Constant voltage driving circuit, PCB and iron shell power supply

Abstract

The utility model discloses a constant voltage drive circuit, a PCB and an iron casing power supply, the constant voltage drive circuit comprises an input processing unit, a constant voltage adjusting unit, a transformer T1, an output processing unit and an output adjusting unit, the output end of the input processing unit is connected with a primary coil of the transformer T1; an auxiliary coil of the transformer T1 is connected with the power supply end of the constant-voltage adjusting unit, the feedback end of the constant-voltage adjusting unit is connected with the input processing unit and the output adjusting unit, and the output end of the constant-voltage adjusting unit is connected with the input processing unit and a primary coil of the transformer T1; a secondary coil of the transformer T1 is connected with the input end of the output processing unit, and the output adjusting unit is connected with the output processing unit; the constant-voltage driving circuit disclosed by the utility model comprises the output adjusting unit which can receive the output voltage adjusting signal fed back by the user to adjust the working states of the constant-voltage adjusting unit and the output processing unit, so that the constant-voltage operation of the circuit is maintained while the voltage requirement of the user is met.

Description

Technical Field

[0001] This utility model relates to the field of drive circuit technology, and in particular to a constant voltage drive circuit, PCB board and iron shell power supply. Background Technology

[0002] In modern lighting system design, constant voltage load luminaires at the user end play a crucial role. Lighting drivers provide a stable power environment for various lighting devices by maintaining a constant voltage, thereby preventing equipment damage or performance degradation that may be caused by voltage fluctuations. In the commercial and residential lighting sectors, constant voltage luminaires are highly favored for their superior performance and reliability. Constant voltage luminaires can not only meet various complex lighting needs, but also maintain high efficiency during long-term operation, reducing maintenance costs.

[0003] However, when the voltage of a constant voltage luminaire inevitably deviates, or when a user wants to adjust the actual power of the luminaire based on specific needs, traditional fixed-output drivers become inadequate. Fixed-output drivers were not designed with flexibility and adaptability in mind, so they cannot provide the necessary matching or adjustment functions when faced with voltage fluctuations or power adjustments. This not only limits the performance of the luminaire but may also lead to unsatisfactory lighting effects and even adversely affect the lifespan of the luminaire.

[0004] It is evident that existing technologies still need improvement and enhancement. Utility Model Content

[0005] In view of the shortcomings of the prior art, the purpose of this utility model is to provide a constant voltage drive circuit that can meet different voltage requirements of users and ensure constant voltage operation of the circuit.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A constant voltage drive circuit includes an input processing unit, a constant voltage adjustment unit, a transformer T1, an output processing unit, and an output adjustment unit. The input terminal of the input processing unit is connected to an external power supply device, and the output terminal of the input processing unit is connected to the primary coil of the transformer T1. The auxiliary coil of the transformer T1 is connected to the power supply terminal of the constant voltage adjustment unit. The feedback terminal of the constant voltage adjustment unit is connected to both the input processing unit and the output adjustment unit. The output terminal of the constant voltage adjustment unit is connected to both the input processing unit and the primary coil of the transformer T1. The secondary coil of the transformer T1 is connected to the input terminal of the output processing unit. The output terminal of the output processing unit is used to connect to a lighting fixture, and the output terminal of the output adjustment unit is connected to the output processing unit.

[0008] In the constant voltage drive circuit, the constant voltage adjustment unit includes a constant voltage drive section and a power switch section. The feedback terminal of the constant voltage drive section is connected to the input processing unit, and the output terminal of the constant voltage drive section is connected to the input processing unit. The feedback terminal of the power switch section is connected to the output adjustment unit, the output terminal of the power switch section is connected to the primary coil of the transformer T1, and the high voltage terminal of the power switch section is connected to the input processing unit.

[0009] In the constant voltage drive circuit, the input processing unit includes a filter section, a rectifier section, a first voltage regulator section, and a voltage divider section. The input terminal of the filter section is used to connect to an external power supply device. The output terminal of the filter section is connected to the input terminal of the rectifier section. The output terminals of the rectifier section and the constant voltage drive section are respectively connected to the input terminal of the first voltage regulator section. The output terminal of the first voltage regulator section is respectively connected to the input terminal of the voltage divider section, the feedback terminal of the constant voltage drive section, and the high-voltage terminal of the power switch section. The output terminal of the voltage divider section is connected to the primary coil of the transformer T1.

[0010] The constant voltage drive circuit also includes a synchronous rectification unit, the input terminal and the trigger terminal of which are respectively connected to the output processing unit.

[0011] In the constant voltage drive circuit, the synchronous rectification unit includes a third control chip U3 and a first field-effect transistor Q1; the pins VDD, VIN, and SDT of the third control chip U3 are respectively connected to the output processing unit, the pin GATE of the third control chip U3 is connected to the gate of the first field-effect transistor Q1, the drain of the first field-effect transistor Q1 is connected to the secondary coil of the transformer T1, and the source of the first field-effect transistor Q1 is connected to the output processing unit.

[0012] In the constant voltage drive circuit, the constant voltage drive unit includes a first control chip U1, a sampling group, a first voltage regulator group, and a feedback group; the pin FB of the first control chip U1 is connected to the output terminal of the first voltage regulator group through the feedback group, the pin VCC of the first control chip U1 is connected to the auxiliary coil of the transformer T1 through the first voltage regulator group, the pin CS of the first control chip U1 is connected to the output terminal of the rectifier group through the sampling group, and the pin D of the first control chip U1 is connected to the input terminal of the first voltage regulator group.

[0013] In the constant voltage drive circuit, the power switching section includes a second control chip U2, a second voltage regulator group, and a receiving terminal of an optocoupler U4; the VCC pin of the second control chip U2 is connected to the auxiliary coil of the transformer T1 through the second voltage regulator group, the SW pin of the second control chip U2 is connected to the primary coil of the transformer T1, the FB pin of the second control chip U2 is connected to the output adjustment unit through the receiving terminal of the optocoupler U4, and the HV pin of the second control chip U2 is connected to the output terminal of the first voltage regulator section.

[0014] In the constant voltage drive circuit, the output adjustment unit includes an adjustable resistor RP1, a second voltage regulator, a third voltage regulator, and the transmitter of an optocoupler U4. One end of the adjustable resistor RP1 and the positive terminal of the transmitter of the optocoupler U4 are connected to the output processing unit through the second voltage regulator. The other end of the adjustable resistor RP1 and the negative terminal of the transmitter of the optocoupler U4 are grounded through the third voltage regulator. The transmitter of the optocoupler U4 is inductively connected to the receiver of the optocoupler U4.

[0015] This utility model also provides a PCB board, on which the constant voltage drive circuit described above is printed.

[0016] This utility model also provides a metal-cased power supply, which uses a constant voltage drive circuit as described above to achieve operation control.

[0017] Beneficial effects:

[0018] This utility model provides a constant voltage drive circuit, including an output adjustment unit. The output adjustment unit is used to receive the output voltage adjustment signal fed back by the user and feed the output voltage signal back to the constant voltage adjustment unit and the output processing unit to adjust the working state of the constant voltage adjustment unit and the output processing unit. This ensures that while meeting the user's voltage requirements for the lighting device, the entire drive circuit can maintain constant voltage operation, thereby ensuring the stability, reliability and flexibility of the iron-shell power supply when it is working. Attached Figure Description

[0019] Figure 1 A circuit block diagram of the constant voltage drive circuit provided by this utility model;

[0020] Figure 2 The circuit diagram of the constant voltage drive circuit provided by this utility model.

[0021] Explanation of key component symbols: 1-Input processing unit, 11-Filtering section, 12-Rectifying section, 13-First voltage regulator section, 14-Voltage divider section, 2-Constant voltage adjustment unit, 21-Constant voltage drive section, 211-Sampling group, 212-First voltage regulator group, 213-Feedback group, 22-Power switch section, 221-Second voltage regulator group, 3-Output processing unit, 4-Output adjustment unit, 41-Second voltage regulator section, 42-Third voltage regulator section, 5-Synchronous rectification unit. Detailed Implementation

[0022] This utility model provides a constant voltage drive circuit, a PCB board, and a metal-cased power supply. To make the purpose, technical solution, and effects of this utility model clearer and more explicit, the following describes this utility model in further detail with reference to the accompanying drawings and examples.

[0023] In the description of this utility model, it should be understood that the terms "installation" and "connection" should be interpreted broadly, and those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0024] Please see Figure 1 and Figure 2 This utility model provides a constant voltage drive circuit, including an input processing unit, a constant voltage adjustment unit, a transformer T1, an output processing unit, and an output adjustment unit. The input terminal of the input processing unit is used to connect to an external power supply device, and the output terminal of the input processing unit is connected to the primary coil of the transformer T1. The auxiliary coil of the transformer T1 is connected to the power supply terminal of the constant voltage adjustment unit, and the feedback terminal of the constant voltage adjustment unit is connected to both the input processing unit and the output adjustment unit. The output terminal of the constant voltage adjustment unit is connected to both the input processing unit and the primary coil of the transformer T1. The secondary coil of the transformer T1 is connected to the input terminal of the output processing unit, and the output terminal of the output processing unit is used to connect to a lighting fixture. The output terminal of the output adjustment unit is connected to the output processing unit.

[0025] The constant voltage drive circuit disclosed in this application includes an output adjustment unit. The output adjustment unit is used to receive the output voltage adjustment signal fed back by the user and feed the output voltage signal back to the constant voltage adjustment unit and the output processing unit to adjust the working state of the constant voltage adjustment unit and the output processing unit. This ensures that while meeting the user's voltage requirements for the lighting device, the constant voltage operation of the entire drive circuit can be maintained, thereby ensuring the stability, reliability and flexibility of the iron-cased power supply during operation.

[0026] Further, please refer to Figure 1 and Figure 2The constant voltage adjustment unit includes a constant voltage drive unit and a power switch unit. The feedback terminal of the constant voltage drive unit is connected to the input processing unit, and the output terminal of the constant voltage drive unit is connected to the input processing unit. The feedback terminal of the power switch unit is connected to the output adjustment unit, the output terminal of the power switch unit is connected to the primary coil of the transformer T1, and the high voltage terminal of the power switch unit is connected to the input processing unit.

[0027] Further, please refer to Figure 1 and Figure 2 The input processing unit includes a filtering section, a rectifier section, a first voltage regulator section, and a voltage divider section. The input terminal of the filtering section is used to connect to an external power supply device. The output terminal of the filtering section is connected to the input terminal of the rectifier section. The output terminal of the rectifier section and the output terminal of the constant voltage drive section are respectively connected to the input terminal of the first voltage regulator section. The output terminal of the first voltage regulator section is respectively connected to the input terminal of the voltage divider section, the feedback terminal of the constant voltage drive section, and the high voltage terminal of the power switch section. The output terminal of the voltage divider section is connected to the primary coil of the transformer T1.

[0028] In this embodiment, the filtering section includes a first connector CN1, a first excitation coil LF1, a second excitation coil LF2, and a first inductor L1; the rectifier section includes a rectifier bridge BD1; the first voltage regulator section includes a first capacitor C1, a first Zener diode D1, a second Zener diode D2, a third Zener diode D3, and a ninth Zener diode D9; the voltage divider section includes multiple resistor groups, each resistor group including two resistors, and the multiple resistor groups are connected in parallel; the first connector CN1 is used to connect an external power supply device, which can be AC ​​power; the output terminal of the first connector CN1 is connected to one end of the first excitation coil LF1, and the other end of the first excitation coil LF1 is connected to one end of the second excitation coil LF2; the other end of the second excitation coil LF2 is connected through the... The first inductor L1 is connected to the input terminal of the rectifier bridge BD1. The output terminal of the rectifier bridge BD1 and pin D of the first control chip U1 are respectively connected to one end of the first capacitor C1, the positive terminal of the first Zener diode D1, the positive terminal of the second Zener diode D2, the positive terminal of the third Zener diode D3, and the positive terminal of the ninth Zener diode D9. The other end of the first capacitor C1 and the negative terminal of the first Zener diode D1 are respectively connected to pin HV of the second control chip U2 and pin FB of the first control chip U1. The other end of the first capacitor C1, the negative terminals of the first Zener diode D1, the second Zener diode D2, the third Zener diode D3, and the ninth Zener diode D9 are connected to the primary coil of the transformer T1 through the voltage divider.

[0029] In this embodiment, the filtering section includes a first excitation coil LF1 and a second excitation coil LF2 connected in series. This not only optimizes the current transmission path but also makes the circuit more efficient in handling high-power input, reducing energy loss and thus improving the overall energy efficiency ratio. The rectifier section includes a rectifier bridge BD1, which converts AC power to DC power, ensuring that subsequent circuits can obtain a continuous and stable DC power supply, thereby guaranteeing the stability and reliability of the circuit under various operating conditions. The first voltage regulator section consists of multiple Zener diodes (D1, D2, D3, D9) and a capacitor C1. Through the coordinated operation of electronic components, it can effectively stabilize the voltage and prevent potential damage to the circuit caused by voltage fluctuations. This not only improves the stability and reliability of the circuit but also extends its service life. The voltage divider section consists of multiple parallel resistor groups, each containing two resistors. This not only achieves precise voltage division but also ensures that the primary coil of transformer T1 receives a suitable input voltage, avoiding overload problems in transformer T1 and improving the safety and stability of the circuit during operation.

[0030] Further, please refer to Figure 1 and Figure 2 The constant voltage drive circuit further includes a synchronous rectification unit, the input terminal and the trigger terminal of which are respectively connected to the output processing unit.

[0031] Further, please refer to Figure 2 The synchronous rectification unit includes a third control chip U3 and a first field-effect transistor Q1; the pins VDD, VIN and SDT of the third control chip U3 are respectively connected to the output processing unit, the pin GATE of the third control chip U3 is connected to the gate of the first field-effect transistor Q1, the drain of the first field-effect transistor Q1 is connected to the secondary coil of the transformer T1, and the source of the first field-effect transistor Q1 is connected to the output processing unit.

[0032] In this embodiment, the third control chip U3 is model OB2009. This chip is widely used in the field of synchronous rectification due to its excellent performance and stability. The OB2009 chip can provide precise control signals, ensuring the high efficiency and stability of the rectification process, thus providing reliable support for the operation of the entire drive circuit. Through the third control chip U3 in conjunction with the first field-effect transistor Q1, the synchronous rectification unit can achieve precise control and efficient rectification of the output current of the secondary coil of transformer T1. The pins VDD, VIN, and SDT of the third control chip U3 are closely connected to the output processing unit to ensure signal... The accurate transmission and real-time feedback make the entire synchronous rectification process more stable and reliable. In addition, the GATE pin of the third control chip U3 is connected to the gate of the first field-effect transistor Q1, which not only simplifies the circuit connection but also improves the control sensitivity and response speed. As a rectifier, the drain of the first field-effect transistor Q1 is connected to the secondary coil of the transformer T1, while the source is connected to the output processing unit. This fully utilizes the low internal resistance and fast switching characteristics of the field-effect transistor, significantly improving the rectification efficiency. At the same time, the use of the first field-effect transistor Q1 reduces energy loss, resulting in a significant improvement in the energy efficiency ratio of the entire constant voltage drive circuit.

[0033] Further, please refer to Figure 1 and Figure 2 The constant voltage drive unit includes a first control chip U1, a sampling group, a first voltage regulator group, and a feedback group; the pin FB of the first control chip U1 is connected to the output terminal of the first voltage regulator group through the feedback group, the pin VCC of the first control chip U1 is connected to the auxiliary coil of the transformer T1 through the first voltage regulator group, the pin CS of the first control chip U1 is connected to the output terminal of the rectifier group through the sampling group, and the pin D of the first control chip U1 is connected to the input terminal of the first voltage regulator group.

[0034] In this embodiment, the first control chip U1 is model BP2636DA; the sampling group includes a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7; the first voltage regulator group includes a fifth diode D5 and a twelfth resistor R12; the feedback group includes an eighth resistor R8 and a ninth resistor R9; one end of the fifth resistor R5 is connected to the pin CS of the first control chip U1, the anode of the second voltage regulator diode D2, the anode of the third voltage regulator diode D3, and the anode of the ninth voltage regulator diode D9, respectively; one end of the sixth resistor R6 and one end of the seventh resistor R7 are respectively connected to... The CS pin of the first control chip U1 is connected, and the other ends of the fifth resistor R5, the sixth resistor R7, and the seventh resistor R7 are respectively grounded; the FB pin of the first control chip U1 is connected to the cathode of the first Zener diode D1 and the other end of the first capacitor C1 through the series-connected eighth resistor R8 and the ninth resistor R9; the anode of the fifth diode D5 is connected to the auxiliary coil of the transformer T1, and the cathode of the fifth diode D5 is connected to the VCC pin of the first control chip U1 through the twelfth resistor R12.

[0035] In this embodiment, the first control chip U1 can achieve fine adjustment of the output voltage, ensuring that the entire circuit remains stable under various operating conditions, thereby providing users with reliable and consistent performance. The sampling group includes the fifth resistor R5, the sixth resistor R6, and the seventh resistor R7, which can not only accurately sample the output current of the rectifier section, but also provide real-time current feedback information to the first control chip U1. This feedback mechanism ensures that current fluctuations can be detected in a timely manner and adjusted accordingly, thereby avoiding possible overload or underload situations. The first voltage regulator group consists of the fifth diode D5 and the twelfth resistor R12, which can effectively stabilize the first control chip U1. The operating voltage is ensured, and it can also ensure that it maintains optimal performance in various complex working environments; the feedback group includes the eighth resistor R8 and the ninth resistor R9 connected in series, which can accurately feed back the output voltage of the first voltage regulator to the pin FB of the first control chip U1, forming an efficient closed-loop control system; enabling the first control chip U1 to automatically adjust its output according to the feedback voltage information to maintain the stability of the output voltage; this closed-loop control mechanism not only improves the stability and accuracy of the output voltage, but also greatly enhances the response speed and adaptability of the entire circuit, ensuring that the circuit can react quickly to various load changes and maintain a constant output voltage.

[0036] Further, please refer to Figure 2The power switching unit includes a second control chip U2, a second voltage regulator group, and a receiving terminal of an optocoupler U4. The VCC pin of the second control chip U2 is connected to the auxiliary coil of the transformer T1 through the second voltage regulator group, the SW pin of the second control chip U2 is connected to the primary coil of the transformer T1, the FB pin of the second control chip U2 is connected to the output adjustment unit through the receiving terminal of the optocoupler U4, and the HV pin of the second control chip U2 is connected to the output terminal of the first voltage regulator unit.

[0037] In this embodiment, the second control chip U2 is model DK045G, and the optocoupler U4 is model PC817; the second voltage regulator group includes a tenth diode D10 and a thirty-seventh resistor R37; the positive terminal of the tenth diode D10 is connected to the auxiliary coil of the transformer T1, and the negative terminal of the tenth diode D10 is connected to the VCC pin of the second control chip U2 through the thirty-seventh resistor R37; the FB pin of the second control chip U2 is connected to the receiving end of the optocoupler U4, and the receiving end of the optocoupler U4 is inductively connected to the transmitting end of the optocoupler U4.

[0038] In this embodiment, the power switch section achieves precise control of the power switch through the close cooperation of key components such as the second control chip U2, the second voltage regulator group, and the receiver of the optocoupler U4. This not only improves the efficiency of the circuit but also ensures the stability and reliability of the metal-cased power supply under various operating conditions. The second control chip U2, model DK045G, has advanced control functions and high reliability, capable of handling various complex power management needs. The second voltage regulator group consists of the tenth diode D10 and the thirty-seventh resistor R37, providing a stable voltage input for the second control chip U2, thereby enhancing the anti-interference capability of the entire circuit. In addition, the pin FB of the second control chip U2 is connected to the receiver of the optocoupler U4, realizing precise feedback control of the output adjustment unit. The receiver of the optocoupler U4 is inductively connected to the transmitter, which not only improves the accuracy of signal transmission but also enhances the isolation performance of the circuit, thereby improving the overall performance of the power switch.

[0039] Further, please refer to Figure 1 and Figure 2 The output adjustment unit includes an adjustable resistor RP1, a second voltage regulator, a third voltage regulator, and the transmitter of an optocoupler U4. One end of the adjustable resistor RP1 and the positive terminal of the transmitter of the optocoupler U4 are connected to the output processing unit through the second voltage regulator. The other end of the adjustable resistor RP1 and the negative terminal of the transmitter of the optocoupler U4 are grounded through the third voltage regulator. The transmitter of the optocoupler U4 is inductively connected to the receiver of the optocoupler U4.

[0040] In this embodiment, the second voltage regulator section includes a Zener diode ZD1, a 25th resistor R25, and a Zener diode ZD2; the third voltage regulator section includes a voltage regulator chip U5, which is model 431; one end of the adjustable resistor RP1 is connected to one end of the 25th resistor R25, the other end of the 25th resistor R25, the cathode of the Zener diode ZD1, and the cathode of the Zener diode ZD2 are respectively connected to the output processing unit, the anodes of the Zener diode ZD1 and ZD2, and pin 3 of the voltage regulator chip U5 are respectively connected to the transmitter of the optocoupler OP1, the other end of the adjustable resistor RP1 is connected to pin 2 of the voltage regulator chip U5, and pin 1 of the voltage regulator chip U5 is grounded.

[0041] In this embodiment, precise adjustment and control of the output signal are achieved through the combination of adjustable resistor RP1, the second voltage regulator, the third voltage regulator, and the transmitter of optocoupler U4. The second voltage regulator, including Zener diode ZD1, resistor R25, and Zener diode ZD2, provides a stable voltage output and protects the circuit from voltage fluctuations. The third voltage regulator uses a 431 voltage regulator chip U5, further enhancing the circuit's voltage regulation performance and ensuring the stability of the output signal. The flexible adjustability of adjustable resistor RP1 allows the output adjustment unit to adapt to different operating requirements, improving the circuit's applicability and flexibility. The transmitter and receiver of optocoupler U4 are inductively connected, achieving electrical isolation between circuits and improving the circuit's safety and reliability.

[0042] In this embodiment, please refer to Figure 2 The output processing unit includes a sixth capacitor C6, a twenty-first resistor R21, a seventh Zener diode D7, a second filter capacitor CE2, a third excitation coil LF3, and a second connector CN2. One end of the sixth capacitor C6 and the negative terminal of the seventh Zener diode D7 are connected to the secondary coil of the transformer T1, and the other end of the sixth capacitor C6 is connected to one end of the twenty-first resistor R21. The other end of the twenty-first resistor R21 and the positive terminal of the seventh Zener diode D7 are connected to the source of the first field-effect transistor Q1, respectively. The positive terminal of the second filter capacitor CE2 and one end of the third excitation coil LF3 are connected to the secondary coil of the transformer T1, and the other end of the third excitation coil LF3 is connected to the second connector CN2, which is used to connect a lighting device.

[0043] In this embodiment, the combination of the sixth capacitor C6 and the seventh Zener diode D7 can effectively stabilize the voltage output from the secondary coil of transformer T1, preventing voltage fluctuations from adversely affecting subsequent circuits. The twenty-first resistor R21 provides a stable current source for the first MOSFET Q1, helping to ensure the stable operation of the first MOSFET Q1 and improving the stability and reliability of the entire circuit. The combination of the second filter capacitor CE2 and the third excitation coil LF3 can further filter and stabilize the voltage, improving the quality of the output voltage.

[0044] This utility model also provides a PCB board, on which the constant voltage drive circuit described above is printed.

[0045] This utility model also provides a metal-cased power supply, which uses a constant voltage drive circuit as described above to achieve operation control.

[0046] It is understood that those skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of this utility model, and all such substitutions or changes should fall within the protection scope of this utility model.

Claims

1. A constant voltage drive circuit, characterized in that, The system includes an input processing unit, a constant voltage adjustment unit, a transformer T1, an output processing unit, and an output adjustment unit. The input terminal of the input processing unit is used to connect to an external power supply device, and the output terminal of the input processing unit is connected to the primary coil of the transformer T1. The auxiliary coil of the transformer T1 is connected to the power supply terminal of the constant voltage adjustment unit, and the feedback terminal of the constant voltage adjustment unit is connected to both the input processing unit and the output adjustment unit. The output terminal of the constant voltage adjustment unit is connected to both the input processing unit and the primary coil of the transformer T1. The secondary coil of the transformer T1 is connected to the input terminal of the output processing unit, and the output terminal of the output processing unit is used to connect to a lighting fixture. The output terminal of the output adjustment unit is connected to the output processing unit.

2. The constant voltage drive circuit according to claim 1, characterized in that, The constant voltage adjustment unit includes a constant voltage drive unit and a power switch unit. The feedback terminal of the constant voltage drive unit is connected to the input processing unit, and the output terminal of the constant voltage drive unit is connected to the input processing unit. The feedback terminal of the power switch unit is connected to the output adjustment unit, the output terminal of the power switch unit is connected to the primary coil of the transformer T1, and the high voltage terminal of the power switch unit is connected to the input processing unit.

3. The constant voltage drive circuit according to claim 2, characterized in that, The input processing unit includes a filtering section, a rectifier section, a first voltage regulator section, and a voltage divider section. The input terminal of the filtering section is used to connect to an external power supply device. The output terminal of the filtering section is connected to the input terminal of the rectifier section. The output terminal of the rectifier section and the output terminal of the constant voltage drive section are respectively connected to the input terminal of the first voltage regulator section. The output terminal of the first voltage regulator section is respectively connected to the input terminal of the voltage divider section, the feedback terminal of the constant voltage drive section, and the high voltage terminal of the power switch section. The output terminal of the voltage divider section is connected to the primary coil of the transformer T1.

4. The constant voltage drive circuit according to claim 1, characterized in that, It also includes a synchronous rectification unit, the input terminal and the trigger terminal of which are respectively connected to the output processing unit.

5. A constant voltage drive circuit according to claim 4, characterized in that, The synchronous rectification unit includes a third control chip U3 and a first field-effect transistor Q1; the pins VDD, VIN and SDT of the third control chip U3 are respectively connected to the output processing unit, the pin GATE of the third control chip U3 is connected to the gate of the first field-effect transistor Q1, the drain of the first field-effect transistor Q1 is connected to the secondary coil of the transformer T1, and the source of the first field-effect transistor Q1 is connected to the output processing unit.

6. A constant voltage drive circuit according to claim 3, characterized in that, The constant voltage drive unit includes a first control chip U1, a sampling group, a first voltage regulator group, and a feedback group; the pin FB of the first control chip U1 is connected to the output terminal of the first voltage regulator group through the feedback group, the pin VCC of the first control chip U1 is connected to the auxiliary coil of the transformer T1 through the first voltage regulator group, the pin CS of the first control chip U1 is connected to the output terminal of the rectifier group through the sampling group, and the pin D of the first control chip U1 is connected to the input terminal of the first voltage regulator group.

7. A constant voltage drive circuit according to claim 3, characterized in that, The power switching unit includes a second control chip U2, a second voltage regulator group, and a receiving terminal of an optocoupler U4; the VCC pin of the second control chip U2 is connected to the auxiliary coil of the transformer T1 through the second voltage regulator group, the SW pin of the second control chip U2 is connected to the primary coil of the transformer T1, the FB pin of the second control chip U2 is connected to the output adjustment unit through the receiving terminal of the optocoupler U4, and the HV pin of the second control chip U2 is connected to the output terminal of the first voltage regulator unit.

8. A constant voltage drive circuit according to claim 7, characterized in that, The output adjustment unit includes an adjustable resistor RP1, a second voltage regulator, a third voltage regulator, and the transmitter of an optocoupler U4. One end of the adjustable resistor RP1 and the positive terminal of the transmitter of the optocoupler U4 are connected to the output processing unit through the second voltage regulator. The other end of the adjustable resistor RP1 and the negative terminal of the transmitter of the optocoupler U4 are grounded through the third voltage regulator. The transmitter of the optocoupler U4 is inductively connected to the receiver of the optocoupler U4.

9. A PCB board, characterized in that, The PCB board is printed with a constant voltage drive circuit as described in any one of claims 1-8.

10. A power supply with an iron casing, characterized in that, The iron-shell power supply uses a constant voltage drive circuit as described in any one of claims 1-8 to achieve operation control.

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