Circuit capable of reducing output power along with input voltage and LED driving power supply

Abstract

The utility model relates to a circuit capable of reducing output power along with input voltage and an LED driving power supply. The circuit comprises an input detection module, a switch module, a level adjustment module and a power reduction module. The input end of the input detection module receives input voltage, the output end of the input detection module is connected with the switch module, the input end of the switch module is connected with power supply signals, the output end of the switch module is connected with the level adjusting module, and the power reduction module is connected with the level adjusting module. The input detection module outputs a detection signal based on the input voltage; the switch module enters different conduction states according to the detection signal and outputs corresponding conduction voltage; the level adjusting module adjusts the level of the power reduction module according to the conduction voltage; the power reduction module reduces the output power according to the level adjustment. According to the utility model, on the basis of not adding a single-chip microcomputer, the function of automatically adjusting and reducing the output power according to the input voltage can be realized through a simple circuit structure, and the performance of the product is optimized.

Description

Technical Field

[0001] This utility model relates to the technical field of LED driver power supplies, and more specifically, to a circuit and an LED driver power supply that reduce output power in response to input voltage. Background Technology

[0002] Currently, most LED driver power supply circuit designs use chip solutions with primary-side feedback output voltage, primary-side feedback output current, and constant current output. For LED power supply devices with primary-side feedback output current, the output current can be automatically and linearly reduced to follow changes in input voltage, thereby achieving automatic and linear reduction in output power.

[0003] To achieve the above functions, current LED driver power supplies typically employ two methods:

[0004] The first method involves adjusting the output power based on the input voltage. This method requires manual load setting, consulting the specifications, and recording adjustment parameters during testing to avoid errors and repetitive testing. Furthermore, if the terminal load is fixed at full load, human error in setting the input voltage or fluctuations in the power grid within the derating range may prevent the actual power reduction from being achieved. The second method involves adding a microcontroller to adjust the output power. However, this method has a complex circuit structure and high cost. Utility Model Content

[0005] The technical problem to be solved by this utility model is to provide a circuit and an LED driver power supply that reduce output power according to the input voltage, in order to address the problems existing in the prior art.

[0006] The technical solution adopted by this utility model to solve its technical problem is: to construct a circuit that reduces output power according to the input voltage, including: an input detection module, a switch module, a level adjustment module and a power reduction module;

[0007] The input terminal of the input detection module receives the input voltage, the output terminal of the input detection module is connected to the switch module, the input terminal of the switch module is connected to the power supply signal, the output terminal of the switch module is connected to the level adjustment module, and the power reduction module is connected to the level adjustment module.

[0008] The input detection module is used to detect the input voltage and output a detection signal based on the input voltage;

[0009] The switching module is used to enter different conduction states according to the detection signal, and output corresponding conduction voltages based on the different conduction states;

[0010] The level adjustment module adjusts the level of the power reduction module according to the on-voltage;

[0011] The power reduction module reduces the output power according to the level adjustment module.

[0012] In the circuit that reduces output power by following the input voltage according to this utility model, the different conduction states include: fully conduction state and variable resistance region state;

[0013] When the input voltage is at its minimum value within the input voltage range, the switching module enters the fully conducting state.

[0014] When the input voltage is greater than the minimum value and less than the minimum rated voltage, the switching module enters the variable resistance region state.

[0015] In the circuit that reduces output power by following the input voltage according to this utility model, the input detection module includes: an input detection circuit and a voltage divider circuit;

[0016] The input terminal of the input detection circuit receives the input voltage, and the output terminal of the input detection circuit is connected to the voltage divider circuit and then to the switching module.

[0017] In the circuit that reduces output power by following the input voltage according to this utility model, the input detection circuit includes: a first resistor, a second resistor, a third resistor, a first Zener diode, and a fourth resistor;

[0018] The first end of the first resistor is connected to the input voltage, the second end of the first resistor is connected to the cathode of the first Zener diode in sequence through the second resistor and the third resistor, the anode of the first Zener diode is connected to the first end of the fourth resistor, and the connection node between the anode of the first Zener diode and the first end of the fourth resistor is also connected to the switching module, and the second end of the fourth resistor is grounded.

[0019] The connection node between the anode of the first Zener diode and the first end of the fourth resistor is the output terminal of the input detection module.

[0020] The circuit for reducing output power by following the input voltage described in this utility model also includes: a filter circuit;

[0021] The filter circuit and the voltage divider circuit are connected in parallel.

[0022] In the circuit that reduces output power by following the input voltage according to this utility model, the filter circuit includes: a first capacitor;

[0023] The first capacitor is connected in parallel with the fourth resistor.

[0024] In the circuit that reduces output power by following the input voltage according to this utility model, the switching module includes: a fifth resistor, a second Zener diode, and a first switching transistor;

[0025] The first end of the fifth resistor is connected to the power supply signal, the second end of the fifth resistor is connected to the cathode of the second Zener diode, the anode of the second Zener diode is connected to the third end of the first switching transistor, and the third end of the first switching transistor is also connected to the switching module. The second end of the first switching transistor is grounded, and the first end of the first switching transistor is connected to the input detection module.

[0026] The first terminal of the first switching transistor is the output terminal of the switching module.

[0027] In the circuit that reduces output power by following the input voltage according to this utility model, the level adjustment module includes: a sixth resistor, a second switching transistor, and a second capacitor;

[0028] The first end of the second switching transistor is connected to the switching module, the third end of the second switching transistor is connected to the first end of the sixth resistor, the second end of the sixth resistor is connected to the power reduction module, the second end of the second switching transistor is grounded, and the second capacitor is connected between the first and second ends of the second switching transistor.

[0029] In the circuit for reducing output power by following the input voltage described in this utility model, the power reduction module includes: a power reduction chip;

[0030] The level detection pin of the power reduction chip is connected to a reference level, and the level detection pin is also connected to the first end of the sixth resistor. The control terminal of the power reduction chip outputs a power reduction control signal.

[0031] This invention also provides an LED driver power supply, including the circuit described above that reduces output power by following the input voltage.

[0032] The circuit and LED driver power supply of this invention, which reduce output power based on input voltage, have the following advantages: It includes an input detection module, a switching module, a level adjustment module, and a power reduction module. The input terminal of the input detection module receives the input voltage, and its output terminal is connected to the switching module. The input terminal of the switching module is connected to the power supply signal, and its output terminal is connected to the level adjustment module. The power reduction module is connected to the level adjustment module. The input detection module outputs a detection signal based on the input voltage. The switching module enters different conduction states according to the detection signal and outputs corresponding conduction voltages. The level adjustment module adjusts the level of the power reduction module according to the conduction voltage. The power reduction module reduces the output power according to the level adjustment. This invention achieves the function of automatically adjusting and reducing output power based on input voltage through a simple circuit structure without adding a microcontroller, thus optimizing product performance. Attached Figure Description

[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0034] Figure 1 This is a block diagram of the circuit that reduces output power by following the input voltage, provided by this utility model.

[0035] Figure 2 This is a circuit diagram of the circuit provided by this utility model that reduces output power by following the input voltage. Detailed Implementation

[0036] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0037] refer to Figure 1 , Figure 1 The schematic diagram of the circuit for reducing output power by following the input voltage provided by this utility model.

[0038] Specifically, such as Figure 1 As shown, the circuit that reduces output power following the input voltage includes: an input detection module 11, a switching module 12, a level adjustment module 13, and a power reduction module 14.

[0039] The input detection module 11 receives the input voltage at its input terminal, and its output terminal is connected to the switch module 12. The input terminal of the switch module 12 is connected to the power supply signal, and its output terminal is connected to the level adjustment module 13. The power reduction module 14 is connected to the level adjustment module 13. The input detection module 11 is used to detect the input voltage and output a detection signal based on the input voltage. The switch module 12 is used to enter different conduction states according to the detection signal and output corresponding conduction voltages based on the different conduction states. The level adjustment module 13 adjusts the level of the power reduction module 14 according to the conduction voltage. The power reduction module 14 reduces the output power according to the level adjustment module 13.

[0040] Optionally, in this embodiment of the invention, the different conduction states include: a fully conduction state and a variable resistance zone state; when the input voltage is at the minimum value of the input voltage range, the switch module 12 enters the fully conduction state; when the input voltage is greater than the minimum value but less than the minimum rated voltage, the switch module 12 enters the variable resistance zone state. Further, the circuit that reduces output power following the input voltage also includes a cutoff state. Specifically, when the input voltage increases and reaches the minimum rated voltage, it enters the cutoff state. Specifically, when in the fully conduction state, the power reduction module 14 controls the output current to decrease following the input voltage, and it outputs the minimum power for power reduction. When in the variable resistance zone state, the power reduction module 14 controls the output current to decrease linearly following the input voltage, achieving linear power reduction following the input voltage; wherein, the variable resistance zone is the range for linear power reduction following the input voltage. When in the cutoff state, the power reduction module 14 controls the output current to be at normal output, i.e., output according to the rated load, and does not perform power reduction operation.

[0041] Optionally, in this embodiment of the present invention, the input detection module 11 includes: an input detection circuit and a voltage divider circuit; the input terminal of the input detection circuit receives the input voltage, and the output terminal of the input detection circuit is connected to the voltage divider circuit and connected to the switch module 12.

[0042] Furthermore, in some embodiments, the circuit that reduces output power following the input voltage further includes: a filter circuit; the filter circuit is connected in parallel with the voltage divider circuit.

[0043] The following is a specific embodiment for illustration.

[0044] refer to Figure 2 The input detection circuit includes: a first resistor R1, a second resistor R2, a third resistor R3, a first Zener diode ZD1, and a fourth resistor R4.

[0045] The first end of the first resistor R1 is connected to the input voltage. The second end of the first resistor R1 is connected to the cathode of the first Zener diode ZD1 through the second resistor R2 and the third resistor R3 in sequence. The anode of the first Zener diode ZD1 is connected to the first end of the fourth resistor R4. The connection node between the anode of the first Zener diode ZD1 and the first end of the fourth resistor R4 is also connected to the switch module 12. The second end of the fourth resistor R4 is grounded. The connection node between the anode of the first Zener diode ZD1 and the first end of the fourth resistor R4 is the output terminal of the input detection module 11.

[0046] In this embodiment, the filter circuit includes: a first capacitor; the first capacitor and the fourth resistor R4 are connected in parallel.

[0047] In this embodiment, the switching module 12 includes: a fifth resistor R5, a second Zener diode ZD2, and a first switching transistor Q1.

[0048] The first end of the fifth resistor R5 is connected to the power supply signal, the second end of the fifth resistor R5 is connected to the cathode of the second Zener diode ZD2, the anode of the second Zener diode ZD2 is connected to the third end of the first switch Q1, and the third end of the first switch Q1 is also connected to the switch module 12. The second end of the first switch Q1 is grounded (that is, the second end of the first switch Q1 is connected to the connection node between the anode of the first Zener diode ZD1 and the first end of the fourth resistor R4), the first end of the first switch Q1 is connected to the input detection module 11, and the first end of the first switch Q1 is the output end of the switch module 12.

[0049] In this embodiment, the level adjustment module 13 includes a sixth resistor, a second switch Q2, and a second capacitor. The first end of the second switch Q2 is connected to the switch module 12, the third end of the second switch Q2 is connected to the first end of the sixth resistor, the second end of the sixth resistor is connected to the power reduction module 14, the second end of the second switch Q2 is connected to the output terminal of the switch module 12 (i.e., the second end of the second switch Q2 is connected to the first end of the first switch Q1), the third end of the second switch Q2 is grounded, and the second capacitor is connected between the first end and the second end of the second switch Q2.

[0050] Optionally, in this embodiment of the invention, both the first switch Q1 and the second switch Q2 can be MOSFETs. Specifically, the first terminal of the first switch Q1 is the gate of the MOSFET, the second terminal of the first switch Q1 is the source of the MOSFET, and the third terminal of the first switch Q1 is the drain of the MOSFET. Similarly, the first terminal of the second switch Q2 is the gate of the MOSFET, the second terminal of the second switch Q2 is the source of the MOSFET, and the third terminal of the second switch Q2 is the drain of the MOSFET.

[0051] In this embodiment, the power reduction module 14 includes: a power reduction chip U1; the level detection pin of the power reduction chip U1 is connected to a reference level, and the level detection pin is also connected to the first end of the sixth resistor; the control terminal of the power reduction chip U1 outputs a power reduction control signal.

[0052] refer to Figure 2 , Figure 2 The circuit diagram for the circuit that reduces output power based on the input voltage.

[0053] like Figure 2 As shown, when the input voltage drops to the minimum value of the input voltage range (e.g., 90Vac), the input voltage (i.e., ACHV in the figure) is detected through the first resistor R1, the second resistor R2, the third resistor R3, and the first Zener diode ZD1, and forms a voltage divider with the fourth resistor R4. At this time, the voltage at this point is just less than the minimum turn-on voltage required by the VGS of the first switch Q1. At this time, the first switch Q1 is cut off, that is, it does not conduct. The power supply signal (VCC) provides voltage to the gate of the second switch Q2 through the fifth resistor R5 and the second Zener diode ZD2, which is at a high level. This voltage is just greater than the saturation conduction voltage (VGS) required for the second switch Q2 to turn on, putting the second switch Q2 in a fully conducting state. At this point, a voltage divider is formed between the sixth resistor and the upper resistor (R in the diagram) inside the power reduction chip U1, dividing the reference level (VREF in the diagram). This pulls down the reference voltage (i.e., the level detection pin) of the power reduction chip U1, causing the control terminal controlled by the power reduction chip U1 to output a power reduction control signal, thus controlling the output current to decrease accordingly. This is the minimum power output for power reduction. The power reduction chip U1 is a flyback chip with primary-side feedback in the LED driver power supply. VCC is the power supply signal provided internally by the LED driver power supply, which could be the power supply signal provided by the auxiliary source in the LED driver power supply.

[0054] like Figure 2As shown, when the input voltage increases and reaches the minimum rated voltage (e.g., 120Vac), the input voltage is detected through the first resistor R1, the second resistor R2, the third resistor R3, and the first Zener diode ZD1. This voltage is then divided by the first resistor R4, ensuring that the voltage reaches the saturation turn-on voltage required for the first switch Q1's VGS. At this point, the first switch Q1 is fully saturated and conducting. VCC provides voltage to the second switch Q2's VGS through the fifth resistor R5 (connected in series) and the second Zener diode ZD2, effectively pulling the voltage down. Since the first switch Q1 is conducting, the voltage becomes low, preventing the second switch Q2 from conducting; it remains in the off state. The sixth resistor and the upper resistor inside the power reduction chip U1 cannot form a voltage divider, so the reference voltage of the power reduction chip U1 remains the original VREF voltage. The power reduction chip U1 controls the output current to be at its normal output and rated load.

[0055] like Figure 2 As shown, when the input voltage increases and is between the minimum value of the input voltage range (e.g., 90Vac) and the minimum rated voltage (e.g., 120Vac), the first switch Q1 and the second switch Q2 can be equivalent to adjustable resistors in this region. The input voltage ACHV is detected by the first resistor R1, the second resistor R2, the third resistor R3 and the first Zener diode ZD1, and forms a voltage divider with the fourth resistor R4. This voltage reaches and exceeds the minimum turn-on voltage required for the first switch Q1 to VGS, so the first switch Q1 enters the variable resistance region. VCC provides the VGS voltage to the second switch Q2 through the fifth resistor R5, the second Zener diode ZD2 and the voltage divider of the first switch Q1's resistance value. At this point, the voltage is also the voltage that allows the second switch Q2 to enter the variable resistance region. The equivalent resistance value of the second switch Q2 is connected in series with the sixth resistor and the internal resistor R of the power reduction chip U1, which divides the voltage, causing the reference voltage VREF of the power reduction chip U1 to be pulled low. Then the power reduction chip U1 outputs a PWM control signal, which controls the output current to follow the decrease of the input voltage, so as to achieve the purpose of the output power following the decrease of the input voltage. The variable resistance range of the first switching transistor Q1 determines the variable resistance range of the second switching transistor Q2. The second switching transistor Q2 is connected in series with the sixth resistor and the internal resistor R of the power reduction chip U1. Adjusting the resistance range of the second switching transistor Q2 ensures that the VREF reference voltage of the power reduction chip U1 varies within a set controllable range. This range represents the range where the power is linearly reduced in response to the input voltage.

[0056] This invention utilizes the switching characteristics of a MOSFET to fix the upper and lower limits of the range in which the output current follows the input voltage, and then uses the amplification characteristics of the MOSFET to achieve automatic output current following the input voltage with linear power reduction.

[0057] This utility model also provides an LED driver power supply, including the circuit disclosed in the embodiments of this utility model that reduces output power by following the input voltage.

[0058] This invention, employing a simple circuit, saves PCB space and reduces the number of components, thus lowering device costs. Furthermore, when the input voltage is lower than the rated voltage, the output current can decrease linearly with the input voltage, or it can decrease in a stepwise manner, resulting in a reduction in output power. In contrast, conventional circuits, with a constant load, will have a higher input current as the input voltage decreases. However, in this invention, the output current decreases as the input voltage decreases, while still maintaining the input current at the rated input voltage, or even lower. This allows for reduced design margins and fewer selection margins for main power components while ensuring electrical performance, resulting in a more cost-effective product. It has been widely used in outdoor and commercial lighting and has a promising market prospect.

[0059] The above embodiments are only for illustrating the technical concept and features of this utility model, and are intended to enable those skilled in the art to understand the content of this utility model and implement it accordingly. They do not limit the scope of protection of this utility model. All equivalent changes and modifications made within the scope of the claims of this utility model should fall within the scope of the claims of this utility model.

Claims

1. A circuit that reduces output power in response to input voltage, characterized in that, include: Input detection module, switch module, level adjustment module, and power reduction module; The input terminal of the input detection module receives the input voltage, the output terminal of the input detection module is connected to the switch module, the input terminal of the switch module is connected to the power supply signal, the output terminal of the switch module is connected to the level adjustment module, and the power reduction module is connected to the level adjustment module. The input detection module is used to detect the input voltage and output a detection signal based on the input voltage; The switching module is used to enter different conduction states according to the detection signal, and output corresponding conduction voltages based on the different conduction states; The level adjustment module adjusts the level of the power reduction module according to the on-voltage; The power reduction module reduces the output power according to the level adjustment module.

2. The circuit for reducing output power by following the input voltage according to claim 1, characterized in that, The different conduction states include: fully conduction state and variable resistance region state; When the input voltage is at its minimum value within the input voltage range, the switching module enters the fully conducting state. When the input voltage is greater than the minimum value and less than the minimum rated voltage, the switching module enters the variable resistance region state.

3. The circuit for reducing output power by following the input voltage according to claim 1, characterized in that, The input detection module includes: an input detection circuit and a voltage divider circuit; The input terminal of the input detection circuit receives the input voltage, and the output terminal of the input detection circuit is connected to the voltage divider circuit and then to the switching module.

4. The circuit for reducing output power by following the input voltage according to claim 3, characterized in that, The input detection circuit includes: a first resistor, a second resistor, a third resistor, a first Zener diode, and a fourth resistor; The first end of the first resistor is connected to the input voltage, the second end of the first resistor is connected to the cathode of the first Zener diode in sequence through the second resistor and the third resistor, the anode of the first Zener diode is connected to the first end of the fourth resistor, and the connection node between the anode of the first Zener diode and the first end of the fourth resistor is also connected to the switching module, and the second end of the fourth resistor is grounded. The connection node between the anode of the first Zener diode and the first end of the fourth resistor is the output terminal of the input detection module.

5. The circuit for reducing output power by following the input voltage according to claim 4, characterized in that, Also includes: Filtering circuit; The filter circuit and the voltage divider circuit are connected in parallel.

6. The circuit for reducing output power by following the input voltage according to claim 5, characterized in that, The filter circuit includes: a first capacitor; The first capacitor is connected in parallel with the fourth resistor.

7. The circuit for reducing output power by following the input voltage according to claim 1, characterized in that, The switching module includes: a fifth resistor, a second Zener diode, and a first switching transistor; The first end of the fifth resistor is connected to the power supply signal, the second end of the fifth resistor is connected to the cathode of the second Zener diode, the anode of the second Zener diode is connected to the third end of the first switching transistor, and the third end of the first switching transistor is also connected to the switching module. The second end of the first switching transistor is grounded, and the first end of the first switching transistor is connected to the input detection module. The first terminal of the first switching transistor is the output terminal of the switching module.

8. The circuit for reducing output power by following the input voltage according to claim 1, characterized in that, The level adjustment module includes: a sixth resistor, a second switching transistor, and a second capacitor; The first end of the second switching transistor is connected to the switching module, the third end of the second switching transistor is connected to the first end of the sixth resistor, the second end of the sixth resistor is connected to the power reduction module, the second end of the second switching transistor is grounded, and the second capacitor is connected between the first and second ends of the second switching transistor.

9. The circuit for reducing output power by following the input voltage according to claim 8, characterized in that, The power reduction module includes: a power reduction chip; The level detection pin of the power reduction chip is connected to a reference level, and the level detection pin is also connected to the first end of the sixth resistor. The control terminal of the power reduction chip outputs a power reduction control signal.

10. An LED driver power supply, characterized in that, Includes the circuit that reduces output power following the input voltage as described in any one of claims 1-9.

Images