Switching power supply circuit and dimming device using same

Abstract

The utility model discloses a switching power supply circuit and a dimming device using the switching power supply circuit, the circuit comprises a rectification circuit, a boost circuit, a flyback circuit, a feedback circuit, a power supply circuit and a module, the voltage output end of the rectification circuit is connected with the voltage input end of the boost circuit; the voltage output end of the booster circuit is connected with the voltage input end of the flyback circuit, and the voltage output end of the flyback circuit is connected with the voltage input end of the feedback circuit and the voltage input end of the DALI module; the flyback circuit comprises a flyback primary control circuit and a flyback secondary rectification circuit, the switching power supply circuit further comprises a protection circuit, and the protection circuit comprises a PNP type triode, a fifth diode, a ninth resistor, a seventh resistor, an eighth resistor, a tenth resistor, a first voltage stabilizer and an eleventh resistor. Through the arrangement of the protection circuit, the DALI module connected with the flyback secondary rectification circuit can rapidly detect a power-off signal, and the use requirement of the DALI module is met.

Description

Technical Field

[0001] This utility model relates to the field of circuit technology, and in particular to a switching power supply circuit and a dimming device using the switching power supply circuit. Background Technology

[0002] The DALI (Digital Addressable Lighting Interface) dimming power supply requires a 5-second restart after an AC (Alternating Current) power outage to collect the power outage signal.

[0003] The current solution for obtaining power failure information on the market is to discharge through a dummy load. This solution has a slightly longer discharge time and higher power consumption, and cannot meet the requirement of issuing a power failure signal within the 5-second restart time.

[0004] When the dimming power supply is under light load, after the AC power is cut off, the output energy consumption is very small and cannot be quickly dissipated. This can cause a flickering effect when the power is turned on again, affecting the consumer's visual experience and causing discomfort. For example... Figure 1 As shown, the circuit consists of an AC rectifier circuit, a PFC boost circuit, a flyback circuit, a feedback circuit, and a DALI module. After the AC power is cut off, because the electrolytic capacitor EC1 in the PFC boost circuit has a large capacitance, high voltage, and large stored energy, it can still maintain the operation of the primary control circuit of the flyback circuit for a short time. Energy continues to be coupled to the secondary rectifier circuit. The secondary circuit only releases through the dummy load R21, and the discharge time is long. It cannot meet the requirement of issuing a power-off signal before restarting after 5 seconds, and cannot quickly consume the output energy. Utility Model Content

[0005] To address the problems in the prior art, this utility model provides an improved switching power supply circuit and a dimming device using the switching power supply circuit.

[0006] In a first aspect, this utility model discloses a switching power supply circuit, including an AC rectifier circuit, a PFC boost circuit, a flyback circuit, a feedback circuit, a VCC power supply circuit, and a DALI module. The voltage output terminal of the AC rectifier circuit is connected to the voltage input terminal of the PFC boost circuit, the voltage output terminal of the PFC boost circuit is connected to the voltage input terminal of the flyback circuit, and the voltage output terminal of the flyback circuit is connected to the voltage input terminal of the feedback circuit and the voltage input terminal of the DALI module. The flyback circuit includes a flyback primary control circuit and a flyback secondary rectifier circuit.

[0007] The VCC power supply circuit includes a third electrolytic capacitor EC3, the flyback circuit includes a control chip U2, the switching power supply circuit further includes a protection circuit, the protection circuit includes a PNP type transistor Q3, a fifth diode D5, a ninth resistor R9, a seventh resistor R7, an eighth resistor R8, a tenth resistor R10, a first voltage stabilizer U3, and an eleventh resistor R11.

[0008] The positive electrode of the third electrolytic capacitor EC3 is connected to the emitter of the PNP type transistor Q3, the collector of the PNP type transistor Q3 is connected to the control chip U2 to provide a stable power supply for the control chip U2, the collector of the PNP type transistor Q3 is also connected to the positive electrode of the fifth diode D5, the negative electrode of the fifth diode D5 is connected to the first end of the ninth resistor R9, the second end of the ninth resistor R9 is connected to the reference electrode of the first voltage stabilizer U3, the first end of the seventh resistor R7 is connected to the high voltage end HV of the AC rectifier circuit, the second end of the seventh resistor R7 is connected to the reference electrode of the first voltage stabilizer U3 and the first end of the eighth resistor R8, the anode of the first voltage stabilizer U3 is connected to the second end of the eighth resistor R8, the second end of the ninth resistor R9, and the ground, the first end of the tenth resistor R10 is connected to the cathode of the first voltage stabilizer U3, the second end of the tenth resistor R10 is connected to one end of the eleventh resistor R11 and the gate of the PNP type transistor Q3, and the other end of the eleventh resistor R11 is connected to the positive electrode of the third electrolytic capacitor EC3 and the emitter of the PNP type transistor Q3.

[0009] In some embodiments, the protection circuit further includes an eighth capacitor C8, one end of the eighth capacitor C8 is connected to the second end of the seventh resistor R7 and the second end of the ninth resistor R9, and the other end of the eighth capacitor C8 is grounded.

[0010] In some embodiments, the reference voltage of the first voltage stabilizer U3 is 2.5V.

[0011] In some embodiments, the PFC boost circuit includes a first electrolytic capacitor EC1, the flyback primary control circuit includes a primary winding and an N-channel MOS transistor Q2, the positive electrode of the first electrolytic capacitor EC1 is connected to the first end of the primary winding, and the negative electrode of the first electrolytic capacitor EC1 is grounded, the second end of the primary winding is connected to the drain of the N-channel MOS transistor Q2, the source of the N-channel MOS transistor Q2 is grounded, and the gate of the N-channel MOS transistor Q2 is connected to the control chip U2.

[0012] In some embodiments, the flyback secondary rectifier circuit comprises a first secondary winding and a second electrolytic capacitor EC2; a negative pole of the second electrolytic capacitor EC2 is connected to a first end of the first secondary winding and the ground, and a positive pole of the second electrolytic capacitor EC2 is connected to a second end of the first secondary winding and the DALI module.

[0013] In some embodiments, the flyback secondary rectifier circuit further comprises a twenty-first resistor R21; a first end of the twenty-first resistor R21 is connected to the positive pole of the second electrolytic capacitor EC2 and the DALI module, and a second end of the twenty-first resistor R21 is connected to the ground and the negative pole of the second electrolytic capacitor EC2; a capacitance of the second electrolytic capacitor EC2 is less than a capacitance of the first electrolytic capacitor EC1.

[0014] In some embodiments, the VCC power supply circuit further comprises a second secondary winding coupled with the primary winding; a first end of the second secondary winding is connected to the ground and a negative pole of a third electrolytic capacitor EC3, and a second end of the second secondary winding is connected to a positive pole of the third electrolytic capacitor EC3, one end of an eleventh resistor R11 and an emitter of a PNP triode Q3.

[0015] In some embodiments, the flyback primary control circuit further comprises a second diode D2, a second capacitor C2 and a third resistor R3; a positive pole of the second diode D2 is connected to a drain of the N-channel MOS Q2 and a second end of the primary winding, and a negative pole of the second diode D2 is connected to one end of the second capacitor C2 and one end of the third resistor R3 at the same time, and the other end of the second capacitor C2 and the other end of the third resistor R3 are connected to a first end of the primary winding.

[0016] In some embodiments, the flyback primary control circuit further comprises a sixth resistor R6, a first end of the sixth resistor R6 is connected to a high voltage end HV of the AC rectifier circuit, and a second end of the sixth resistor R6 is connected to the control chip U2 to provide a starting voltage for the control chip U2.

[0017] In the second aspect, the utility model discloses a dimming device applying the switching power supply circuit, which comprises a lamp and the switching power supply circuit of the first aspect, and the lamp is connected with the DALI module.

[0018] The utility model discloses beneficial effect: the utility model discloses the switch power supply circuit provided by the embodiment, through with high flat voltage terminal HV connects the first stabilizer U3, and through the first stabilizer U3 control PNP type triode Q3's on-off, when AC power failure or voltage drops, can rapidly shut off PNP type triode Q3, make VCC power supply circuit's third electrolytic capacitor EC3 cannot continue to supply power to control chip U2, control chip U2 cannot control the work of flyback primary control circuit, thereby make flyback primary control circuit and flyback secondary rectifier circuit disconnect, and then make the first electrolytic capacitor EC1 of PFC boost circuit's storage electric energy cannot be coupled to flyback secondary rectifier circuit, therefore, the DALI module connected with flyback secondary rectifier circuit can rapidly detect the power failure signal, satisfy its use requirement. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical scheme of the utility model embodiment, the following will briefly introduce the drawing needed to be used in the embodiment description, and obviously, the following description of the drawing is some embodiments of the utility model, and for those skilled in the art, under the premise of not creating labor, other drawings can also be obtained according to these drawings.

[0020] Figure 1 It is the circuit diagram of the switch power supply circuit in prior art;

[0021] Figure 2 It is the circuit diagram of the switch power supply circuit provided by the utility model embodiment. DETAILED DESCRIPTION

[0022] The technical scheme in the utility model embodiment will be described clearly and completely in the following by combining with the drawings in the utility model embodiment, and obviously, the described embodiment is a part of the embodiment of the utility model, rather than all the embodiments. Based on the embodiment in the utility model, all other embodiments obtained by those skilled in the art without creating labor belong to the scope of protection of the utility model.

[0023] It should be understood that, when using in the specification and the appended claims, the terms "include" and "contain" indicate the existence of the described features, whole, step, operation, element and, or component, but do not exclude the existence or addition of one or more other features, whole, step, operation, element, component and, or its set.

[0024] It should also be noted that, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing", "setting" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements or the interaction relationship between two elements. When an element is referred to as "on" or "below" another element, the element can be "directly" or "indirectly" above the other element, or there can be one or more intervening elements. The terms "first", "second", "third" and the like are only for the convenience of describing the technical solutions, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features with "first", "second", "third" and the like can be explicitly or implicitly include one or more features. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0025] It should also be understood that the terms used in the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in the present application and the appended claims, unless otherwise clearly indicated by the context, the singular forms "a", "an" and "the" are intended to include the plural forms.

[0026] It should be further understood that the terms "and / or" used in the present application and the appended claims refer to any combination of one or more of the associated listed items and all possible combinations, and include these combinations.

[0027] As Figure 2The utility model discloses an opening and closing power supply circuit, including AC rectifier circuit, PFC voltage increasing circuit, flyback circuit, feedback circuit, VCC power supply circuit and DALI module, the voltage output of AC rectifier circuit is connected with the voltage input of PFC voltage increasing circuit, the voltage output of PFC voltage increasing circuit is connected with the voltage input of flyback circuit, the voltage output of flyback circuit is connected with the voltage input of feedback circuit and the voltage input of DALI module, flyback circuit includes flyback primary control circuit and flyback secondary rectifier circuit, VCC power supply circuit includes third electrolytic capacitor EC3, flyback circuit includes control chip U2, the opening and closing power supply circuit still includes protection circuit, and protection circuit includes and PNP triode Q3, fifth diode D5, ninth resistance R9, seventh resistance R7, eighth resistance R8, tenth resistance R10, first voltage stabilizer U3, eleventh resistance R11, the positive pole of third electrolytic capacitor EC3 is connected the emitter of PNP triode Q3, the collector of PNP triode Q3 is connected control chip U2, to provide stable power supply for the control chip U2 of working, the collector of PNP triode Q3 is also connected the positive pole of fifth diode D5, the negative pole of fifth diode D5 is connected the first end of ninth resistance R9, the second end of ninth resistance R9 is connected the reference pole of first voltage stabilizer U3, the first end of seventh resistance R7 is connected the high flat voltage end HV of above-mentioned AC rectifier circuit, the second end of seventh resistance R7 is connected the reference pole of first voltage stabilizer U3 and the first end of eighth resistance R8 simultaneously, the anode of first voltage stabilizer U3 is connected the second end of eighth resistance R8, the second end of ninth resistance R9 and ground, the first end of tenth resistance R10 is connected the cathode of first voltage stabilizer U3, the second end of tenth resistance R10 is connected one end of eleventh resistance R11 and the gate of PNP triode Q3 simultaneously, the other end of eleventh resistance R11 is connected the positive pole of third electrolytic capacitor EC3 and the emitter of PNP triode Q3.

[0028] In the embodiment, the positive pole of the third electrolytic capacitor EC3 is connected to the emitter of the PNP triode Q3, the collector of the PNP triode Q3 is connected to the fifth pin (VCC) of the control chip U2, to provide a stable working voltage for the control chip U2, and the control chip U2 controls the on-off of the flyback primary control circuit and the flyback secondary rectifier circuit through the sixth pin (GATE) thereof.

[0029] Specifically, when the AC rectifier circuit is normally powered on, the mains is rectified into a high flat DC voltage of 310V. The seventh resistance R7 and the eighth resistance R8 divide the voltage of the high flat voltage end HV rectified by the AC rectifier circuit, so that the voltage of the high flat voltage end HV is divided into two parts, one part is the reference voltage of the first voltage stabilizer U3, and the other part is the voltage of the second voltage stabilizer U3. Figure 2The voltage at point A is maintained above the reference voltage of the first voltage stabilizer U3, specifically between 2.5-36V, so that the first voltage stabilizer U3 works normally. When the first voltage stabilizer U3 works normally, the reference electrode is at a high level, i.e. equal to the voltage at point A, the cathode is at a low level, and the tenth resistor R10 is used to pull down the base level of the PNP transistor Q3, so that the base of the PNP transistor Q3 is at a low level, the PNP transistor Q3 is turned on, the VCC power supply circuit provides a voltage to the fifth pin of the control chip U2 to make it work stably, and the control chip U2 outputs a PWM signal through the sixth pin to control the on-off of the flyback primary control circuit and the flyback secondary rectifier circuit. When the flyback primary control circuit and the flyback secondary rectifier circuit are turned on, the energy of the flyback primary control circuit can be coupled to the flyback secondary rectifier circuit, thereby controlling the work of the DALI module.

[0030] Further, when the PNP transistor Q3 is turned on, part of the current is provided to the reference electrode of the first voltage stabilizer U3 through the fifth diode D5 and the ninth resistor R9, and the seventh resistor R7 and the eighth resistor R8 together provide working current for the reference electrode of the first voltage stabilizer U3, thereby improving the reference electrode current and making the first voltage stabilizer U3 work more stably.

[0031] When the AC voltage decreases, the voltage of the high voltage terminal HV decreases, and the voltage at point A also decreases through the seventh resistor R7 and the eighth resistor R8. When it decreases below the reference voltage of the first voltage stabilizer U3, the reference electrode level of the first voltage stabilizer U3 decreases. The first voltage stabilizer U3 is cut off, the cathode and anode of the first voltage stabilizer U3 are in a disconnected state, the cathode of the first voltage stabilizer U3 is at a high level, the base potential of the PNP transistor Q3 is pulled up to a high level through the eleventh resistor R11, the emitter and base potential of the PNP transistor Q3 are the same, the PNP transistor Q3 is cut off, the VCC power supply circuit cannot continue to supply power to the fifth pin of the control chip U2, the flyback primary control circuit and the flyback secondary rectifier circuit are disconnected, the energy of the flyback primary control circuit cannot be coupled to the flyback secondary rectifier circuit, and therefore the DALI module can quickly detect the power-off signal.

[0032] When the AC power is off, the voltage of the high flat voltage terminal HV rapidly decreases, the voltage of point A rapidly decreases after being divided by the seventh resistor R7 and the eighth resistor R8, and is lower than the reference voltage, the reference electrode of the first voltage stabilizer U3 is low, the first voltage stabilizer U3 is in the off state, the cathode and the anode of the first voltage stabilizer U3 are in the off state, the base electrode potential of the PNP type transistor Q3 is pulled up to the high level through the eleventh resistor R11, the emitter electrode and the base electrode potential of the PNP type transistor Q3 are the same, the PNP type transistor Q3 is in the off state, the VCC power supply circuit cannot continue to supply power to the fifth pin of the control chip U2, the flyback primary control circuit and the flyback secondary rectifier circuit are disconnected, the flyback primary control circuit cannot couple the flyback secondary rectifier circuit, and then the DALI module can rapidly detect the power-off signal.

[0033] However Figure 1 As shown in the circuit, a part of electric energy is still stored in the first electrolytic capacitor EC1 of the PFC boost circuit and the third electrolytic capacitor EC3 of the VCC power supply circuit after the AC power is off, the VCC power supply circuit can continue to supply power to the control chip U2 for a short time, therefore, the electric energy stored in the first electrolytic capacitor EC1 of the PFC boost circuit can maintain the flyback primary control circuit to work for a short time, and energy can continue to be coupled to the flyback secondary rectifier circuit, so that the DALI module cannot rapidly detect the power-off signal.

[0034] Therefore, the switch power supply circuit provided by the embodiment of the present application can connect the high flat voltage terminal HV to the first voltage stabilizer U3, and control the on-off of the PNP type transistor Q3 through the first voltage stabilizer U3, when the AC power is off or the voltage decreases, the PNP type transistor Q3 can be rapidly turned off, the third electrolytic capacitor EC3 of the VCC power supply circuit cannot continue to supply power to the control chip U2, the control chip U2 cannot control the flyback primary control circuit to work, so that the flyback primary control circuit and the flyback secondary rectifier circuit are disconnected, and then the electric energy stored in the first electrolytic capacitor EC1 of the PFC boost circuit cannot be coupled to the flyback secondary rectifier circuit, therefore, the DALI module connected to the flyback secondary rectifier circuit can rapidly detect the power-off signal within 3s, and the use requirement is met.

[0035] Further, the first voltage stabilizer U3 has a reference voltage, when the voltage of the AC decreases, the reference electrode level of the first voltage stabilizer U3 also decreases, when the reference electrode level is lower than the reference voltage of the U3, the power supply of the VCC power supply circuit to the control chip U2 can also be rapidly cut off, the flyback primary control circuit and the flyback secondary rectifier circuit are disconnected, and the switch power supply circuit stops voltage output, so as to play the role of under-voltage protection.

[0036] In some embodiments, the protection circuit further comprises an eighth capacitor C8; one end of the eighth capacitor C8 is connected to the second end of the seventh resistor R7 and the second end of the ninth resistor R9, and the other end of the eighth capacitor C8 is grounded. The eighth capacitor C8 is used for filtering and energy storage.

[0037] In some embodiments, the reference voltage of the first voltage regulator U3 is 2.5V.

[0038] Specifically, when the level of point A drops below 2.5V, the anode and cathode of the first voltage regulator U3 are disconnected, and when the level of point A is 2.5V or above, the anode and cathode of the first voltage regulator U3 are connected. Since the first end of the seventh resistor R7 is connected to the high voltage end HV of the AC rectifier circuit, the level of point A is the same as the level of the high voltage end HV, and the first voltage regulator U3 can monitor the voltage of the high voltage end HV and provide under-voltage protection.

[0039] In some embodiments, the PFC boost circuit comprises a first electrolytic capacitor EC1, and the flyback primary control circuit comprises a primary winding and an N-channel MOS tube Q2; the positive electrode of the first electrolytic capacitor EC1 is connected to the first end of the primary winding, and the negative electrode of the first electrolytic capacitor EC1 is grounded; the second end of the primary winding is connected to the drain of the N-channel MOS tube Q2, and the source of the N-channel MOS tube Q2 is grounded; the gate of the N-channel MOS tube Q2 is connected to the control chip U2.

[0040] Specifically, the flyback primary control circuit can further comprise a fifteenth resistor R15 and a sixteenth resistor R16. The first end of the fifteenth resistor is connected to the sixth pin of the control chip U2, and the second end of the fifteenth resistor is connected to the gate of the N-channel MOS tube Q2, so that the gate of the N-channel MOS tube Q2 is connected to the control chip U2. The fifteenth resistor R15 is used to provide a driving voltage for the N-channel MOS tube Q2, and the control chip U2 outputs a PWM signal to the gate of the N-channel MOS tube Q2 through the sixth pin to control the N-channel MOS tube Q2. When the PWM signal is high, the N-channel MOS tube Q2 is turned on; when the PWM signal is low, the N-channel MOS tube Q2 is turned off. The first end of the sixteenth resistor R16 is connected to the source of the N-channel MOS tube Q2 and the fourth pin (CS) of the control chip U2, and the second end of the sixteenth resistor R16 is grounded, so that the source of the N-channel MOS tube Q2 is grounded. The sixteenth resistor R16 can be used as a sampling resistor.

[0041] In some embodiments, the flyback secondary rectifier circuit comprises a first secondary winding and a second electrolytic capacitor EC2; the negative electrode of the second electrolytic capacitor EC2 is connected to the first end of the first secondary winding and the ground, and the positive electrode of the second electrolytic capacitor EC2 is connected to the second end of the first secondary winding and the DALI module.

[0042] Specifically, the flyback secondary rectifier circuit can further comprise an eighth diode D8. The anode of the eighth diode D8 is connected with the second end of the first secondary winding, and the cathode of the eighth diode D8 is connected with the voltage input end of the DALI module and the voltage input end of the feedback circuit. The anode of the second electrolytic capacitor EC2 is connected with the voltage input end of the DALI module and the voltage input end of the feedback circuit. The first secondary winding is coupled with the primary winding of the flyback primary control circuit. When the DC is normally powered, the VCC power supply circuit supplies power to the control chip U2, the control chip U2 controls the N-channel MOS tube Q2 to work, so that the primary winding and the line where the N-channel MOS tube Q2 is located work normally, and then the flyback secondary rectifier circuit and the flyback primary control circuit are turned on to control the DALI module to work. The eighth diode D8 is used for rectification, and the second electrolytic capacitor EC2 is used for filtering and energy storage.

[0043] In some embodiments, the flyback secondary rectifier circuit further comprises a twenty-first resistor R21; the first end of the twenty-first resistor R21 is connected with the anode of the second electrolytic capacitor EC2 and the DALI module, the second end of the twenty-first resistor R21 is grounded and the cathode of the second electrolytic capacitor EC2; the capacitance of the second electrolytic capacitor EC2 is smaller than the capacitance of the first electrolytic capacitor EC1.

[0044] Specifically, the twenty-first resistor R21 is used as a dummy load. When the flyback secondary rectifier circuit is disconnected with the flyback primary control circuit, the twenty-first resistor R21 can be used to release the electrical energy stored in the second electrolytic capacitor EC2. When the AC is powered off, the PNP transistor Q3 of the protection circuit is cut off, the VCC power supply circuit stops supplying power to the control chip U2, and the control chip U2 no longer controls the N-channel MOS tube Q2 to be turned on. After the N-channel MOS tube Q2 is cut off, since the line where the primary winding is located is not conductive, the electrical energy stored in the first electrolytic capacitor EC1 of the PFC boost circuit cannot be coupled to the first secondary winding through the primary winding. The twenty-first resistor R21 only needs to release the electrical energy stored in the second electrolytic capacitor EC2. Since the capacitance of the second electrolytic capacitor EC2 is small and smaller than the capacitance of the first electrolytic capacitor EC1, the release speed of the twenty-first resistor R21 is very fast, and the DALI module can detect the power-off signal within 3S. And avoid the phenomenon of back flashing of the lamp when the AC is reconnected, ensure the visual experience of the user, and improve the comfort.

[0045] In some embodiments, the VCC power supply circuit further comprises a second secondary winding coupled with the primary winding; a first end of the second secondary winding is connected to ground and a negative pole of the third electrolytic capacitor EC3, and a second end of the second secondary winding is connected to a positive pole of the third electrolytic capacitor EC3, one end of the eleventh resistor R11 and an emitter of the PNP triode Q3.

[0046] Specifically, the second secondary winding is coupled with the primary winding, and when the AC is normally powered, the energy of the flyback primary control circuit is coupled to the VCC power supply circuit through the primary winding and the second secondary winding to provide a stable working voltage for the control chip U2.

[0047] In some embodiments, the flyback primary control circuit further comprises a sixth resistor R6, a first end of the sixth resistor R6 is connected to a high voltage end HV of the AC rectifier circuit, and a second end of the sixth resistor R6 is connected to the control chip U2 to provide a starting voltage for the control chip U2.

[0048] Specifically, the high voltage end HV of the AC rectifier circuit is further connected to a fifth pin of the control chip U2 through the sixth resistor R6, and the sixth resistor R6 serves as a starting resistor to provide a starting power supply voltage for the control chip U2. The VCC power supply circuit described above provides a subsequent stable working voltage for the control chip U2.

[0049] In some embodiments, the flyback primary control circuit further comprises a second diode D2, a second capacitor C2 and a third resistor R3; a positive pole of the second diode D2 is connected to a drain of the N-channel MOS Q2 and a second end of the primary winding, a negative pole of the second diode D2 is connected to one end of the second capacitor C2 and one end of the third resistor R3, and the other end of the second capacitor C2 and the other end of the third resistor R3 are connected to a first end of the primary winding.

[0050] Specifically, when the AC is powered off, a sharp voltage is generated at the second end of the primary winding and the drain of the N-channel MOS Q2, and to protect the circuit from being damaged, the second capacitor C2 is a small capacitor with a large impedance, which can be used to suppress the sharp voltage generated at the moment when the AC is powered off. The third resistor R3 is used to consume the energy generated when the sharp voltage is generated.

[0051] In some embodiments, the feedback circuit comprises an optocoupler U4, a third pin of the optocoupler U4 is connected to ground, and a fourth pin of the optocoupler U4 is a feedback pin, and the fourth pin is connected to a second pin (FB) of the control chip U2. The control chip U2 adjusts the duty cycle of the PWM signal output according to the feedback signal of the optocoupler U4, thereby avoiding the light emitted by the lamp being too bright or too dark.

[0052] The utility model discloses a switching power supply circuit, including AC rectifier circuit, PFC voltage -raising circuit, flyback circuit, feedback circuit, VCC power supply circuit and DALI module, the voltage output of AC rectifier circuit is connected with the voltage input of PFC voltage -raising circuit, the voltage output of PFC voltage -raising circuit is connected with the voltage input of flyback circuit, the voltage output of flyback circuit is connected with the voltage input of feedback circuit and the voltage input of DALI module, the flyback circuit includes flyback primary control circuit and flyback secondary rectifier circuit,

[0053] The VCC power supply circuit includes a third electrolytic capacitor EC3, the flyback circuit includes a control chip U2, and the switching power supply circuit further includes a protection circuit, the protection circuit includes a PNP-type triode Q3, a fifth diode D5, a ninth resistor R9, a seventh resistor R7, an eighth resistor R8, a tenth resistor R10, a first voltage stabilizer U3, and an eleventh resistor R11.

[0054] The positive electrode of the third electrolytic capacitor EC3 is connected to the emitter of the PNP-type triode Q3, the collector of the PNP-type triode Q3 is connected to the control chip U2 to provide a stable power supply for the control chip U2, the collector of the PNP-type triode Q3 is also connected to the positive electrode of the fifth diode D5, the negative electrode of the fifth diode D5 is connected to the first end of the ninth resistor R9, the second end of the ninth resistor R9 is connected to the reference electrode of the first voltage stabilizer U3, the first end of the seventh resistor R7 is connected to the high voltage end HV of the AC rectifier circuit, the second end of the seventh resistor R7 is connected to the reference electrode of the first voltage stabilizer U3 and the first end of the eighth resistor R8, the anode of the first voltage stabilizer U3 is connected to the second end of the eighth resistor R8, the second end of the ninth resistor R9, and the ground, the first end of the tenth resistor R10 is connected to the cathode of the first voltage stabilizer U3, the second end of the tenth resistor R10 is connected to one end of the eleventh resistor R11 and the gate of the PNP-type triode Q3, and the other end of the eleventh resistor R11 is connected to the positive electrode of the third electrolytic capacitor EC3 and the emitter of the PNP-type triode Q3.

[0055] By connecting the high voltage terminal HV to the first voltage stabilizer U3, and controlling the on-off of the PNP triode Q3 through the first voltage stabilizer U3, when AC power is cut off or voltage is reduced, the PNP triode Q3 can be quickly turned off, the third electrolytic capacitor EC3 of the VCC power supply circuit cannot continue to supply power to the control chip U2, the control chip U2 cannot control the work of the flyback primary control circuit, so that the flyback primary control circuit and the flyback secondary rectifier circuit are disconnected, and then the electric energy stored in the first electrolytic capacitor EC1 of the PFC boost circuit cannot be coupled to the flyback secondary rectifier circuit, therefore, the DALI module connected with the flyback secondary rectifier circuit can quickly detect the power-off signal, and the use requirement is met

[0056] The utility model embodiment further provides a dimming device applying the switching power supply circuit, including lamps and lanterns and the switching power supply circuit described in above embodiment, the lamps and lanterns are connected with the DALI module.

[0057] The above is only a specific implementation manner of the utility model, but the protection scope of the utility model is not limited to this, any skilled person in the art can easily think of various equivalent modifications or replacements within the technical range disclosed by the utility model, and these modifications or replacements should be covered in the protection scope of the utility model. Therefore, the protection scope of the utility model should be subject to the protection scope of claims.

Claims

1. A switching power supply circuit, characterized by comprising: The AC rectifier circuit, the PFC boost circuit, the flyback circuit, the feedback circuit, the VCC power supply circuit and the DALI module, the voltage output end of the AC rectifier circuit is connected with the voltage input end of the PFC boost circuit, the voltage output end of the PFC boost circuit is connected with the voltage input end of the flyback circuit, the voltage output end of the flyback circuit is connected with the voltage input end of the feedback circuit and the voltage input end of the DALI module; the flyback circuit comprises a flyback primary control circuit and a flyback secondary rectifier circuit; The VCC power supply circuit comprises a third electrolytic capacitor EC3, the flyback circuit comprises a control chip U2, the switching power supply circuit further comprises a protection circuit, the protection circuit comprises a PNP type triode Q3, a fifth diode D5, a ninth resistor R9, a seventh resistor R7, an eighth resistor R8, a tenth resistor R10, a first voltage stabilizer U3 and an eleventh resistor R11. The positive electrode of the third electrolytic capacitor EC3 is connected with the emitter of the PNP type triode Q3, the collector of the PNP type triode Q3 is connected with the control chip U2, so as to provide a stable power supply for the control chip U2; the collector of the PNP type triode Q3 is also connected with the positive electrode of the fifth diode D5, the negative electrode of the fifth diode D5 is connected with the first end of the ninth resistor R9, the second end of the ninth resistor R9 is connected with the reference electrode of the first voltage stabilizer U3; the first end of the seventh resistor R7 is connected with the high voltage end HV of the AC rectifier circuit, the second end of the seventh resistor R7 is connected with the reference electrode of the first voltage stabilizer U3 and the first end of the eighth resistor R8, the anode of the first voltage stabilizer U3 is connected with the second end of the eighth resistor R8, the second end of the ninth resistor R9 and the ground; the first end of the tenth resistor R10 is connected with the cathode of the first voltage stabilizer U3, the second end of the tenth resistor R10 is connected with one end of the eleventh resistor R11 and the gate of the PNP type triode Q3, the other end of the eleventh resistor R11 is connected with the positive electrode of the third electrolytic capacitor EC3 and the emitter of the PNP type triode Q3.

2. The switching power supply circuit according to claim 1, characterized by The protection circuit further comprises an eighth capacitor C8; one end of the eighth capacitor C8 is connected with the second end of the seventh resistor R7 and the second end of the ninth resistor R9, the other end of the eighth capacitor C8 is grounded.

3. The switching power supply circuit according to claim 1, characterized by The reference voltage of the first voltage stabilizer U3 is 2.5V.

4. The switching power supply circuit according to claim 1, characterized by The PFC boost circuit comprises a first electrolytic capacitor EC1, the flyback primary control circuit comprises a primary winding and an N-channel MOS tube Q2; the positive electrode of the first electrolytic capacitor EC1 is connected with the first end of the primary winding, and the negative electrode of the first electrolytic capacitor EC1 is grounded; the second end of the primary winding is connected with the drain of the N-channel MOS tube Q2, and the source of the N-channel MOS tube Q2 is grounded; the gate of the N-channel MOS tube Q2 is connected with the control chip U2.

5. The switching power supply circuit according to claim 4, characterized in that, The flyback secondary rectifier circuit comprises a first secondary winding and a second electrolytic capacitor EC2; a negative electrode of the second electrolytic capacitor EC2 is connected to a first end of the first secondary winding and the ground, and a positive electrode of the second electrolytic capacitor EC2 is connected to a second end of the first secondary winding and the DALI module.

6. The switching power supply circuit according to claim 5, characterized in that, The flyback secondary rectifier circuit further comprises a twenty-first resistor R21; a first end of the twenty-first resistor R21 is connected to the positive electrode of the second electrolytic capacitor EC2 and the DALI module, a second end of the twenty-first resistor R21 is connected to the ground and the negative electrode of the second electrolytic capacitor EC2; a capacitance of the second electrolytic capacitor EC2 is less than a capacitance of the first electrolytic capacitor EC1.

7. The switching power supply circuit according to claim 4, characterized by The VCC power supply circuit further comprises a second secondary winding, the second secondary winding is coupled with the primary winding; a first end of the second secondary winding is connected to the ground and a negative electrode of a third electrolytic capacitor EC3, and a second end of the second secondary winding is connected to a positive electrode of the third electrolytic capacitor EC3, one end of an eleventh resistor R11 and an emitter of a PNP triode Q3.

8. The switching power supply circuit according to claim 4, characterized by The flyback primary control circuit further comprises a second diode D2, a second capacitor C2 and a third resistor R3; a positive electrode of the second diode D2 is connected to a drain of an N-channel MOS Q2 and a second end of the primary winding, a negative electrode of the second diode D2 is connected to one end of the second capacitor C2 and one end of the third resistor R3 at the same time, and the other end of the second capacitor C2 and the other end of the third resistor R3 are connected to a first end of the primary winding.

9. The switching power supply circuit according to claim 1, characterized by The flyback primary control circuit further comprises a sixth resistor R6, a first end of the sixth resistor R6 is connected to a high voltage end HV of the AC rectifier circuit, and a second end of the sixth resistor R6 is connected to the control chip U2 to provide a starting voltage for the control chip U2.

10. A dimming device, characterized by The light fixture and the switching power supply circuit of any one of claims 1 to 9 are connected. The light fixture and the switching power supply circuit of any one of claims 1 to 9 are connected.

Images