Circuit that can change the capacitor voltage division between the input / output side of the isolated LED driver power supply

Abstract

The present invention relates to the technical field of LED driver power supply, and provides a circuit capable of changing the capacitor voltage division between the input and output sides of an isolated LED driver power supply and the ground, including a primary side circuit for accessing an AC input; wherein the circuit output end of the primary side circuit is connected to the input end of an isolation transformer, and a capacitor voltage division circuit is arranged between the ground wire of the primary side circuit; the capacitor voltage division circuit is used to set a voltage division ratio, and the voltage division ratio is used to change the output voltage of the primary side circuit; the isolation transformer is used to transform the output voltage of the primary side circuit; wherein the output end of the isolation transformer is connected to a secondary side circuit; and the secondary side circuit is used to output a DC current. Through the circuit of the present invention, a lightning surge protection circuit can select a discharge tube with a lower operating voltage to improve the lightning protection effect, reduce the residual voltage, and better protect the subsequent circuit and load. The afterglow problem can also be solved by increasing the capacity of the output to ground capacitor, and no afterglow can be achieved at a lower cost.

Description

Technical Field

[0001] The invention relates to the field of LED driving power supplies, and in particular to a circuit capable of changing the voltage division of a capacitor between an input / output side and a ground of an isolated LED driving power supply. Background Art

[0002] At present, as the main power supply for most industrial equipment, communication equipment, household appliances, smart terminals and lighting equipment, switching power supply has always been an important technical indicator for lightning surge protection. An effective lightning surge protection circuit can not only protect the power supply itself from being damaged by lightning, but also protect the terminal equipment it powers to the greatest extent. At present, most lightning surge protection circuits use a varistor connected in series with a discharge tube to solve the common-mode lightning surge problem, and discharge the lightning surge current to the ground through the varistor and the discharge tube.

[0003] In actual circuits, there is capacitance to ground on both the input and output sides of the power supply. Due to the safety standard's requirements for leakage current, the capacitance of the input side to ground must be less than a certain capacitance value. If the capacitance value is exceeded, the leakage current does not meet the safety standard.

[0004] In addition, since there are parasitic capacitors or Y capacitors on the input / output side of the isolated LED driver power supply, these capacitors divide the voltage with the capacitance of the output side to the ground. If the voltage divided by the output side to the ground is greater than the conduction voltage of the LED lamp beads, the AC current will flow through these capacitors through the LED lamp beads and the parasitic capacitance of the lamp board to the ground when the dimming is turned off, resulting in afterglow. Therefore, in order to avoid the afterglow phenomenon, the capacitance of the output side to the ground is often much larger than the capacitance of the input to the ground, resulting in the test voltage being almost all applied to the input side to the ground when testing the primary and secondary withstand voltage. In order to ensure that the discharge tube is not broken down during the withstand voltage test, only discharge tubes with an action voltage close to the withstand voltage test voltage or higher can be selected.

[0005] The higher the action voltage of the discharge tube, the higher the action voltage of the lightning surge protection circuit will be, the slower the response time will be, the worse the lightning surge protection effect will be, the higher the residual voltage will be, and the lightning surge voltage lower than the action voltage of the discharge tube will have no protection effect at all, and the risk of product damage will increase greatly. Therefore, the existing circuit cannot meet the requirements of no afterglow, withstand voltage test and effective lightning surge protection at the same time. Summary of the invention

[0006] The present invention provides a circuit capable of changing the voltage division of the capacitor between the input / output side of an isolated LED driving power supply and the ground, which is used to solve the problem that the existing circuit cannot simultaneously meet the requirements of no afterglow, withstand voltage test and effective lightning surge protection.

[0007] The present invention provides a circuit capable of changing the voltage division of the capacitor between the input and output sides of an isolated LED driving power supply and ground, comprising:

[0008] A primary side circuit is used to access the AC input; wherein the circuit output end of the primary side circuit is connected to the input end of the isolation transformer, and a capacitive voltage divider circuit is provided between the ground wire of the primary side circuit;

[0009] A capacitor voltage divider circuit, used to set a voltage divider ratio, which is used to change the output voltage of the primary side circuit;

[0010] An isolation transformer is used to transform the output voltage of the primary side circuit; wherein the output end of the isolation transformer is connected to the secondary side circuit;

[0011] The secondary side circuit is used for DC output.

[0012] As an embodiment of the present invention: the capacitive voltage divider circuit is a first voltage divider circuit, a second voltage divider circuit or a third voltage divider circuit; wherein,

[0013] The first voltage divider circuit is composed of a first capacitor and a voltage-sensitive circuit in series;

[0014] The second voltage divider circuit is composed of a second capacitor and a gas discharge tube in series;

[0015] The third voltage-dividing circuit is composed of a third capacitor and a semiconductor element, wherein the semiconductor element has a voltage cutoff characteristic.

[0016] As an embodiment of the present invention: the primary side circuit includes a rectifier bridge; wherein the capacitor voltage divider circuit is connected to the front end of the rectifier bridge or the rear end of the rectifier bridge;

[0017] When the capacitor voltage divider circuit is connected to the front end of the rectifier bridge, the connection mode of the capacitor voltage divider circuit includes: the capacitor voltage divider circuit is set between any position of the live wire in front of the rectifier bridge and the ground wire, or the capacitor voltage divider circuit is set between any position of the neutral wire in front of the rectifier bridge and the ground wire;

[0018] When the capacitor voltage divider circuit is connected to the rear end of the rectifier bridge, the connection mode of the capacitor voltage divider circuit includes: the capacitor voltage divider circuit is set between any position of the positive loop of the rear end of the rectifier bridge and the ground wire, or the capacitor voltage divider circuit is set between any position of the negative loop of the rear end of the rectifier bridge and the ground wire;

[0019] As an embodiment of the present invention: the first voltage divider circuit is also used for an external digital control circuit, wherein the digital control circuit includes a microcontroller, a digital potentiometer, an analog circuit and a dimming controller;

[0020] A digital potentiometer is connected in series with the first voltage divider circuit, and an input end of the digital potentiometer is connected to the microcontroller, and the digital potentiometer is used to adjust the voltage division ratio of the first voltage divider circuit;

[0021] The input end of the microcontroller is connected to the analog circuit and the dimming controller, and the microcontroller is used to control the digital potentiometer to adjust the resistance value;

[0022] The output end of the analog controller is connected to the input end of the microcontroller, and the analog controller is used to receive the light-sensing signal of the dimming controller;

[0023] The output end of the dimming controller is connected to the input end of the analog controller, and the dimming controller is used to measure the photosensitive signal of the LEC lamp.

[0024] As an embodiment of the present invention: the microprocessor is provided with an analog operation array, wherein the analog operation array is used for:

[0025] Receive the dimming signal of the analog circuit and input it into the analog operation array to perform a voltage ratio operation function; wherein the dimming signal passes through the analog operation array to determine the brightness difference between the real-time brightness of the LED lamp and the expected brightness;

[0026] According to the voltage ratio operation function, an adjustment value of the voltage division ratio of at least one first voltage division circuit is determined, and when the digital potentiometer adjusts the voltage division ratio of the first voltage division circuit to meet the adjustment value, the brightness difference value returns to 0.

[0027] The beneficial effects of the present invention are:

[0028] Through the circuit of the present invention, the lightning surge protection circuit can select a discharge tube with a lower operating voltage to improve the lightning protection effect, reduce the residual voltage, and better protect the subsequent circuit and load. The afterglow problem can also be solved by increasing the capacity of the output to ground capacitor, and no afterglow can be achieved at a lower cost.

[0029] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings.

[0030] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0032] Figure 1 It is a circuit schematic diagram of a circuit for isolating the capacitor voltage division between the input and output sides of the LED driving power supply and the ground in an embodiment of the present invention;

[0033] Figure 2 Schematic diagram of three different voltage division modes in an embodiment of the present invention;

[0034] Figure 3 is a schematic structural diagram of a first voltage divider circuit in an embodiment of the present invention;

[0035] Figure 4 is a schematic structural diagram of a second voltage divider circuit in an embodiment of the present invention;

[0036] Figure 5 FIG. 4 is a schematic diagram of the structure of a third voltage divider circuit in an embodiment of the present invention. DETAILED DESCRIPTION

[0037] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0038] like Figure 1 As shown, this embodiment provides a circuit capable of changing the capacitor voltage division between the input and output sides of the isolated LED driving power supply and the ground, including:

[0039] A primary side circuit is used to access the AC input; wherein the circuit output end of the primary side circuit is connected to the input end of the isolation transformer, and a capacitive voltage divider circuit is provided between the ground wire of the primary side circuit;

[0040] A capacitor voltage divider circuit is used to set a voltage divider ratio, which is used to change the voltage divider ratio between the primary side circuit and the secondary side circuit during a withstand voltage test;

[0041] An isolation transformer is used to transform the output voltage of the primary side circuit; wherein the output end of the isolation transformer is connected to the secondary side circuit;

[0042] Secondary side circuit, power output end, connects LED lamp beads for DC output.

[0043] The principle of the above technical solution is:

[0044] like Figure 1As shown, a variable voltage divider circuit is added to the input side to the ground. The action voltage of the variable voltage divider circuit can be set according to the action voltage of the discharge tube of the lightning surge protection circuit and the highest input voltage of the power supply. The action voltage of the variable voltage divider circuit is set between the two. The voltage divider ratio of the variable voltage divider circuit can be set according to the size of the input / output side to ground capacitance, so the output side to ground capacitance can be increased to achieve no afterglow. A discharge tube with a lower action voltage can be selected to ensure the protection effect of the lightning surge protection circuit, and better protect the power supply itself and the terminal equipment. During the withstand voltage test, the variable voltage divider circuit is activated, the voltage divider ratio of the input / output side to the ground is changed, and the voltage divided by the input side to the ground is reduced to be lower than the action voltage of the discharge tube, so as to ensure that the withstand voltage test passes. The variable voltage divider circuit will not be activated when the power supply is working normally, and will not affect the leakage current of the power supply. Therefore, the variable voltage divider circuit can simultaneously meet the requirements of no afterglow, withstand voltage test and effective lightning surge protection.

[0045] In the specific implementation process, a voltage follower and a measurement controller can be set for the secondary side circuit. The in-phase end of the voltage follower is used to access the output voltage of the primary side circuit, and the output end of the voltage follower is connected to the capacitor voltage divider circuit; the measurement controller is set between the voltage follower and the capacitor voltage divider circuit to output real-time voltage divider ratio information. The voltage follower (also called a buffer amplifier) ​​is a special operational amplifier circuit that has the characteristics of high input impedance and low output impedance. Its main function is to keep the input voltage unchanged and pass it to the output end, that is, the output voltage "follows" the input voltage change. The in-phase end of the voltage follower is connected to the output voltage of the primary side circuit. This means that the voltage follower will monitor the output voltage of the primary side circuit. The output end of the voltage follower is connected to the capacitor voltage divider circuit. In this way, the output voltage of the primary side circuit is passed to the capacitor voltage divider circuit through the voltage follower, and the voltage of the primary side circuit will not be affected by the load of the capacitor voltage divider circuit. The function of the measurement controller is to monitor the real-time voltage divider ratio of the capacitor voltage divider circuit and output relevant information. This allows the system to understand the working status of the capacitor voltage divider circuit in real time and make necessary adjustments. The measurement controller is set between the voltage follower and the capacitor voltage divider circuit. It may contain an A / D converter, a microprocessor or other signal processing circuitry to process the output signal of the voltage follower.

[0046] In the specific implementation process, a voltage doubling circuit can also be set for the primary side circuit. The voltage doubling circuit is electrically connected to the capacitive voltage divider circuit and is used to output a voltage ratio signal of the capacitive voltage divider circuit, and control the output voltage of the primary side circuit based on the voltage ratio signal.

[0047] A voltage doubler is an electronic circuit that amplifies an input voltage by two or more times. This circuit is often used in applications that require a voltage higher than the input supply voltage. The voltage doubler is electrically connected to the capacitor divider, which means that the output of the voltage doubler affects the operation of the capacitor divider. The capacitor divider is used to provide a variable voltage divider between the input and output sides to ground to monitor and control the voltage level of the circuit. The voltage doubler controls the output voltage of the primary circuit based on the voltage ratio signal output by the capacitor divider. Specifically, the voltage doubler may adjust its output based on the voltage ratio signal to change the output voltage of the primary circuit. When the capacitor divider detects that the voltage ratio has changed, it outputs a signal to the voltage doubler. After receiving this signal, the voltage doubler adjusts its output voltage through internal control logic (which may include comparators, transistors, relays, etc.). By changing the output of the voltage doubler, the output voltage of the primary circuit can be indirectly controlled to meet the design requirements.

[0048] The beneficial effects of the above technical solution are:

[0049] Through the circuit of the present invention, the lightning surge protection circuit can select a discharge tube with a lower operating voltage to improve the lightning protection effect, reduce the residual voltage, and better protect the subsequent circuit and load. The afterglow problem can also be solved by increasing the capacity of the output to ground capacitor, and no afterglow can be achieved at a lower cost.

[0050] As an embodiment of the present invention: Figure 2 As shown, when the capacitor voltage divider circuit is specifically set, the capacitor voltage divider circuit is of three types, the first type of voltage divider circuit, the second type of voltage divider circuit or the third type of voltage divider circuit; wherein,

[0051] The first type of voltage divider circuit is composed of a first capacitor and a voltage-sensitive circuit in series, such as Figure 3 As shown;

[0052] The second type of voltage divider circuit is composed of a second capacitor and a gas discharge tube in series, such as Figure 4 As shown;

[0053] The third type of voltage divider circuit is composed of a third capacitor and a semiconductor element, wherein the semiconductor element has a voltage cutoff characteristic, such as Figure 5 shown.

[0054] The principle of the above technical solution is:

[0055] In the specific implementation process of the present invention, a variable voltage divider circuit is added between the input side circuit and the ground line. The variable voltage divider circuit is composed of a capacitor and a varistor or a gas discharge tube or a semiconductor device with a voltage isolation characteristic (such as a semiconductor discharge tube TSS, a bidirectional TVS and other devices) connected in series.

[0056] As attached Figure 1 As shown, the variable voltage divider circuit can be composed of the following three forms: 1. a varistor in series with a capacitor; 2. a gas discharge tube in series with a capacitor; 3. a semiconductor device in series with a capacitor. The following takes form 1, a varistor in series with a capacitor, as an example to illustrate the working principle of the variable voltage divider circuit (the working principles of forms 2 and 3 are the same as form 1). When the voltage across the variable voltage divider circuit is greater than the breakdown voltage of the varistor, the varistor is broken down and turned on, and the series capacitor is connected, thereby increasing the capacitance of the input side circuit to the ground wire and reducing the divided voltage. When the voltage across the variable voltage divider circuit is less than the breakdown voltage of the varistor, the varistor is not turned on, the series capacitor will not be connected, and there will be no effect on the circuit. Therefore, the action voltage of the variable voltage divider circuit can be set by the breakdown voltage of the varistor, and the voltage divider ratio of the variable voltage divider circuit can be set by the capacity of the series capacitor.

[0057] For the second type of voltage divider circuit, a voltage limiting circuit can be connected; wherein the voltage limiting circuit includes a first diode, a main control switch tube and a constant current control circuit, the anode of the first diode is connected to the input end of the primary side, the cathode of the first diode is connected between the source and the collector of the main control switch tube, the output end of the constant current control circuit is connected to the anode of the first diode, and the input end of the constant current control circuit is connected to the gate of the main control switch tube. The function of the voltage limiting circuit is that when the input voltage is within the normal range, the first diode is in a cut-off state (not conducting), so it will not affect the operation of the main control switch tube. The constant current control circuit adjusts the gate voltage of the main control switch tube as needed, thereby controlling the conduction and cutoff of the switch tube, thereby maintaining the constant current of the LED. If the input voltage is too high, the first diode will be turned on because it is a forward biased diode. When the first diode is turned on, it will direct the current between the source and the collector of the main control switch tube, which will cause the gate voltage of the switch tube to decrease (because the output end of the constant current control circuit is connected to the anode of the first diode, and the input end is connected to the gate of the switch tube). The gate voltage of the main control switch tube decreases, causing the switch tube to be cut off, thereby cutting off the current flowing to the LED and protecting the LED from being damaged by excessive current. The output of the second voltage divider circuit may be used to adjust the reference voltage of the constant current control circuit, so that the constant current of the LED can be maintained under different input voltage conditions. When a voltage abnormality is detected, the operating point of the constant current control circuit can be adjusted by changing the voltage divider ratio, further protecting the LED from damage.

[0058] While setting the voltage limiting circuit, the constant current control circuit of the voltage limiting circuit includes an input node, an output node and a plurality of LED drivers connected in series, the input node is used to connect the output end of the rectifier bridge of the primary side circuit; the output node is used to connect the input end of the isolation transformer; the plurality of LED drivers connected in series are connected in series between the input node and the output node, and the voltage difference between the input node and the output node is associated with the number of LED drivers. The output node of the constant current control circuit is connected to the input end of the isolation transformer. The isolation transformer is used to provide electrical isolation between the input side and the output side, and the output voltage can be adjusted as needed. The LED drivers are connected in series, and they are located between the input node and the output node. Each LED driver is responsible for controlling the current flowing through a specific LED or LED group. When the rectifier bridge outputs pulsating direct current, the current flows to the input end of the isolation transformer through the LED drivers connected in series. Each LED driver is capable of adjusting the current flowing through its corresponding LED to ensure that the current remains at a constant value to prevent the LED from being damaged or degraded due to current fluctuations. Since the LED drivers are connected in series, the voltage difference between the input node and the output node is distributed according to the number of LED drivers. Each LED driver consumes a certain voltage according to its design parameters, so the total voltage difference is distributed across all LED drivers. The constant current control circuit maintains a constant current by monitoring the current and adjusting the conduction level of the LED driver through a feedback mechanism. If the current exceeds the set value, the constant current control circuit will reduce the conduction level of the LED driver, thereby reducing the current; conversely, if the current is lower than the set value, the conduction level will be increased.

[0059] As an embodiment of the present invention: the primary side circuit includes a rectifier bridge; wherein the capacitor voltage divider circuit is connected to the front end of the rectifier bridge or the rear end of the rectifier bridge;

[0060] When the capacitor voltage divider circuit is connected to the front end of the rectifier bridge, the connection mode of the capacitor voltage divider circuit includes: the capacitor voltage divider circuit is set between any position of the live wire in front of the rectifier bridge and the ground wire, or the capacitor voltage divider circuit is set between any position of the neutral wire in front of the rectifier bridge and the ground wire;

[0061] When the capacitor voltage divider circuit is connected to the rear end of the rectifier bridge, the connection method of the capacitor voltage divider circuit includes: the capacitor voltage divider circuit is set between any position of the positive loop at the rear end of the rectifier bridge and the ground wire, or the capacitor voltage divider circuit is set between any position of the negative loop at the rear end of the rectifier bridge and the ground wire.

[0062] The principle of the above technical solution is:

[0063] The variable voltage divider circuit of the present invention can be connected to any of the following positions to work the same: 1. Between any position of the L line (live line) in front of the rectifier bridge and the ground line; 2. Between any position of the N line (neutral line) in front of the rectifier bridge and the ground line; 3. Between any position of the positive loop after the rectifier bridge and the ground line; 4. Between any position of the negative loop after the rectifier bridge and the ground line. The action voltage of the variable voltage divider circuit is set according to the action voltage of the discharge tube of the lightning surge protection circuit and the highest input voltage of the power supply. The action voltage of the variable voltage divider circuit is set between the two. The voltage divider ratio of the variable voltage divider circuit can be set according to the size of the input / output side to ground capacitance, reducing the voltage divided by the input side to the ground line, thereby avoiding the discharge tube of the lightning surge protection circuit from being broken down during the withstand voltage test and avoiding the failure of the withstand voltage test.

[0064] As an embodiment of the present invention: the first voltage divider circuit is also used for an external digital control circuit, wherein the digital control circuit includes a microcontroller, a digital potentiometer, an analog circuit and a dimming controller;

[0065] A digital potentiometer is connected in series with the first voltage divider circuit, and an input end of the digital potentiometer is connected to the microcontroller, and the digital potentiometer is used to adjust the voltage division ratio of the first voltage divider circuit;

[0066] The input end of the microcontroller is connected to the analog circuit and the dimming controller, and the microcontroller is used to control the digital potentiometer to adjust the resistance value;

[0067] The output end of the analog controller is connected to the input end of the microcontroller, and the analog controller is used to receive the light-sensing signal of the dimming controller;

[0068] The output end of the dimming controller is connected to the input end of the analog controller, and the dimming controller is used to measure the photosensitive signal of the LEC lamp.

[0069] The principle of the above technical solution is:

[0070] First, a circuit that can change the voltage division of the capacitors to ground on the input and output sides of the isolated LED driver power supply is provided. The circuit divides the voltage of the capacitors to ground on the input and output sides, thereby achieving proportional voltage division control of the primary and secondary voltages of the LED driver power supply.

[0071] Secondly, the circuit can also be used for external digital control circuit. The digital control circuit includes a microcontroller (MCU), a digital potentiometer DIP, an analog circuit (Amp) and a dimming controller LDR. These components can be connected together through a specific interface to form a complete digital control system. In the digital control system, the digital potentiometer DIP is connected in series to the first voltage divider circuit, and its input end is directly connected to the microcontroller MCU. The purpose of this design is to allow the digital potentiometer to adjust the voltage divider ratio of the first voltage divider circuit, so as to achieve precise control of the LED drive power supply voltage. In addition, the input end of the microcontroller MCU is connected to the analog circuit Amp and the dimming controller LDR, which is responsible for controlling the resistance value of the digital potentiometer DIP. This design allows the microcontroller to indirectly control the working state of the digital potentiometer by controlling the analog circuit, thereby further realizing precise control of the LED drive power supply voltage. At the same time, the output end of the analog circuit Amp is also directly connected to the input end of the microcontroller MCU, which is responsible for receiving and processing the light-sensitive signal from the dimming controller LDR. This signal is usually used to detect the intensity of ambient light to determine the brightness of the LED.

[0072] In a specific implementation process, the analog controller includes an analog-to-digital converter, and the analog-to-digital converter is electrically connected to the output end of the secondary side circuit and the input end of the primary side circuit to set the real-time voltage division ratio.

[0073] Finally, the output of the dimming controller LDR is directly connected to the input of the analog circuit Amp, which is responsible for measuring the photosensitive signal emitted by the LED. This signal is usually used to detect the actual working state of the LED, such as temperature, current and other parameters.

[0074] As an embodiment of the present invention: the microprocessor is provided with an analog operation array, wherein the analog operation array is used for:

[0075] Receive the dimming signal of the analog circuit and input it into the analog operation array to perform a voltage ratio operation function; wherein the dimming signal passes through the analog operation array to determine the brightness difference between the real-time brightness of the LED lamp and the expected brightness;

[0076] According to the voltage ratio operation function, an adjustment value of the voltage division ratio of at least one first voltage division circuit is determined, and when the digital potentiometer adjusts the voltage division ratio of the first voltage division circuit to meet the adjustment value, the brightness difference value returns to 0.

[0077] The principle of the above technical solution is:

[0078] The functions of the analog operation array mainly include two aspects: first, receiving the dimming signal from the analog circuit and inputting it into the analog operation array; second, calculating the adjustment value of the voltage divider ratio of at least one first voltage divider circuit according to the input dimming signal and the result of the analog operation array. This adjustment value will be output for the microcontroller (MCU) to adjust the voltage divider ratio of the first voltage divider circuit as needed. In addition, in order to improve the accuracy and efficiency of the algorithm, the analog operation array also includes a series of algorithms and logic designs, such as weight optimization, threshold setting, data processing and other functions. Specifically, the analog operation array can use some pre-set parameters (such as gain, time constant, etc.) in the received dimming signal to compensate for the influence of ambient light, so as to obtain a more accurate difference between the actual brightness and the expected brightness of the LED lamp. In addition, when the digital potentiometer adjusts the voltage divider ratio of the first voltage divider circuit to match the adjustment value calculated by the analog operation array, since the values ​​of the two have reached a balance, the brightness difference will be returned to 0. This can not only eliminate errors, but also ensure the stability of the entire system and avoid problems such as system crashes caused by parameter mismatch.

[0079] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A circuit capable of changing the voltage division of the capacitor between the input and output sides of an isolated LED driving power supply, characterized in that: include: A primary side circuit is used to access the AC input; wherein the circuit output end of the primary side circuit is connected to the input end of the isolation transformer, and a capacitive voltage divider circuit is provided between the ground wire of the primary side circuit; A capacitor voltage divider circuit, used to set a voltage divider ratio, which is used to change the output voltage of the primary side circuit; An isolation transformer is used to transform the output voltage of the primary side circuit; wherein the output end of the isolation transformer is connected to the secondary side circuit; A secondary circuit for DC output; The capacitive voltage divider circuit is a first voltage divider circuit, a second voltage divider circuit or a third voltage divider circuit; wherein, The first voltage divider circuit is composed of a first capacitor and a voltage-sensitive circuit in series; The second voltage divider circuit is composed of a second capacitor and a gas discharge tube in series; The third voltage divider circuit is composed of a third capacitor and a semiconductor element, wherein the semiconductor element has a voltage cutoff characteristic; The first voltage divider circuit is also used to connect to an external digital control circuit, wherein the digital control circuit includes a microcontroller, a digital potentiometer, an analog circuit and a dimming controller; A digital potentiometer is connected in series with the first voltage divider circuit, and an input end of the digital potentiometer is connected to the microcontroller, and the digital potentiometer is used to adjust the voltage division ratio of the first voltage divider circuit; The input end of the microcontroller is connected to the analog circuit and the dimming controller, and the microcontroller is used to control the digital potentiometer to adjust the resistance value; The output end of the analog controller is connected to the input end of the microcontroller, and the analog controller is used to receive the light-sensing signal of the dimming controller; The output end of the dimming controller is connected to the input end of the analog controller, and the dimming controller is used to measure the photosensitive signal of the LEC lamp.

2. The circuit capable of changing the capacitor voltage division between the input and output sides of the isolated LED driving power supply as claimed in claim 1, characterized in that: The primary side circuit includes a rectifier bridge; wherein the capacitor voltage divider circuit is connected to the front end of the rectifier bridge or the rear end of the rectifier bridge; When the capacitor voltage divider circuit is connected to the front end of the rectifier bridge, the connection mode of the capacitor voltage divider circuit includes: the capacitor voltage divider circuit is set between any position of the live wire in front of the rectifier bridge and the ground wire, or the capacitor voltage divider circuit is set between any position of the neutral wire in front of the rectifier bridge and the ground wire; When the capacitor voltage divider circuit is connected to the rear end of the rectifier bridge, the connection method of the capacitor voltage divider circuit includes: the capacitor voltage divider circuit is set between any position of the positive loop at the rear end of the rectifier bridge and the ground wire, or the capacitor voltage divider circuit is set between any position of the negative loop at the rear end of the rectifier bridge and the ground wire.

3. The circuit capable of changing the capacitor voltage division between the input and output sides of the isolated LED driving power supply as claimed in claim 1, characterized in that: The microcontroller is provided with an analog operation array, wherein the analog operation array is used for: Receive the dimming signal of the analog circuit and input it into the analog operation array to perform a voltage ratio operation function; wherein the dimming signal passes through the analog operation array to determine the brightness difference between the real-time brightness of the LED lamp and the expected brightness; According to the voltage ratio operation function, an adjustment value of the voltage division ratio of at least one first voltage division circuit is determined, and when the digital potentiometer adjusts the voltage division ratio of the first voltage division circuit to meet the adjustment value, the brightness difference value returns to 0.

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