dual color temperature control and drive circuit (A10) composed of discrete components and connected to an optocoupler (A8), the secondary rectification and filtering circuit (A9), and an external cold color temperature LED and a warm color temperature LED, respectively; the secondary rectification and filtering circuit (A9) is used to rectify and filter the alternating current output from the secondary side of the transformer into direct current to supply power to the dual color temperature control and drive circuit (A10); the dual color temperature control and drive circuit (A10) is used to receive a color temperature control signal transmitted through isolation and adjust the current ratio of the cold color temperature LED to the warm color temperature LED.

2. The LED driving circuit according to claim 1, wherein: The latter circuit further includes: An output short-circuit protection control circuit (A11) is connected to the dual-color temperature control and drive circuit (A10) and is used to control the dual-color temperature control and drive circuit (A10) to shut down when the output end is short-circuited to achieve protection.

3. The LED driving circuit according to claim 1, wherein: The EMI and rectification and filtering circuit (A1) comprises: an AC input interface (COM1), a varistor (VR1), a first capacitor (CX1), a common-mode inductor (LF1), a rectifier bridge (DB1), a fuse (F1), and a pre-stage filtering circuit (A111); the varistor (VR1) and the first capacitor (CX1) are connected in parallel between the two output ends of the AC input interface (COM1), the neutral line output end of the AC input interface (COM1) is connected to the fourth pin of the common-mode inductor (LF1), and the live line output end is connected to the fourth pin of the common-mode inductor (LF1) through the fuse. (F1) is connected to the second pin of the common-mode inductor (LF1); the first pin of the common-mode inductor (LF1) is connected to the first pin of the rectifier bridge (DB1), and the third pin is connected to the second pin of the rectifier bridge (DB1); the fourth pin of the rectifier bridge (DB1) is grounded, and the third pin is connected to the front-stage filter circuit (A111) as a preliminary DC voltage output terminal; the output terminal of the front-stage filter circuit (A111) serves as a filtered DC voltage output terminal to output a smooth and stable DC, which is used to provide a rectified and filtered DC input for the front-stage circuit.

4. The LED driving circuit according to claim 1, wherein: The DC power supply circuit (A2) comprises: a first chip (IC1), a first diode (D1), a second diode (D2), a third diode (D3), a first resistor (R7), a first polarity capacitor (C1), a second polarity capacitor (C6), a second capacitor (C3), a third capacitor (C8), and a first inductor (L2); the first chip (IC1) is a low-power Buck-type DC-DC control chip; the anode of the first diode (D1) serves as the input end of the DC power supply circuit (A2) and is connected to the output end of the EMI and rectifier filter circuit (A1), and the cathode is connected to the first pin of the first chip (IC1); the first polarity capacitor (C1) is connected in parallel to the cathode of the first diode (D1). The first chip (IC1) is connected between the positive electrode of the second polarity capacitor (C6) and the ground, and is used to filter the voltage ripple input to the first chip (IC1); the second diode (D2) is connected in a forward direction between the ground and the output end of the first chip (IC1); the third pin of the first chip (IC1) is connected to the positive electrode of the second polarity capacitor (C6), one end of the first resistor (R7), and one end of the third capacitor (C8) through the first inductor (L2), and the common connection point of the three is connected to the intelligent control module circuit (A5) as the power supply output end; the negative electrode of the second polarity capacitor (C6), the other end of the first resistor (R7), and the other end of the third capacitor (C8) are grounded; the third diode (D3) is connected in a forward direction between the positive electrode of the second polarity capacitor (C6) and the second pin of the first chip (IC1).

5. The LED driving circuit according to claim 1, wherein: The primary chip on-off control circuit (A3) comprises: a first transistor (Q2), a first NMOS transistor (Q3), a second resistor (R15), a third resistor (R16), a fourth resistor (R17), a fifth resistor (R12), and a bidirectional voltage regulator diode (D4); The first transistor (Q2) is a PNP-type transistor, the emitter of which is connected to the positive output terminal of the EMI and rectifier filter circuit (A1), and the collector of which is connected to the power supply input terminal of the primary constant current dimming chip circuit (A6); the second resistor (R15) is connected between the collector and the emitter of the first transistor (Q2), and is used to achieve voltage isolation when the first transistor (Q2) is cut off and provide a current path when it is turned on; one end of the third resistor (R16) is connected to the collector of the first transistor (Q2), and the other end is connected to the base of the first transistor (Q2) and connected to the drain of the first NMOS transistor (Q3) through the fourth resistor (R17), and the source of the first NMOS transistor (Q3) is grounded; one end of the fifth resistor (R12) is connected to the intelligent control module circuit (A5) as a control signal input terminal, and the other end is connected to the gate of the first NMOS transistor (Q3); the bidirectional voltage regulator diode (D4) is connected between one end of the fifth resistor (R12) and the ground.

6. The LED driving circuit according to claim 1 or 5, characterized in that: The front-stage circuit further includes: a high-voltage on-off detection circuit (A4) connected between the EMI and rectifier filter circuit (A1) and the intelligent control module circuit (A5) for detecting the high-voltage input state; an input end of the high-voltage on-off detection circuit (A4) is connected to the positive output end of the EMI and rectifier filter circuit (A1) as a high-voltage on-off signal input end, and the output end transmits the detection signal to the intelligent control module circuit (A5); The high-voltage on-off detection circuit (A4) comprises: a sixth resistor (R2), a seventh resistor (R3), an eighth resistor (R4), a fourth capacitor (C7), a second transistor (Q1), and a ninth resistor (R9); one end of the sixth resistor (R2) is connected to the positive output end of the EMI and rectifier filter circuit (A1) as the high-voltage on-off signal input end, and the other end is connected to one end of the eighth resistor (R4), one end of the fourth capacitor (C7), and the base of the second transistor (Q1) through the seventh resistor (R3); the other end of the eighth resistor (R4), the other end of the fourth capacitor (C7), and the emitter of the second transistor (Q1) are grounded; the second transistor (Q1) is an NPN transistor, and the collector is connected to the intelligent control module circuit (A5) as the detection signal output end; one end of the ninth resistor (R9) is connected to the collector of the second transistor (Q1), and the other end is connected to the DC power supply circuit (A2) as the power supply input end.

7. The LED driving circuit according to claim 6, characterized in that: The intelligent control module circuit (A5) is provided with a power supply input terminal connected to the voltage output terminal of the DC power supply circuit (A2), a high-voltage on-off signal detection input terminal connected to the output terminal of the high-voltage on-off detection circuit (A4), a dimming control signal output terminal connected to the input terminal of the primary constant current dimming chip circuit (A6), and a color temperature control signal output terminal connected to the input terminal of the dual color temperature control and drive circuit (A10) via an optical coupler (A8); The primary constant current dimming chip circuit (A6) comprises: a primary constant current dimming chip (IC2) and its peripheral circuit; the primary constant current dimming chip (IC2) is provided with a power supply input terminal (T1) connected to the output terminal of the primary chip on / off control circuit (A3), a ground terminal (T2), a dimming control signal input terminal (T3) connected to the dimming control signal output terminal of the intelligent control module circuit (A5), a first power output terminal (T4), and a second power output terminal (T5); The primary winding of the transformer (A7) is composed of two primary coils, one end of the first primary coil is connected to the positive output terminal of the EMI and rectifier filter circuit (A1), The other end is connected to the first power output terminal (T4) of the primary constant current dimming chip (IC2); one end of the second primary coil is connected to the second power output terminal (T5) of the primary constant current dimming chip (IC2), and the other end is grounded; The secondary winding of the transformer (A7) is a coil, and its two ends are respectively connected to the input end of the subsequent circuit.

8. The LED driving circuit according to claim 7, characterized in that: The secondary side rectification and filtering circuit (A9) comprises: a tenth resistor (R23), a fifth capacitor (C15), a fourth diode (D7), and a third polarity capacitor (C14); the connection point between the positive electrode of the fourth diode (D7) and one end of the tenth resistor (R23) is connected to one end of the secondary coil of the secondary winding as an input end, the negative electrode of the fourth diode (D7) is connected to the positive electrode of the third polarity capacitor (C14), and the negative electrode of the third polarity capacitor (C14) is connected to the other end of the secondary coil of the secondary winding and to a digital ground; the other end of the tenth resistor (R23) is connected to the positive electrode of the third polarity capacitor (C14) via the fifth capacitor (C15), and the connection point between the two is connected to the dual color temperature control and drive circuit (A10) as an output end.

9. The LED driving circuit according to claim 1, wherein: The dual-color temperature control and drive circuit (A10) includes: an eleventh resistor (R25), a twelfth resistor (R27), a thirteenth resistor (R24), a fourteenth resistor (R26), a fifth diode (D10), a sixth diode (D8), a seventh diode (D9), an eighth diode (D12), a ninth diode (D11), a first voltage-stabilizing diode (DZ1), a second voltage-stabilizing diode (DZ2), a second NMOS transistor (Q5), a third NMOS transistor (Q6), a sixth capacitor (C17), a seventh capacitor (C18), and an output interface (COM2) for connecting to an external LED; One end of the eleventh resistor (R25) is connected to the output end of the secondary side rectification and filtering circuit (A9), and the other end is connected to the gate of the second NMOS tube (Q5); one end of the twelfth resistor (R27) is connected to the third end of the output interface (COM2) as the positive electrode connection end of the LED light source, so as to be connected to the positive electrode of the external LED light source; the other end of the twelfth resistor (R27) is connected back to the third end of the output interface (COM2) through the fifth diode (D10) and the ninth diode (D11) connected in the forward direction in sequence; the second NMOS The drain of the S transistor (Q5) is connected to the second end of the output interface (COM2) as the negative electrode connection terminal of the warm color temperature LED to provide connection for the negative electrode of the external warm color temperature LED light string; the source of the second NMOS transistor (Q5) is connected to the digital ground; a first forward voltage stabilizing diode (DZ1) and a thirteenth resistor (R24) are connected in parallel between the emitter terminal and the collector terminal of the transistor of the optocoupler (A8); the collector of the transistor of the optocoupler (A8) is connected to the gate of the second NMOS transistor (Q5), and the emitter of the transistor is connected to the digital ground; The gate of the third NMOS tube (Q6) is respectively connected to the anode of the fifth diode (D10), the anode of the seventh diode (D9), one end of the fourteenth resistor (R26), and the cathode of the second voltage-stabilizing diode (DZ2); the other end of the fourteenth resistor (R26), the anode of the second voltage-stabilizing diode (DZ2), and the source of the third NMOS tube (Q6) are all connected to the digital ground; the drain of the second NMOS tube (Q5) is connected to the digital ground with the sixth capacitor (C17); the drain of the third NMOS tube (Q6) is connected to the digital ground with the seventh capacitor (C18); the drain of the third NMOS tube (Q6) is connected to the first end of the output interface (COM2) as the negative electrode connection terminal of the cold color temperature LED, so as to be connected to the negative electrode of the external cold color temperature LED light string; A sixth diode (D8) in the forward direction is connected between the collector terminal of the triode of the optical coupler (A8) and the negative electrode of the seventh diode (D9).

10. The LED driving circuit according to claim 9, characterized in that: The output short-circuit protection control circuit (A11) comprises: a fifteenth resistor (R28), a sixteenth resistor (R29), a tenth diode (D13), an eleventh diode (D14), a third voltage-stabilizing diode (DZ3), a fourth voltage-stabilizing diode (DZ4), an eighth capacitor (C16), and a fourth NMOS transistor (Q4); the anode of the tenth diode (D13) is connected to the second end of the output interface (COM2) as a warm color temperature LED voltage detection input end, and the anode of the eleventh diode (D14) is connected to the first end of the output interface (COM2) as a cold color temperature LED voltage detection input end; the cathode of the tenth diode (D13) is connected to the first end of the output interface (COM2) as a cold color temperature LED voltage detection input end; The connection point with the cathode of the eleventh diode (D14) is connected to the cathode of the fourth voltage stabilizing diode (DZ4); the anode of the fourth voltage stabilizing diode (DZ4) is respectively connected to the anode of the third voltage stabilizing diode (DZ3) and the other end of the sixteenth resistor (R29); one end of the sixteenth resistor (R29) is respectively connected to one end of the sixteenth resistor (R29), one end of the eighth capacitor (C16), and the gate of the fourth NMOS transistor (Q4); the other end of the sixteenth resistor (R29), the other end of the eighth capacitor (C16), and the source of the fourth NMOS transistor (Q4) are connected to the digital ground; and the drain of the fourth NMOS transistor (Q4) is connected to the cathode of the seventh diode (D9).

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