Power-down holding circuit and LED drive circuit

Abstract

The invention provides a power-down holding circuit and an LED driving circuit, and the power-down holding circuit comprises a driving module which converts the voltage of an AC end; the input end of the step-down module is connected with the driving module, and the step-down module is configured to convert the voltage of the driving module; a communication module configured to communicate with the outside; the control module is connected with the driving module and is configured to control the operation of the driving module; the output end of the voltage reduction module is connected with the input end of the communication module and the input end of the control module, and the voltage reduction module is configured to provide voltage for the control module and the communication module; the step-down module comprises an MOS circuit, and the control module controls the step-down module to start / stop supplying power to the communication module by controlling the on / off of the MOS circuit. After the control module of the power failure holding circuit detects the power failure of the AC end, the voltage reduction module is controlled to stop supplying power to the communication module, the consumption of residual voltage in the driving module is reduced, and the working time of the control module after the power failure of the AC end is prolonged.

Description

Technical Field

[0001] The present invention relates to the field of lighting, and in particular to a power-off holding circuit and an LED driving circuit. Background Art

[0002] With the improvement of living standards, LED lighting is increasingly used in many scenarios, among which smart lighting is also increasingly widely used in people's real lives. People control LED lamps to meet more usage needs.

[0003] Smart lighting can easily adjust the color temperature and current of LED lamps through various control methods such as Bluetooth, WIFI, PLC, DALI, 0-10V, etc., to meet people's diverse usage scenarios and needs. In smart lighting, communication modules (Bluetooth, WIFI, PLC, DALI, 0-10V, etc.) are generally used to communicate with the outside, and the external control information is transmitted to the MCU. The MCU then converts the transmitted control information into a PWM signal to control the working state of the driver. The driver MCU needs to be able to work for a period of time (generally more than 3S) after the AC power is turned off to facilitate the processing of some information. The driver MCU and the control module are usually powered by an integrated power supply. The driver MCU consumes less power, and the control module consumes more power. After the AC power is turned off, the power consumption of the control module will affect the power supply of the MCU, resulting in insufficient power-off retention time (the power-off retention time is defined as the time the MCU continues to work after the AC power is turned off). The general practice is to increase the input and output capacitance of the power supply line to meet the power-off retention time, which will make the added capacitance larger, increasing the size and cost of the driver.

[0004] In view of this, it is indeed necessary to provide a power-off holding circuit and an LED driving circuit to solve the above problems. Summary of the invention

[0005] The object of the present invention is to provide a power-off holding circuit and an LED driving circuit.

[0006] To achieve the above object, the present invention provides a power-off holding circuit, comprising:

[0007] A driving module, connected to the AC terminal, converting the voltage of the AC terminal;

[0008] A step-down module, the input end of which is connected to the driving module and configured to convert the voltage of the driving module;

[0009] A communication module configured to communicate with the outside;

[0010] A control module, connected to the driving module and configured to control the operation of the driving module;

[0011] The output end of the step-down module is respectively connected to the input end of the communication module and the input end of the control module, and the step-down module is configured to provide voltage to the control module and the communication module; the output end of the control module is connected to the step-down module, and the step-down module includes a MOS circuit. The control module controls the on / off of the MOS circuit to control the step-down module to start / stop supplying power to the communication module.

[0012] As a further improvement of the present invention, the step-down module includes a high-voltage step-down module and a secondary step-down module, the input end of the high-voltage step-down module is connected to the driving module, and the output end of the high-voltage step-down module is respectively connected to the input end of the secondary step-down module.

[0013] As a further improvement of the present invention, the output end of the secondary buck module is respectively connected to the input end of the control module and the communication module, and is configured to provide working voltage to the control module and the communication module.

[0014] As a further improvement of the present invention, the secondary buck module includes the MOS circuit, the output end of the control module is connected to the secondary buck module, and the control module realizes on / off of the MOS circuit by outputting a high / low level.

[0015] As a further improvement of the present invention, the secondary step-down module includes a voltage stabilizing chip, a third capacitor, a second capacitor, a ninth resistor, a tenth resistor, an eleventh resistor, a MOS tube, and a triode, wherein the voltage stabilizing chip, the third capacitor, and the second capacitor form a linear voltage stabilizing circuit to power the control module; the ninth resistor, the tenth resistor, the eleventh resistor, the MOS tube, and the triode form a controlled MOS circuit to control the secondary step-down module to power the communication module.

[0016] As a further improvement of the present invention, the power-off holding circuit also includes a power-off detection module, the input end of the power-off detection module is connected to the AC end, and the output end of the power-off detection module is connected to the input end of the control module; when the control module detects that the power-off detection module generates a voltage, the control module controls the step-down module to start providing a working voltage to the communication module; when the control module detects that the voltage of the power-off detection module is zero, the control module controls the step-down module to stop providing a working voltage to the communication module.

[0017] As a further improvement of the present invention, the power-off holding circuit further includes a power-off detection module, and an input end of the power-off detection module can be connected to any one or both of the L line or the N line of the AC end.

[0018] As a further improvement of the present invention, the driving module includes a driving capacitor, and the driving capacitor is used to maintain the operation of the control module after the AC end loses power.

[0019] Another object of the present invention is to provide an LED driving circuit including the above-mentioned power-off holding circuit.

[0020] To achieve the above object, the present invention provides an LED driving circuit, including the above power-off holding circuit.

[0021] As a further improvement of the present invention, the LED driving circuit includes a driving module, the driving module includes two output ends, one output end is connected to a warm-color LED lamp bead, and the other output end is connected to a cool-color LED lamp bead. The warm-color LED lamp bead and the cool-color LED lamp bead are controlled by the driving module to output separately or to output mixed colors simultaneously.

[0022] The beneficial effects of the present invention are as follows: compared with the prior art, in the power-off holding circuit of the present invention, after the control module detects that the AC end is powered off, the control module controls the step-down module to stop supplying power to the communication module, so that the consumption of the residual voltage in the drive module is reduced, and only the control module continues to consume energy. Through logical control, the working time of the control module after the AC end is powered off is greatly extended without increasing the driving capacitor in the drive module, and the circuit has good practicality and economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a principle block diagram of a power-off holding circuit according to a preferred embodiment of the present invention.

[0024] Figure 2 It is a circuit diagram of a driving module in the power-off holding circuit of the present invention.

[0025] Figure 3 It is a circuit diagram of a voltage reduction module, a control module and a communication module in a power-off holding circuit in a preferred embodiment of the present invention.

[0026] Figure 4 It is a principle block diagram of a power-off holding circuit according to another preferred embodiment of the present invention.

[0027] Figure 5 It is a circuit diagram of a voltage reduction module, a control module and a communication module in a power-off holding circuit in another preferred embodiment of the present invention.

[0028] 100-power-off holding circuit;

[0029] 10 - driving module; 20 - buck module, 21 - high voltage buck module, 22 - first secondary buck module, 23 - second secondary buck module, 24 - secondary buck module; 30 - control module; 40 - communication module; 50 - power-off detection module. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] It should be noted here that in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the scheme of the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0032] In addition, it should be noted that the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0033] See also Figure 1-2 FIG. 1 is a power-off holding circuit 100 of the present invention, and the power-off holding circuit 100 includes:

[0034] The driving module 10 is connected to the AC terminal and converts the voltage of the AC terminal;

[0035] A step-down module 20, the input end of which is connected to the driving module 10, and is configured to convert the voltage of the driving module 10;

[0036] A communication module 40, configured to communicate with the outside;

[0037] The control module 30 is connected to the driving module 10 and configured to control the operation of the driving module 10;

[0038] The output end of the step-down module 20 is respectively connected to the input end of the communication module 40 and the input end of the control module 30, and the step-down module 20 is configured to provide voltage to the control module 30 and the communication module 40; the output end of the control module 30 is connected to the step-down module 20, and the control module 30 controls the step-down module 20 to start / stop supplying power to the communication module 40.

[0039] The function of the driver module 10 is to convert the mains electricity into voltage and current that can be used by LED lamps. The driver module 10 can have single-channel output or multi-channel output; the function of the control module 30 is communication, signal sampling, logic control and PWM signal conversion; the function of the communication module 40 is to communicate with the control module 30 after converting the user's needs through various control methods such as Bluetooth, WIFI, PLC, DALI, 0-10V, etc. The driver module 10, the control module 30, and the communication module 40 are not limited to topology architecture, solution, manufacturer, chip model, and working mode.

[0040] When the AC is powered on, the driving module 10 converts the AC power into a voltage that can be used by the LED lamp. The step-down module 20 takes power from the driving module 10 and converts it into low-voltage power, and then converts it into working voltage and provides it to the control module 30 and the communication module 40 respectively. The communication module 40 and the control module 30 start to work normally. The communication module 40 receives external control requirements and sends them to the control module 30 after conversion. The control module 30 outputs a PWM signal to control the operation of the driving module 10.

[0041] When the AC end loses power, the driving module 10 stops working, there is no external power input, and there is residual voltage in the driving module 10 to continue to supply power to the buck module 20. At this time, the control module 30 detects that the AC end loses power, and the control module 30 controls the buck module 20 to stop supplying power to the communication module 40. The communication module 40 stops working and no longer consumes energy. The residual voltage loss in the driving module 10 is reduced, and only the control module 30 continues to consume energy. The control module 30 can continue to work for a longer time after the AC end loses power.

[0042] In some embodiments, the buck module 20 further includes an EN pin, the output end of the control module 30 is connected to the EN pin of the buck module 20 , and the control module 30 controls the buck module 20 to start / stop supplying power to the communication module 40 through the EN pin of the buck module 20 .

[0043] The output end of the control module 30 is connected to the EN pin of the buck module 20. When the control module 30 outputs a high level to the EN pin, the EN pin is activated, and the buck module 20 starts to supply power to the communication module 40. When the control module 30 outputs a low level, the EN pin is not activated, and the buck module 20 stops supplying power to the communication module 40.

[0044] The power-off holding circuit 100 also includes a power-off detection module 50, the input end of the power-off detection module 50 is connected to the AC end, and the output end of the power-off detection module 50 is connected to the input end of the control module 30; when the control module 30 detects that the power-off detection module 50 generates a voltage, the control module 30 controls the buck module 20 to start providing a working voltage to the communication module 40, that is, the control module 30 outputs a high level to the EN pin of the buck module 20; when the control module 30 detects that the voltage of the power-off detection module 50 is zero, the control module 30 controls the buck module 20 to stop providing a working voltage to the communication module 40, that is, the control module 30 outputs a low level to the EN pin of the buck module 20.

[0045] The step-down module 20 includes a high-voltage step-down module 21, a first secondary step-down module 22 and a second secondary step-down module 23. The input end of the high-voltage step-down module 21 is connected to the driving module 10, and the output end of the high-voltage step-down module 21 is respectively connected to the input end of the first secondary step-down module 22 and the input end of the second secondary step-down module 23.

[0046] The high-voltage buck module 21 is connected to the driving module 10 to convert the higher voltage in the driving module 10 into a low voltage. The buck module 20 can be any suitable power supply topology architecture, not limited to a switching power supply architecture or a linear architecture, and not limited to a model. The first secondary buck module 22 and the second secondary buck module 23 are linear voltage stabilization modules, which are used to convert the voltage provided by the high-voltage buck module 21 into a voltage that can be used by the control module 30 and the signal module, without limiting the chip manufacturer and model used.

[0047] The output end of the first secondary buck module 22 is connected to the control module 30, and the output end of the control module 30 is connected to the EN pin of the first secondary buck module 22. The control module 30 controls the first secondary buck module 22 through the EN pin to start / stop supplying voltage to the control module 30. The first secondary buck module 22 includes a linear LDO chip with an EN pin function. The control module 30 can control the on and off of the first secondary buck module 22 through the EN pin. When the control module 30 inputs a high level to the EN pin of the first secondary buck module 22, the EN pin is activated, and the first secondary buck module 22 starts to supply power to the communication module 40. When the control module 30 inputs a low level to the EN pin of the first secondary buck module 22, the first secondary buck module 22 stops supplying power to the communication module 40.

[0048] The output end of the second secondary buck module 23 is connected to the input end of the control module 30 , and is configured to provide an operating voltage to the control module 30 .

[0049] like Figure 4As shown, in some embodiments, the output end of the control module 30 is connected to the buck module 20, and the buck module 20 includes a MOS circuit. The control module 30 controls the on / off of the MOS circuit to control the buck module 20 to start / stop supplying power to the communication module 40.

[0050] The step-down module 20 includes a high-voltage step-down module 21 and a secondary step-down module 24 . The input end of the high-voltage step-down module 21 is connected to the driving module 10 , and the output end of the high-voltage step-down module 21 is connected to the input end of the secondary step-down module 20 .

[0051] The high-voltage buck module 21 is connected to the driving module 10 to convert the higher voltage in the driving module 10 into a low voltage. The buck module 20 can be any suitable power supply topology architecture, not limited to a switching power supply architecture or a linear architecture, and not limited to a model; the secondary buck module 24 is used to convert the voltage provided by the high-voltage buck module 21 into a voltage that can be used by the control module 30 and the signal module, and is not limited to the chip manufacturer and model used.

[0052] The output end of the secondary buck module 24 is connected to the input end of the control module 30 and the communication module 40 respectively, and is configured to provide working voltage to the control module 30 and the communication module 40 .

[0053] The secondary buck module 24 includes a MOS circuit. The output end of the control module 30 is connected to the secondary buck module 24. The control module 30 switches the MOS circuit on and off by outputting a high / low level.

[0054] When the control module 30 detects that the voltage input to the power-off detection module 50 is greater than zero, the control module 30 outputs a high level to the secondary buck module 24. At this time, the MOS circuit is turned on, and the secondary buck module 24 starts to supply power to the communication module 40; when the control module 30 detects that the voltage input to the power-off detection module 50 is zero, the control module 30 outputs a low level to the secondary buck module 24. At this time, the MOS circuit is disconnected, and the secondary buck module 24 stops supplying power to the communication module 40.

[0055] The secondary buck module 24 includes a voltage stabilizing chip U1, a third capacitor C3, a second capacitor C2, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a MOS tube Q1, and a transistor Q2, wherein the voltage stabilizing chip U1, the third capacitor C3, and the second capacitor C2 form a linear voltage stabilizing circuit to power the control module 30; the ninth resistor R9, the tenth resistor R10, the eleventh resistor R11, the MOS tube Q1, and the transistor Q2 form a controlled MOS circuit to control the secondary buck module 24 to power the communication module 40.

[0056] The input end of the power failure detection module 50 can be connected to any one or both of the L line or the N line of the AC end.

[0057] The power failure detection module 50 is connected to the AC power terminal, which can be connected to the L and N single lines or double lines. It is used to detect the AC power working status of the AC terminal. When the AC terminal is turned off and there is no voltage, the signal is transmitted to the control module 30 for processing.

[0058] The driving module 10 includes a driving capacitor, which is used to maintain the control module 30 after the AC end loses power. After the AC end loses power, the driving module 10 stops working, there is no external power input, and some voltage remains in the driving capacitor of the driving module 10 to maintain the control module 30 to continue working.

[0059] In this embodiment, the control module 30 uses an MCU controller. In other embodiments, other control devices may also be used, and the present invention is not limited to this.

[0060] The present invention further provides an LED driving circuit, comprising the above-mentioned power-off holding circuit 100.

[0061] The LED driving circuit includes a driving module 10, which includes two output terminals, one of which is connected to a warm-color LED lamp bead, and the other is connected to a cool-color LED lamp bead. The warm-color LED lamp bead and the cool-color LED lamp bead are controlled by the driving module 10 to output separately or simultaneously in mixed colors, thereby meeting the usage requirements of different application scenarios.

[0062] Please participate Figures 1 to 3 FIG. 1 is a LED driving circuit according to a specific embodiment of the present invention.

[0063] The WIFI-controlled intelligent LED driver has two outputs, which are connected to warm and cold LEDs. It consists of a driver module 10, a power-off detection module 50, an MCU, a communication module 40, a first secondary buck module 22, a second secondary buck module 23, and a high-voltage buck module 21. The driver input is L, N connected to AC mains, and the driver output is LED+, LEDW- connected to warm LED lamp beads, and LED+, LEDC- connected to cold LED lamp beads. The two warm and cold LED lamp beads are controlled by the driver module 10 to output separately, or to output mixed colors at the same time, and the output current can be changed to change the output brightness. The entire LED driver circuit has dimming and color adjustment functions to meet the needs of different application scenarios.

[0064] The function of the driver module 10 is to convert the input mains into a voltage and current suitable for LED driving. The output current can be adjusted by connecting the PWM pins of the driver chips U4 and U7 through an external PWM signal. In this embodiment, the PWM dimming driver is a single-stage low PF BUCK architecture. It can also be a two-stage architecture (BOOST+BUCK), a single-stage high PF BUCK architecture, or any other suitable constant current architecture. As long as this architecture can output a constant current to drive the LED, and the output current of the driver can be adjusted by PWM.

[0065] The function of the communication module 40 is to convert external dimming and color adjustment requirements and communicate with the MCU. In this embodiment, it is WIFI controlled, and in other embodiments, it can also be other control schemes (Bluetooth, DALI, 0-10V, PLC, etc.). The control scheme is not limited, as long as it can communicate with the MCU. In this embodiment, the communication with the MCU is I2C, and in other embodiments, the communication method can also be diverse, serial port, SPI, I2C, CAN, etc., the present invention is not limited to this.

[0066] The function of MCU is to communicate with the communication module 40, output PWM control drive, AC end detection, control the operation of the first secondary buck module 22, and other logic detection and control. In this embodiment, the single-chip microcomputer has two PWMs, namely PWMW and PWMC, which correspond to the PWM ports of the two chips of the driving module 10 respectively. The PIN14 of MCU is connected to the CP signal to detect the working status of the AC end. MCU PIN2 can output high or low level, connected to the EN pin of the first secondary buck module 22 chip U3. When PIN2 outputs high, U3 works, and when PIN2 outputs low level, U3 stops working. The PIN of MCU is also responsible for other logic control functions.

[0067] The function of the high-voltage buck module 21 is to provide the output 5V voltage to the first secondary buck module 22 and the second secondary buck module 23. In this embodiment, the high-voltage buck module 21 is connected to the VBUS after the rectifier bridge of the driving module 10, and can convert the high-voltage signal into 5V. In this embodiment, it is a BUCK architecture, and in other embodiments, it can also be a variety of other architectures, which can be a switching power supply solution or a linear solution. As long as it can convert high voltage into low voltage, it is not limited to manufacturers and models. The location where the high-voltage buck module 21 draws power is also diverse. It can be taken from the VBUS after the rectifier bridge, or it can be other suitable places, depending on the topological architecture of the module.

[0068] The first secondary buck module 22 is connected to the high voltage buck module 21, and outputs 3.3V voltage to the communication module 40; the first secondary buck module 22 is a linear voltage regulator structure, and the chip U3 of the first secondary buck module 22 is not limited to the manufacturer or model. U3 PIN3 is the EN pin. When the EN pin voltage is high, the circuit works to convert 5V to 3.3V. When the EN pin voltage is low, the circuit does not work and outputs 0V.

[0069] The second secondary buck module 23 is connected to the high voltage buck module 21 and outputs 3.3V voltage to the MCU. The structure is a linear voltage regulator, and the voltage regulator chip U1 of the second secondary buck module 23 is not limited to a manufacturer or a model.

[0070] The power-off detection module 50 is composed of two resistors, the seventh resistor R7 and the eighth resistor R8. After reasonable voltage division, the voltage at the AC end can be proportionally reduced to the Pin 14 of the MCU U6. In this embodiment, the seventh resistor R7 is connected to the N line of the AC end, and can also be connected to the L line, or to the L and N double lines. However, when connecting the double lines, a diode needs to be connected in series at the upper end of the electronic to prevent short circuit.

[0071] The working process of the LED drive circuit is as follows:

[0072] When the AC end is powered on, the high-voltage buck module 21 works to generate 5V, the second secondary buck module 23 takes power from the high-voltage buck module 21 and converts it into the MCU working voltage 3.3V, the MCU starts to work normally, outputs 2 PWM signals to control the driving module 10 to work, the MCU PIN2 outputs a high level to the chip U3 PIN3 of the first secondary buck module 22, U3 generates 3.3V to the communication module 40U5, the chip U5 of the communication module 40 starts to communicate with the outside, converts the external demand to the MCU, and the MCU and the communication module 40 communicate and convert the demand to control the driving module 10. The MCU detects the state of the voltage after the seventh resistor R7 and the eighth resistor R8 of the power-off detection module 50 are divided in real time.

[0073] After the AC end is powered off, the driving module 10 stops working, and there is no external power input, but there is residual voltage in the third electrolytic capacitor EC3 of the driving module 10, the second electrolytic capacitor EC2, the third capacitor C3 in the buck module 20, the fourth capacitor C4, and the second capacitor C2, and the MCU can continue to work. The seventh resistor R7 of the power-off detection module 50 and the eighth resistor R8 have a voltage of 0V after voltage division. The U5 of the MCU outputs a low-level control through the PIN2 pin to stop the chip U3 of the first secondary buck module 22, and then the communication module 40 stops working and does not consume energy. The consumption of the residual voltage of the capacitor becomes lower, and the overall loss is only the loss of the MUC module. Usually, the consumption of the MCU is much smaller than that of the communication module 40, so that the MCU can continue to work longer. If such a logic switch is not made, the MCU and the control module 30 work at the same time after the power is off, and the residual voltage in the driving capacitor can be consumed quickly, which cannot meet the power-off holding time requirement.

[0074] Please continue reading Figure 2 , Figures 4-5 FIG. 1 is a LED driving circuit according to another specific embodiment of the present invention.

[0075] The WIFI-controlled intelligent LED driver has two outputs, which are connected to warm and cold LEDs. It consists of a driver module 10, a power-off detection module 50, an MCU, a communication module 40, a first secondary buck module 22, a second secondary buck module 23, and a high-voltage buck module 21. The driver input is L, N connected to AC mains, and the driver output is LED+, LEDW- connected to warm LED lamp beads, and LED+, LEDC- connected to cold LED lamp beads. The two warm and cold LED lamp beads are controlled by the driver module 10 to output separately, or to output mixed colors at the same time, and the output current can be changed to change the output brightness. The entire LED driver circuit has dimming and color adjustment functions to meet the needs of different application scenarios.

[0076] The function of the driver module 10 is to convert the AC power input into a voltage and current suitable for LED driving. The output current can be adjusted by connecting the external PWM signal to the PWM pins of the driver chip U4 and the chip U7. In this embodiment, it is a PWM dimming driver with a single-stage low PF BUCK architecture. In other embodiments, it can also be a two-stage architecture (BOOST+BUCK), a single-stage high PF BUCK architecture, or any other suitable constant current architecture. As long as this architecture can output a constant current to drive the LED, and the output current of the driver can be adjusted by PWM.

[0077] The function of the communication module 40 is to convert external dimming and color adjustment requirements and communicate with the MCU. In this embodiment, it is WIFI controlled, and in other embodiments, it can also be other control schemes (Bluetooth, DALI, 0-10V, PLC, etc.). The control scheme is not limited, as long as it can communicate with the MCU. In this embodiment, the communication with the MCU is I2C, and in other embodiments, the communication method can also be diverse, serial port, SPI, I2C, CAN, etc., the present invention is not limited to this.

[0078] The function of MCU is to communicate with the communication module 40, output PWM control drive, AC end detection, control the operation of the secondary buck module 24, and other logic detection and control. In this embodiment, the single-chip microcomputer has two PWMs, namely PWMW and PWMC, which correspond to the PWM ports of the two chips of the driving module 10 respectively. The function of the MCU's PIN14 connected to the CP signal is to detect the AC working condition of the input end. MCUPIN2 can output high or low level, and is connected to the B pole of the NPN transistor Q2 through the tenth resistor R10. When the MCU PIN2 outputs a high level, the transistor Q2 is turned on, and the G pole of the MOS tube Q1 is pulled to 0V, Q1 is turned on, and 3.3V is provided to the communication module 40. When PIN2 outputs a low level, the voltage of the B pole of the transistor Q2 is 0V, the transistor Q2 is not turned on, the G pole of Q1 is high level, Q1 is not turned on, and 3.3V cannot be provided to the communication module 40.

[0079] The function of the high-voltage buck module 21 is to provide the output 5V voltage to the secondary buck module 24. In this embodiment, the high-voltage buck module 21 is connected to the VBUS after the rectifier bridge of the driving module 10, and can convert the high-voltage signal into 5V. In this embodiment, it is a BUCK architecture, but it can also be a variety of other architectures, which can be a switching power supply solution or a linear solution. As long as the high voltage can be converted into a low voltage, the manufacturer and model are not limited. The location of power supply is also diverse, and it can be taken from the VBUS after the rectifier bridge, or it can be other suitable places, depending on the topological architecture of the module.

[0080] The secondary step-down module 24 includes an LDO voltage regulator chip U1, a third capacitor C3, a second capacitor C2, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a MOS tube Q1, and a PNP transistor Q2. The voltage regulator chip U1, the third capacitor C3, and the second capacitor C2 form a linear voltage regulator circuit to convert 5V into 3.3V. This 3.3V is directly provided to the MCU for power supply, and is simultaneously connected to the MOS tube Q1, the ninth resistor R9, the tenth resistor R10, the eleventh resistor R11, and the transistor Q2 to form a controlled MOS on-off circuit, and then connected to the communication module 40. When the MCU PIN2 output is a high level, the circuit works to provide 3.3V electricity to the communication module 40. When the MCU PIN2 output is a low level, the circuit does not work, outputs 0V, and the communication module 40 is powered off and stops working.

[0081] The power-off detection module 50 is composed of two resistors, the seventh resistor R7 and the eighth resistor R8. After reasonable voltage division, the voltage at the AC end can be proportionally reduced to the Pin 14 of the MCU U6. In this embodiment, the seventh resistor R7 is connected to the N line of the driver, and can also be connected to the L line, or to the L and N double lines. However, when connecting the double lines, a diode needs to be connected in series at the upper end of the electronic circuit to prevent short circuit.

[0082] The working process of the LED drive circuit is as follows:

[0083] When AC is powered on, the high-voltage buck module 21 generates 5V, the secondary buck module 24 takes power from the high-voltage buck module 21 and converts it into MCU working voltage 3.3V, the MCU starts working normally, outputs 2 PWM signals to control the driving module 10 to work, MCUPIN2 outputs a high level to the B pole of the transistor Q2, the transistor Q2 is turned on to pull the G pole of the MOS tube Q1 low, the MOS tube Q1 is turned on, 3.3V is provided to the communication module 40 to start working, the communication module 40U5 starts to communicate with the outside, converts the external demand to the MCU, and the MCU and the communication module 40 communicate and convert the demand to control the driving module 10. The MCU detects the state of the voltage after the seventh resistor R7 and the eighth resistor R8 of the power-off detection module 50 in real time.

[0084] After the AC end loses power, the driving module 10 stops working, and there is no external power input. However, there is residual voltage in the third electrolytic capacitor EC3 of the driving module 10, the second electrolytic capacitor EC2, the third capacitor C3 in the step-down module 20, the fourth capacitor C4, and the second capacitor C2, and the MCU can continue to work. The seventh resistor R7 and the eighth resistor R8 of the power-off detection module 50 have a voltage of 0V after voltage division. The MCU outputs a low level to the B pole of the transistor Q2 through the PIN2 pin, and the transistor Q2 is not turned on. The G pole of the MOS tube Q1 is a high level, and the MOS tube Q1 is not turned on. When the communication module 40 loses power, the communication module 40 stops working and does not consume energy. The consumption of the residual voltage of the capacitor becomes lower, and the overall loss is only the loss of the MUC module. Usually, the consumption of the MCU is much smaller than that of the communication module 40, so that the MCU can continue to work for a longer time and meet the requirements of the power-off holding time.

[0085] In summary, in the power-off holding circuit 100 of the present invention, after the control module 30 detects that the AC end is powered off, the step-down module 20 stops supplying power to the communication module 40, so that the consumption of the residual voltage in the driving module 10 is reduced, and only the control module 30 continues to consume energy. Through logical control, the working time of the control module 30 after the AC end is powered off is greatly extended without increasing the driving capacitor in the driving module 10, and the circuit has good practicality and economy.

[0086] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A power-off holding circuit, characterized in that: include: A driving module (10) is connected to the AC terminal and converts the voltage of the AC terminal; A step-down module (20), the input end of which is connected to the driving module (10) and is configured to convert the voltage of the driving module (10); A communication module (40) configured to communicate with the outside; A control module (30) connected to the driving module (10) and configured to control the operation of the driving module (10); The output end of the step-down module (20) is respectively connected to the input end of the communication module (40) and the input end of the control module (30), and the step-down module (20) is configured to provide voltage to the control module (30) and the communication module (40); the output end of the control module (30) is connected to the step-down module (20), and the step-down module (20) comprises a MOS circuit, and the control module (30) controls the on / off of the MOS circuit to control the step-down module (20) to start / stop supplying power to the communication module (40).

2. The power-off holding circuit according to claim 1, characterized in that: The voltage reduction module (20) comprises a high-voltage voltage reduction module (20) and a secondary voltage reduction module (24); the input end of the high-voltage voltage reduction module (20) is connected to the driving module (10); and the output end of the high-voltage voltage reduction module (20) is respectively connected to the input end of the secondary voltage reduction module (20).

3. The power-off holding circuit according to claim 2, characterized in that: The output end of the secondary buck module (24) is respectively connected to the input ends of the control module (30) and the communication module (40), and is configured to provide an operating voltage to the control module (30) and the communication module (40).

4. The power-off holding circuit according to claim 2, characterized in that: The secondary buck module (24) comprises the MOS circuit, the output end of the control module (30) is connected to the secondary buck module (24), and the control module (30) switches the MOS circuit on / off by outputting a high / low level.

5. The power-off holding circuit according to claim 2, characterized in that: The secondary buck module (24) comprises a voltage stabilizing chip (U1), a third capacitor (C3), a second capacitor (C2), a ninth resistor (R9), a tenth resistor (R10), an eleventh resistor (R11), a MOS tube (Q1), and a triode (Q2), wherein the voltage stabilizing chip (U1), the third capacitor (C3), and the second capacitor (C2) form a linear voltage stabilizing circuit to supply power to the control module (30); and the ninth resistor (R9), the tenth resistor (R10), the eleventh resistor (R11), the MOS tube (Q1), and the triode (Q2) form a controlled MOS circuit to control the secondary buck module (24) to supply power to the communication module (40).

6. The power-off holding circuit according to claim 1, characterized in that: The power-off holding circuit further comprises a power-off detection module (50), the input end of the power-off detection module (50) being connected to the AC end, and the output end of the power-off detection module (50) being connected to the input end of the control module (30); when the control module (30) detects that the power-off detection module (50) generates a voltage, the control module (30) controls the voltage reduction module (20) to start providing the communication module (40) with a working voltage; when the control module (30) detects that the voltage of the power-off detection module (50) is zero, the control module (30) controls the voltage reduction module (20) to stop providing the communication module (40) with a working voltage.

7. The power-off holding circuit according to claim 1, characterized in that: The power-off holding circuit further comprises a power-off detection module (50), and an input end of the power-off detection module (50) can be connected to any one or both of the L line or the N line of the AC end.

8. The power-off holding circuit according to claim 1, characterized in that: The driving module (10) comprises a driving capacitor, and the driving capacitor is used to maintain the operation of the control module (30) after the AC end loses power.

9. An LED driving circuit, characterized in that: The invention comprises the power-off holding circuit as claimed in any one of claims 1 to 8.

10. The LED driving circuit according to claim 9, characterized in that: The LED driving circuit comprises a driving module (10), wherein the driving module (10) comprises two output terminals, one of which is connected to a warm-color LED lamp bead, and the other is connected to a cold-color LED lamp bead, wherein the warm-color LED lamp bead and the cold-color LED lamp bead are controlled by the driving module (10) to output separately or simultaneously in mixed colors.

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