Linear dimming loss-reducing LED driving power supply circuit

Abstract

The utility model particularly relates to a linear dimming loss-reducing LED driving power supply circuit, which comprises a VIN end, three light-emitting diodes, three field-effect transistors, three dimming controllers and a voltage comparator U1 which are combined for use. The circuit realizes high-efficiency loss reduction through a multi-stage linear dimming control and dynamic voltage adaptation technology. Three independent dimming channels are arranged, and PWM or analog dimming is supported; the lowest conduction voltage drop of the LED branch is monitored in real time through the diode; and a voltage feedback closed loop is realized based on a resistor and a voltage comparator U1. The circuit has the advantages of adaptive voltage tracking, multi-channel cooperative control, no stroboflash in linear dimming, high thermal stability, high efficiency in different working modes and controllable cost, and is suitable for scenes of intelligent illumination and the like.

Description

Technical Field

[0001] This utility model specifically relates to a linear dimming and loss-reducing LED driver power supply circuit. Background Technology

[0002] Linear dimming changes the LED branch current by adjusting the conduction level of the MOS-FET. It has advantages such as no flicker and simple circuit structure, and is widely used in commercial lighting, stage lighting and other scenarios with high requirements for dimming smoothness.

[0003] In practical applications, multi-path linear dimming faces the following key technical bottlenecks with multiple LED chips: voltage drop dispersion (ΔV). f Due to the influence of semiconductor material process tolerances, junction temperature drift, and aging, the forward voltage drop of LED chips in the same batch exhibits a discrete distribution of ±5%-10% (data source: LED Manufacturing White Paper, 2021). Additionally, there are differences in power specifications: when mixing LED chips of different power levels (e.g., 1W / 3W / 5W), their rated operating voltage ranges can differ by 3-12V (see IEEE Standard 1789-2015). Existing solutions and shortcomings: To address the above issues, the industry currently widely adopts voltage redundancy design. The principle of this technology is to convert the input voltage V... in Increase to 1.2-1.5 times the voltage required by the highest branch, expressed by the formula: V in = max(V f1 V f2 ,..., V fn< / } ) × k (k is the safety factor, usually taken as 1.3); the problem is energy efficiency degradation: redundant voltage ΔV = V in -V f All power is applied to the MOSFET, resulting in power loss P. loss =I LED ×ΔV, actual measurements show that the system efficiency is less than 60% (compared to 85%+ for switching power supply solutions). Furthermore, there is a risk of thermal runaway: the MOSFET junction temperature rise rate is quadratic with ΔV; when ΔV > 5V, the temperature rise can reach 70℃ / s (referencing JEDEC 51-2 thermal test data), requiring a large-area heatsink or forced air cooling. There is also a deterioration in dimming nonlinearity: under high voltage differential, the MOSFET operates in a deeply linear region, causing a "dead zone" in the PWM dimming curve, with measured THD > 15% (data source: CN105338700A patent document).

[0004] Although it has high energy efficiency, it has significant EMI noise (43% of CISPR15 Class B exceedance rate) and requires complex inductor components (increasing cost by more than 30%). In addition, configuring independent DC-DC modules for each channel solves the voltage difference problem, but increases the system size by 2 to 3 times, which does not conform to the trend of miniaturization of recessed lighting fixtures. Summary of the Invention

[0005] This invention aims to solve at least one of the technical problems existing in the prior art. Therefore, one objective of this invention is to provide a linear dimming and loss-reducing LED driver power supply circuit, which further simplifies the overall circuit, reduces its size, eliminates the lowest voltage drop, puts the entire circuit in the optimal loss region, and improves heat dissipation.

[0006] According to the present invention, a linear dimming and loss-reducing LED driver power supply circuit includes a VIN terminal, a first light-emitting diode (LED1), a second light-emitting diode (LED2), and a third light-emitting diode (LED3). The VIN terminal is connected to one end of each of the LEDs. The circuit also includes a first field-effect transistor (FET) Q1, a second field-effect transistor (FET) Q2, and a third field-effect transistor (FET) Q3, a first dimming controller, a second dimming controller, a third dimming controller, a voltage comparator U1, a first resistor R1, a second resistor R2, an FB terminal, and a VCC terminal. The VCC terminal is connected to pin 5 of the voltage comparator U1. Pin 1 of the voltage comparator U1 is connected to one end of the second resistor R2, and the other end of the second resistor R2 is connected to ground (GND). A first voltage comparator is connected between pins 1 and 5 of the voltage comparator U1. Resistor R1 connects pin 4 of voltage comparator U1 to the FB terminal. First LED (LED1) is connected to pin 2 of first MOSFET Q1. Second LED (LED2) is connected to pin 2 of second MOSFET Q2. Third LED (LED3) is connected to pin 2 of third MOSFET Q3. Three leads from the VCC terminal are connected to the common terminal between LED1 and pin 2 of first MOSFET Q1, the common terminal between LED2 and pin 2 of second MOSFET Q2, and the common terminal between LED3 and pin 2 of third MOSFET Q3. First MOSFET Q1 is connected to the first dimming controller, second MOSFET Q2 is connected to the second dimming controller, and third MOSFET Q3 is connected to the third dimming controller. The FB terminal is connected to the front-end voltage control circuit.

[0007] Specifically, pin 1 of the first field-effect transistor Q1 is connected to a first gate resistor R_G1, pins 1 and 3 of the first field-effect transistor Q1 are connected to a first drain resistor R_D1, pin 3 of the first field-effect transistor Q1 is connected to a first source resistor R_S1, and the first source resistor R_S1 is also connected to a ground terminal GND.

[0008] Specifically, the resistance values ​​of the first gate resistor R_G1, the first drain resistor R_D1, and the first source resistor R_S1 are 0.1Ω to 0.5Ω, and the power rating of the first gate resistor R_G1, the first drain resistor R_D1, and the first source resistor R_S1 is 1W.

[0009] Specifically, pin 1 of the second field-effect transistor Q2 is connected to a second gate resistor R_G2, pins 1 and 3 of the second field-effect transistor Q2 are connected to a second drain resistor R_D2, pin 3 of the second field-effect transistor Q2 is connected to a second source resistor R_S2, and the second source resistor R_S2 is also connected to a ground terminal GND.

[0010] Specifically, the resistance values ​​of the second gate resistor R_G2, the second drain resistor R_D2, and the second source resistor R_S2 are 0.1Ω to 0.5Ω, and the power rating of the second gate resistor R_G2, the second drain resistor R_D2, and the second source resistor R_S2 is 1W.

[0011] Specifically, pin 1 of the third field-effect transistor Q3 is connected to a third gate resistor R_G3, pins 1 and 3 of the first field-effect transistor Q1 are connected to a third drain resistor R_D3, pin 3 of the third field-effect transistor Q3 is connected to a third source resistor R_S3, and the third source resistor R_S3 is also connected to a ground terminal GND.

[0012] Specifically, the resistance values ​​of the third gate resistor R_G3, the third drain resistor R_D3, and the third source resistor R_S3 are 0.1Ω to 0.5Ω, and the power rating of the third gate resistor R_G3, the third drain resistor R_D3, and the third source resistor R_S3 is 1W.

[0013] Specifically, the resistance of the first resistor R1 and the second resistor R2 is 47KΩ, and the voltage division ratio of the first resistor R1 and the second resistor R2 is 1:1.

[0014] Furthermore, the VCC terminal is also connected to a third resistor R3, and the third resistor R3 is connected to a first diode D1, a second diode D2, and a third diode D3. The first diode D1, the second diode D2, and the third diode D3 are respectively connected to a first light-emitting diode LED1, a second light-emitting diode LED2, and a third light-emitting diode LED3.

[0015] Specifically, a first capacitor C1 is connected to the common terminal between pin 4 and FB of the voltage comparator U1. The first capacitor C1 is connected to a fourth resistor R4, which is connected to pin 3 of the voltage comparator U1.

[0016] The beneficial effects of this invention are as follows: It employs multi-level linear dimming control and dynamic voltage adaptation technology, dynamically adjusting the VIN terminal according to load demand, reducing power loss by 20%-40% compared to a fixed voltage scheme. Closed-loop control minimizes the on-resistance of the first MOSFET Q1, second MOSFET Q2, and third MOSFET Q3, and these transistors reduce losses by at least 50% compared to traditional fixed redundancy schemes, achieving high efficiency in loss reduction. The three independent dimming channels support PWM or analog dimming, achieving global optimization through minimum voltage drop detection, avoiding the impact of single-channel dimming on overall efficiency and achieving multi-channel synergy. Maintaining the circuit in the linear region ensures flicker-free linear dimming, avoiding electromagnetic interference issues caused by PWM dimming, resulting in high-quality dimming. Limiting the minimum V_DS prevents the MOSFET from entering the deep linear region, mitigating thermal runaway risks and achieving strong thermal stability. No high-precision ADC or independent DC-DC converter is required. DC modules result in a BOM cost increase of less than 5%, ensuring cost control. They also offer flexible operating modes: maintaining the system in its optimal efficiency range across various modes such as full brightness, 50% dimming, and deep dimming. This makes them suitable for scenarios like smart lighting systems with wide dynamic dimming and stringent thermal management requirements. Attached Figure Description

[0017] The above and / or additional aspects and advantages of this invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings.

[0018] Figure 1 This is the circuit diagram of this utility model. Detailed Implementation

[0019] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0020] The following is for reference. Figure 1A linear dimming and loss-reducing LED driver power supply circuit according to an embodiment of the present invention includes a VIN terminal, a first light-emitting diode (LED1), a second light-emitting diode (LED2), and a third light-emitting diode (LED3). The VIN terminal is connected to one end of each of the LEDs. The circuit also includes a first field-effect transistor (FET) Q1, a second field-effect transistor (FET) Q2, and a third field-effect transistor (FET) Q3, a first dimming controller, a second dimming controller, a third dimming controller, a voltage comparator U1, a first resistor R1, a second resistor R2, an FB terminal, and a VCC terminal. The VCC terminal is connected to pin 5 of the voltage comparator U1. Pin 1 of the voltage comparator U1 is connected to one end of the second resistor R2, and the other end of the second resistor R2 is connected to ground (GND). A third field-effect transistor (FB) is connected between pins 1 and 5 of the voltage comparator U1. A resistor R1 is connected to pin 4 of voltage comparator U1 and the FB terminal. A first LED (LED1) is connected to pin 2 of the first MOSFET Q1, a second LED (LED2) is connected to pin 2 of the second MOSFET Q2, and a third LED (LED3) is connected to pin 2 of the third MOSFET Q3. Three leads from the VCC terminal are connected to the common terminal between LED1 and pin 2 of the first MOSFET Q1, the common terminal between LED2 and pin 2 of the second MOSFET Q2, and the common terminal between LED3 and pin 2 of the third MOSFET Q3. MOSFET Q1 is connected to the first dimming controller, MOSFET Q2 is connected to the second dimming controller, and MOSFET Q3 is connected to the third dimming controller. The FB terminal is connected to a front-end voltage control circuit.

[0021] This circuit achieves high-efficiency loss reduction in LED driver power supplies through multi-level linear dimming control and dynamic voltage adaptation technology. The core design includes the following modules:

[0022] The three independent dimming channels, consisting of the first field-effect transistor Q1, the second field-effect transistor Q2, and the third field-effect transistor Q, and the corresponding first dimming controller, second dimming controller, and third dimming controller, support PWM or analog dimming and achieve multi-channel linear dimming.

[0023] The circuit uses diodes D1, D2, and D3 to monitor the minimum forward voltage drop of each LED branch in real time, thus achieving dynamic voltage drop detection.

[0024] The circuit is based on the reference voltage of the first resistor R1 and the second resistor R2 and the error amplification function of the voltage comparator U1. It adjusts the power supply voltage of the front-end voltage control circuit through the FB terminal and sends it to the VIN terminal, thus playing the role of voltage feedback closed loop.

[0025] Front-end voltage control circuits mainly refer to the following types of circuit designs or application scenarios:

[0026] I. Voltage Converters and Voltage Divider Control Circuits: These circuits achieve stable voltage conversion through voltage divider units, switching units, and reference voltage adjustment. For example, the combination of voltage divider and switching units used in RF switch chips achieves high voltage withstand capability by adjusting the internal reference voltage, avoiding the size issues of traditional MOSFET stacked designs. In drive circuits, step-down circuits and current mirror structures dynamically adjust the control voltage to achieve output voltage regulation, suitable for applications such as battery management systems.

[0027] II. Analog front-end power management circuit, mainly used for monitoring and restarting multi-device power supply systems. For example, it generates power supply parameter signals through a microcontroller and combines them with a digital output module to power and restart analog front-end devices, resolving communication anomalies. The front-end circuit design in the battery management chip integrates voltage monitoring, temperature detection, and passive balancing functions, supporting a wide voltage range of 6-36V.

[0028] 3. Dynamic Voltage Frequency Scaling (DVFS) circuit: In low-power scenarios, the supply voltage is dynamically adjusted. For example, in a system-on-a-chip (SoC), the voltage regulation control module is linked with the power interface master / slave module to achieve fast voltage switching, reduce the duration of high voltage and reduce power consumption.

[0029] IV. Bootstrap circuits and voltage boosting technology are used to generate high-voltage drive signals from low-voltage sources. For example, by using capacitor energy storage and switching, a 6V power supply can be boosted to a 12V output, which is suitable for the high-side drive requirements in Buck / Boost power chips.

[0030] V. Protective voltage control circuits, including overvoltage and undervoltage protection mechanisms. For example, the Crowbar circuit uses a thyristor to trigger a short circuit, working in conjunction with a fuse to achieve overvoltage protection; this is commonly found in the protection of downstream power supply equipment. Light-controlled / temperature-controlled switches in relay control circuits utilize voltage changes to trigger relay operation, achieving equipment on / off protection.

[0031] Detailed working principle of this circuit:

[0032] Dimming control and voltage drop generation: The first dimming controller controls the conduction level by adjusting the voltage at pin 1 of the first field-effect transistor Q1, thereby changing the LED current to achieve dimming.

[0033] During the dimming process, the first field-effect transistor Q1 operates in the linear region (non-saturation region), and its drain-source voltage drop V_DS changes with the conduction state. The voltage drop formula is: V_DS = VIN - V_LEDx - V_Dx, where V_LEDx is the forward voltage drop of the LED string and V_Dx is the voltage drop of the detection diode. Based on the same operating principle, the other second field-effect transistor Q2 and the second field-effect transistor Q3 have the same operating principle, which will not be elaborated here. Additionally, the first dimming controller, the second dimming controller, and the third dimming controller are core devices used to adjust the brightness, color temperature, or color of lighting equipment, enabling intelligent control of lights through electronic control technology.

[0034] Reference voltage setting and comparison control: The first resistor R1 / second resistor R2 voltage division network sets the minimum allowable voltage drop threshold V_ref for the first field-effect transistor Q1, the second field-effect transistor Q2, and the third field-effect transistor Q3: V_ref = (R2 / (R1+R2))* VCC. The voltage comparator U1 compares the detected minimum V_DS with V_ref. When V_DS<V_ref, U1 outputs a feedback signal to the FB terminal, requesting the front end to reduce VIN; when V_DS>V_ref, maintain or increase VIN to ensure the dimming margin.

[0035] Dynamic voltage adaptation process: After receiving the signal at the FB terminal, the front-end control circuit (such as a Buck converter) changes VIN by adjusting the duty cycle or frequency: VIN_optimal = V_LEDx + V_DS_min + V_Dx, where V_DS_min is controlled to be slightly higher than V_ref, and the adjustment accuracy needs to reach ±50mV to balance efficiency and stability. This dynamic adjustment makes all the first field-effect transistor Q1, the second field-effect transistor Q2, and the third field-effect transistor Q3 operate near the critical conduction state, concentrating the power loss at the necessary minimum value.

[0036] Loss optimization mathematical model, the total circuit loss can be expressed as: P_loss = Σ(I_LEDx^2 * R_DS(on)_x) + P_comp + P_frontend, where: R_DS(on)_x changes dynamically with V_DS, and through closed-loop control, it tends to the minimum value.

[0037] The efficiency η_frontend of the front-end circuit satisfies: η_system = (ΣP_LEDx) / (ΣP_LEDx + P_loss).

[0038] Key technological advantages: Adaptive voltage tracking: VIN is dynamically adjusted according to load demand, which can reduce power loss by 20%-40% compared to fixed voltage solutions; Multi-channel collaborative control: Global optimization is achieved through minimum voltage drop detection, avoiding the impact of single-channel dimming on overall efficiency; Flicker-free linear dimming: Keeps the MOS-FET operating in the linear region, avoiding electromagnetic interference problems caused by PWM dimming; Enhanced thermal stability: Limiting the minimum V_DS prevents the MOS-FET from entering the deep linear region, avoiding the risk of thermal runaway.

[0039] Analysis of the circuit's operating status:

[0040] First, the working mode is full brightness mode, and the VIN setting strategy is VIN=Max(V_LEDx+V_Dx+V_DS_min), with a peak efficiency of >92%.

[0041] Second, the working mode is 50% dimming mode, and the VIN setting strategy is to dynamically reduce VIN by 10%-15% while maintaining efficiency of 85%+.

[0042] Third, the working mode is deep dimming mode, and the VIN setting strategy is that VIN is close to ∑V_LEDx, and the efficiency curve transitions smoothly.

[0043] This design maintains the system operating in the optimal efficiency range under wide dimming conditions through a closed-loop negative feedback mechanism, making it particularly suitable for applications such as smart lighting systems that require wide dynamic dimming and have stringent thermal management requirements.

[0044] In this circuit, pin 1 of the first field-effect transistor Q1 is connected to a first gate resistor R_G1, pins 1 and 3 of the first field-effect transistor Q1 are connected to a first drain resistor R_D1, and pin 3 of the first field-effect transistor Q1 is connected to a first source resistor R_S1. The first source resistor R_S1 is also connected to ground GND. The resistance values ​​of the first gate resistor R_G1, the first drain resistor R_D1, and the first source resistor R_S1 in this circuit are 0.1Ω to 0.5Ω, and the power rating of the first gate resistor R_G1, the first drain resistor R_D1, and the first source resistor R_S1 is 1W.

[0045] In this circuit, pin 1 of the second field-effect transistor Q2 is connected to a second gate resistor R_G2, pins 1 and 3 of the second field-effect transistor Q2 are connected to a second drain resistor R_D2, and pin 3 of the second field-effect transistor Q2 is connected to a second source resistor R_S2. The second source resistor R_S2 is also connected to ground GND. The resistance values ​​of the second gate resistor R_G2, the second drain resistor R_D2, and the second source resistor R_S2 in this circuit are 0.1Ω to 0.5Ω, and the power rating of the second gate resistor R_G2, the second drain resistor R_D2, and the second source resistor R_S2 is 1W.

[0046] In this circuit, pin 1 of the third field-effect transistor Q3 is connected to a third gate resistor R_G3, pins 1 and 3 of the first field-effect transistor Q1 are connected to a third drain resistor R_D3, and pin 3 of the third field-effect transistor Q3 is connected to a third source resistor R_S3. The third source resistor R_S3 is also connected to ground GND. The resistance values ​​of the third gate resistor R_G3, the third drain resistor R_D3, and the third source resistor R_S3 in this circuit are 0.1Ω to 0.5Ω, and the power rating of the third gate resistor R_G3, the third drain resistor R_D3, and the third source resistor R_S3 is 1W.

[0047] Among them, the first gate resistor R_G1, the second gate resistor R_G2 and the third gate resistor R_G3 are used to control the switching rate and suppress gate voltage oscillation. The resistance value is usually between 10Ω and 100Ω and needs to be adjusted according to the switching frequency and drive current.

[0048] Among them, the first source resistor R_S1, the second source resistor R_S2 and the third source resistor R_S3 are used to balance the source potential.

[0049] Among them, the first drain resistor R_D1, the second drain resistor R_D2 and the third drain resistor R_D3 are used to suppress drain voltage spikes.

[0050] In this circuit, the resistance of the first resistor R1 and the second resistor R2 is 47KΩ, and the voltage division of the first resistor R1 and the second resistor R2 is 1:1.

[0051] The VCC terminal of this circuit is also connected to a third resistor R3, which is connected to a first diode D1, a second diode D2, and a third diode D3. These diodes are then connected to a first light-emitting diode LED1, a second light-emitting diode LED2, and a third light-emitting diode LED3, respectively. This circuit uses a wired-AND logic formed by the first diode D1, the second diode D2, and the third diode D3 to automatically select the branch with the lowest voltage drop among the three paths. The common terminal of each branch (the connection point between LEDx and Qx) is connected to the input of voltage comparator U1 via the first diode D1, the second diode D2, and the third diode D3. The diode of the branch with the lowest conduction voltage drop is given priority to conduct, locking in the current lowest V_DS of the system. The detection network is equivalent to a minimized analog circuit, ensuring that the system always tracks the branch closest to the critical conduction state, implementing a minimum voltage drop detection mechanism.

[0052] In this circuit, the common terminal between pin 4 and FB of the voltage comparator U1 is connected to a first capacitor C1. The first capacitor C1 is connected to a fourth resistor R4, which is connected to pin 3 of the voltage comparator U1.

[0053] The comparison between this circuit and existing technologies yields the following conclusions: Energy efficiency optimization: Compared to traditional fixed redundancy schemes, the first MOSFET Q1, the second MOSFET Q2, and the third MOSFET Q3 can reduce losses by at least 50% (assuming ΔV decreases from 5V to 2.5V). Cost controllable: No high-precision ADC or independent DC-DC module is required, resulting in a BOM cost increase of <5%.

[0054] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A linear dimming and loss-reducing LED driver power supply circuit, comprising a VIN terminal, a first light-emitting diode LED1, a second light-emitting diode LED2, and a third light-emitting diode LED3, wherein the VIN terminal is respectively connected to one end of the first light-emitting diode LED1, the second light-emitting diode LED2, and the third light-emitting diode LED3, characterized in that: It also includes a first field-effect transistor Q1, a second field-effect transistor Q2, and a third field-effect transistor Q3; a first dimming controller, a second dimming controller, a third dimming controller; a voltage comparator U1; a first resistor R1; a second resistor R2; an FB terminal; and a VCC terminal. The VCC terminal is connected to pin 5 of the voltage comparator U1. Pin 1 of the voltage comparator U1 is connected to one end of the second resistor R2, and the other end of the second resistor R2 is connected to ground GND. The first resistor R1 is connected between pins 1 and 5 of the voltage comparator U1. Pin 4 of the voltage comparator U1 is connected to the FB terminal. The first light-emitting diode LED1 is connected to pin 2 of the first field-effect transistor Q1, and the second light-emitting diode LED... 2 is connected to pin 2 of the second field-effect transistor Q2, and the third light-emitting diode LED32 is connected to pin 2 of the third field-effect transistor Q3. The VCC terminal is led out in three ways and connected to the common terminal between the first light-emitting diode LED1 and pin 2 of the first field-effect transistor Q1, the common terminal between the second light-emitting diode LED2 and pin 2 of the second field-effect transistor Q2, and the common terminal between the third light-emitting diode LED3 and pin 2 of the third field-effect transistor Q3. The first field-effect transistor Q1 is connected to the first dimming controller, the second field-effect transistor Q2 is connected to the second dimming controller, and the third field-effect transistor Q3 is connected to the third dimming controller. The FB terminal is connected to the front-end voltage control circuit.

2. The linear dimming and loss-reducing LED driver power supply circuit according to claim 1, characterized in that: The first field-effect transistor Q1 has a first gate resistor R_G1 connected to pin 1, a first drain resistor R_D1 connected to pins 1 and 3 of the first field-effect transistor Q1, a first source resistor R_S1 connected to pin 3 of the first field-effect transistor Q1, and a ground terminal GND connected to the first source resistor R_S1.

3. The linear dimming and loss-reducing LED driver power supply circuit according to claim 2, characterized in that: The resistance values ​​of the first gate resistor R_G1, the first drain resistor R_D1, and the first source resistor R_S1 are 0.1Ω to 0.5Ω, and the power rating of the first gate resistor R_G1, the first drain resistor R_D1, and the first source resistor R_S1 is 1W.

4. The linear dimming and loss-reducing LED driver power supply circuit according to claim 1, characterized in that: The second field-effect transistor Q2 has a second gate resistor R_G2 connected to pin 1, a second drain resistor R_D2 connected to pins 1 and 3, a second source resistor R_S2 connected to pin 3, and a ground terminal GND connected to the second source resistor R_S2.

5. The linear dimming and loss-reducing LED driver power supply circuit according to claim 4, characterized in that: The resistance values ​​of the second gate resistor R_G2, the second drain resistor R_D2, and the second source resistor R_S2 are 0.1Ω to 0.5Ω, and the power rating of the second gate resistor R_G2, the second drain resistor R_D2, and the second source resistor R_S2 is 1W.

6. The linear dimming and loss-reducing LED driver power supply circuit according to claim 1, characterized in that: The third field-effect transistor Q3 has a third gate resistor R_G3 connected to pin 1, the first field-effect transistor Q1 has a third drain resistor R_D3 connected to pin 1 and pin 3, the third field-effect transistor Q3 has a third source resistor R_S3 connected to pin 3, and the third source resistor R_S3 is also connected to the ground terminal GND.

7. The linear dimming and loss-reducing LED driver power supply circuit according to claim 6, characterized in that: The resistance values ​​of the third gate resistor R_G3, the third drain resistor R_D3, and the third source resistor R_S3 are 0.1Ω to 0.5Ω, and the power rating of the third gate resistor R_G3, the third drain resistor R_D3, and the third source resistor R_S3 is 1W.

8. The linear dimming and loss-reducing LED driver power supply circuit according to claim 2, characterized in that: The resistance of the first resistor R1 and the second resistor R2 is 47KΩ, and the voltage division ratio of the first resistor R1 and the second resistor R2 is 1:

1.

9. The linear dimming and loss-reducing LED driver power supply circuit according to claim 1, characterized in that: The VCC terminal is also connected to a third resistor R3, and the third resistor R3 is connected to a first diode D1, a second diode D2, and a third diode D3. The first diode D1, the second diode D2, and the third diode D3 are respectively connected to a first light-emitting diode LED1, a second light-emitting diode LED2, and a third light-emitting diode LED3.

10. The linear dimming and loss-reducing LED driver power supply circuit according to claim 1, characterized in that: The common terminal between pin 4 and FB of the voltage comparator U1 is connected to a first capacitor C1, and the first capacitor C1 is connected to a fourth resistor R4, which is connected to pin 3 of the voltage comparator U1.

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