Isolated dimming and color mixing LED driving circuit

Abstract

The utility model discloses an isolation type light modulation and color modulation LED drive circuit, including former circuit, after stage circuit and photoelectric coupling A8. In former circuit, EMI and rectifier filter circuit A1 handle commercial power, and direct current power supply power supply circuit A2 supplies 3.3V electricity for intelligent control module circuit A5, and the primary side chip on-off control circuit A3 cuts off the primary side constant current light modulation chip circuit A6 power supply to reduce power consumption when standby, in after stage circuit, two color temperature control and drive circuit A10 use discrete component to adjust cold / warm LED current ratio, and output short circuit protection control circuit A11 detects LED negative pole voltage to realize protection. Photoelectric coupling A8 isolates signal, and the whole simplifies framework, and reduces cost and consumption, and is applicable to smart home lighting.

Description

Technical Field

[0001] This utility model relates to the field of LED lighting drivers, specifically to an isolated dimming and color-tuning LED driver circuit. Background Technology

[0002] In the current lighting field, with the popularization of smart lighting, the application of isolated LED dimming and color-tuning drivers is becoming increasingly widespread. Existing isolated LED dimming and color-tuning drivers have the following problems: 1. Many isolated LED dimming and color-tuning drivers often employ a two-stage control method, consisting of a front-stage AC-DC isolation circuit and a rear-stage DC-CC constant current dimming and color-tuning driver circuit. This architecture results in a large number of components in the circuit. For example, the front-stage AC-DC isolation circuit requires a series of rectifiers, filters, and transformers, while the rear-stage DC-CC constant current dimming and color-tuning driver circuit includes various control chips and power devices. This increased number of components not only enhances the complexity of the circuit design but also leads to a significant increase in cost, hindering the large-scale promotion and application of the product in the market.

[0003] 2. To achieve low standby power consumption, existing technologies often rely on MCUs or other control methods to cut off the power supply to the front-end AC-DC main circuit or the rear-end DC-CC dimming power supply circuit. However, this process requires the use of high-power switching components, such as the high-voltage, high-current MOSFETs used in some solutions. These components are inherently expensive, and additional drive and protection circuits are needed to ensure reliable switching during control, further increasing costs. Furthermore, high-power switching components may generate electromagnetic interference during switching, affecting circuit stability.

[0004] Secondly, Chinese Patent Publication No. CN208285597U discloses a thyristor-controlled dimming constant current power supply and LED system, including a separate AC controller with a 485 communication interface and at least one thyristor power supply. The AC controller performs MOS chopping on the mains power, changing the output power by adjusting the chopping conduction angle, thereby adjusting the brightness, color temperature, and color of the LED. The thyristor power supply includes a fuse resistor, a varistor, a rectifier bridge, a driver chip, and a transformer, supporting one controller to control multiple power supplies and one power supply to control multiple LED lamps, solving the problem of traditional LEDs' difficulty in flexible dimming. However, this prior art still has limitations. The system includes multiple components such as a thyristor power supply, fuse resistor, varistor, rectifier bridge, driver chip, and transformer, making the overall circuit structure not simple. There is still room for improvement in the accuracy of dimming and color adjustment, as well as energy consumption control. When implementing complex dimming and color adjustment functions, due to the inherent characteristics of its circuit design, it may not be able to adjust the current of LEDs with different color temperatures with extreme precision, resulting in a deviation between the mixing effect and the expected result, affecting the lighting quality. Furthermore, in standby mode, some components in the circuit may still be powered on or operating at low power consumption, resulting in unnecessary energy loss.

[0005] Furthermore, some traditional isolated driver circuits require converting input electrical energy into high-frequency AC and then isolating and stepping it down via a transformer. This process results in significant energy loss, reducing the overall energy efficiency of the LED lighting system and increasing the size and weight of the equipment, thus limiting design flexibility. Simultaneously, some dimming technologies, such as those using PWM modulation, may exhibit linear distortion due to transformer leakage inductance and parasitic oscillations, affecting dimming performance. Additionally, some driver circuits show significant losses in the transformer, switching transistors, and the chip's own circuitry under light load or standby conditions. Moreover, methods used to reduce startup resistor power consumption and address standby power consumption issues, such as adding secondary transformer coupling voltage feedback to power the chip, actually increase circuit complexity and introduce new electromagnetic compatibility problems.

[0006] In summary, existing isolated LED dimming and color-tuning driver devices have shortcomings in terms of circuit structure, standby power consumption, and dimming and color-tuning performance. A new design solution is urgently needed to overcome these defects in order to meet the market demand for efficient, low-cost, and high-performance lighting driver devices. Utility Model Content

[0007] This invention overcomes the shortcomings of the aforementioned technologies and provides an isolated dimming and color-tuning LED driver circuit. Through ingenious circuit design, apart from the intelligent module control circuit, the entire driver circuit uses only two integrated circuit chips, IC1 and IC2. The rest are built using low-cost discrete electronic components. This achieves dimming and color-tuning driving and control of LED lighting with extremely low-cost circuit components, while also achieving ultra-low standby power consumption and short-circuit protection for the output, giving the circuit extremely high cost-effectiveness and product competitiveness. To achieve the above objectives, this invention adopts the following technical solution: An isolated dimming and color-tuning LED driver circuit 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 and for controlling the color temperature of the LED light source, and an optocoupler A8 for achieving signal isolation transmission between the front-end circuit and the back-end circuit. The front-end circuit includes: an EMI and rectification filter circuit A1, a DC power supply circuit A2, a primary-side chip on / off control circuit A3, an intelligent control module circuit A5, a primary-side constant current dimming chip circuit A6, and the primary winding of a transformer A7 connected to the primary-side constant current dimming chip circuit A6; the EMI and rectification filter circuit A1 is connected to an external AC power source to provide rectified and filtered DC input to the front-end circuit; the DC power supply circuit A2 is connected to the output of the EMI and rectification filter circuit A1 and supplies power to the intelligent control module circuit A5; the primary-side chip on / off control circuit A3 is connected to the EMI and rectification filter circuit... The output terminal of A1 is connected to the input terminal of the primary-side constant current dimming chip circuit A6, which 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 optocoupler A8, respectively. It is used to generate a dimming control signal and send it to the primary-side constant current dimming chip circuit A6, and to generate a color temperature control signal and send it to the optocoupler A8, and to 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 subsequent circuit includes: The secondary winding of transformer A7; The secondary rectifier and filter circuit A9 is connected to the secondary winding of transformer A7; The dual-color temperature control and driving circuit A10, composed of discrete components, is connected to the optocoupler A8 and the secondary-side rectification and filtering circuit A9, respectively. It receives the isolated color temperature control signal and adjusts the current ratio of the external cool color temperature LED and warm color temperature LED. The primary-side chip on / off control circuit A3 ensures that the standby power consumption of the front-end circuit is below a preset threshold in standby mode.

[0008] Preferably, the EMI and rectifier filter circuit A1 includes: 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 filter circuit A111. The varistor VR1 and the first capacitor CX1 are connected in parallel between the two output terminals of the AC input interface COM1. The neutral output terminal of the AC input interface COM1 is connected to the fourth pin of the common-mode inductor LF1, and the live output terminal is connected to the second pin of the common-mode inductor LF1 through the fuse F1. 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 serves as the initial DC voltage output terminal connected to the pre-stage filter circuit A111. The output terminal of the pre-stage filter circuit A111 serves as the filtered DC voltage output terminal to output a smooth and stable DC, which is used to provide the rectified and filtered DC input to the pre-stage circuit.

[0009] Preferably, the DC 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 polarized capacitor C1, a second polarized 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 terminal of the DC power supply circuit A2, connected to the initial DC voltage output terminal of the EMI and rectifier filter circuit A1, and the cathode is connected to the first pin of the first chip IC1; the first polarized capacitor C1 is connected in parallel between the cathode of the first diode D1 and ground to filter out the voltage ripple input to the first chip IC1; the second diode D2 is forward connected to ground and the first... Between the output terminals of chip IC1, the third pin of the first chip IC1 is connected to the positive terminal of the second polarized 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 these three is connected to the intelligent control module circuit A5 as the power supply output terminal; the negative terminal of the second polarized 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 forward-biased between the positive terminal of the second polarized capacitor C6 and the second pin of the first chip IC1; specifically, the anode of the third diode D3 is connected to the positive terminal of the second polarized capacitor C6, and the cathode is connected to the second pin of the first chip IC1, which is used to feed the output voltage back to the feedback adjustment terminal of IC1, so as to achieve precise voltage regulation of 3.3V output voltage with IC1.

[0010] Preferably, the primary-side 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 Zener diode D4; the first transistor Q2 is a PNP transistor, with its emitter connected to the positive output terminal of the EMI and rectifier filter circuit A1, and its collector connected to the power supply input terminal of the primary-side constant current dimming chip circuit A6; the second resistor R15 is connected between the collector and emitter of the first transistor Q2, used for the first... When transistor Q2 is off, it provides voltage isolation; when it is on, it provides a current 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 and connected to the drain of the first NMOS transistor Q3 through the fourth resistor R17. 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 Zener diode D4 is connected between one end of the fifth resistor R12 and ground.

[0011] Preferably, the front-end 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; the input terminal of the high-voltage on / off detection circuit A4 is connected to the positive output terminal of the EMI and rectifier filter circuit A1 as the high-voltage on / off signal input terminal, and the output terminal transmits the detection signal to the intelligent control module circuit A5; 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 transistor Q1, and a ninth resistor R9; one end of the sixth resistor R2 serves as the... The high-voltage on / off signal input terminal is connected to the positive output terminal of the EMI and rectifier filter circuit A1. 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 its collector is connected to the intelligent control module circuit A5 as the detection signal output terminal. 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 terminal.

[0012] Preferably, 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 side 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 driving circuit A10 through an optocoupler A8.

[0013] Preferably, the primary-side constant current dimming chip circuit A6 includes: a primary-side constant current dimming chip IC2 and its peripheral circuits; the primary-side constant current dimming chip IC2 is provided with a power supply input terminal T1 connected to the output terminal of the primary-side 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 consists of two primary coils, wherein: one end of the first primary coil is connected to the positive output terminal of the EMI and rectifier filter circuit A1, and the other end is connected to the first power output terminal T4 of the primary-side constant current dimming chip IC2; one end of the second primary coil is connected to the second power output terminal T5 of the primary-side 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 terminals of the subsequent circuits.

[0014] Preferably, 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 terminal of the fourth diode D7 and one end of the tenth resistor R23 serves as the input terminal and is connected to one end of the secondary coil of the secondary winding; the negative terminal of the fourth diode D7 is connected to the positive terminal of the third polarity capacitor C14; the negative terminal of the third polarity capacitor C14 is connected to the other end of the secondary coil of the secondary winding and is connected to digital ground; the other end of the tenth resistor R23 is connected to the positive terminal of the third polarity capacitor C14 through the fifth capacitor C15, and the connection point serves as the output terminal and is connected to the dual color temperature control and driving circuit A10.

[0015] Preferably, 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 Zener diode DZ1, a second 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 terminal of the secondary-side rectifier and filter circuit A9, and the other end is connected to the gate of the second NMOS transistor Q5; one end of the twelfth resistor R27 serves as the positive terminal of the LED light source and is connected to the third terminal of the output interface COM2 for external LED light source positive terminal connection; the other end of the twelfth resistor R27 is connected back to the third terminal of the output interface COM2 in sequence through the forward-connected fifth diode D10 and ninth diode D11; the drain of the second NMOS transistor Q5 serves as the negative terminal of the warm color temperature LED and is connected to the second terminal of the output interface COM2 for external warm color temperature LED string negative terminal connection; the source of the second NMOS transistor Q5 is connected to digital ground; a forward-biased first Zener diode DZ1 and a thirteenth resistor R24 ​​are connected in parallel between the emitter and collector terminals of the transistor in the optocoupler A8; the collector of the transistor in the optocoupler A8 is connected to the gate of the second NMOS transistor Q5, and the emitter of the transistor is connected to digital ground; The gate of the third NMOS transistor Q6 is 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 Zener diode DZ2. The other end of the fourteenth resistor R26, the anode of the second Zener diode DZ2, and the source of the third NMOS transistor Q6 are all connected to digital ground. The drain of the second NMOS transistor Q5 is connected to the digital ground via the sixth capacitor C17, and the drain of the third NMOS transistor Q6 is connected to the digital ground via the seventh capacitor C18. The drain of the third NMOS transistor Q6 serves as the negative terminal for cool color temperature LEDs and is connected to the first terminal of the output interface COM2 for connection to the negative terminal of an external cool color temperature LED string. A forward-biased sixth diode D8 is connected between the collector of the transistor in the optocoupler A8 and the cathode of the seventh diode D9.

[0016] Preferably, the subsequent circuit further includes: an output short-circuit protection control circuit A11, connected to the dual-color temperature control and drive circuit A10, used to control the dual-color temperature control and drive circuit A10 to shut down when the output terminal is short-circuited to achieve protection; the output short-circuit protection control circuit A11 includes: a fifteenth resistor R28, a sixteenth resistor R29, a tenth diode D13, an eleventh diode D14, a third Zener diode DZ3, a fourth Zener diode DZ4, an eighth capacitor C16, and a fourth NMOS transistor Q4; the positive terminal of the tenth diode D13 is connected to the second terminal of the output interface COM2 as the warm color temperature LED voltage detection input terminal, and the positive terminal of the eleventh diode D14 is connected to the cold color temperature LED voltage detection input terminal. The color temperature LED voltage detection input terminal is connected to the first terminal of the output interface COM2; the connection point between the negative terminals of the tenth diode D13 and the eleventh diode D14 is connected to the negative terminal of the fourth Zener diode DZ4; the positive terminal of the fourth Zener diode DZ4 is connected to the positive terminal of the third Zener diode DZ3 and the other end of the sixteenth resistor R29; one end of the sixteenth resistor R29 is 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 digital ground; the drain of the fourth NMOS transistor Q4 is connected to the negative terminal of the seventh diode D9.

[0017] Compared with the prior art, the beneficial effects of this utility model are: 1. This design employs an architecture of pre-stage brightness control, post-stage color temperature control, and optocoupler signal isolation. This achieves electrical isolation between the pre-stage and post-stage, meeting safety regulations while separating brightness and color temperature control into independent circuits, simplifying the control logic and avoiding the cross-interference issues found in traditional two-stage control systems (pre-stage AC-DC + post-stage DC-CC). The pre-stage directly achieves constant current and brightness control through a primary-side constant current dimming chip circuit, eliminating the need for an additional DC-CC module. The post-stage uses discrete components to build a dual-color temperature drive circuit, eliminating the need for a dedicated control chip. Compared to existing technologies, this reduces the number of core components, lowering circuit complexity and cost. The primary-side chip on / off control circuit can cut off the power supply to the primary-side chip during standby, avoiding the need for a high-power switch to cut off the main circuit in traditional solutions, significantly reducing standby power consumption and minimizing electromagnetic interference risks.

[0018] 2. In this case, the primary-side chip on / off control circuit A3 uses a low-power PNP transistor Q2 and an NMOS transistor Q3 working together to cut off the VCC power supply of A6 with only microampere-level control current. During standby, A6 is completely de-energized, with no no-load loss, reducing standby power consumption from hundreds of milliwatts in traditional solutions to below tens of milliwatts. Furthermore, it eliminates the need for high-power switching components and additional drive circuits, reducing costs, avoiding electromagnetic interference from high-power component switching, improving circuit stability, meeting ultra-low standby power consumption energy efficiency standards, and solving the problems of high cost and high standby power consumption of high-power switching components.

[0019] 3. The output short-circuit protection control circuit A11 in this case is built using discrete components: diodes D13 / D14, NMOS transistor Q4, and Zener diodes DZ3 / DZ4. It directly detects the voltage status of WLED- and CLED-. In the event of a short circuit, an abnormal voltage can trigger protection in microseconds. By pulling down the potential of the critical node A10 through Q4, Q5 and Q6 are quickly turned off to prevent the MOS transistors from burning out due to overcurrent. Compared with the comparator and dedicated chip solution, this not only reduces costs but also avoids untimely protection caused by chip delay. At the same time, DZ3 / DZ4 clamps the voltage, and C16 filters to prevent false triggering due to voltage fluctuations, balancing protection speed and reliability, and solving the defects of traditional protection circuits such as complexity, slow response, and susceptibility to false triggering. Attached Figure Description

[0020] Figure 1 This is a circuit structure block diagram of Embodiment 1 of this case.

[0021] Figure 2 This is the circuit schematic diagram of Embodiment 2 in this case. Detailed Implementation

[0022] The following examples provide a more detailed description of the features and other related characteristics of this utility model, to facilitate understanding by those skilled in the art: like Figure 1 and Figure 2 As shown, an isolated dimming and color-tuning LED driver circuit has the following main structure: a front-end circuit for controlling the brightness of the LED light source, a back-end circuit that is electrically isolated from the front-end circuit and is responsible 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 preamplifier circuit includes: The EMI and rectification filter sub-circuit A1 serves as the input preprocessing module for the front-end circuit. It is used to suppress electromagnetic interference (EMI) from the external AC input, rectify the AC to DC, and filter to reduce voltage fluctuations. This provides a clean and stable DC input for all subsequent front-end modules, preventing power grid interference from affecting circuit performance.

[0023] The DC power supply circuit A2 adopts a high-efficiency, low-power BuckDC-DC 3.3V circuit to provide an independent and stable low-voltage power supply for the front-end core control module, namely the LED intelligent control module circuit A5 in this case. It reduces the input voltage to 3.3V to ensure the low-power operation of the intelligent control module circuit, while avoiding power supply interference from other modules to the control circuit.

[0024] The primary-side chip on / off control circuit A3 is used to cut off the power supply to the VCC pin of the primary-side constant current dimming chip A6 when the LED light source is turned off and in standby mode. It achieves ultra-low standby power consumption by controlling the on / off state with only a small current, without the need for high-power components, thus reducing costs.

[0025] The high-voltage on / off detection circuit A4 is used to detect the on / off status of the high-voltage input in real time and transmit the detection signal to the intelligent control module circuit A5. This provides the intelligent control module circuit A5 with a basis for judging the input power supply status and action execution of the circuit in advance (for example, when the 220V input is de-energized, the A5 circuit needs to immediately save the current brightness and color temperature parameters so that it can restore the working state before the power failure when the power is restored).

[0026] The intelligent control module circuit A5, as the control center of the front-end circuit, executes two core commands after receiving wireless or wired lighting control command signals: First, it sends a dimming control signal to the primary-side constant current dimming chip A6 to adjust the brightness, and controls the power supply of the primary-side constant current dimming chip A6 through the primary-side chip on / off control circuit A3 to manage the standby state based on whether the brightness value is 0; Second, it sends a color temperature control signal to the subsequent stage after isolation through optocoupler A8. The primary constant current dimming chip circuit A6 is the core of the front-end brightness control. It receives the dimming control signal sent by the intelligent control module circuit A5 and directly controls the brightness of the LED light source by adjusting the constant value of the output current, ensuring accurate and stable brightness adjustment.

[0027] Transformer A7 transfers energy from the front-end circuit (primary side, mainly the primary-side constant current dimming chip circuit A6) to the subsequent circuit via electromagnetic induction coupling. This provides the necessary power for the subsequent circuitry, including modules such as A9 and A10, ensuring that the subsequent dual-color temperature control and drive circuit A10 can properly drive both cool color temperature LEDs (CLED) and warm color temperature LEDs (WLED), achieving dimming and color adjustment functions. In this way, the transformer effectively isolates the front-end high-voltage circuit from the subsequent low-voltage circuit, preventing direct connection between the subsequent circuit and the front-end high-voltage section, reducing the risk of electric shock to users. It also prevents electrical interference from the front-end circuit from affecting the subsequent circuit, ensuring stable and accurate operation of the subsequent circuit, such as making the color temperature control of the subsequent circuit more stable and accurate.

[0028] The primary winding of transformer A7, as the energy input and control terminal, is directly connected to the primary constant current dimming chip circuit A6 of the front-end circuit, and achieves energy transfer with its own secondary winding through electromagnetic induction, while ensuring electrical isolation between the front-end circuit and the back-end circuit. Optocoupler A8: As a signal isolation bridge between the front-end circuit and the back-end circuit, it transmits the color temperature control signal generated by the intelligent control module circuit A5 to the dual color temperature control and drive circuit A10 after electrical isolation, avoiding signal interference between the front-end high-voltage circuit and the back-end low-voltage circuit, while ensuring circuit safety.

[0029] The subsequent circuitry, primarily used for color temperature adjustment and short-circuit protection in this case, specifically includes: The secondary winding of transformer A7, serving as the energy output and isolation terminal, is connected to the subsequent secondary rectifier and filter circuit A9, forming the low-voltage core of the isolation architecture in this case. The secondary rectifier and filter circuit A9 is connected to the secondary winding of transformer A7 and is used to rectify and filter the AC power output from the secondary winding of the transformer into DC power to power the dual-color temperature control and drive circuit A10. The dual-color temperature control and drive circuit A10, as the core execution module of the subsequent circuit, receives the color temperature PWM signal isolated by optocoupler A8. By controlling the on / off time of the two internal MOSFETs (corresponding to the cool color temperature LED (CLED) and the warm color temperature LED (WLED) respectively), it adjusts the current ratio of the cool and warm LEDs, and finally achieves precise color temperature switching (such as the transition from cool white light to warm yellow light). At the same time, it needs to respond to the protection signal of the output short-circuit protection control circuit A11 and turn off the MOSFETs when a short circuit occurs.

[0030] The output short-circuit protection control circuit A11, which serves as a safety protection module for the subsequent circuit, is composed of discrete components. It determines whether a short circuit is occurring by real-time monitoring of the voltage values ​​of WLED- (the negative terminal of the warm color temperature LED) or CLED- (the negative terminal of the cool color temperature LED). When a short circuit occurs at the output terminal, the voltage of WLED- or CLED- will instantly rise. At this time, the output short-circuit protection control circuit A11 immediately sends a control signal to the dual color temperature control and drive circuit A10 to turn off its two internal MOSFETs, preventing the MOSFETs from burning out due to overcurrent and overheating, thus protecting the subsequent circuit and the LED light source.

[0031] As described above, the isolated dimming and color-tuning LED driver circuit in this case, through an electrical isolation architecture between the front-end brightness control and the back-end color temperature control, combined with optocoupler A8 to achieve safe transmission of color temperature control signals and the design of the primary-side chip on / off control circuit A3, significantly reduces circuit cost and standby power consumption. In the front-end circuit, the EMI and rectification filter circuit A1 and the DC power supply circuit A2 work together to provide a stable and independent power supply for the intelligent control module A5. At the same time, the primary-side chip on / off control circuit A3, through a low-current on / off design, cuts off the VCC power supply of the primary-side constant current dimming chip A6 in standby mode, achieving ultra-low standby power consumption without the use of high-power components. The intelligent control module A5 coordinates wired or wireless lighting control commands and high-voltage on / off detection signals to generate PWM signal outputs for brightness and color temperature control, as well as standby state control signals. Among them, the PWM signal for color temperature control is precisely controlled by the back-end circuit after being isolated by optocoupler A8. The subsequent circuit uses discrete components to construct the dual-color temperature control and drive circuit A10. It achieves smooth color temperature switching by adjusting the current ratio of the cool / warm color temperature LEDs, eliminating the need for a dedicated control chip and significantly reducing hardware costs. The secondary-side rectification and filtering circuit A9 converts the secondary AC power of the transformer into DC power, providing a stable power supply for the subsequent stages. Furthermore, the output short-circuit protection control circuit A11 monitors the LED negative electrode voltage in real time and quickly shuts off the MOSFET in the dual-color temperature drive circuit during a short circuit, preventing overheating and burnout, and improving system reliability. The overall circuit, through modular design and multiple protection mechanisms, balances low cost, high performance, and high security, making it particularly suitable for scenarios requiring frequent dimming and color adjustment, such as smart homes.

[0032] like Figure 2 As shown, in one specific implementation, the EMI and rectifier filter circuit A1 includes: 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 filter circuit A111 composed of an inductor L1, a resistor R1, and capacitors C2 and C4; the varistor VR1 and the first capacitor CX1 are connected in parallel between the two output terminals of the AC input interface COM1; the neutral output terminal of the AC input interface COM1 is connected to the fourth pin of the common-mode inductor LF1, and the live output terminal is connected to the second pin of the common-mode inductor LF1 through the fuse F1; 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 serves as the initial DC voltage output terminal connected to the pre-stage filter circuit A111; the output terminal of the pre-stage filter circuit A111 serves as the filtered DC voltage output terminal. Specifically, the 220V voltage is first rectified into unidirectional pulsating DC and output at the initial DC voltage output terminal. Then, it passes through the pre-stage filter circuit A111 to output a smooth and stable DC at the filtered DC voltage output terminal.

[0033] As described above, the common-mode inductor L2 in the EMI and rectifier filter circuit A1 of this case is used to suppress common-mode electromagnetic interference from the mains input, preventing interference signals from affecting subsequent circuits and solving the problems of dimming flicker and color temperature drift caused by insufficient EMI suppression in traditional circuits. The varistor VR1 is used to break down and conduct when the mains voltage is too high, protecting subsequent circuits from overvoltage damage; the fuse F1 is used to blow and cut off the power supply circuit when an overcurrent fault occurs in the circuit; the fuse F1 and the varistor VR1 constitute overcurrent and overvoltage protection, preventing mains fluctuations such as lightning strikes and voltage surges from damaging the circuit and improving equipment reliability. The rectifier bridge DB1 is used to rectify the mains AC power into unidirectional pulsating DC power; in the pre-stage filter circuit, the inductor and capacitor form an LC filter network, which, together with the resistor, consumes high-frequency ripple energy, filters the rectified pulsating DC power, and outputs a stable DC voltage to power the subsequent circuits.

[0034] like Figure 2 As shown, in one specific implementation, the DC 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 polarized capacitor C1, a second polarized 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 terminal of the DC power supply circuit A2, connected to the initial DC voltage output terminal of the EMI and rectifier filter circuit A1, and the cathode is connected to... The first pin of the first chip IC1 is connected; the first polarized capacitor C1 is connected in parallel between the cathode of diode D1 and ground to filter out the voltage ripple input to the first chip IC1; the second diode D2 is forward-biased and connected between ground and the output terminal of the first chip IC1; the third pin of the first chip IC1 is connected through the first inductor L2 to the positive terminal of the second polarized capacitor C6, one end of the first resistor R7, and one end of the third capacitor C8, and the common connection point of these three is connected as the power supply output terminal to the intelligent control module circuit A5 to provide a stable 3.3V power supply to the intelligent control module circuit A5. The negative terminal of the second polarized 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 forward-biased and connected between the positive terminal of the second polarized capacitor C6 and the second pin of the first chip IC1. The first chip IC1 can be a synchronous buck DC-DC converter chip of model H4020, which is designed for applications requiring high efficiency, low power consumption, and precise voltage / current control. It integrates a high-voltage MOSFET, supports a wide input voltage range of 5V-36V, and can provide a continuous output current of up to 1A. By adjusting the voltage divider resistor at the FB feedback port, users can easily set the output voltage between 2.5V and 24V. The pin definitions of the first chip IC1 are as follows: The first pin is the voltage input VIN pin; the second pin is the feedback adjustment pin FB pin; the third pin is the switch output pin SW pin, which connects to the drain or source of the internal switching transistor. Through the periodic switching of the transistor, it controls the transfer and release of energy to inductor L2, serving as the power conversion node of the Buck circuit. The positive terminal of the second polarity capacitor C6 serves as the output terminal of the DC power supply circuit A2.

[0035] As described above, the DC power supply circuit A2 in this case uses a low-power Buck-type DC-DC chip IC1, which significantly improves conversion efficiency. Compared with traditional linear voltage regulator circuits, it greatly reduces the power consumption of the power supply circuit, especially in standby mode, where it only needs to provide microamp-level current to the intelligent control module, further reducing overall standby power consumption. The independent power supply design ensures that the intelligent control module A5 is not affected by fluctuations in the preceding high-voltage circuit, solving the problem of control signal interference and improving the stability and accuracy of dimming and color temperature control.

[0036] like Figure 2 As shown, in a preferred embodiment, the primary-side 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 Zener diode D4; the first transistor Q2 is a PNP transistor, its emitter is connected to the filtered DC voltage output terminal of the EMI and rectifier filter circuit A1, and its collector is connected to the power supply input terminal of the primary-side constant current dimming chip circuit A6; the second resistor R15 is connected between the collector and emitter of the first transistor Q2, used to achieve voltage isolation when the first transistor Q2 is off, and to provide power when it is on. The circuit consists of a current 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 point 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 as a control signal input terminal to the control signal output terminal of the intelligent control module circuit A5, and the other end is connected to the gate of the first NMOS transistor Q3; the bidirectional Zener diode D4 is connected between one end of the fifth resistor R12 and ground 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 low-current on / off control circuit, this project successfully achieved precise control of the power supply to the A6VCC pin of the primary-side constant current dimming chip circuit. This circuit utilizes the synergistic effect of the low-power PNP transistor Q2 and the NMOS transistor Q3, avoiding the use of high-power components, significantly reducing cost and circuit size, and improving the overall integration of the design. When the LED light source enters the off standby state, the intelligent control module circuit A5 outputs a control signal, causing the NMOS transistor Q3 to turn off, thereby pulling down the base potential of the first transistor Q2 and causing it to quickly turn off, thus cutting off the VCC power supply to the primary-side constant current dimming chip A6, effectively reducing standby power consumption. Conversely, when power needs to be restored, the control module outputs a high-level signal, turning on the transistor and NMOS transistor, restoring the VCC power supply. This process requires only a very small control current, greatly improving energy utilization efficiency and further optimizing the low-power performance of the circuit. Meanwhile, the second resistor R15 provides voltage isolation when the transistor is off, ensuring circuit safety; and provides a stable current path when it is on, ensuring normal chip operation. The introduction of the bidirectional Zener diode D4 effectively clamps the gate voltage of the NMOS transistor Q3, preventing overvoltage damage and improving the reliability and stability of the circuit. Thus, the overall circuit design is economical and efficient, meeting energy-saving requirements while ensuring the stability and safety of the circuit under various operating conditions.

[0038] like Figure 2 As shown, in a preferred embodiment, the front-end 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; the input terminal of the high-voltage on / off detection circuit A4 is connected to the positive output terminal of the EMI and rectifier filter circuit A1 as the high-voltage on / off signal input terminal, and the output terminal transmits the detection signal to the intelligent control module circuit A5, providing a basis for the intelligent control module circuit A5 to determine the circuit operating state (such as whether to start standby mode or whether to perform 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 transistor Q1, and a ninth resistor R9. One end of the sixth resistor R2 serves as the high-voltage on / off signal input terminal and is connected to the positive output terminal / filtered DC voltage output terminal of the EMI and rectifier filter circuit A1. 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 its collector serves as the detection signal output terminal connected to the intelligent control module circuit A5. One end of the ninth resistor R9 is connected to the collector of the second transistor Q1, and the other end serves as the power supply input terminal connected to the power supply output terminal of the DC power supply circuit A2.

[0039] As described above, the high-voltage on / off detection circuit A4 in this case uses a precise resistor-capacitor-transistor voltage divider network to achieve real-time monitoring of the high-voltage status at the output of the EMI and rectifier filter circuit A1. 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 the range that the base of the second transistor Q1 can withstand, triggering the second transistor Q1 to conduct. The low-level signal output from its 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 transistor Q1 remains in the off state, outputting a high-level signal. This design, through the filtering effect of the fourth capacitor C7, effectively suppresses false triggering caused by voltage fluctuations, ensuring the stability of the detection signal. At the same time, the ninth resistor R9 provides a stable bias current for the second transistor Q1, ensuring reliable operation of the circuit under low voltage drop conditions. This circuit not only provides the intelligent control module with accurate high-voltage on / off status information, supporting its 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 circuit's anti-interference capability.

[0040] In one specific implementation, the intelligent control module circuit A5 includes 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 MS connected to the output terminal of the high-voltage on / off detection circuit A4, a dimming control signal output terminal (CW / TX) connected to the input terminal of the primary-side constant current dimming chip circuit A6, and a color temperature control signal output terminal (WW / RX) connected to the input terminal of the dual color temperature control and drive circuit A10 via an optocoupler A8. The intelligent control module circuit A5 can be a microcontroller module with wireless communication capabilities, such as an STM32 series chip. The intelligent control module circuit A5 integrates an MCU core module, a PWM signal generation module, and a signal detection module. The MCU core module receives the detection signal from the high-voltage on / off detection circuit A4, determines the circuit's operating status, and issues corresponding control commands. The PWM signal generation module generates dimming PWM control signals / dimming control signals and color temperature PWM control / color temperature control signals according to the commands from the MCU core module. The signal detection module filters and levels the input high-voltage on / off detection signal to ensure accurate recognition by the MCU core module. Thus, by further clarifying the pin functions and connections of the intelligent control module A5, this design makes the module a unified control core, avoiding the logical confusion caused by dimming, color temperature, and standby control being scattered across different chips in traditional circuits, and simplifying system integration. The independent power input, signal detection, and control output terminals achieve separation of power supply, detection, and control, improving anti-interference capabilities. The color temperature control signal is isolated and output via optocoupler A8, meeting the electrical isolation requirements between the front and rear stages and complying with safety standards. In practical implementation, the intelligent control module circuit A5 can use an STM32F030C8T6 microcontroller. Its VCC pin (3.3V) serves as the power supply input, connected to the output of the DC power supply circuit A2, while its GND pin is grounded. The high-voltage on / off signal detection input MS is connected to the collector of Q1 in the high-voltage on / off detection circuit A4, receiving the mains power on / off signal. The dimming control signal output CW / TX is connected to the DIM pin of the primary-side constant current dimming chip circuit A6, outputting a PWM signal with a 0-100% duty cycle to adjust the LED brightness. The color temperature control signal output WW / RX is connected to the primary-side anode of the optocoupler A8, controlling the dual color temperature ratio of the subsequent stage through changes in the PWM signal duty cycle (e.g., 0% corresponds to a cool color, 100% to a warm color). The other IO pin OFF of the module is connected to the gate of Q3 in the primary-side chip on / off control circuit A3, outputting high and low levels to control the on / off state of Q3, thereby cutting off / restoring the power supply to the primary-side chip.

[0041] like Figure 2As shown, in one specific implementation, the primary-side constant current dimming chip circuit A6 includes: a primary-side constant current dimming chip IC2 and its peripheral circuits; the primary-side constant current dimming chip IC2 is provided with a power supply input terminal T1 connected to the output terminal of the primary-side 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 consists of two primary coils, one at a time. 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 two primary coils are connected in series to form a complete primary winding, forming the main circuit for energy conversion. The secondary winding of transformer A7 is a coil, with its two ends connected to the input terminals of the subsequent circuit. Energy transfer from the primary to the secondary side is achieved through electromagnetic induction. In conjunction with the primary side constant current dimming chip IC2, constant current drive is achieved for the LED load.

[0042] Specifically, the primary-side constant current dimming chip IC2 can also be called a primary-side feedback chip or a primary-side feedback power supply chip, such as the GP8891CS primary-side feedback power supply chip. After receiving the dimming control signal, the primary-side constant current dimming chip IC2 adjusts the current of the primary winding of the transformer through the first power output terminal T4 and the second power output terminal T5, thereby controlling the secondary output current and ultimately realizing the brightness adjustment of the LED light source.

[0043] As described above, the primary-side constant current dimming chip circuit A6, with the primary-side constant current dimming chip IC2 as 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. The transformer A7's primary winding employs a two-primary-coil design, reducing voltage stress on individual coils and minimizing 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, solving the problems of high energy conversion losses and low efficiency in traditional isolated drive circuits. Simultaneously, the primary-side constant current dimming chip IC2 directly controls the transformer's primary current, eliminating the need for feedback from the subsequent sampling resistor, avoiding feedback delay, accelerating brightness adjustment response speed, and improving the brightness jumps and linear distortion problems caused by delays in traditional dimming, ensuring stable lighting quality. Furthermore, the primary-side dual-coil series structure of the transformer can adapt to different input voltage ranges, improving product market adaptability. The power supply terminal of the primary-side constant current dimming chip IC2 is directly connected to the primary-side chip on / off control circuit A3, which can quickly cut off the power supply in standby mode to avoid no-load losses. The secondary-side single-coil design simplifies the wiring logic of the secondary-side rectifier and filter circuit A9, reduces subsequent drive failures, and improves circuit reliability. Compared with the traditional secondary-side constant current drive scheme, the primary-side constant current design eliminates many components, reducing costs. Moreover, the high integration of the primary-side constant current dimming chip reduces the size of the front-end circuit, adapting to the installation requirements of miniaturized LED lighting products and improving design flexibility.

[0044] like Figure 2As shown, in one specific implementation, 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 terminal of the fourth diode D7 and one end of the tenth resistor R23 serves as the input terminal and is connected to one end of the secondary coil of the secondary winding; the negative terminal of the fourth diode D7 is connected to the positive terminal of the third polarity capacitor C14; the negative terminal of the third polarity capacitor C14 is connected to the other end of the secondary coil of the secondary winding and is connected to digital ground; the other end of the tenth resistor R23 is connected to the positive terminal of the third polarity capacitor C14 through the fifth capacitor C15, and the connection point serves as the output terminal and is connected to the dual color temperature control and driving circuit A10. Thus, the secondary-side rectification and filtering circuit A9 achieves efficient rectification of the AC output from the transformer secondary winding through the fourth diode D7. Combined with the filtering effect of the third polarity capacitor C14, it converts the pulsating AC signal into a smooth and stable DC voltage, providing reliable power to the subsequent dual-color temperature control and drive circuit A10. This avoids problems such as brightness flickering and color temperature drift in the LED light source caused by voltage fluctuations, ensuring stable lighting effects. Simultaneously, the RC absorption circuit composed of the tenth resistor R23 and the fifth capacitor C15 effectively suppresses voltage spikes and high-frequency interference generated during rectification, preventing damage to subsequent components such as MOSFETs due to overvoltage and improving the overall reliability of the circuit. Furthermore, the entire circuit achieves rectification, filtering, and interference suppression functions through a simple combination of discrete components, eliminating the need for complex integrated chips. This simplifies the circuit structure, reduces costs, and facilitates later maintenance and troubleshooting, meeting the low-cost, high-stability design requirements of the drive circuit.

[0045] like Figure 2 As shown, in 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 Zener diode DZ1, a second 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 terminal of the secondary-side rectifier and filter circuit A9, and the other end is connected to the gate of the second NMOS transistor Q5; one end of the twelfth resistor R27 serves as the positive terminal of the LED light source and is connected to the third terminal of the output interface COM2 for external LED light source positive terminal connection; the other end of the twelfth resistor R27 is connected back to the third terminal of the output interface COM2 in sequence through the forward-connected fifth diode D10 and ninth diode D11; the drain of the second NMOS transistor Q5 serves as the negative terminal of the warm color temperature LED and is connected to the second terminal of the output interface COM2 for external warm color temperature LED string negative terminal connection; the source of the second NMOS transistor Q5 is connected to digital ground; a forward-biased first Zener diode DZ1 and a thirteenth resistor R24 ​​are connected in parallel between the emitter and collector terminals of the transistor in the optocoupler A8; the collector of the transistor in the optocoupler A8 is connected to the gate of the second NMOS transistor Q5, and the emitter of the transistor is connected to digital ground; The gate of the third NMOS transistor Q6 is connected to the fifth diode D10, the positive terminal of the seventh diode D9, one end of the fourteenth resistor R26, and the negative terminal of the second Zener diode DZ2. The other end of the fourteenth resistor R26, the positive terminal of the second Zener diode DZ2, and the source of the third NMOS transistor Q6 are all connected to digital ground. The drain of the second NMOS transistor Q5 is connected to the sixth capacitor C17, and the drain of the third NMOS transistor Q6 is connected to the seventh capacitor C18. The drain of the third NMOS transistor Q6 serves as the negative terminal for cool color temperature LEDs and is connected to the first terminal of the output interface COM2 for connection to the negative terminal of an external cool color temperature LED string. A forward-biased sixth diode D8 is connected between the collector terminal of the transistor in the optocoupler A8 and the negative terminal of the seventh diode D9.

[0046] As described above, the dual-color temperature control and driving circuit A10 is built using discrete components, eliminating the need for a dedicated control chip. The second NMOS transistor Q5 and the third NMOS transistor Q6 control the current paths of the warm and cool color temperature LED strings respectively. Combined with the isolated color temperature control signal transmitted by optocoupler A8, the current ratio of the two types of LED strings can be precisely adjusted, achieving stable color temperature switching and control to meet the lighting needs of different scenarios and avoiding the compatibility limitations caused by the fixed functions of dedicated chips. Simultaneously, the first Zener diode DZ1 and the second Zener diode DZ2 protect the gates of the MOS transistors from overvoltage damage, the sixth capacitor C17 and the seventh capacitor C18 suppress current fluctuations, and components such as the fifth diode D10 and the sixth diode D8 further optimize signal transmission and loop protection, ensuring reliable circuit operation. In addition, the use of discrete components not only significantly reduces circuit costs and avoids the extra expenses brought by dedicated chips, but also simplifies the circuit structure, makes it easier to flexibly adjust component parameters according to actual needs, improves circuit adaptability, and reduces the difficulty of later maintenance and troubleshooting, which is in line with the design goals of low cost, high reliability and flexible adaptability of drive circuits.

[0047] like Figure 2 As shown, the subsequent circuit also includes: The 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 terminal is short-circuited in order to achieve protection. The output short-circuit protection control circuit A11 includes: a fifteenth resistor R28, a sixteenth resistor R29, a tenth diode D13, an eleventh diode D14, a third Zener diode DZ3, a fourth Zener diode DZ4, an eighth capacitor C16, and a fourth NMOS transistor Q4; the positive terminal of the tenth diode D13 is connected to the second terminal of the output interface COM2 as the input terminal for the warm color temperature LED voltage detection, and the positive terminal of the eleventh diode D14 is connected to the first terminal of the output interface COM2 as the input terminal for the cool color temperature LED voltage detection; the negative terminal of the tenth diode D13... The connection point of the eleventh diode D14 to the negative terminal is connected to the negative terminal of the fourth Zener diode DZ4. The positive terminal of the fourth Zener diode DZ4 is connected to the positive terminal of the third Zener diode DZ3 and the other end of the sixteenth resistor R29. One end of the sixteenth resistor R29 is 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 digital ground. The drain of the fourth NMOS transistor Q4 is connected to the negative terminal of the seventh diode D9.

[0048] As mentioned above, the output short-circuit protection control circuit A11 in this case is also built with simple discrete components, without relying on complex protection chips. This significantly reduces circuit costs while simplifying the overall structure, facilitating later maintenance and troubleshooting. The circuit directly detects the voltage state of the negative terminals of the warm and cool color temperature LEDs through the tenth diode D13 and the eleventh diode D14, quickly capturing voltage anomalies during output short circuits. Compared to traditional indirect detection schemes, this provides a faster response and can trigger protection actions promptly. When a short circuit is detected, the circuit uses the fourth NMOS transistor Q4 to act on the critical control node of the dual-color temperature control and drive circuit A10, quickly turning off the MOS transistor responsible for driving the LEDs. This effectively prevents the MOS transistors from overheating and burning out due to excessive current generated by the short circuit, while simultaneously protecting the LED light source and subsequent circuitry from damage, significantly improving the overall circuit reliability and safety. Furthermore, the combination of the third Zener diode DZ3, the fourth Zener diode DZ4, and the eighth capacitor C16 suppresses voltage fluctuations and interference signals, preventing false triggering of protection actions and ensuring the stability of the circuit under normal operating conditions, meeting the design requirements of high cost-effectiveness and high reliability for the drive circuit.

[0049] The specific working principle of this case is as follows: 1. Brightness control: The LED intelligent control module circuit A5 executes brightness control instructions and sends a dimming PWM signal / dimming control signal to the primary constant current dimming chip circuit (A6) to realize 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 adjustment signal by executing the color temperature control command. After signal isolation by the optocoupler (A8), the signal is sent to the dual color temperature control and drive circuit (A10) for color temperature control.

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

[0052] 4. Short circuit protection: The output short circuit protection control circuit A11 detects the voltage value of WLED- or CLED-. When a short circuit occurs at the output terminal, it sends a control signal to the dual color temperature control and drive circuit (A10) to shut down its two NMOS transistors to prevent overheating and burnout.

[0053] Thus, through the circuit design in this case, a low-cost, high-performance LED intelligent dimming and color-tuning driver circuit was realized, while also possessing ultra-low standby power consumption and output short-circuit protection functions.

[0054] In summary, this utility model discloses an isolated dimming and color-tuning LED driver circuit, including a pre-stage circuit, a post-stage circuit, and an optocoupler A8. The pre-stage circuit includes an EMI and rectification filter circuit A1, a DC power supply circuit A2, a primary-side chip on / off control circuit A3, a high-voltage on / off detection circuit A4, an intelligent control module circuit A5, a primary-side constant current dimming chip circuit A6, and a transformer A7 primary winding. A1 processes the mains input, A2 supplies 3.3V to A5, A3 cuts off the power supply to A6 in standby mode to reduce power consumption, and A5 generates dimming / color temperature signals. The post-stage circuit includes an A7 secondary winding, a secondary-side rectification and filtering circuit A9, a dual color temperature control and driving circuit A10, and an output short-circuit protection control circuit A11. A9 provides rectification and filtering power supply, A10 uses discrete components to adjust the cold / warm LED current ratio, and A11 detects the LED negative voltage to achieve short-circuit protection. The A8 isolates the preamplifier and power amplifier signals, simplifying the overall architecture, reducing costs and power consumption, and is suitable for smart home lighting.

[0055] As stated above, this case protects an isolated dimming and color-tuning LED driver circuit, and all technical solutions that are the same as or similar to this case should be considered to fall within the protection scope of this case.

Claims

1. An isolated dimming and color-tuning LED driver circuit, characterized in that, include: A front-end circuit for controlling the brightness of the LED light source, a back-end circuit electrically isolated from the front-end circuit and for controlling the color temperature of the LED light source, and an optocoupler (A8) for achieving signal isolation transmission between the front-end circuit and the back-end circuit. The front-end circuit includes: an EMI and rectification filter circuit (A1), a DC power supply circuit (A2), a primary-side chip on / off control circuit (A3), an intelligent control module circuit (A5), a primary-side constant current dimming chip circuit (A6), and the primary winding of a transformer (A7) connected to the primary-side constant current dimming chip circuit (A6). The EMI and rectification filter circuit (A1) is connected to an external AC power source to provide rectified and filtered DC input to the front-end circuit. The DC power supply circuit (A2) supplies power to the intelligent control module circuit (A5). The primary-side chip on / off control circuit (A3) is connected to the output terminal of the EMI and rectification filter circuit (A1) and the primary winding of the transformer (A7). The circuit between the input terminals of the primary-side constant current dimming chip circuit (A6) 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 optocoupler (A8) respectively, and is used to generate a dimming control signal and send it to the primary-side constant current dimming chip circuit (A6), and generate a color temperature control signal and send it to the optocoupler (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 subsequent circuit includes: the secondary winding of a transformer (A7), a secondary rectifier and filter 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 rectifier and filter circuit (A9), and external cool color temperature LEDs and warm color temperature LEDs, respectively. The secondary rectifier and filter circuit (A9) is used to rectify and filter the AC power output from the secondary winding of the transformer into DC power to power the dual color temperature control and drive circuit (A10). The dual color temperature control and drive circuit (A10) is used to receive the isolated color temperature control signal and adjust the current ratio of the cool color temperature LED and the warm color temperature LED.

2. The LED driving circuit according to claim 1, characterized in that, The subsequent circuit also includes: The 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 terminal is short-circuited in order to achieve protection.

3. The LED driving circuit according to claim 1, characterized in that, The EMI and rectifier filter circuit (A1) includes: 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 filter circuit (A111). The varistor (VR1) and the first capacitor (CX1) are connected in parallel between the two output terminals of the AC input interface (COM1). The neutral output terminal of the AC input interface (COM1) is connected to the fourth pin of the common-mode inductor (LF1), and the live output terminal is connected to 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), 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 pre-stage filter circuit (A111) as the initial DC voltage output terminal. The output terminal of the pre-stage filter circuit (A111) is used as the filtered DC voltage output terminal to output a smooth and stable DC, which is used to provide the rectified and filtered DC input to the pre-stage circuit.

4. The LED driving circuit according to claim 1, characterized in that, The DC 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 polarized capacitor (C1), a second polarized 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 terminal of the DC power supply circuit (A2), connected to the output terminal of the EMI and rectifier filter circuit (A1), and the cathode is connected to the first pin of the first chip (IC1); the first polarized capacitor (C1) is connected in parallel to the cathode of the first diode (D1). Between the electrode and ground, it is used to filter out the voltage ripple input to the first chip (IC1); the second diode (D2) is forward connected between ground and the output terminal of the first chip (IC1); the third pin of the first chip (IC1) is connected to the positive terminal of the second polarized 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 these three is connected to the intelligent control module circuit (A5) as the power supply output terminal; the negative terminal of the second polarized 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 forward connected between the positive terminal of the second polarized capacitor (C6) and the second pin of the first chip (IC1).

5. The LED driving circuit according to claim 1, characterized in that, The primary-side 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 Zener diode (D4). The first transistor (Q2) is a PNP transistor, with its emitter connected to the positive output terminal of the EMI and rectifier filter circuit (A1) and its collector connected to the power supply input terminal of the primary-side constant current dimming chip circuit (A6). The second resistor (R15) is connected between the collector and emitter of the first transistor (Q2) to provide voltage isolation when the first transistor (Q2) is off and to provide a current path when it is 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). 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 Zener diode (D4) is connected between one end of the fifth resistor (R12) and ground.

6. The LED driving circuit according to claim 1 or 5, characterized in that, The front-end circuit also 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 status; the input terminal of the high-voltage on / off detection circuit (A4) is connected to the positive output terminal of the EMI and rectifier filter circuit (A1) as the high-voltage on / off signal input terminal, and the output terminal transmits the detection signal to the intelligent control module circuit (A5). 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 transistor (Q1), and a ninth resistor (R9). One end of the sixth resistor (R2) serves as the high-voltage on / off signal input terminal and is connected to the positive output terminal of the EMI and rectifier filter circuit (A1). 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 its collector serves as the detection signal output terminal connected to the intelligent control module circuit (A5). One end of the ninth resistor (R9) is connected to the collector of the second transistor (Q1), and the other end serves as the power supply input terminal connected to the DC power supply circuit (A2).

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 side 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) through an optocoupler (A8). The primary-side constant current dimming chip circuit (A6) includes: a primary-side constant current dimming chip (IC2) and its peripheral circuits; the primary-side constant current dimming chip (IC2) is provided with a power supply input terminal (T1) connected to the output terminal of the primary-side 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) consists of two primary coils, one at a time. 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-side constant current dimming chip (IC2); one end of the second primary coil is connected to the second power output terminal (T5) of the primary-side 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 connected to the input terminals of the subsequent circuit.

8. The LED driving circuit according to claim 7, characterized in that, 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 terminal of the fourth diode (D7) and one end of the tenth resistor (R23) serves as the input terminal and is connected to one end of the secondary coil of the secondary winding; the negative terminal of the fourth diode (D7) is connected to the positive terminal of the third polarity capacitor (C14), and the negative terminal of the third polarity capacitor (C14) is connected to the other end of the secondary coil of the secondary winding and connected to digital ground; the other end of the tenth resistor (R23) is connected to the positive terminal of the third polarity capacitor (C14) through the fifth capacitor (C15), and the connection point serves as the output terminal and is connected to the dual color temperature control and driving circuit (A10).

9. The LED driving circuit according to claim 2, characterized in that, 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 Zener diode (DZ1), a second 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 terminal of the secondary-side rectifier and filter circuit (A9), and the other end is connected to the gate of the second NMOS transistor (Q5); one end of the twelfth resistor (R27) serves as the positive terminal of the LED light source and is connected to the third terminal of the output interface (COM2) for external LED light source positive terminal connection; the other end of the twelfth resistor (R27) is connected back to the third terminal of the output interface (COM2) in sequence through the forward-connected fifth diode (D10) and ninth diode (D11); the second NMOS transistor... The drain of the S-tube (Q5) is connected to the second terminal of the output interface (COM2) as the negative terminal of the warm color temperature LED, so as to provide the negative terminal connection for the external warm color temperature LED string; the source of the second NMOS tube (Q5) is connected to digital ground; a forward-biased first Zener diode (DZ1) and a thirteenth resistor (R24) are connected in parallel between the emitter and collector terminals of the transistor in the optocoupler (A8); the collector of the transistor in the optocoupler (A8) is connected to the gate of the second NMOS tube (Q5), and the emitter of the transistor is connected to digital ground; The gate of the third NMOS transistor (Q6) is 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 Zener diode (DZ2). The other end of the fourteenth resistor (R26), the anode of the second Zener diode (DZ2), and the source of the third NMOS transistor (Q6) are all connected to digital ground. The drain of the second NMOS transistor (Q5) is connected to the sixth capacitor (C17), and the drain of the third NMOS transistor (Q6) is connected to the seventh capacitor (C18). The drain of the third NMOS transistor (Q6) is connected to the first terminal of the output interface (COM2) as the negative terminal of the cool color temperature LED, so as to provide the negative terminal connection for the external cool color temperature LED string. A forward-biased sixth diode (D8) is connected between the collector terminal of the transistor in the optocoupler (A8) and the negative terminal 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) includes: a fifteenth resistor (R28), a sixteenth resistor (R29), a tenth diode (D13), an eleventh diode (D14), a third Zener diode (DZ3), a fourth Zener diode (DZ4), an eighth capacitor (C16), and a fourth NMOS transistor (Q4). The anode of the tenth diode (D13) is connected to the second terminal of the output interface (COM2) as the input terminal for the warm color temperature LED voltage detection, and the anode of the eleventh diode (D14) is connected to the first terminal of the output interface (COM2) as the input terminal for the cool color temperature LED voltage detection; the cathode of the tenth diode (D13) is... The connection point of the eleventh diode (D14) to the negative terminal is connected to the negative terminal of the fourth Zener diode (DZ4). The positive terminal of the fourth Zener diode (DZ4) is connected to the positive terminal of the third Zener diode (DZ3) and the other end of the sixteenth resistor (R29). One end of the sixteenth resistor (R29) is 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 digital ground. The drain of the fourth NMOS transistor (Q4) is connected to the negative terminal of the seventh diode (D9).

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