Gallium nitride LED drive circuit with constant voltage at primary side

Abstract

The utility model discloses a primary side constant voltage gallium nitride LED drive circuit, which comprises an EMI filter power supply circuit, a rectification circuit, a transformer, a microprocessor, a common mode inductor, a synchronous rectification circuit and a protection circuit, and is characterized in that voltage regulation is directly carried out at the input end of the drive circuit, so that the working state of a switch element MOS tube is regulated; and the output voltage of the whole control circuit is kept constant. The synchronous rectification circuit is composed of an MOS tube Q1, an MOS tube Q2, a protection circuit and a synchronous rectification controller, the MOS tube Q1 and the MOS tube Q2 are connected with the protection circuit in parallel, and the synchronous rectification controller drives the MOS tube Q1 and the MOS tube Q2 which are connected in parallel, so that current can pass through a low-impedance path when flowing in two directions, the on-resistance is further reduced, the efficiency is greatly improved, and the service life of the circuit is prolonged. And higher current bearing capacity is provided. In addition, the gallium nitride third-generation semiconductor technology is used, the high-integration design is achieved, the number of components is small, and the product cost is reduced.

Description

Technical Field

[0001] This utility model relates to the field of electronics, and in particular to a gallium nitride LED driving circuit with primary-side constant voltage. Background Technology

[0002] LEDs have advantages such as high brightness, small size, durability, environmental friendliness, and low cost, and are therefore increasingly widely used in lighting, display, and other fields. Existing gallium nitride (GaN) LED driver circuits generally require a combination of controller, driver, and GaN power device design. This necessitates additional components to build a secondary constant voltage, resulting in a complex circuit layout, relatively difficult product development, low efficiency, high heat dissipation, and high cost. Utility Model Content

[0003] In view of this, the purpose of this application is to provide a gallium nitride LED driving circuit with primary-side constant voltage to solve the above technical problems.

[0004] This application provides a primary-side constant voltage gallium nitride LED driving circuit, including: an EMI filter power supply circuit, a rectifier circuit, a transformer, a microprocessor, a common-mode inductor, a synchronous rectifier circuit, and a protection circuit. The microprocessor is an active single-stage PFC flyback chip with an enhancement-mode gallium nitride switch. The transformer is divided into a first transformer and a second transformer. The second and third nodes of the AC input terminal of the rectifier are connected to the EMI filter power supply circuit. The fourth node of the rectifier is connected to one end of a parallel connection of inductor L1 with resistors R4, R5, and C1, and is connected to the input terminal 5 of the primary winding of the second transformer. The other end of the parallel connection of resistors R4, R5, and C1 is connected to one end of a parallel connection of resistors R6, R7, R8, and diode D3. The other end of the parallel connection of resistors R6, R7, R8, and D3 is connected to one end of diode D4. The other end of diode D4 is connected to the input terminal 4 of the primary winding of the second transformer. Inductor L1, capacitors CBB1 and CBB2 form a π-type filter circuit.

[0005] Pins 2-4 of the microprocessor are grounded. Pin 11 of the microprocessor is connected to capacitor C3, which is connected to pin 10 and then to the primary winding input terminal interface 4 of the second transformer. Pin 9 of the microprocessor is connected to the parallel interface of resistors RS1, RS2, and RS3. Pin 6 of the microprocessor is connected in series with resistors RS10 and RS11 and then to the secondary winding output terminal interface 1 of the first transformer.

[0006] The secondary winding output terminal 7 of the second transformer is connected to one end of parallel capacitors EC3, EC4, EC5 and EC6, and also to one end of common mode inductor LF4;

[0007] The synchronous rectification circuit consists of MOSFETs Q1 and Q2, a protection circuit, and a synchronous rectification controller. MOSFETs Q1 and Q2 are connected in parallel with the protection circuit. The VCC pin of the synchronous rectification controller is connected to the source S of MOSFETs Q1 and Q2 via capacitor C11, and is also connected to the other end of parallel capacitors EC3, EC4, EC5, and EC6. The VD pin is connected to the gate G of MOSFETs Q1 and Q2 via resistor R16. The VG pin is connected to the drain D of MOSFETs Q1 and Q2. The SET pin is connected to the other end of parallel capacitors EC3, EC4, EC5, and EC6 via resistor R17. The protection circuit consists of resistor R15 connected in parallel with diode D8, and then connected in series with capacitor C10.

[0008] In some alternative implementations, the microprocessor uses an active single-stage PFC flyback chip with an enhanced gallium nitride switch, model BP83223, and the synchronous rectifier controller uses a synchronous rectifier controller, model BP62110.

[0009] In some alternative implementations, capacitors EC3, EC4, EC5 and C6 are all energy storage capacitors.

[0010] In some optional implementations, diodes D3, D4, and D8 are all silicon controlled rectifiers (SCRs) for dimming.

[0011] Based on the above technical solution, this application provides a gallium nitride LED driving circuit with constant voltage at the input terminal. By directly regulating the voltage at the input terminal of the circuit and adjusting the operating state of switching elements (such as MOSFETs), the output voltage is kept constant. Specifically, the rectifier converts AC power to DC power, which is stored in capacitor EC1. Part of the DC power is used by the microprocessor and diode D1, while the other part is transformed by the second transformer and stored in capacitors EC3, EC4, EC5, and EC6 for use by diode D8. The secondary winding of the second transformer, through a synchronous rectification circuit, ensures that the current flows through a low-impedance path in both directions, further reducing the on-resistance, greatly improving efficiency, and providing a greater current carrying capacity. The synchronous rectification circuit comprises MOSFETs Q1 and Q2, a protection circuit, and a synchronous rectification controller. MOSFETs Q1 and Q2 are connected in parallel with the protection circuit. The synchronous rectification controller drives the parallel-connected MOSFETs Q1 and Q2. The synchronous rectification controller typically detects the power supply's output voltage and switching signal, and based on these, drives MOSFETs Q1 and Q2. When the synchronous rectification controller turns on MOSFET Q2, current flows from the input to the output; when it turns on MOSFET Q1, the current flows in the opposite direction, completing the rectification process. This allows current to flow through a low-impedance path in both directions, further reducing on-resistance, significantly improving efficiency, and providing greater current carrying capacity. This solution allows a single chip to perform the functions of several chips, not only improving the overall performance of the solution but also helping to reduce PCB space, shrink product size, and lower material costs. Attached Figure Description

[0012] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is an overall circuit diagram of a primary-side constant voltage gallium nitride LED driving circuit provided in an embodiment of this application. Detailed Implementation

[0014] The specific embodiments of this application will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely a part of the embodiments of this application, and not all of them. Based on the description of this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0015] In the description of this application, unless otherwise expressly specified and limited, the terms "connection," "setup," "installation," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0016] The terms “upper,” “lower,” “left,” “right,” “front,” “back,” “center,” “top,” “bottom,” “inner,” “outer,” “vertical,” “horizontal,” “clockwise,” “counterclockwise,” “axial,” “radial,” and “circumferential” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of description and simplification, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0017] The terms “first,” “second,” “third,” etc., are used only to distinguish elements with similar properties, and do not indicate or imply relative importance or a specific order, unless otherwise explicitly stated or limited.

[0018] The terms “comprising,” “including,” “having,” or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase “comprising one…” does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0019] The term "multiple" means two or more (including two).

[0020] The term "and / or" describes the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three cases: A exists alone, A and B exist simultaneously, and B exists alone.

[0021] The terms "an embodiment," "as an example," and "in one implementation" refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which may be included in at least one embodiment or example of this application. These illustrative expressions do not necessarily refer to the same embodiment, nor are they independent or alternative embodiments mutually exclusive with other embodiments. Where there is no conflict, the embodiments and features described in these embodiments can be combined in a suitable manner.

[0022] Figure 1 This is a schematic diagram of the overall circuit structure of a primary-side constant voltage gallium nitride LED driving circuit provided in an embodiment of this application.

[0023] Specifically, a primary-side constant voltage gallium nitride LED driver circuit includes: an EMI filter power supply circuit, a rectifier circuit, a transformer, a microprocessor, a common-mode inductor, a synchronous rectifier circuit, and a protection circuit. Specifically, the microprocessor is an active single-stage PFC flyback chip with an enhancement-mode gallium nitride switch. The transformer is divided into a first transformer and a second transformer. The second and third nodes of the AC input of the rectifier circuit are connected to the EMI filter power supply circuit. The fourth node of the rectifier circuit is connected to resistors R4 and R5 through inductor L1. One end of capacitor C1 is connected in parallel and connected to the input terminal 5 of the primary winding of the second transformer. The other end of the parallel connection of resistors R4, R5, and capacitor C1 is connected to one end of the parallel connection of resistors R6, R7, R8, and diode D3. The other end of the parallel connection of resistors R6, R7, R8, and diode D3 is connected to one end of diode D4. The other end of diode D4 is connected to the input terminal 4 of the primary winding of the second transformer. Inductor L1 and capacitors CBB1 and CBB2 form a π-type filter circuit.

[0024] Pins 2-4 of the microprocessor are grounded. Pin 11 of the microprocessor is connected to capacitor C3, which is connected to pin 10 and then to the primary winding input terminal interface 4 of the second transformer. Pin 9 of the microprocessor is connected to the parallel interface of resistors RS1, RS2, and RS3. Pin 6 of the microprocessor is connected in series with resistors RS10 and RS11 and then to the secondary winding output terminal interface 1 of the first transformer.

[0025] The secondary winding output terminal 7 of the second transformer is connected to one end of parallel capacitors EC3, EC4, EC5 and EC6, and also to one end of common mode inductor LF4;

[0026] The synchronous rectification circuit consists of MOSFETs Q1 and Q2, a protection circuit, and a synchronous rectification controller. MOSFETs Q1 and Q2 are connected in parallel with the protection circuit. The VCC pin of the synchronous rectification controller is connected to the source S of MOSFETs Q1 and Q2 through capacitor C11, and is also connected to the other end of parallel capacitors EC3, EC4, EC5, and EC6. The VG pin is connected to the gate G of MOSFETs Q1 and Q2 through resistor R16. The VD pin is connected to the drain D of MOSFETs Q1 and Q2. The SET pin is connected to the other end of parallel capacitors EC3, EC4, EC5, and EC6 through resistor R17. The protection circuit consists of resistor R15 connected in parallel with diode D8, and then connected in series with capacitor C10.

[0027] The protection circuit mentioned above is usually called an RC (resistor-capacitor) snubber circuit or an RC filter circuit. It is commonly used in power supply circuits to protect the circuit from voltage surges. The resistor and capacitor are connected in series to form a low-pass filter, which can smooth voltage changes. The diode is connected in parallel across the resistor, mainly to clamp the voltage. When the voltage exceeds a certain threshold, the diode conducts, diverting the overvoltage to ground, thereby protecting the downstream circuits from damage by high voltage.

[0028] The rectifier used is the RBU1506L model from World Industry: a rectifier bridge is a common electronic component in power supply circuits, its function is to convert alternating current (AC) to direct current (DC). The circuit structure of a rectifier bridge generally consists of four diodes, and rectification is achieved through a bridge rectifier circuit.

[0029] Worldex's RBU1506L low-dropout rectifier bridge features a low forward voltage drop, effectively reducing energy consumption and improving efficiency, exhibiting a low voltage drop in forward conduction mode. Meanwhile, the RBU package is approximately 12.6mm high and can handle a maximum current of 15A, meeting the new demands of ultra-thin applications and high-density power supplies for bridge rectifiers, particularly for higher power applications.

[0030] The Wald Industrial RBU1506L low-dropout rectifier bridge can withstand a maximum peak reverse voltage of 600V, an average rectified output current of 15A, and a maximum forward surge current of 300A under 8.3 millisecond conditions. It can operate and be stored normally in conditions ranging from -55℃ to 150℃.

[0031] The forward voltage drop of the Wald Industrial RBU1506L low-dropout rectifier bridge is significantly superior to similar products in the industry. At a current of 7.5A, it can withstand a maximum forward voltage drop of only 0.95V. This means that the RBU1506L low-dropout rectifier bridge can maintain low power consumption even under high current loads, helping to reduce energy consumption and improve power efficiency, making it suitable for applications such as motor drives, ultra-thin adapters, high-density power supplies, and fast chargers.

[0032] The microprocessor uses an active single-stage PFC flyback chip with an enhanced gallium nitride switch, model BP83223, and the synchronous rectifier controller uses a synchronous rectifier controller, model BP62110.

[0033] In this embodiment, the Chipown BP83223 microprocessor is an active single-stage PFC flyback chip with an integrated 650V withstand voltage and 115mΩ on-resistance enhancement-mode gallium nitride (GaN) switch. Its single-stage structure reduces size and cost. It integrates high-voltage startup and input voltage sampling circuits and features an enhanced power factor (PF) control algorithm. It requires very few external components to achieve high-precision constant voltage output, high power factor, and low current harmonics. The BP83223 can output up to 100W with extremely low standby power consumption (less than 100mW at 230V). It exhibits excellent line regulation and load regulation, and incorporates a dynamic acceleration module to effectively improve system response to loads and provide stable output voltage performance.

[0034] In this embodiment, the synchronous rectification circuit consists of MOSFETs Q1 and Q2, a protection circuit, and a synchronous rectification controller. MOSFETs Q1 and Q2 are connected in parallel with the protection circuit, and the synchronous rectification controller drives the parallel-connected MOSFETs Q1 and Q2. Specifically, when the main switch is closed, the synchronous rectification controller drives Q2 to conduct, allowing current to flow from the input to the output direction. When the main switch is open, the synchronous rectification controller drives Q1 to conduct, allowing the current to flow in the opposite direction, completing the rectification process. In this way, the current can flow through a low-impedance path in both directions, further reducing the on-resistance, greatly improving efficiency, and providing a greater current carrying capacity.

[0035] Synchronous rectification is a technique to improve the efficiency of switching power supplies. In this embodiment, MOSFETs are used instead of diodes for rectification because the on-resistance of a MOSFET is much smaller than the forward voltage drop of a diode. Therefore, under high current, it can significantly reduce losses and improve efficiency. Furthermore, by setting MOSFETs Q1 and Q2 to operate in parallel, the on-resistance is further reduced, providing a greater current carrying capacity. The U2BP62110 is a synchronous rectification controller whose main function is to drive MOSFETs Q1 and Q2, ensuring they turn on and off at appropriate times to achieve efficient rectification.

[0036] The specific working process is roughly as follows: The synchronous rectifier controller usually detects the output voltage and switching signal of the power supply, and drives MOSFET Q1 and MOSFET Q2 based on the detected output voltage and switching signal. When the synchronous rectifier controller drives Q2 to conduct, it allows current to flow from the input to the output; when the synchronous rectifier controller drives Q1 to conduct, it allows the current to flow in the opposite direction, thus completing the rectification process.

[0037] Using two MOSFETs in parallel can increase the current carrying capacity of the circuit and improve heat dissipation because current can flow through both devices simultaneously. At the same time, the BP62110 controls the synchronous switching of these two MOSFETs to ensure stable circuit operation.

[0038] It is important to note that in practical applications, it is necessary to select appropriate MOSFETs and synchronous rectifier controllers based on the specific power supply design and load requirements, and to correctly set their control signals to ensure the stable and efficient operation of the system.

[0039] Optionally, capacitors EC3, EC4, EC5, and EC6 are all energy storage capacitors. The capacitance of capacitors EC3, EC5, and EC6 is 820μF, the rated voltage is 25V, and the size is 8*17mm. The capacitance of capacitor EC4 is 1200μF, the rated voltage is 25V, and the size is 8*17mm.

[0040] Optionally, diodes D1, D3, D4, D5, and D8 are all SCR dimming diodes. Diode D1 is a surface-mount rectifier diode with a forward current of 2A and a reverse voltage of 1000V in an SMAF package. Diode D3 is a surface-mount diode with a forward current of 1A and a reverse voltage of 200V in an SOD-123FL package. Diode D4 is a surface-mount diode with a forward current of 5A and a reverse voltage of 1000V in an SMBF package. Diode D5 is a surface-mount fast recovery diode with a current of 1A and a reverse voltage of 1000V in an SOD-123FL package.

[0041] In summary, this application maintains a constant output voltage by directly regulating the voltage at the circuit edge or input terminal and adjusting the operating state of switching elements (such as MOSFETs). Furthermore, by setting MOSFETs Q1 and Q2 to operate in parallel, the on-resistance is further reduced, providing greater current carrying capacity. The use of a synchronous rectification controller U2BP62110 to drive MOSFETs Q1 and Q2 ensures they turn on and off at appropriate times, achieving not only reduced on-resistance and greater current carrying capacity but also efficient rectification. Finally, by integrating gallium nitride power devices, PWM control, driving, and protection functions onto a single chip, a single chip can perform the functions of several chips, improving overall solution performance, reducing PCB space footprint, minimizing product size, and lowering material costs.

[0042] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in this application, and these should all be included within the scope of protection of this application.

Claims

1. A primary-side constant-voltage gallium nitride LED driving circuit, comprising: The EMI filter power supply circuit, rectifier circuit, transformer, microprocessor, common mode inductor, synchronous rectifier circuit and protection circuit are characterized in that the microprocessor is an active single-stage PFC flyback chip of an enhanced gallium nitride switch tube; the transformer is divided into a first transformer and a second transformer; the second and third nodes of the AC input end of the rectifier circuit are connected with the EMI filter power supply circuit; the fourth node of the rectifier circuit is connected with the input end 5 of the primary winding of the second transformer through the parallel connection of the inductor L1, the resistor R4, the resistor R5 and the capacitor C1; the other end of the parallel connection of the resistor R4, the resistor R5 and the capacitor C1 is connected with the parallel connection of the resistor R6, the resistor R7, the resistor R8 and the diode D3; the other end of the parallel connection of the resistor R6, the resistor R7, the resistor R8 and the diode D3 is connected with one end of the diode D4; the other end of the diode D4 is connected with the input end 4 of the primary winding of the second transformer, wherein the inductor L1, the capacitor CBB1 and the capacitor CBB2 constitute a π-type filter circuit; the pin 2-4 of the microprocessor is grounded, the pin 11 of the microprocessor is connected to the pin 10 through the capacitor C3 and connected to the input end interface 4 of the primary winding of the second transformer, the pin 9 of the microprocessor is connected to one end of the parallel connection interface of the resistor RS1, the resistor RS2 and the resistor RS3, and the pin 6 of the microprocessor is connected to the output end interface 1 of the secondary winding of the first transformer through the series connection of the resistor RS11 and the resistor RS10; the output end 7 interface of the secondary winding of the second transformer is connected with one end of the parallel connection of the capacitors EC3, EC4, EC5 and EC6 and connected with one end of the common mode inductor LF4; the synchronous rectifier circuit is composed of the MOS tube Q1, the MOS tube Q2, the protection circuit and the synchronous rectifier controller, wherein the MOS tube Q1, the MOS tube Q2 and the protection circuit are connected in parallel, the pin VCC of the synchronous rectifier controller is connected with the source S of the MOS tube Q1 and the source S of the MOS tube Q2 through the capacitor C11 and connected with one end of the parallel connection of the capacitors EC3, EC4, EC5 and EC6, the pin VD is connected with the gate G of the MOS tube Q1 and the gate G of the MOS tube Q2 through the resistor R16, the pin VG is connected with the drain D of the MOS tube Q1 and the drain D of the MOS tube Q2, and the pin SET is connected with the other end of the parallel connection of the capacitors EC3, EC4, EC5 and EC6 through the resistor R17; wherein the protection circuit is composed of the parallel connection of the resistor R15 and the diode D8 and the series connection of the capacitor C10; by setting the parallel connection of the MOS tube Q1 and the MOS tube Q2, when the MOS tube Q2 is driven to be conductive by the synchronous rectifier controller, the current flows from the positive direction input to the output; when the MOS tube Q1 is driven to be conductive by the synchronous rectifier controller, the current flows in the reverse direction, so that the current can flow through the low-impedance path in both the positive direction and the reverse direction, thereby increasing the current carrying capacity of the driving circuit.

2. The primary-side constant-voltage GaN LED driving circuit according to claim 1, wherein The microprocessor adopts an enhanced gallium nitride switch tube of model BP83223 active single-stage PFC flyback chip, and the synchronous rectification controller adopts a synchronous rectification controller of model BP62110.

3. The primary-side constant-voltage GaN LED driving circuit according to claim 1, wherein The capacitor EC3, the capacitor EC4, the capacitor EC5 and the capacitor EC6 are energy storage capacitors.

4. The primary-side constant-voltage GaN LED driving circuit according to claim 1, wherein The diode D3, the diode D4 and the diode D8 are silicon-controlled dimming.

Images