Driving circuit and lamp
By introducing a BUCK power supply module into the LED driver circuit to extract power from the rectifier module and divide the voltage, the high-power driving cost problem caused by heating of small package IC chips is solved, and lower heat generation and stronger lightning resistance is achieved , simplifies the circuit structure.
Patent Information
- Application Number
- CN202310798603.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-30
- Publication Date
- 2024-12-31
AI Technical Summary
In high-power applications, existing LED driving circuits have high manufacturing costs and are difficult to drive loads of more than 30W due to heating problems of small package IC chips.
A driving circuit including a rectifier module, a PFC module and a BUCK module is designed to extract power from the rectifier module through a BUCK power supply module, and divide the input voltage through a combined structure of a second diode, an electrolytic capacitor and a resistor. , reduce the input voltage of the BUCK module, thereby reducing heat generation, and integrate lightning protection lines to enhance lightning resistance.
It effectively reduces the loss and heating of the BUCK module, improves the lightning resistance of the driving circuit, simplifies the overall structure, reduces manufacturing costs, and can drive a load with a higher power.
Smart Images
Figure CN119233481A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of lighting, and in particular to a driving circuit and a lamp. Background Art
[0002] With the improvement of living standards, people have higher and higher demands for lighting in different scenarios. LED has been widely used in the field of lighting due to its advantages of energy saving, environmental protection, long life and high light efficiency. In the process of popularization and application of LED lighting, since LED lamp beads have high requirements for current stability, it is necessary to set up a corresponding driving circuit to drive them.
[0003] To this end, the industry has proposed a variety of solutions, and many LED driving solutions have also appeared in LED lighting. Among them, a high PF (Power Factor) non-isolated two-stage solution is one of the commonly used line architectures, usually a front-stage PFC (Power Factor Correction) architecture and a back-stage BUCK (step-down) architecture.
[0004] In the BUCK architecture, more and more manufacturers integrate power MOS tubes into IC chips for cost considerations. The heat generated by IC chips in the integrated power MOS solution is mainly caused by the heat generated by the internal power supply circuit, built-in MOS and logic control circuit, and small-package IC chips (such as SOP8 or SOP7) are usually unable to drive loads above 30W. For higher power applications, only IC chips with large-package built-in MOS solutions, or external MOS solutions, or additional heat dissipation measures can be used, which will increase the overall manufacturing cost.
[0005] In view of this, it is indeed necessary to provide a driving circuit and a lamp, which can reduce the manufacturing cost by adopting a BUCK architecture solution with a small package and a built-in MOS. Summary of the invention
[0006] The object of the present invention is to provide a driving circuit and a lamp which can effectively control the amount of heat.
[0007] To achieve the above object, the present invention provides a driving circuit, comprising:
[0008] Rectifier module, used to convert external AC power into half-wave AC power;
[0009] A PFC module, used for boosting and adjusting the half-wave AC power and outputting DC power of a first voltage, the PFC module being connected to the rectifier module;
[0010] A BUCK module, used for stepping down the direct current of the first voltage output by the PFC module and providing the direct current to a load, wherein the BUCK module is connected to the output end of the PFC module;
[0011] A BUCK power supply module is used to supply power to the BUCK module, wherein an input end of the BUCK power supply module is connected to an output end of the rectifier module, and an output end of the BUCK power supply module is connected to the BUCK module.
[0012] Optionally, the BUCK power supply module includes a second diode, a third electrolytic capacitor and a fourth electrolytic capacitor connected in series in sequence, the third electrolytic capacitor and the fourth electrolytic capacitor are charged through the second diode, and the voltage output by the second diode is provided to the BUCK module after being divided by the third electrolytic capacitor and the fourth electrolytic capacitor.
[0013] Optionally, the BUCK power supply module also includes: a fifth resistor, used to reduce the current output by the BUCK power supply module, wherein both ends of the fifth resistor are respectively connected to the BUCK module and the positive electrode of the fourth electrolytic capacitor, and the current output by the fourth electrolytic capacitor flows into the BUCK module through the fifth resistor.
[0014] Optionally, the second electrolytic capacitor has the same capacity as the third electrolytic capacitor.
[0015] Optionally, the third electrolytic capacitor and the fourth electrolytic capacitor are both aluminum electrolytic capacitors, and the capacity of the third electrolytic capacitor is greater than 6.8uF, and the capacity of the fourth electrolytic capacitor is greater than 6.8uF.
[0016] Optionally, the BUCK power supply module includes a second diode and a second capacitor, the anode of the second diode is connected to the output end of the rectifier module, the cathode of the second diode is connected to the second capacitor and charges the second capacitor, the input end of the BUCK module is connected to the second capacitor, and the second capacitor supplies power to the BUCK module.
[0017] Optionally, the BUCK power supply module also includes a fifth resistor for reducing the current output by the BUCK power supply module, wherein two ends of the fifth resistor are respectively connected to the second capacitor and the BUCK module, and the current output by the second capacitor flows into the BUCK module after passing through the fifth resistor.
[0018] Optionally, the capacity of the second capacitor is between 33nF and 100nF.
[0019] Optionally, the driving circuit further includes a lightning protection module for suppressing external lightning voltage, one end of the lightning protection module is connected to the external mains, and the other end is connected to the PFC module.
[0020] Optionally, the lightning protection module includes a fuse resistor and a varistor, and the L end of the drive circuit is connected to the N end of the drive circuit through the fuse resistor and the varistor in sequence.
[0021] Optionally, the BUCK module includes a buck chip, which is used to power an internal HV pin, and the HV pin of the buck chip is connected to the output end of the BUCK power supply module.
[0022] Optionally, the buck chip has a built-in power MOS, and the BUCK module operates in a BUCK topology.
[0023] Optionally, the working topology of the PFC module is a BOOST structure.
[0024] Another object of the present invention is to provide a lamp including the above-mentioned driving circuit.
[0025] To achieve the above object, the present invention provides a lamp, comprising the above driving circuit and a load, wherein the load is connected to the output end of the driving circuit.
[0026] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: the driving circuit of the present invention takes power from the rectifier module through the provided BUCK power supply module, and the BUCK power supply module divides the input voltage and supplies power to the BUCK module. Compared with the BUCK module taking power directly from the PFC module, the technical solution of the present invention greatly reduces the input voltage of the BUCK module, thereby reducing the loss and heat generation of the BUCK module. At the same time, through the design of the line structure of the BUCK power supply module, the lightning protection line and the power supply line are integrated, so that lightning surge voltage can be prevented while supplying power to the BUCK module. The overall structure is simple and has strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 is a principle block diagram of a driving circuit according to an embodiment of the present invention;
[0028] Figure 2 yes Figure 1 Circuit diagram of
[0029] Figure 3 is a principle block diagram of a driving circuit according to another preferred embodiment of the present invention;
[0030] Figure 4 yes Figure 3 Circuit diagram of the .
[0031] 100- driving circuit;
[0032] 10-rectifier module, 20-PFC module, 30-BUCK module, 40-BUCK power supply module, 50-lightning protection module. DETAILED DESCRIPTION
[0033] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.
[0034] It should be noted here that in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the scheme of the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.
[0035] In addition, it should be noted that the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.
[0036] See also Figures 1-2 FIG. 1 is a driving circuit 100 according to a preferred embodiment of the present invention, comprising:
[0037] The rectifier module 10 is used to convert external AC power into half-wave AC power;
[0038] A PFC module 20, used for boosting and adjusting the half-wave AC power and outputting DC power of a first voltage, wherein the PFC module 20 is connected to the rectifier module 10;
[0039] A BUCK module 30, used for stepping down the DC power of the first voltage output by the PFC module 20 and providing the power to a load, wherein the BUCK module 30 is connected to the output end of the PFC module 20;
[0040] The BUCK power supply module 40 has an input end connected to the output end of the rectifier module 10 , and an output end of the BUCK power supply module 40 connected to the BUCK module 30 to supply power to the BUCK module 30 .
[0041] The heat generated by the BUCK module 30 is mainly caused by the loss of the HV power supply part of the buck chip U2 in the BUCK module 30, the loss of the built-in power MOS, and the loss of the logic control circuit. The loss of the built-in power MOS and the loss of the logic control circuit have been finalized and cannot be changed. The loss calculation formula of the HV power supply part of the buck chip U2 is P_loss=(Vin-V_cc)*I_cc, where V_cc is the internal operating voltage of the buck chip U2, I_cc is the operating current of the buck chip U2, and Vin is the input voltage of the HV pin of the buck chip U2. It can be seen that the lower the input voltage of the HV pin of the buck chip U2, the lower the power supply loss of the buck chip U2.
[0042] The BUCK power supply module 40 is provided to the BUCK module 30 after taking power from the rectifier module 10 and before the PFC module 20. Compared with the BUCK module 30 taking power directly from the electrolytic capacitor after the PFC module 20 is boosted, the input voltage of the buck chip U2 of the BUCK module 30 can be effectively reduced, thereby reducing the power supply loss of the buck chip U2 and optimizing the loss and heat generation of the BUCK module 30. The BUCK power supply module 40 includes a second diode D2, a third electrolytic capacitor EC3, and a fourth electrolytic capacitor EC4 connected in series. The third electrolytic capacitor EC3 and the fourth electrolytic capacitor EC4 are charged by the second diode D2. The BUCK module 30 is connected to the positive electrode of the fourth electrolytic capacitor EC4. The third electrolytic capacitor EC3 and the fourth electrolytic capacitor EC4 divide the voltage output by the second diode D2 and provide it to the BUCK module 30.
[0043] The BUCK power supply module 40 further includes a fifth resistor R5 . The BUCK module 30 is connected to the positive electrode of the fourth electrolytic capacitor EC4 via the fifth resistor R5 . The BUCK power supply module 40 supplies power to the BUCK module 30 after current limiting via the fifth resistor R5 .
[0044] like Figure 2 As shown, the BUCK power supply module 40 is composed of a second diode D2, a third electrolytic capacitor EC3, a fourth electrolytic capacitor EC4 and a fifth resistor R5. When working normally, the AC power is rectified to obtain high-voltage half-wave AC power, and the third electrolytic capacitor EC3 and the fourth electrolytic capacitor EC4 are charged through the second diode D2. The capacity of the third electrolytic capacitor EC3 and the fourth electrolytic capacitor EC4 is large, the power consumption of the buck chip U2 of the BUCK module 30 is small, and the voltage on the third electrolytic capacitor EC3 is DC power.
[0045] In some embodiments, when the AC input is 220V, the voltage on the third electrolytic capacitor EC3 is substantially 220V*1.4=300V. After voltage division by the third electrolytic capacitor EC3 and the fourth electrolytic capacitor EC4, the voltage on the fourth electrolytic capacitor EC4 is 150V, which is then limited by the fifth resistor R5 and provided to the HV pin of the buck chip U2. Compared with the traditional solution of directly connecting the first electrolytic capacitor EC1, the power supply loss of the buck chip U2 is reduced to 1 / 3 of the original, and the temperature of the buck chip U2 is reduced, so that it can be used in higher power applications.
[0046] When there is a high-voltage lightning strike at the AC input end, the third electrolytic capacitor EC3 and the fourth electrolytic capacitor EC4 can absorb the impact energy as electrolytic capacitors, and limit the current through the fifth resistor R5. The two-phase action protects the HV pin of the buck chip U2 and can meet the requirements of the lightning strike test.
[0047] In some embodiments, the second electrolytic capacitor EC2 and the third electrolytic capacitor EC3 have the same capacity. Compared with using electrolytic capacitors of different specifications, using electrolytic capacitors of the same specification has more advantages in manufacturing cost.
[0048] The third electrolytic capacitor EC3 and the fourth electrolytic capacitor EC4 are both high-voltage aluminum electrolytic capacitors with a capacity greater than 6.8uF. The capacity of the third electrolytic capacitor EC3 and the fourth electrolytic capacitor EC4 is determined according to the lightning strike requirements. Usually, 6.8uF 250V or above can prevent 1kV lightning strikes. The use of high-voltage aluminum electrolytic capacitors can have a larger capacity and can meet higher lightning protection requirements.
[0049] The BUCK power supply module 40 is set to draw power from the rectifier module 10. The third electrolytic capacitor EC3 and the fourth electrolytic capacitor EC4 in the BUCK power supply module 40 divide the input voltage and then supply power to the HV pin of the BUCK module 30 through the fifth resistor R5, which greatly reduces the input voltage of the buck chip U2 of the BUCK module 30, thereby reducing the loss and heat of the power supply part of the buck chip U2. At the same time, when there is a high-voltage lightning strike at the AC input end, the third electrolytic capacitor EC3 and the fourth electrolytic capacitor EC4 can also absorb the impact energy, effectively protecting the HV pin of the buck chip, integrating the lightning protection line with the power supply line, and preventing lightning surge voltage while supplying power to the BUCK module 30.
[0050] See also Figures 3-4 FIG. 1 is a driving circuit 100 according to another preferred embodiment of the present invention, comprising:
[0051] A lightning protection module 50 is connected to the external mains to suppress external high voltage lightning strikes;
[0052] The rectifier module 10 is connected to the lightning protection module 50 and is used to convert the input AC power into half-wave AC power;
[0053] A PFC module 20, used for boosting and adjusting the half-wave AC power and outputting DC power of a first voltage, wherein the PFC module 20 is connected to the rectifier module 10;
[0054] A BUCK module 30, used to step down the first voltage DC power output by the PFC module 20 and provide it to a load, and the BUCK module 30 is connected to the output end of the PFC module 20;
[0055] The BUCK power supply module 40 has an input end connected to the output end of the rectifier module 10 , and an output end of the BUCK power supply module 40 connected to the BUCK module 30 to supply power to the BUCK module 30 .
[0056] The BUCK power supply module 40 is set up to take power from behind the rectifier module 10 and before the PFC module 20 and then provide it to the BUCK module 30. Compared with the BUCK module 30 taking power directly from the electrolytic capacitor after the PFC module 20 is boosted, the input voltage of the buck chip U2 of the BUCK module 30 can be effectively reduced, thereby reducing the power supply loss of the buck chip U2 and optimizing the loss and heat generation of the BUCK module 30. At the same time, because the BUCK module 30 takes power from behind the rectifier module 10, the buck chip U2 of the BUCK module 30 will have insufficient lightning protection capability. Therefore, a lightning protection module 50 is added in front of the rectifier module 10 to enhance the lightning protection capability of the drive circuit 100.
[0057] The BUCK power supply module 40 includes a second diode D2, a second capacitor C2 and a fifth resistor R5. One end of the second diode D2 is connected to the output end of the rectifier module 10, and the other end is connected to the second capacitor C2 and charges the second capacitor C2. The input end of the BUCK module 30 is connected to the second capacitor C2, and the second capacitor C2 supplies power to the BUCK module 30.
[0058] The BUCK power supply module 40 further includes a fifth resistor R5. The BUCK module 30 is connected to the second capacitor C2 via the fifth resistor R5. The voltage on the second capacitor C2 is current limited by the fifth resistor R5 to supply power to the BUCK module 30. The capacity of the second capacitor C2 is between 33nF and 100nF.
[0059] like Figure 4As shown, the BUCK power supply module 40 is composed of a second diode D2, a second capacitor C2, and a fifth resistor R5. The second capacitor C2 is a thin film capacitor of CBB or CL specifications. The capacity of the second capacitor C2 is relatively low, usually below 100nF. When the drive circuit 100 is working, the high-voltage half-wave AC rectified by the rectifier module 10 passes through the second diode D2 to the second capacitor C2. The capacity of the second capacitor C2 is relatively low. The waveform on the second capacitor C2 is a high-voltage half-wave. However, at the bottom of the half-wave, the voltage will not reach 0V due to the existence of the second capacitor C2. The appropriate capacitance of the second capacitor C2 is selected so that the valley voltage is greater than the minimum working voltage of the buck chip U2, which is usually more than 30V. The buck chip U2 does not stop working due to low voltage. The energy consumed by the buck chip U2 is not large. The capacity of the second capacitor C2 is not too large. Usually, it can make the valley voltage greater than the minimum working voltage of the buck chip U2 when it is below 33nF-100nF. The voltage on the second capacitor C2 then provides power to the buck chip U2 through the fifth resistor R5. The function of the fifth resistor R5 is to limit the current and improve the lightning strike capability. The voltage on the second capacitor C2 is a high voltage half-wave, and the average voltage is 2*√2*Vac / π. In some embodiments, when the AC terminal voltage is 220V, the average voltage on the second capacitor C2 is 198V. Compared with the traditional solution of directly connecting the first electrolytic capacitor EC1, the power supply loss of the buck chip U2 is reduced by half, and the temperature of the buck chip U2 is reduced, which can be used in higher power applications.
[0060] The lightning protection module 50 includes a safety resistor RF1 and a varistor MOV1. The safety resistor RF1 is connected to the L terminal of the driving circuit 100, and then connected to the N terminal of the driving circuit 100 through the varistor MOV1. Through the lightning protection module 50, when a lightning strike occurs, an instantaneous high voltage will be generated at the AC input terminal. At this time, the resistance value of the varistor MOV1 will instantly decrease, and the internal circuit will be instantly short-circuited. In this way, when a lightning strike occurs, the L terminal of the driving circuit 100 is directly connected to the ground, and the strong voltage and current are unloaded.
[0061] In this embodiment, the BUCK power supply module 40 is set to draw power from the rectifier module 10, and the voltage on the second capacitor C2 in the BUCK power supply module 40 provides power to the buck chip U2 through the fifth resistor R5, which can further improve the lightning resistance while limiting the current. Compared with the traditional solution of directly connecting the buck chip U2 to the first electrolytic capacitor EC1, the power supply loss of the buck chip U2 is reduced by half, and the temperature of the buck chip U2 is significantly reduced. While controlling the size of the buck chip U2, it can drive a higher power LED load, and the overall circuit structure of the drive circuit 100 is relatively simple.
[0062] In some embodiments, the BUCK module 30 includes a buck chip U2, which supplies high voltage to the internal HV pin. The HV pin of the buck chip U2 is connected to the output end of the BUCK power supply module 40. The BUCK module 30 converts the high-voltage direct current on the first electrolytic capacitor EC1 into a lower-voltage direct current on the second electrolytic capacitor EC2. The output terminals LED+ and LED- are respectively connected to the positive and negative terminals of the second electrolytic capacitor EC2. The buck chip U2 is packaged in SOP8 and is widely used in designs below 30W.
[0063] The buck chip U2 has a built-in power MOS, and the BUCK module 30 works in a BUCK topology structure, with fewer circuit components and relatively simple circuits, while also achieving higher conversion efficiency and lower electromagnetic interference.
[0064] In some embodiments, the working topology of the PFC module 20 is a BOOST structure.
[0065] The output end of the BUCK module 30 includes LED+ and LED-, which are used to be connected to a load to provide a voltage required for the load to work.
[0066] The present invention further provides a lamp, comprising the above-mentioned driving circuit 100 and a load, wherein the load is connected to the output end of the driving circuit 100, so as to achieve driving a load with relatively high power while the overall volume of the driving circuit 100 is relatively small.
[0067] To summarize, the driving circuit of the present invention, through the BUCK power supply module 40 provided, takes power from the rectifier module 10 and provides it to the BUCK module. Compared with the traditional BUCK module 30 taking power from the PFC module 20, the input voltage of the buck chip U2 of the BUCK module 30 is greatly reduced, thereby reducing the loss and heat generation of the power supply part of the buck chip U2. At the same time, the circuit design of the BUCK power supply module 40 can also absorb the impact energy when encountering high-voltage lightning strikes, effectively protecting the HV pin of the buck chip U2 and improving the safety performance. The overall circuit structure is also relatively simple and has strong practicality.
[0068] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.
Claims
1. A driving circuit, characterized in that: include: A rectifier module (10), used for converting external alternating current into half-wave alternating current; A PFC module (20) is used to step up and adjust the half-wave alternating current and output direct current of a first voltage, the PFC module (20) being connected to the rectifier module (10); A BUCK module (30) is used to step down the direct current of the first voltage output by the PFC module (20) and provide it to a load, the BUCK module (30) being connected to the output end of the PFC module (20); A BUCK power supply module (40) is used to supply power to the BUCK module (30), wherein an input end of the BUCK power supply module (40) is connected to an output end of the rectifier module (10), and an output end of the BUCK power supply module (40) is connected to the BUCK module (30).
2. The driving circuit according to claim 1, characterized in that: The BUCK power supply module (40) comprises a second diode (D2), a third electrolytic capacitor (EC3) and a fourth electrolytic capacitor (EC4) which are connected in series in sequence, the third electrolytic capacitor (EC3) and the fourth electrolytic capacitor (EC4) are charged via the second diode (D2), and the voltage output by the second diode (D2) is provided to the BUCK module (30) after being divided by the third electrolytic capacitor (EC3) and the fourth electrolytic capacitor (EC4).
3. The driving circuit according to claim 2, characterized in that: The BUCK power supply module (40) further comprises: a fifth resistor (R5) for reducing the current output by the BUCK power supply module (40); two ends of the fifth resistor (R5) are respectively connected to the BUCK module (30) and the positive electrode of the fourth electrolytic capacitor (EC4); the current output by the fourth electrolytic capacitor (EC4) flows into the BUCK module (30) through the fifth resistor (R5).
4. The driving circuit according to claim 2, characterized in that: The second electrolytic capacitor (EC2) and the third electrolytic capacitor (EC3) have the same capacity.
5. The driving circuit according to claim 2, characterized in that: The third electrolytic capacitor (EC3) and the fourth electrolytic capacitor (EC4) are both aluminum electrolytic capacitors, and the capacity of the third electrolytic capacitor (EC3) is greater than 6.8uF, and the capacity of the fourth electrolytic capacitor (EC4) is greater than 6.8uF.
6. The driving circuit according to claim 1, characterized in that: The BUCK power supply module (40) comprises a second diode (D2) and a second capacitor (C2); the anode of the second diode (D2) is connected to the output end of the rectifier module (10); the cathode of the second diode (D2) is connected to the second capacitor (C2) and charges the second capacitor (C2); the input end of the BUCK module (30) is connected to the second capacitor (C2); and the second capacitor (C2) supplies power to the BUCK module (30).
7. The driving circuit according to claim 6, characterized in that: The BUCK power supply module (40) further comprises a fifth resistor (R5) for reducing the current output by the BUCK power supply module (40); two ends of the fifth resistor (R5) are respectively connected to the second capacitor (C2) and the BUCK module (30); the current output by the second capacitor (C2) flows into the BUCK module (30) after passing through the fifth resistor (R5).
8. The driving circuit according to claim 6, characterized in that: The capacity of the second capacitor (C2) is between 33nF and 100nF.
9. The driving circuit according to claim 1, characterized in that: The driving circuit also includes a lightning protection module (50) for suppressing external lightning voltage, one end of the lightning protection module (50) being connected to the external mains power, and the other end being connected to the PFC module (20).
10. The driving circuit according to claim 9, characterized in that: The lightning protection module (50) comprises a safety resistor (RF1) and a varistor (MOV1), and the L end of the drive circuit is connected to the N end of the drive circuit via the safety resistor (RF1) and the varistor (MOV1) in sequence.
11. The driving circuit according to claim 1, characterized in that: The BUCK module (30) comprises a buck chip (U2), the buck chip (U2) is used to supply power to an internal HV pin, and the HV pin of the buck chip (U2) is connected to the output end of the BUCK power supply module (40).
12. The driving circuit according to claim 11, characterized in that: The buck chip (U2) has a built-in power MOS, and the BUCK module (30) operates in a BUCK topology structure.
13. The driving circuit according to claim 1, characterized in that: The working topology structure of the PFC module (20) is a BOOST structure.
14. A lamp, characterized in that: The invention comprises the driving circuit according to any one of claims 1 to 13 and a load, wherein the load is connected to the output end of the driving circuit.