LED constant current control circuit
By changing the connection mode of depletion-type devices in the LED constant current control circuit and using the pinch-off voltage of the MOS tube, the problem of high energy consumption of the constant current control circuit in the prior art is solved, and more efficient power supply and longer LED light module for life.
Patent Information
- Application Number
- CN202420829569.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-19
- Publication Date
- 2024-12-20
- Estimated Expiration
- 2034-04-19
AI Technical Summary
The existing constant current control circuit has the problem of high energy consumption. The connection between the gate and source of the depleted device leads to an increase in circuit energy consumption. The enhanced MOS tube needs to have high voltage resistance characteristics, which increases circuit cost and complexity.
Design an LED constant current control circuit, convert AC current into pulsating DC through the rectifier module, and use depletion devices and enhanced MOS tubes to achieve constant current control, changing the connection mode of depletion devices, so that the enhanced MOS tubes only It needs to withstand the pinch voltage, and the pinch voltage of the MOS tube is used through the second LED lamp module to reduce circuit energy consumption.
It effectively reduces circuit energy consumption, improves power supply efficiency, reduces heating, extends the service life of LED lamp modules, and improves luminous efficiency.
Smart Images
Figure CN222215998U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of light emitting diode lighting, and in particular to an LED constant current control circuit. Background Art
[0002] Light-emitting diode (LED) is a light-emitting display device made of semiconductor materials such as gallium phosphide (GaP) that can directly convert electrical energy into light energy. It is increasingly widely used in the field of lighting fixtures. LED has the advantages of low power consumption, high luminous intensity, energy saving and environmental protection. Compared with traditional lamps such as incandescent lamps and fluorescent lamps, it is increasingly favored by users.
[0003] In actual needs and applications, although many loads (such as LEDs) do not consume much power, they require that the power supply current and voltage must remain relatively stable within a certain range, and at the same time require a certain degree of protection for some components in the load. To solve the problem of power supply for such loads, a constant current or voltage-stabilized power supply is usually used, and an overcurrent protection circuit for some components in the load under abnormal conditions needs to be added to the power supply circuit. This makes this type of power supply have the disadvantages of many components, complex circuits, and a large power consumption ratio.
[0004] The constant current control circuit in the prior art is as follows Figure 1 As shown, the maximum current capacity of the depletion-type field effect transistor itself is used to achieve the purpose of current limiting control and circuit simplification, wherein the depletion-type device and the enhancement-type MOS tube are connected in series in the LED lamp group, the drain of the depletion-type device is connected to the DC output end of the rectifier circuit, and the gate and source of the depletion-type device are connected. By controlling the conduction strength of the enhancement-type MOS tube, the working current of the LED lamp group is stabilized to achieve the purpose of constant current control.
[0005] The prior art has the following defects: since the depletion-type device mainly plays the role of withstanding high voltage in the circuit and does not have the function of regulating voltage, when the enhancement-type MOS tube is turned off, the source of the enhancement-type MOS tube will be subjected to high voltage, which requires the enhancement-type MOS tube to have the characteristic of withstanding high voltage, thereby increasing the cost and complexity of the circuit, and in the constant current control circuit of the prior art, the gate and source of the depletion-type device are connected, which wastes the voltage difference between the gate and source of the depletion-type device, resulting in increased energy consumption of the circuit, and this situation needs to be improved. Utility Model Content
[0006] In order to solve the problem of high energy consumption of the constant current control circuit in the prior art, the present application provides an LED constant current control circuit.
[0007] The present application provides an LED constant current control circuit, which adopts the following technical solution:
[0008] An LED constant current control circuit comprises a rectifier module, a first LED lamp module, a control module, a depletion-type device and an enhanced MOS tube; the rectifier module is connected to a power supply, and is configured to convert the alternating current output by the power supply into pulsating direct current; the drain of the depletion-type device is connected to one end of the rectifier module, and the source of the depletion-type device is connected to the drain of the enhanced MOS tube; the source of the enhanced MOS tube is respectively connected to the input end of the first LED lamp module, the gate of the depletion-type device and the ground pin of the control module, the output end of the first LED lamp module is connected to the other end of the rectifier module, the gate of the enhanced MOS tube is connected to the output end of the control module, and the control module is configured to control the conduction strength of the enhanced MOS tube.
[0009] By adopting the above technical solution, when the power supply supplies power to the first LED lamp module, the power supply outputs AC power to the rectifier module, and the rectifier module converts the AC power into pulsating DC power and then supplies power to the first LED lamp module. In order to stabilize the working current of the first LED lamp module, a depletion-type device and an enhancement-type MOS tube are connected in series between the rectifier module and the first LED lamp module. The conduction strength of the enhancement-type MOS tube is controlled by the control module to achieve the purpose of constant current control. In order to reduce the energy consumption of the circuit, the voltage difference between the gate and the source of the depletion-type device is utilized, and the connection mode of the depletion-type device is changed so that the enhancement-type MOS tube only needs to withstand the pinch-off voltage of the depletion-type device. This not only solves the high-voltage resistance problem of the depletion-type device, but also utilizes the voltage difference between the gate and the source of the depletion-type device, which is conducive to solving the problem of high energy consumption of the constant current control circuit in the prior art.
[0010] Optionally, the depletion mode device is a depletion mode gallium nitride D-mode GaN.
[0011] By adopting the above technical solutions, gallium nitride (GaN) is a wide bandgap semiconductor material with excellent electronic properties and high electron mobility. GaN power devices are widely used in high-efficiency energy consumption and high-frequency electronic devices. Depletion-mode gallium nitride D-mode GaN refers to depletion-mode (D-mode) GaN power devices. Depletion-mode GaN devices have the advantages of large bandgap width, high breakdown voltage, high thermal conductivity, and high switching frequency.
[0012] Optionally, it further comprises a second LED lamp module, wherein the input end of the second LED lamp module is connected to the source of the depletion-mode device, and the output end of the second LED lamp module is connected to the drain of the enhancement-mode MOS tube;
[0013] By adopting the above technical solution, a second LED lamp module is added between the source of the depletion-mode device and the drain of the enhancement-mode MOS tube, and the pinch-off voltage of the MOS tube can be used to power the second LED lamp module, thereby improving the power supply efficiency.
[0014] Optionally, a conduction voltage drop of the second LED lamp module is smaller than a conduction voltage drop of the depletion-mode device.
[0015] By adopting the above technical solution, the conduction voltage drop of the second LED lamp module is designed to be smaller than the conduction voltage drop of the depletion-type device, so as to ensure that the depletion-type device is normally turned on while effectively utilizing the pinch-off voltage of the MOS tube to power the second LED lamp module, thereby improving the power supply efficiency. In the above circuit, the voltage of the LED lamp module is LED light energy converted from the effective voltage, and the voltage of the depletion-type device is an invalid voltage that will be converted into heat energy to generate heat. This circuit connects the second LED lamp module between the source and the gate of the depletion-type device, and utilizes the pinch-off voltage space of the depletion-type device to power the second LED lamp module, thereby fully utilizing the space of the power supply voltage, reducing losses, reducing heat, improving voltage utilization, and increasing the service life of the LED lamp module, thereby improving the luminous efficiency.
[0016] Optionally, a first resistor is also included, wherein the first end of the first resistor is respectively connected to the source of the enhancement mode MOS tube and the control module, and the second end of the first resistor is respectively connected to the input end of the first LED lamp module and the gate of the depletion mode device.
[0017] By adopting the above technical solution, in order to accurately control the current of the first LED lamp module and maintain a stable constant current output, a first resistor is connected in series between the source of the enhanced MOS tube and the first LED lamp module, and the control module samples the voltage on the first resistor. The control module generates a corresponding control signal according to the size of the sampled voltage, and controls the conduction strength of the enhanced MOS tube through the control signal.
[0018] Optionally, the first LED lamp module includes N LED lamps, and the second LED lamp module includes M LED lamps, wherein N is an integer greater than or equal to 1, and M is an integer greater than or equal to 1.
[0019] By adopting the above technical solution, the number of LED lamps in the first LED lamp module and the number of LED lamps in the second LED lamp module can be adjusted according to actual conditions, wherein M is equal to N, M is less than N or M is greater than N. If M is equal to 3 and N is equal to 3, the input voltage can be reduced if the overall brightness needs to be kept unchanged. For example, M and N can be adjusted, M can be adjusted to 4 and N can be adjusted to 2, that is, some LED lamps can be connected in series between the enhancement MOS tube and the depletion mode device.
[0020] In summary, the present application includes at least one of the following beneficial technical effects:
[0021] 1. The conduction strength of the enhanced MOS tube is controlled by the control module to achieve the purpose of constant current control. In order to reduce the energy consumption of the circuit, the voltage difference between the gate and the source of the depletion-type device is utilized, and the connection mode of the depletion-type device is changed so that the enhanced MOS tube only needs to withstand the pinch-off voltage of the depletion-type device. This not only solves the high-voltage resistance problem of the depletion-type device, but also utilizes the voltage difference between the gate and the source of the depletion-type device, which is conducive to solving the problem of high energy consumption in the constant current control circuit in the prior art;
[0022] 2. The conduction voltage drop of the second LED lamp module is designed to be smaller than the conduction voltage drop of the depletion-type device, so as to ensure that the depletion-type device is normally turned on while effectively utilizing the pinch-off voltage of the MOS tube to power the second LED lamp module, thereby improving the power supply efficiency;
[0023] 3. In order to accurately control the current of the first LED lamp module and maintain a stable constant current output, a first resistor is connected in series between the source of the enhanced MOS tube and the first LED lamp module. The control module samples the voltage on the first resistor. The control module generates a corresponding control signal according to the size of the sampled voltage, and controls the conduction strength of the enhanced MOS tube through the control signal. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 This is a schematic diagram of the constant current control circuit of the prior art
[0025] Figure 2 is a schematic diagram of an LED constant current control circuit according to an embodiment of the present application;
[0026] Figure 3 is a schematic diagram of an LED constant current control circuit including a second LED lamp module in an embodiment of the present application;
[0027] Figure 4 is a schematic diagram of an LED constant current control circuit including a first resistor in an embodiment of the present application;
[0028] Figure 5 This is a waveform comparison diagram between the present application and the prior art.
[0029] Description of reference numerals:
[0030] 1. Rectifier module; 2. First LED lamp module; 3. Control module; 4. Depletion-type device; 5. Enhanced MOS tube; 6. Power supply; 8. Second LED lamp module. DETAILED DESCRIPTION
[0031] The following embodiments of the technical solution of the utility model are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the utility model, and are therefore only used as examples, and cannot be used to limit the protection scope of the utility model.
[0032] The "connection" in the present invention includes both direct connection and indirect connection, such as connection through some active devices, passive devices or electrically conductive media; it may also include connection through other active devices or passive devices on the basis of achieving the same or similar functional purposes as is well known to those skilled in the art, such as connection through circuits or components such as switches and follower circuits.
[0033] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by technicians in the field to which the utility model belongs.
[0034] In order to facilitate the understanding of the present application scheme, the depletion mode MOS tube (depletion mode gallium nitride D-mode GaN) is described below:
[0035] Gallium nitride semiconductor is a wide bandgap semiconductor material with excellent electronic properties and advantages such as high electron mobility, large bandgap width, high breakdown voltage, large thermal conductivity, and high switching frequency. Device manufacturing has gradually matured and is widely used in high-efficiency energy consumption and high-frequency electronic equipment such as power conversion systems such as switching power supplies. It has not yet been used in LED control systems. The present invention provides an application architecture of depletion-mode gallium nitride devices in LED systems, which can promote the development of third-generation semiconductor devices, namely gallium nitride semiconductors. The solution in this application is an improvement based on D-mode GaN (third-generation semiconductor devices).
[0036] Example 1
[0037] The present application embodiment discloses a LED constant current control circuit. Figure 2 An LED constant current control circuit includes a rectifier module 1, a first LED lamp module 2, a control module 3, a depletion-mode device 4, and an enhancement-mode MOS tube 5. The depletion-mode device 4 is D-mode GaN, which is a high-performance power semiconductor device depletion-mode gallium nitride with high electron mobility and low on-resistance, so that it can achieve low switching loss and high efficiency.
[0038] The rectifier module 1 is connected to the power supply 6, the input end of the first LED lamp module 2 is connected to one end of the rectifier module 1, and the output end of the first LED lamp module 2 is grounded. When the power supply 6 supplies power, the output current is supplied to the rectifier module 1, and the rectifier module 1 converts the AC power into pulsating DC power.
[0039] In one embodiment, the rectifier module 1 includes a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4. The rectifier module 1 is composed of the first diode D1, the second diode D2, the third diode D3, and the fourth diode D4. The current of the power supply 6 passes through the rectifier module 1 to supply power to the second LED lamp module 8. Specifically, the input end of the first diode D1 is connected to the output end of the power supply 6 and the third diode D3 respectively, the output end of the first diode D1 is connected to the output end of the second diode D2, the input end of the second diode D2 is connected to the output end of the fourth diode D4, the connection node of the second diode D2 and the fourth diode D4 is connected to the power supply 6, and the input end of the third diode D3 is connected to the fourth diode D4. It should be noted that the rectifier module can be any one of the conventional rectifier bridge connection modes, and its connection mode is not limited here. The scheme in this application is configured by the rectifier module 1. Regardless of the polarity of the input alternating current, at least two diodes will be turned on, so that the current can only flow in one direction in the rectifier module 1, thereby realizing the rectification of the alternating current.
[0040] In order to stabilize the working current of the first LED lamp module 2, a depletion-type device 4 and an enhancement-type MOS tube 5 are connected in series between the rectifier module 1 and the first LED lamp module 2. The drain of the depletion-type device 4 is connected to the output end of the rectifier module 1, and the source of the depletion-type device 4 is connected to the drain of the enhancement-type MOS tube 5; the source of the enhancement-type MOS tube 5 is respectively connected to the gates of the first LED lamp module 2 and the depletion-type device 4, the gate of the enhancement-type MOS tube 5 is connected to the output end of the control module 3, and the ground end of the control module 3 is connected to the input end of the first LED lamp module 2. The control module 3 stabilizes the working current of the first LED lamp module 2 by controlling the conduction strength of the enhancement-type MOS tube 5, thereby achieving the purpose of constant current control. In order to reduce the energy consumption of the circuit, the scheme in the present application utilizes the voltage difference between the gate and the source of the depletion-type device 4, and changes the connection mode of the depletion-type device 4, so that the enhancement-type MOS tube 5 only needs to withstand the pinch-off voltage of the depletion-type device 4, which is conducive to solving the high-voltage resistance problem of the depletion-type device 4. For ease of understanding, the following examples are given:
[0041] If the grid voltage is 120V after passing through the rectifier module 1, and the pinch-off voltage of the depletion-type device 4 is 30V, when the control module 3 controls the depletion-type device 4 to turn on, the LED lamp in the first LED lamp module 2 lights up, and the total effective voltage of the LED lamp is 90V (i.e., 120V-30V), and the enhancement-type MOS tube 5 only needs to withstand the pinch-off voltage of the depletion-type device 4. However, when the enhancement-type MOS tube 5 withstands the pinch-off voltage of the depletion-type device 4, the enhancement-type MOS tube 5 will also heat up, resulting in loss, and embodiment 2 is provided for this.
[0042] Example 2
[0043] The difference between Example 2 and Example 1 is that a second LED lamp module 8 is connected in series between the enhancement mode MOS tube 5 and the depletion mode device 4. Figure 3 , the first end of the second LED lamp module 8 is connected to the source of the depletion-type device 4, the second end of the second LED lamp module 8 is connected to the drain of the enhancement-type MOS tube 5, and the conduction voltage drop of the second LED lamp module 8 is designed to be less than the pinch-off voltage of the depletion-type device 4, so as to ensure that the depletion-type device 4 is normally turned on while effectively utilizing the pinch-off voltage of the depletion-type device 4 to power the second LED lamp module 8, thereby improving the power supply efficiency. For ease of understanding, an example is given below:
[0044] If the grid voltage is 120V after passing through the rectifier module 1, when the control module 3 controls the enhanced MOS tube 5 to be turned on, the LED lights in the first LED lamp module 2 and the second LED lamp module 8 light up, and the pinch-off voltage of the depletion-type device 4 is added to the enhanced MOS tube 5 and the second LED lamp module 8. If the pinch-off voltage of the depletion-type device 4 is equal to 30V, and the total voltage of the second LED lamp module 8 when working normally is designed to be 29V, the voltage on the enhanced MOS tube 5 is 1V, and the enhanced MOS tube 5 will not generate heat when working normally; at the same time, the effective total voltage of the first LED lamp module 2 is still 90V, and the LED lamp group has the same power but brighter illumination, and the pinch-off voltage of the depletion-type device 4 is used to improve the overall efficiency of the circuit.
[0045] In the above circuit, the voltage of the LED lamp module is LED light energy converted from effective voltage, and the voltage of the depletion-type device is invalid voltage which will be converted into heat energy to generate heat. This circuit connects the second LED lamp module between the source and the gate of the depletion-type device, and uses the pinch-off voltage space of the depletion-type device to power the second LED lamp module, making full use of the space of the power supply voltage, reducing losses, reducing heat, improving voltage utilization, and increasing the service life of the LED lamp module and the luminous efficiency.
[0046] In one embodiment, the first LED lamp module 2 includes N LED lamps, and the second LED lamp module 8 includes M LED lamps. The number of LED lamps in the first LED lamp module 2 and the number of LED lamps in the second LED lamp module 8 can be adjusted according to actual conditions. If you want to keep the overall brightness unchanged, you can also reduce the input voltage. Some LED lamps can be connected in series between the enhanced MOS tube 5 and the depletion-type device 4. For example, assuming that the first LED lamp module 2 includes 3 LED lamps and the second LED lamp module 8 includes 3 LED lamps, the LED lamps in the second LED lamp module 8 can be adjusted to the first LED lamp module 2, that is, the first LED lamp module 2 includes 4 LED lamps and the second LED lamp module 8 includes 4 LED lamps. At this time, the overall LED light brightness remains unchanged, but the input voltage is reduced.
[0047] Another comparative example, in Figure 1 Set up 20 LED lights in the system. Figure 3 The first LED lamp module is set with 15 LED lamps, and the second LED lamp module is set with 5 LED lamps. The total number of LED lamps in the two systems is equal. The input power is set to an effective value of 100V AC. Figure 1 The current of the middle lamp is I new , flows through Figure 3 The current of the middle lamp is I old , its waveform comparison chart reference Figure 5 , it can be seen intuitively that Figure 3 The system has a higher current utilization rate and a brighter Figure 1 The system is brighter, and the required on-voltage is lower than the on-voltage in the prior art by a pinch-off voltage of a depletion-type device, converting the pinch-off voltage wasted in the prior art into effective LED light energy, making full use of the space of the power supply voltage, improving the voltage utilization rate, and improving the luminous efficiency.
[0048] Example 3
[0049] In order to accurately control the current of the first LED lamp module 2 and maintain a stable constant current output, Example 3 is adjusted on the basis of Example 2. The difference between Example 3 and Example 2 is that a first resistor R1 is connected in series between the enhanced MOS tube 5 and the first LED lamp module 2. Figure 4, the first end of the first resistor R1 is connected to the source of the enhancement MOS tube 5 and the sampling end of the control module 3 respectively, and the second end of the first resistor R1 is connected to the input end of the first LED lamp module 2 and the gate of the depletion-type device 4 respectively. The control module 3 samples the voltage on the first resistor R1, and the control module 3 generates a corresponding control signal according to the size of the sampled voltage, and controls the conduction strength of the enhancement MOS tube 5 through the control signal, so as to stabilize the working current of the first LED lamp module 2 and achieve the purpose of precise constant current control. For ease of understanding, the following examples are given:
[0050] like Figure 4 As shown, the gate of the depletion-mode device 4 is connected to the second end of the first resistor R1 and the input end of the first LED lamp module 2 respectively, and the first end of the first resistor R1 is connected to the source of the enhancement-mode MOS tube 5, and a sampling signal (i.e. Figure 4 VCS) to the control module 3, and the control module 3 outputs the control information (i.e. Figure 4 S1) to the enhancement mode MOS transistor 5 to control the conduction strength of the enhancement mode MOS transistor 5.
[0051] It should be noted that the solution in this application is an improvement based on depletion-mode gallium nitride D-mode GaN (third-generation semiconductor device), wherein depletion-mode gallium nitride D-mode GaN refers to a depletion-mode (D-mode) GaN power device. Depletion-mode GaN devices have the advantages of large bandgap width, high breakdown voltage, high thermal conductivity, and high switching frequency.
[0052] Specifically, the high switching frequency means that the application circuit can use smaller passive devices; the high breakdown voltage means that the voltage tolerance is higher than that of traditional silicon materials and will not affect the on-resistance performance, thereby reducing conduction losses.
[0053] Depletion-mode D-mode GaN devices consist of three basic parts: source (S), gate (G) and drain (D). Their functions are similar to those of ordinary depletion-mode tubes, but they have a higher pinch-off voltage (Vth) than ordinary depletion-mode tubes. When the negative voltage reaches the device's turn-off pinch-off voltage, the depletion-mode D-mode GaN is turned off and the on-current is zero.
[0054] The implementation principle of an LED constant current control circuit in the embodiment of the present application is as follows: the control circuit includes a rectifier module 1, a first LED lamp module 2, a control module 3, a depletion-type device 4 and an enhanced MOS tube 5; when the power supply 6 supplies power, the output current is supplied to the rectifier module 1, and the rectifier module 1 converts the alternating current into pulsating direct current to supply power to the first LED lamp module 2, and then controls the conduction strength of the enhanced MOS tube 5 through the control module 3 to achieve the purpose of constant current control. In order to reduce the energy consumption of the circuit, the voltage difference between the gate and the source of the depletion-type device 4 is utilized, and the connection mode of the depletion-type device 4 is changed so that the enhanced MOS tube 5 only needs To withstand the pinch-off voltage of the depletion-type device 4, not only the high-voltage resistance problem of the depletion-type device 4 is solved, but also the voltage difference between the gate and the source of the depletion-type device 4 is utilized to power the second LED lamp module, and the voltage space is effectively converted into LED light energy, thereby reducing losses, reducing heat, improving voltage utilization, and increasing the service life of the LED lamp module, thereby improving luminous efficiency, and being more conducive to solving the problem of high energy consumption in the constant current control circuit in the prior art. The LED constant current control circuit provided in the present application has the advantages of few components, simple circuit, full utilization of the power supply voltage space, improved working efficiency, and expanded working voltage range.
[0055] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.
Claims
1. An LED constant current control circuit, characterized in that: The invention comprises a rectifier module (1), a first LED lamp module (2), a control module (3), a depletion-type device (4) and an enhanced MOS tube (5); the rectifier module (1) is connected to a power source (6), and the rectifier module (1) is configured to convert the alternating current output by the power source (6) into pulsating direct current; the drain of the depletion-type device (4) is connected to one end of the rectifier module (1), and the source of the depletion-type device (4) is connected to the drain of the enhanced MOS tube (5); the source of the enhanced MOS tube (5) is respectively connected to the input end of the first LED lamp module (2), the gate of the depletion-type device (4) and the ground pin of the control module (3); the output end of the first LED lamp module (2) is connected to the other end of the rectifier module (1), the gate of the enhanced MOS tube (5) is connected to the output end of the control module (3), and the control module (3) is configured to control the conduction strength of the enhanced MOS tube (5).
2. The LED constant current control circuit according to claim 1, characterized in that: The depletion mode device is a depletion mode gallium nitride D-mode GaN.
3. The LED constant current control circuit according to claim 2, characterized in that: It also comprises a second LED lamp module (8), wherein the input end of the second LED lamp module (8) is connected to the source of the depletion-type device (4), and the output end of the second LED lamp module (8) is connected to the drain of the enhancement-type MOS tube (5).
4. The LED constant current control circuit according to claim 3, characterized in that: The voltage drop of the second LED lamp module (8) is less than the pinch-off voltage of the depletion-type device (4).
5. The LED constant current control circuit according to claim 3, characterized in that: It also comprises a first resistor, wherein the first end of the first resistor is respectively connected to the source of the enhancement-mode MOS tube (5) and the control module (3), and the second end of the first resistor is respectively connected to the input end of the first LED lamp module (2) and the gate of the depletion-mode device (4).
6. The LED constant current control circuit according to claim 3, characterized in that: The first LED lamp module (2) includes N LED lamps, and the second LED lamp module (8) includes M LED lamps, wherein N is an integer greater than or equal to 1, and M is an integer greater than or equal to 1.