LED driving power supply power-off maintaining circuit

Abstract

The utility model relates to the technical field of LED driving power supply integrated circuits, in particular to an LED driving power supply power-off holding circuit, which comprises an AC-to-DC constant voltage module, a first power utilization unit, at least one second power utilization unit and at least one voltage conversion unit, and the AC-to-DC constant voltage module comprises a main output unit with an energy storage function and at least one auxiliary output unit; the main output unit is electrically connected with the first power utilization unit; one auxiliary output unit, one voltage conversion unit and one second power utilization unit form a group and are electrically connected in sequence; when the AC-to-DC constant voltage module is powered off and the voltage of the main output unit drops to a preset threshold value, the main output unit generates a first maintaining voltage, and the voltage conversion unit receives the first maintaining voltage through the auxiliary output unit and generates a second maintaining voltage; and power can be supplied to the power utilization units with different power supply voltages for a period of time after permanent power failure is confirmed, so that more functional modules have a power failure time delay function and protection misoperation is prevented.

Description

Technical Field

[0001] The utility model relates to the technical field of LED drive power integrated circuits, in particular to a LED drive power supply power failure maintenance circuit. Background Art

[0002] LED driver power supply is a voltage converter that converts power into a specific voltage and current to drive the LED to emit light. The input of a general LED driver power supply includes high-voltage industrial frequency AC (i.e., mains), low-voltage DC, high-voltage DC, low-voltage high-frequency AC (such as the output of an electronic transformer), etc. The output of the LED driver power supply is mostly a constant current source, which can change the voltage as the forward voltage drop of the LED changes. The core components of the LED power supply include switch controllers, inductors, MOS tubes, feedback resistors, input filters, output filters, etc., and according to the requirements of different occasions, there are also integrated overvoltage protection circuits, input undervoltage protection circuits, LED open circuit protection circuits, overcurrent protection circuits, signal control circuits, etc.

[0003] In order to maintain the power supply for a longer period of time after the power supply circuit is powered off, the existing LED driver power supply integrates a power-off maintenance circuit in order to allow the MCU of the signal control circuit to record all the working states of the LED driver power supply before the power-off so that the state of the last power-off can be fully read after the next power-on. However, the existing power-off maintenance circuit usually adopts the method of setting an electrolytic capacitor in the power supply circuit to release electric energy after power-off to maintain the power supply of the signal control circuit.

[0004] However, when the power supply circuit is unstable and a temporary power outage occurs, the electrolytic capacitor will supply power at the same time. If the power supply circuit is restored at this time, the power supply will be superimposed on the power supply of the electrolytic capacitor, which may trigger overcurrent or overvoltage protection. Even some circuits that need to use the power supply voltage to divide the voltage to obtain a reference value will be misjudged. The capacity of the electrolytic capacitor usually needs to be selected according to the object it supplies power to, and is not suitable for power supply with multiple output voltages. Utility Model Content

[0005] In view of the above-mentioned defects, the purpose of the utility model is to propose an LED driving power supply power-off maintenance circuit, which can supply power to power units with different supply voltages for a period of time after confirming that the power is permanently off, so that more functional modules have a power-off delay function and prevent false protection operations.

[0006] To achieve this purpose, the utility model adopts the following technical solutions:

[0007] A power-off maintenance circuit for an LED driving power supply comprises an AC-to-DC constant voltage module, a first power unit, at least one second power unit and at least one voltage conversion unit, wherein the AC-to-DC constant voltage module comprises a main output unit with an energy storage function and at least one auxiliary output unit; an output end of the main output unit is electrically connected to an input end of the first power unit;

[0008] One auxiliary output unit, one voltage conversion unit and one second power-consuming unit form a group; the power-off maintenance end of the main output unit and the output end of the auxiliary output unit are electrically connected to the input end of the voltage conversion unit, the input end of the second power-consuming unit is electrically connected to the output end of the voltage conversion unit, and the feedback end of the main output unit is electrically connected to the output end of one of the voltage conversion units;

[0009] When the AC to DC constant voltage module is powered off and the voltage of the main output unit drops to a preset threshold, the main output unit generates a first maintenance voltage, and the voltage conversion unit receives the first maintenance voltage through the auxiliary output unit and generates a second maintenance voltage.

[0010] Furthermore, when there is only one auxiliary output unit, one voltage conversion unit and one second power-consuming unit form a group, and the output end of the auxiliary output unit is electrically connected to the input ends of the plurality of voltage conversion units respectively.

[0011] Furthermore, the AC to DC constant voltage module also includes a front-side processing circuit, a transformer T1 and a transformer T2 for rectifying, reducing and stabilizing an external AC power supply; the output end of the front-side processing circuit is electrically connected to the primary side windings of the transformer T1 and the transformer T2, respectively, and the secondary side windings of the transformer T1 and the transformer T2 are electrically connected to the input ends of the main output unit and the auxiliary output unit, respectively.

[0012] Further, the main output unit includes a resistor R12, a resistor R35, a capacitor C2, an electrolytic capacitor EC2, a diode D8 and a power-off maintenance judgment circuit; the anode of the diode D8 and the cathode of the electrolytic capacitor EC2 are used as the input end of the main output unit, the positive electrode of the electrolytic capacitor EC2 is used as the output end of the main output unit, the power-off maintenance end of the power-off maintenance judgment circuit is used as the power-off maintenance end of the main output unit, and the feedback end of the power-off maintenance judgment circuit is used as the feedback end of the main output unit;

[0013] One end of the resistor R12 and one end of the resistor R35 are electrically connected to the anode of the diode D8, the other end of the resistor R12 and the other end of the resistor R35 are electrically connected to one end of the capacitor C2, and the other end of the capacitor C2, the cathode of the diode D8, and the positive electrode of the electrolytic capacitor EC2 are electrically connected to the input end of the power-off maintenance judgment circuit;

[0014] The power-off maintenance judgment circuit is used to generate the first maintenance voltage when the voltage of the power-off maintenance judgment circuit drops to the preset threshold value when the AC-to-DC constant voltage module is powered off.

[0015] Further, the power-off maintenance judgment circuit includes a resistor R2, a resistor R4, a resistor R5, a capacitor C1, a capacitor C22 and a MOS tube Q2; one end of the resistor R4 is used as an input end of the power-off maintenance judgment circuit, the other end of the resistor R4 is used as a power-off maintenance end of the power-off maintenance judgment circuit, and the gate of the MOS tube Q4 is used as a feedback end of the power-off maintenance judgment circuit;

[0016] One end of the resistor R4 and one end of the resistor R5 are electrically connected to one end of the resistor R2, the other end of the resistor R4, the other end of the resistor R5, one end of the capacitor C1, and one end of the capacitor C22 are electrically connected to the source of the MOS transistor Q2, the other end of the resistor R2 is electrically connected to the drain of the MOS transistor Q2, and the other end of the capacitor C1 and the other end of the capacitor C22 are grounded;

[0017] When the MOS transistor Q2 is turned on, the first sustaining voltage is generated.

[0018] Furthermore, the MOS tube Q2 is a depletion-type MOS tube.

[0019] Further, the auxiliary output unit includes a capacitor C16, a capacitor C17, a capacitor C18, a capacitor C21, an inductor L2, a diode D10, a resistor R27 and an electrolytic capacitor CE3; one end and the other end of the capacitor C21 are used as input ends of the auxiliary output unit, and the positive electrode of the electrolytic capacitor CE3 is used as an output end of the auxiliary output unit;

[0020] One end of the capacitor C21 is electrically connected to one end of the inductor L2, the other end of the inductor L2 is electrically connected to the anode of the diode D10, the cathode of the diode D10, one end of the capacitor C16, one end of the capacitor C17, one end of the capacitor C18, and one end of the resistor R27 are all electrically connected to the positive electrode of the electrolytic capacitor CE3, and the other end of the capacitor C21, the other end of the capacitor C16, the other end of the capacitor C17, the other end of the capacitor C18, and the other end of the resistor R27 are all electrically connected to the negative electrode of the electrolytic capacitor CE3.

[0021] Furthermore, the voltage conversion unit includes a capacitor C6, a capacitor C11, a capacitor C12 and a linear voltage regulator chip U3; the input end of the linear voltage regulator chip U3 is used as the input end of the voltage conversion unit, and the output end of the linear voltage regulator chip U3 is used as the output end of the voltage conversion unit;

[0022] One end of the capacitor C11 is electrically connected to the input end of the linear voltage regulator chip U3, one end of the capacitor C6 and one end of the capacitor C12 are electrically connected to the output end of the linear voltage regulator chip U3, and the other end of the capacitor C11, the other end of the capacitor C6, the other end of the capacitor C12 and the ground end of the linear voltage regulator chip U3 are all grounded.

[0023] Furthermore, the linear voltage regulator chip U3 is a 3.3V linear voltage regulator chip.

[0024] The technical solution provided by the utility model may include the following beneficial effects: generally, a plurality of power consumption units with different voltage level requirements are arranged inside an LED driving power supply, wherein the first power consumption unit is a power consumption unit that can directly use the voltage after power processing by an AC to DC constant voltage module, and the second power consumption unit is a power consumption unit that needs to convert the voltage after power processing by the AC to DC constant voltage module to a voltage level before it can supply power. Therefore, according to the different power requirements of different power consumption units, a sub-output unit, a voltage conversion unit and a second power consumption unit are used as a group to perform a voltage level conversion and power supply; therefore, when the LED driving power supply is normally supplied, the power is processed by the AC to DC constant voltage module, and then the main output unit and the sub-output unit output electric energy respectively according to the power demand; when a power outage occurs, the AC to DC constant voltage module cannot be connected to an external AC power supply for conversion and power supply. At this time, the energy storage of the main output unit is used to prepare for power supply, and first It determines whether its own voltage can drop to the preset threshold value. If it is a temporary power outage, the AC to DC constant voltage module will quickly resume power supply, and the voltage of the main output unit will quickly return to a normal level; if the voltage of the main output unit drops to the preset threshold value, it represents a permanent power outage. In addition to generating a first maintenance voltage to supply power to the first power unit it supplies power to, it also supplies the first maintenance voltage to the output end of the auxiliary output unit, that is, the input end of the voltage conversion unit, so that the voltage conversion unit maintains voltage conversion and supplies power to the second power unit; thereby, each power unit with different supply voltages in the LED driver power supply can maintain power supply for a period of time after power outage, so that it can record the working status before power outage to prevent data loss when power is restored, so that more functional modules have a power-off delay function, and improve the data storage stability of the LED driver power supply; more importantly, a power-off type judgment is also set to effectively prevent the impact of temporary power outages on the internal circuit and cause protection malfunctions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the principle of a LED drive power supply power-off maintenance circuit in one embodiment of the utility model. Figure 1 .

[0026] Figure 2 Yes Figure 1 The principle of a LED drive power supply power-off maintenance circuit shown in Figure 2 .

[0027] Figure 3 Yes Figure 1 The schematic diagram of the AC to DC constant voltage module is shown.

[0028] Figure 4 Yes Figure 3 The circuit diagram of the main output unit is shown.

[0029] Figure 5 Yes Figure 1 The circuit diagram of the voltage conversion unit is shown.

[0030] Wherein: AC to DC constant voltage module 1, first power unit 2, voltage conversion unit 3, second power unit 4, main output unit 11, auxiliary output unit 12, front side processing circuit 13, transformer T1, transformer T2, resistor R12, resistor R35, capacitor C2, electrolytic capacitor EC2, diode D8, power failure maintenance judgment circuit 111, resistor R2, resistor R4, resistor R5, capacitor C1, capacitor C22, MOS tube Q2, capacitor C16, capacitor C17, capacitor C18, capacitor C21, inductor L2, diode D10, resistor R27, electrolytic capacitor CE3, capacitor C6, capacitor C11, capacitor C12, linear voltage regulator chip U3. DETAILED DESCRIPTION

[0031] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0032] In the description of the embodiments of the present invention, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0033] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0034] Combine the following Figures 1 to 5 , describing an LED driving power supply power-off maintenance circuit of an embodiment of the utility model.

[0035] A power-off maintenance circuit for an LED driving power supply comprises an AC-to-DC constant voltage module 1, a first power unit 2, at least one second power unit 4 and at least one voltage conversion unit 3, wherein the AC-to-DC constant voltage module 1 comprises a main output unit 11 with an energy storage function and at least one auxiliary output unit 12; an output end of the main output unit 11 is electrically connected to an input end of the first power unit 2;

[0036] A sub-output unit 12, a voltage conversion unit 3 and a second power unit 4 form a group; the power-off maintenance end of the main output unit 11 and the output end of the sub-output unit 12 are electrically connected to the input end of the voltage conversion unit 3, the input end of the second power unit 4 is electrically connected to the output end of the voltage conversion unit 3, and the feedback end of the main output unit 11 is electrically connected to the output end of one of the voltage conversion units 3;

[0037] When the AC to DC constant voltage module 1 is powered off and the voltage of the main output unit 11 drops to a preset threshold, the main output unit 11 generates a first maintenance voltage, and the voltage conversion unit 3 receives the first maintenance voltage through the auxiliary output unit 12 and generates a second maintenance voltage.

[0038] The utility model proposes a preferred embodiment of a LED driving power supply power-off maintenance circuit, such as Figure 1As shown, a general LED driving power supply is internally provided with many power consumption units with different voltage level requirements, wherein the first power consumption unit 2 is a power consumption unit that can directly use the voltage after the power supply processing by the AC to DC constant voltage module 1, and the second power consumption unit 2 is a power consumption unit that needs to convert the voltage after the power supply processing by the AC to DC constant voltage module 1 to a voltage level before supplying power. Therefore, according to the different power demand of different power consumption units, a sub-output unit 12, a voltage conversion unit 3 and a second power consumption unit 4 are used as a group to perform a voltage level conversion and power supply; therefore, when the LED driving power supply is normally powered, the AC to DC constant voltage module 1 performs power supply processing, and then the main output unit 11 and the sub-output unit 12 output electric energy respectively according to the power demand; when encountering a power outage, the AC to DC constant voltage module 1 cannot be connected to an external AC power supply for conversion and power supply. At this time, the energy storage of the main output unit 11 is used to prepare for power supply, and first judges its own voltage Whether it can drop to the preset threshold value, if it is a temporary power outage, the AC to DC constant voltage module 1 will quickly resume power supply, and the voltage of the main output unit 11 will quickly return to a normal level; if the voltage of the main output unit 11 drops to the preset threshold value, it represents a permanent power outage. In addition to generating a first maintenance voltage to supply power to the first power unit 2 powered by itself, the first maintenance voltage is also supplied to the output end of the auxiliary output unit 12, that is, the input end of the voltage conversion unit 3, so that the voltage conversion unit 3 maintains voltage conversion and supplies power to the second power unit 4; thereby, each power unit with different supply voltages in the LED driving power supply can maintain power supply for a period of time after power failure, so that it can record the working status before power failure to prevent data loss when power is restored, so that more functional modules have a power failure delay function, and the data storage stability of the LED driving power supply is improved; more importantly, a power failure type judgment is also set to effectively prevent the impact of temporary power failure on the internal circuit and cause protection malfunction.

[0039] Furthermore, when there is only one auxiliary output unit 12 , one voltage conversion unit 3 and one second power unit 4 form a group, and the output end of the auxiliary output unit 12 is electrically connected to the input ends of the plurality of voltage conversion units 3 , respectively.

[0040] In this embodiment, Figure 2 As shown, when the voltage levels required by the power-consuming units of the LED driving power supply are not rich, that is, when the step-down voltage of only one auxiliary output unit 12 can meet the input voltage requirements of the voltage conversion unit 3 for multiple voltage conversions, one voltage conversion unit 3 and one second power-consuming unit 4 are grouped as one voltage level, and the output end of the auxiliary output unit 12 is electrically connected to the input ends of multiple voltage conversion units 3 respectively, thereby simplifying the circuit structure of the LED driving power supply.

[0041] Furthermore, the AC to DC constant voltage module 1 also includes a front-side processing circuit 13, a transformer T1 and a transformer T2 for rectifying, reducing and stabilizing an external AC power supply; the output end of the front-side processing circuit 13 is electrically connected to the primary side windings of the transformer T1 and the transformer T2, respectively, and the secondary side windings of the transformer T1 and the transformer T2 are electrically connected to the input ends of the main output unit 11 and the auxiliary output unit 12, respectively.

[0042] In this embodiment, the main output unit 11 and the auxiliary output unit 12 of the AC to DC constant voltage module 1 are divided by a transformer. Figure 3 and Figure 5 As shown, taking only one auxiliary output unit 12 as an example (when there are multiple auxiliary output units, transformers T2 with different windings can be added), the AC to DC constant voltage module 1 usually first uses a front-side processing circuit 13 for rectifying, reducing and stabilizing an external AC power supply to process the waveform of the AC power supply, and then obtains a constant DC voltage, which is then reduced by transformers with different windings (transformers T1 and T2) to match the subsequent main output unit 11 and negative output unit 12; wherein the main output unit 11 can directly output power after being reduced by the transformer T1, while the auxiliary output unit 12 needs further voltage conversion by the voltage conversion unit 3 after being reduced by the transformer T2 to obtain a voltage that best matches the second power unit 4.

[0043] Further, the main output unit 11 includes a resistor R12, a resistor R35, a capacitor C2, an electrolytic capacitor EC2, a diode D8 and a power-off maintenance judgment circuit 111; the anode of the diode D8 and the cathode of the electrolytic capacitor EC2 are used as the input end of the main output unit 11, the positive electrode of the electrolytic capacitor EC2 is used as the output end of the main output unit 11, the power-off maintenance end of the power-off maintenance judgment circuit 111 is used as the power-off maintenance end of the main output unit 11, and the feedback end of the power-off maintenance judgment circuit 111 is used as the feedback end of the main output unit 11;

[0044] One end of the resistor R12 and one end of the resistor R35 are electrically connected to the anode of the diode D8, the other end of the resistor R12 and the other end of the resistor R35 are electrically connected to one end of the capacitor C2, the other end of the capacitor C2, the cathode of the diode D8, and the positive electrode of the electrolytic capacitor EC2 are electrically connected to the input end of the power-off maintenance judgment circuit 111;

[0045] The power-off maintenance judgment circuit 111 is used to generate a first maintenance voltage when the voltage of the power-off maintenance judgment circuit 111 drops to a preset threshold value when the AC-to-DC constant voltage module 1 is powered off.

[0046] In this embodiment, Figure 4As shown, when the AC to DC constant voltage module 1 is powered normally, the diode D8 is turned on, and the charging and discharging circuit composed of the resistor R12, the resistor R35 and the capacitor C2 charges the capacitor C2 and the electrolytic capacitor EC2. At the same time, the electrolytic capacitor EC2 plays a role in voltage stabilization, so that the main output unit 11 stably outputs the VBUS power supply voltage, so that the power-off maintenance judgment circuit 111 is between the VBUS voltage and the feedback voltage of the voltage conversion unit 3 (such as Figure 3 V3), the power-off maintenance terminal (such as +15V in the figure) does not output the first maintenance voltage; only when the AC to DC constant voltage module 1 is powered off, the VBUS voltage received by the power-off maintenance judgment circuit 111 begins to decrease, and when it drops to a preset threshold, the power-off maintenance judgment circuit 111 outputs the first maintenance voltage to the auxiliary output unit 12, that is, for example, when the power is off from +15V to +6V, the power-off maintenance terminal outputs +6V, so that the auxiliary output unit 12 obtains the maintenance voltage, and the subsequent voltage conversion unit 3 continues to convert the voltage for power supply.

[0047] Furthermore, the power-off maintenance judgment circuit 111 includes a resistor R2, a resistor R4, a resistor R5, a capacitor C1, a capacitor C22 and a MOS transistor Q2; one end of the resistor R4 is used as an input end of the power-off maintenance judgment circuit 111, the other end of the resistor R4 is used as a power-off maintenance end of the power-off maintenance judgment circuit 111, and the gate of the MOS transistor Q4 is used as a feedback end of the power-off maintenance judgment circuit 111;

[0048] One end of the resistor R4 and one end of the resistor R5 are electrically connected to one end of the resistor R2, the other end of the resistor R4, the other end of the resistor R5, one end of the capacitor C1, and one end of the capacitor C22 are electrically connected to the source of the MOS transistor Q2, the other end of the resistor R2 is electrically connected to the drain of the MOS transistor Q2, and the other end of the capacitor C1 and the other end of the capacitor C22 are grounded;

[0049] When the MOS transistor Q2 is turned on, a first sustain voltage is generated.

[0050] In this embodiment, the preset threshold of the power-off maintenance judgment circuit 11 is actually the on-voltage of the MOS tube Q2, that is, for example, in normal operation, the gate voltage of Q2 is 3.3V, the source voltage is 15V, the Vgs voltage is -11.7V, Q2 is in the cut-off state, and the VBUS power cannot be transmitted to the +15V (power-off maintenance end) line through Q2; when the AC power is cut off, the source +15V voltage starts to lose power, and when it drops to +6V, Q2 starts to turn on, and the +6V voltage can be output to the auxiliary output unit 12.

[0051] Furthermore, the MOS tube Q2 is a depletion-type MOS tube.

[0052] In this embodiment, because the control modes of the depletion-type MOS tube and the enhancement-type MOS tube are different, the Vgs (gate voltage) of the depletion-type MOS tube can be controlled to be turned on by positive, zero, or negative voltages, while the enhancement-type MOS tube must make Vgs>Vgs(th) (gate threshold voltage). Therefore, the turn-on voltage applied to the gate of the depletion-type MOS tube can be positive, zero, or negative voltage, while the turn-on voltage of the enhancement-type MOS tube can only be positive voltage. Therefore, the MOS tube Q2 uses a depletion-type MOS tube, which can be applicable to more scenarios where different voltages drive the turn-on.

[0053] Further, the auxiliary output unit 12 includes a capacitor C16, a capacitor C17, a capacitor C18, a capacitor C21, an inductor L2, a diode D10, a resistor R27 and an electrolytic capacitor CE3; one end and the other end of the capacitor C21 are used as input ends of the auxiliary output unit 12, and the positive electrode of the electrolytic capacitor CE3 is used as an output end of the auxiliary output unit 12;

[0054] One end of capacitor C21 is electrically connected to one end of inductor L2, the other end of inductor L2 is electrically connected to the anode of diode D10, the cathode of diode D10, one end of capacitor C16, one end of capacitor C17, one end of capacitor C18, and one end of resistor R27 are all electrically connected to the positive electrode of electrolytic capacitor CE3, and the other end of capacitor C21, the other end of capacitor C16, the other end of capacitor C17, the other end of capacitor C18, and the other end of resistor R27 are all electrically connected to the negative electrode of electrolytic capacitor CE3.

[0055] In this embodiment, the auxiliary output unit 12 mainly performs a series of voltage processing such as filtering and voltage stabilization on the voltage received from the secondary winding of the transformer T2 during normal power supply, and outputs a stable voltage to the voltage conversion unit 3 for conversion by the electrolytic capacitor CE3; at the same time, when the power is off, the capacitor CE3 stabilizes the first maintenance voltage transmitted from the power-off maintenance end of the main output unit 11 and outputs it to the voltage conversion unit 3.

[0056] Furthermore, the voltage conversion unit 3 includes a capacitor C6, a capacitor C11, a capacitor C12 and a linear voltage regulator chip U3; the input end of the linear voltage regulator chip U3 is used as the input end of the voltage conversion unit 3, and the output end of the linear voltage regulator chip U3 is used as the output end of the voltage conversion unit 3;

[0057] One end of capacitor C11 is electrically connected to the input end of the linear voltage regulator chip U3, one end of capacitor C6 and one end of capacitor C12 are electrically connected to the output end of the linear voltage regulator chip U3, and the other end of capacitor C11, the other end of capacitor C6, the other end of capacitor C12 and the ground end of the linear voltage regulator chip U3 are all grounded.

[0058] In this embodiment, Figure 5As shown, the voltage conversion unit 3 has the same conversion principle when it is powered normally and when it is powered off, and it converts the voltage into the target voltage according to the specification of the linear voltage regulator chip U3.

[0059] Furthermore, the linear voltage regulator chip U3 is a 3.3V linear voltage regulator chip.

[0060] In this embodiment, for the LED driving power supply, the power-consuming unit that most needs the power-off delay function is the integrated processor module (such as MCU), whose operating voltage is 3.3V. Therefore, when simplifying the power-off delay function to save costs, only the power-off delay function of the processor module is retained. Therefore, at this time, the linear voltage regulator chip U3 should be selected with a 3.3V specification.

[0061] Other structures and operations of the LED driving power supply power-off maintenance circuit according to the embodiment of the utility model are known to ordinary technicians in the field and will not be described in detail here.

[0062] In the description of this specification, the description with reference to the terms "embodiment", "example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0063] Although the embodiments of the present invention have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A LED driving power supply power-off maintenance circuit, characterized in that: It includes an AC-to-DC constant voltage module, a first power unit, at least one second power unit and at least one voltage conversion unit, wherein the AC-to-DC constant voltage module includes a main output unit with an energy storage function and at least one auxiliary output unit; the output end of the main output unit is electrically connected to the input end of the first power unit; One auxiliary output unit, one voltage conversion unit and one second power-consuming unit form a group; the power-off maintenance end of the main output unit and the output end of the auxiliary output unit are electrically connected to the input end of the voltage conversion unit, the input end of the second power-consuming unit is electrically connected to the output end of the voltage conversion unit, and the feedback end of the main output unit is electrically connected to the output end of one of the voltage conversion units; When the AC to DC constant voltage module is powered off and the voltage of the main output unit drops to a preset threshold, the main output unit generates a first maintenance voltage, and the voltage conversion unit receives the first maintenance voltage through the auxiliary output unit and generates a second maintenance voltage.

2. The LED driving power supply power-off maintenance circuit according to claim 1, characterized in that: When there is only one auxiliary output unit, one voltage conversion unit and one second power-consuming unit form a group, and the output end of the auxiliary output unit is electrically connected to the input ends of the plurality of voltage conversion units respectively.

3. The LED driving power supply power-off maintenance circuit according to claim 2, characterized in that: The AC to DC constant voltage module also includes a front-side processing circuit, a transformer T1 and a transformer T2 for rectifying, reducing and stabilizing an external AC power supply; the output end of the front-side processing circuit is electrically connected to the primary side windings of the transformer T1 and the transformer T2, respectively, and the secondary side windings of the transformer T1 and the transformer T2 are electrically connected to the input ends of the main output unit and the auxiliary output unit, respectively.

4. The LED driving power supply power-off maintenance circuit according to claim 3, characterized in that: The main output unit includes a resistor R12, a resistor R35, a capacitor C2, an electrolytic capacitor EC2, a diode D8 and a power-off maintenance judgment circuit; the anode of the diode D8 and the cathode of the electrolytic capacitor EC2 are used as the input end of the main output unit, the positive electrode of the electrolytic capacitor EC2 is used as the output end of the main output unit, the power-off maintenance end of the power-off maintenance judgment circuit is used as the power-off maintenance end of the main output unit, and the feedback end of the power-off maintenance judgment circuit is used as the feedback end of the main output unit; One end of the resistor R12 and one end of the resistor R35 are electrically connected to the anode of the diode D8, the other end of the resistor R12 and the other end of the resistor R35 are electrically connected to one end of the capacitor C2, and the other end of the capacitor C2, the cathode of the diode D8, and the positive electrode of the electrolytic capacitor EC2 are electrically connected to the input end of the power-off maintenance judgment circuit; The power-off maintenance judgment circuit is used to generate the first maintenance voltage when the voltage of the power-off maintenance judgment circuit drops to the preset threshold value when the AC-to-DC constant voltage module is powered off.

5. The LED driving power supply power-off maintenance circuit according to claim 4, characterized in that: The power-off maintenance judgment circuit comprises a resistor R2, a resistor R4, a resistor R5, a capacitor C1, a capacitor C22 and a MOS tube Q2; one end of the resistor R4 is used as an input end of the power-off maintenance judgment circuit, the other end of the resistor R4 is used as a power-off maintenance end of the power-off maintenance judgment circuit, and the gate of the MOS tube Q4 is used as a feedback end of the power-off maintenance judgment circuit; One end of the resistor R4 and one end of the resistor R5 are electrically connected to one end of the resistor R2, the other end of the resistor R4, the other end of the resistor R5, one end of the capacitor C1, and one end of the capacitor C22 are electrically connected to the source of the MOS transistor Q2, the other end of the resistor R2 is electrically connected to the drain of the MOS transistor Q2, and the other end of the capacitor C1 and the other end of the capacitor C22 are grounded; When the MOS transistor Q2 is turned on, the first sustaining voltage is generated.

6. The LED driving power supply power-off maintenance circuit according to claim 5, characterized in that: The MOS tube Q2 is a depletion type MOS tube.

7. The LED driving power supply power-off maintenance circuit according to claim 3, characterized in that: The auxiliary output unit includes a capacitor C16, a capacitor C17, a capacitor C18, a capacitor C21, an inductor L2, a diode D10, a resistor R27 and an electrolytic capacitor CE3; one end and the other end of the capacitor C21 are used as input ends of the auxiliary output unit, and the positive electrode of the electrolytic capacitor CE3 is used as the output end of the auxiliary output unit; One end of the capacitor C21 is electrically connected to one end of the inductor L2, the other end of the inductor L2 is electrically connected to the anode of the diode D10, the cathode of the diode D10, one end of the capacitor C16, one end of the capacitor C17, one end of the capacitor C18, and one end of the resistor R27 are all electrically connected to the positive electrode of the electrolytic capacitor CE3, and the other end of the capacitor C21, the other end of the capacitor C16, the other end of the capacitor C17, the other end of the capacitor C18, and the other end of the resistor R27 are all electrically connected to the negative electrode of the electrolytic capacitor CE3.

8. The LED driving power supply power-off maintenance circuit according to claim 1, characterized in that: The voltage conversion unit includes a capacitor C6, a capacitor C11, a capacitor C12 and a linear voltage regulator chip U3; the input end of the linear voltage regulator chip U3 is used as the input end of the voltage conversion unit, and the output end of the linear voltage regulator chip U3 is used as the output end of the voltage conversion unit; One end of the capacitor C11 is electrically connected to the input end of the linear voltage regulator chip U3, one end of the capacitor C6 and one end of the capacitor C12 are electrically connected to the output end of the linear voltage regulator chip U3, and the other end of the capacitor C11, the other end of the capacitor C6, the other end of the capacitor C12 and the ground end of the linear voltage regulator chip U3 are all grounded.

9. The LED driving power supply power-off maintenance circuit according to claim 8, characterized in that: The linear voltage regulator chip U3 is a 3.3V linear voltage regulator chip.

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