An LED driving circuit, an LED driving power supply and a lamp

Abstract

The application is suitable for the technical field of LED, and provides an LED driving circuit, an LED driving power supply and a lamp, which comprise a master control chip configured to determine an initial PWM signal corresponding to a voltage reference signal in the case of receiving the voltage reference signal; wherein the voltage reference signal is determined according to the voltage of an LED load and the power of the LED load; a constant current control unit connected with the master control chip and used for connecting the LED load and configured to convert the initial PWM signal into a control signal for controlling the LED load to emit light; the master control chip is further configured to dynamically adjust the initial PWM signal according to a voltage sampling signal and the voltage reference signal to obtain a target PWM signal; wherein the voltage sampling signal is a sampling signal corresponding to a detection voltage generated on a sampling adjustment resistor when the current output by the constant current control unit flows through the LED load; and a memory, which can simplify a debugging process and save labor cost.

Description

Technical Field

[0001] This application belongs to the field of LED technology, and in particular relates to an LED driver circuit, an LED driver power supply, and a lamp. Background Technology

[0002] Due to manufacturing processes and semiconductor materials, LED chips of different colors may have voltage differences, and even LED chips of the same color may have voltage differences. This inconsistency in chip voltage results in different power outputs under the same operating current, meaning there will be power deviations between LED strings of different colors. The more LED chips in a string, the greater this power deviation will be. This will affect the lifespan of the lighting fixture and cause uneven brightness, impacting its performance.

[0003] The existing method of achieving power balance adjustment by adjusting the resistance value of the sampling adjustment resistor is time-consuming and labor-intensive. Moreover, it cannot be used to solve the problem for products that have already been potted. Summary of the Invention

[0004] This application provides an LED driving circuit, an LED driving power supply, and a lamp, which can reduce power deviation between lamp strings, thereby extending the life of the lamp, reducing uneven brightness, and greatly simplifying the debugging process and saving labor costs.

[0005] In a first aspect, embodiments of this application provide an LED driving circuit, including:

[0006] The main control chip is configured to determine an initial PWM signal corresponding to the voltage reference signal upon receiving the voltage reference signal; wherein the voltage reference signal is determined based on the voltage of the LED load and the power of the LED load.

[0007] A constant current control unit, connected to the main control chip, is used to connect to the LED load and is configured to convert the initial PWM signal into a control signal to control the LED load to emit light;

[0008] The main control chip is also configured to dynamically adjust the initial PWM signal according to the voltage sampling signal and the voltage reference signal to obtain the target PWM signal; wherein, the voltage sampling signal is the sampling signal corresponding to the detection voltage generated on the sampling resistor when the constant current control unit outputs current to the LED load;

[0009] The memory, connected to the main control chip, is configured to store the target PWM signal and the voltage reference signal.

[0010] In one implementation of the first aspect, the constant current control unit includes:

[0011] A low-pass filter component, wherein the input terminal of the low-pass filter component is the input terminal of the constant current control unit, and the output terminal of the low-pass filter component is the output terminal of the constant current control unit, is configured to filter out the high-frequency AC component of the input PWM signal and output an analog voltage corresponding to the duty cycle of the input PWM signal;

[0012] The voltage sampling component is configured to acquire the sampling signal corresponding to the detection voltage generated on the sampling resistor when the constant current control unit outputs current to the load.

[0013] In one implementation of the first aspect, the low-pass filter component includes a low-pass RC filter and an operational amplifier.

[0014] In one implementation of the first aspect, the voltage sampling component includes a sampling resistor and a signal amplifier.

[0015] In one implementation of the first aspect, the LED driving circuit further includes a PWM dimming unit;

[0016] The PWM dimming unit is connected to the constant current control unit and is configured to output a corresponding PWM dimming signal to the constant current control unit according to the external PWM signal.

[0017] The constant current control unit is also configured to convert the PWM dimming signal into a control signal that controls the LED load to emit light.

[0018] In one implementation of the first aspect, the LED driving circuit further includes a MOS driving circuit;

[0019] The MOS driving circuit is connected to the constant current control unit and is configured to turn off the power supply line between the constant current control unit and the LED load according to the turn-off control signal of the constant current control unit.

[0020] The constant current control unit is further configured to output the shutdown control signal to the MOS drive circuit during the process of the main control chip receiving the voltage reference signal.

[0021] In one implementation of the first aspect, the LED driving circuit further includes an overcurrent protection circuit;

[0022] The overcurrent protection circuit is configured to perform overcurrent protection action when the current of the LED driving circuit is greater than a preset current.

[0023] In one implementation of the first aspect, the main control chip is further configured to determine the adjustment amplitude of the initial PWM signal based on the difference between the voltage value of the voltage reference signal and the voltage value of the voltage sampling signal, and to adjust the initial PWM signal based on the determined adjustment amplitude.

[0024] Secondly, embodiments of this application provide an LED driver power supply, including the LED driver circuit as described in the first aspect and any implementation thereof.

[0025] Thirdly, embodiments of this application provide a lighting fixture including an LED load, such as the LED driving circuit in the first aspect and any implementation thereof, or the LED driving power supply as described in the second aspect.

[0026] Implementing the LED driving circuit, LED driving power supply, and lamp provided in this application has the following beneficial effects:

[0027] This system can determine the corresponding voltage reference signal for the load and power, and determine the initial PWM signal corresponding to the voltage reference signal based on the correspondence between the voltage reference signal and the PWM signal. Then, it dynamically adjusts the initial PWM signal according to the voltage sampling signal and the voltage reference signal, so that the voltage sampling signal is infinitely close to the voltage reference signal, and determines the PWM signal under dynamic balance, i.e., the target PWM signal. By storing the final PWM signal and voltage reference signal in memory, it is possible to set the corresponding Vcs (voltage reference signal) for the LED load, thereby achieving power balance setting of the LED lamp. This allows the resistance value of the sampling adjustment resistor to be fixed, eliminating the need for manual adjustment of the resistance value, and still achieving power balance for each circuit of the LED lamp. Even if the smart lamp has already been potted or installed in the application environment, power balance adjustment can be achieved simply by writing the voltage reference signal parameter to the main control chip through an external controller, which greatly simplifies the debugging process and saves labor costs. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the circuit structure of a current LED driver power supply;

[0030] Figure 2 This is a schematic diagram of the structure of an LED driving circuit provided in an embodiment of this application;

[0031] Figure 3 This is a schematic diagram of the structure of a constant current control unit for an LED driving circuit provided in an embodiment of this application;

[0032] Figure 4 This is a schematic diagram of the circuit structure of a constant current control unit for an LED driving circuit according to an embodiment of this application;

[0033] Figure 5 This is a schematic diagram of another LED driving circuit provided in an embodiment of this application;

[0034] Figure 6 This is a schematic diagram of another LED driving circuit provided in the embodiments of this application. Detailed Implementation

[0035] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0036] It should be understood that the term "and / or" as used in this application specification and the appended claims refers to any combination of one or more of the associated listed items, as well as all possible combinations, and includes such combinations. Furthermore, in the description of this application specification and the appended claims, the terms "first," "second," "third," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0037] It should also be understood that references to "one embodiment" or "some embodiments" in this specification mean that one or more embodiments of this application include the specific features, structures, or characteristics described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0038] A light-emitting diode (LED) is a commonly used light-emitting device that can efficiently convert electrical energy into light energy. It has a wide range of applications in modern society, such as lighting and display panels.

[0039] As mentioned above, due to differences in semiconductor materials, manufacturing processes, and chip design, LED chips of different colors may have inconsistent voltages. Under the same operating current, different chip voltages will lead to power differences between different LED strings. Strings with higher power may experience excessive heat generation, thus affecting the lifespan of the luminaire. Furthermore, power differences between LED strings can also cause uneven brightness, impacting the luminaire's performance.

[0040] Currently, the common approach to addressing the power differences between different LED strings in a lighting fixture is to pre-test the desired power of the fixture and then adjust the resistance of the sampling adjustment resistor in the LED driver chip to change the output current of the LED circuit. This reduces the power difference between different LED strings, thereby balancing the power of the lighting fixture.

[0041] For example, Figure 1 A schematic diagram of the current LED driver power supply circuit structure is given, taking the LED driver power supply driving 4 light strings, each string containing 6 LED beads as an example. Figure 1 As shown, each LED string's drive circuit includes a sampling adjustment resistor. For example, the drive circuit for the red LED string (D1-D6) has a sampling adjustment resistor Rcs1, the drive circuit for the white LED string (D11-D61) has a sampling adjustment resistor Rcs2, the drive circuit for the green LED string (D12-D62) has a sampling adjustment resistor Rcs3, and the drive circuit for the blue LED string (D13-D63) has a sampling adjustment resistor Rcs4. When a particular string has higher power, the resistance value of the sampling adjustment resistor in that string can be adjusted to change the current in that string. For example, if the power of the blue LED string is too high, the resistance value of the sampling adjustment resistor Rcs4 can be increased to reduce the output current of that string, thereby reducing its power.

[0042] However, this method is not only time-consuming and labor-intensive, but it also cannot be used to treat products that have already been glued.

[0043] To address the aforementioned issues, this application provides an LED driving circuit. This circuit determines a corresponding voltage reference signal based on the load and power, and determines an initial PWM signal corresponding to the voltage reference signal based on the correspondence between the voltage reference signal and the PWM signal. Then, it dynamically adjusts the initial PWM signal based on the voltage sampling signal and the voltage reference signal, making the voltage sampling signal infinitely close to the voltage reference signal, and determines the PWM signal under dynamic equilibrium, i.e., the target PWM signal. By storing the final PWM signal and voltage reference signal in a memory, the circuit can achieve corresponding Vcs (voltage reference signal) settings for the LED load, thereby realizing power balance settings for the LED lighting fixture. This allows for fixing the resistance value of the sampling adjustment resistor, eliminating the need for manual adjustment, and still achieving power balance across all circuits of the LED lighting fixture. Even if the smart lighting fixture has already been potted or installed in the application environment, power balance adjustment can be achieved simply by writing the voltage reference signal parameter to the main control chip via an external controller, greatly simplifying the debugging process and saving labor costs.

[0044] The LED driver circuit provided in this application is described below with reference to the accompanying drawings:

[0045] Please see Figure 2 , Figure 2 A schematic diagram of an LED driving circuit according to an embodiment of this application is shown. Figure 2 As shown, the LED driving circuit 20 provided in this application embodiment may include a main control chip 21, a constant current control unit 22, and a memory 23.

[0046] The main control chip 21 is connected to the constant current control unit 22, which can be connected to the LED load that needs to be driven. The main control chip 21 is configured to determine the initial PWM signal corresponding to the voltage reference signal PWM_VCS when it receives the voltage reference signal, and output the initial PWM signal to the constant current control unit 22. The constant current control unit 22 is configured to convert the initial PWM signal into a control signal to control the LED load to emit light.

[0047] In this embodiment, the main control chip 21 can also dynamically adjust the initial PWM signal according to the voltage sampling signal and the voltage reference signal to obtain the target PWM signal.

[0048] The aforementioned memory can be used to store the target PWM signal and the aforementioned voltage reference signal.

[0049] In one embodiment of this application, the main control chip 21 can communicate with an external controller, thereby receiving a voltage reference signal input from the external controller. The main control chip 21 can obtain an initial PWM signal corresponding to the voltage reference signal based on a predetermined correspondence between the voltage reference signal and the PWM signal. Then, the constant current control unit 22 converts the initial PWM signal into a control signal (analog signal) for controlling the LED load to emit light. A voltage sampling circuit (which may include a signal amplifier) ​​obtains a voltage sampling signal PAD_VCS corresponding to the voltage Vcs output to the LED load. The main control chip 21 dynamically adjusts the initial PWM signal based on the voltage sampling signal PWM_VCS and the voltage reference signal PAD_VCS, so that the voltage sampling signal is infinitely close to the voltage reference signal, thus determining the PWM signal under dynamic equilibrium, i.e., the target PWM signal.

[0050] For example, the aforementioned external controller can be a Mini controller, which refers to a small, integrated control device. The main control chip 21 can be connected to the Mini controller, which then writes the voltage reference signal. Specifically, the voltage reference signal can be specified as the voltage reference signal for a particular load, allowing the main control chip 21 to adjust the voltage of that load so that the voltage value corresponding to the voltage sampling signal acquired from that load is infinitely close to the voltage value corresponding to the written voltage reference signal.

[0051] It is understood that the aforementioned external controller can also be other types of controllers, and this application embodiment does not impose specific limitations on this.

[0052] It should be noted that the voltage sampling signal mentioned above can be the signal corresponding to the detection voltage Vcs generated on the RCS resistor (sampling resistor) when the constant current control unit 22 outputs current to the load. Specifically, the voltage sampling signal PAD_VCS can be the amplified value of the detection voltage Vcs, which is used by the main control chip (which can be a microcontroller) to fine-tune the PWM signal.

[0053] It should be noted that the aforementioned detection voltage Vcs is on the same link as the LED load.

[0054] It is understood that when the LED driving circuit provided in this application is applied to drive multiple LED strings, a corresponding voltage reference signal can be determined for the load and power of each string. Based on the correspondence between the voltage reference signal and the PWM signal, an initial PWM signal corresponding to the voltage reference signal is determined. Then, the initial PWM signal is dynamically adjusted based on the voltage sampling signal and the voltage reference signal, so that the voltage sampling signal is infinitely close to the voltage reference signal, and a dynamically balanced PWM signal, i.e., the target PWM signal, is determined. The final PWM signal and voltage reference signal are saved in the memory 23, thus enabling the corresponding setting of Vcs (voltage reference signal) for the LED load, thereby achieving power balance setting of the LED lamp. This allows for fixing the resistance value of the sampling adjustment resistor, eliminating the need for manual adjustment, and still achieving power balance for each LED lamp. Even if the smart lamp has already been potted or installed in the application environment, power balance adjustment can be achieved simply by writing the voltage reference signal parameter to the main control chip via an external controller, greatly simplifying the debugging process and saving labor costs.

[0055] Furthermore, existing methods of balancing lamp power by reducing the duty cycle of the PWM signal sacrifice the dimming curve and reduce the dimming effect, i.e., they sacrifice the dimming grayscale of the lamp. Compared to balancing lamp power by reducing the duty cycle of the PWM signal, the LED driver circuit provided in this application adjusts the voltage of each channel. That is, an external small controller can be connected to the main control chip to write an accurate voltage reference signal into the constant current control unit (i.e., the constant current control unit adjusts the voltage sampling signal to be infinitely close to the voltage reference signal). In this way, precise lamp power balancing can be achieved without sacrificing the dimming grayscale of the lamp. Precise dimming can still be achieved while achieving power balance.

[0056] Furthermore, the power supply or lamps using the LED driving circuit provided in the embodiments of this application can achieve full power coverage. By simply setting the maximum power by default and then writing the voltage reference signal according to the power required by the user, the power can be driven according to the user's required operating power while maintaining power balance.

[0057] In practical applications, the main control chip 21 can store voltage values ​​and the duty cycle of PWM signals.

[0058] Please see Figure 3 , Figure 3 A schematic diagram of a constant current control unit in an LED driving circuit according to an embodiment of this application is shown. In one embodiment of this application, as shown in Figure 3, the constant current control unit 22 may include a low-pass filter component 221 and a voltage sampling component 222.

[0059] The input terminal of the low-pass filter component 221 is the input terminal of the constant current control unit 22, and the output terminal of the low-pass filter component 221 is the output terminal of the constant current control unit 22. The low-pass filter component 221 is configured to filter out the high-frequency AC component of the PWM signal and output an analog voltage corresponding to the duty cycle of the PWM signal.

[0060] The voltage sampling component 222 is configured to acquire the detection voltage generated on the sampling resistor when the constant current control unit 22 outputs current to the load, i.e., the voltage sampling signal.

[0061] For example, please refer to Figure 4 , Figure 4 A schematic diagram of the circuit structure of a constant current control unit 22 in an LED driving circuit provided in an embodiment of this application is shown. Figure 4 As shown, the low-pass filter component 221 in this embodiment may include a first-order low-pass RC filter and an operational amplifier U1 (and the peripheral circuitry of the operational amplifier, including a second resistor R2 and a third resistor R3). The first-order low-pass RC filter may include a first resistor R1 and a first capacitor C1. The first terminal of the first resistor R1 is used to receive the voltage reference signal PWM_VCS. The second terminal of the first resistor R1 is connected to the first terminal of the first capacitor C1 and the non-inverting input terminal of the operational amplifier U1. The second terminal of the first capacitor C1 is grounded. The inverting input terminal of the operational amplifier U1 is connected to the first terminal of the second resistor R2. The second terminal of the second resistor R2 is grounded. The first terminal of the second resistor R2 is also connected to the first terminal of the third resistor R3. The second terminal of the third resistor R3 is connected to the output terminal of the operational amplifier U1. The positive power supply terminal of the operational amplifier U1 is connected to the power supply VCC of the operational amplifier U1, and the negative power supply terminal of the operational amplifier U1 is grounded.

[0062] It is understandable that the output of operational amplifier U1 can output the voltage that drives the LED load.

[0063] In order to make the voltage output by the operational amplifier U1 infinitely close to the voltage corresponding to the voltage reference signal, voltage sampling is performed by the voltage sampling component 222.

[0064] Please refer to it again. Figure 4 In this example, the voltage sampling component 222 may include a second capacitor C2, a fourth resistor R4, a fifth resistor R5, a third capacitor C3, a signal amplifier U2 (and the external circuitry of the signal amplifier U2, such as a sixth resistor R6, a seventh resistor R7, and a fourth capacitor C4).

[0065] The first terminal of the second capacitor C2 is connected to the output terminal of the low-pass filter component 221. Figure 4 In the example shown, the output of the low-pass filter component 221 is the second terminal of the eighth resistor R8, and the first terminal of the eighth resistor R8 can be connected to the output of the operational amplifier U1. The second terminal of the second capacitor C2 is connected to the first terminal of the fourth resistor R4, the second terminal of the fourth resistor R4 is connected to the first terminal of the fifth resistor R5, the second terminal of the fifth resistor R5 is connected to the output of the signal amplifier U2, the output of the signal amplifier U2 is also connected to the first terminal of the fourth capacitor C4, the second terminal of the fourth capacitor C4 is grounded, the fourth resistor R4 is also connected in parallel with the third capacitor C3, and the second terminal of the third capacitor C3 outputs the voltage sampling signal PAD_VCS. The non-inverting input of the signal amplifier U2 is connected to the second terminal of the eighth resistor R8, the inverting input of the signal amplifier U2 is connected to the first terminal of the sixth resistor R6, the second terminal of the sixth resistor R6 is grounded, the first terminal of the sixth resistor R6 is also connected to the first terminal of the seventh resistor R7, and the second terminal of the seventh resistor R7 is connected to the output of the signal amplifier U2.

[0066] In practical applications, due to factors such as component consistency deviations or temperature drift, there may be a deviation between the actual output voltage of the constant current control unit 22 and the voltage corresponding to the written voltage reference signal. The aforementioned voltage sampling signal is used to detect whether there is a deviation between the actual driving voltage V / FB / mV obtained by the constant current control unit 22 and the voltage V / FB corresponding to the written voltage reference signal. Since the amplitude of the detected voltage (Vcs), i.e., the voltage sampling signal, is too small, in order to increase the accuracy of the voltage sampling signal, the detected voltage can be output to the main control chip 21 after being preset by the signal amplifier U2. The main control chip 21 reduces the voltage sampling signal amplified by the preset factor by the corresponding factor through its own analog-to-digital conversion circuit, and then compares the obtained voltage sampling signal with the voltage reference signal. If the voltage value corresponding to the voltage sampling signal is greater than the voltage value of the voltage reference signal, the duty cycle of the PWM signal can be reduced; if the voltage value corresponding to the voltage sampling signal is less than the voltage value of the voltage reference signal, the duty cycle of the PWM signal can be increased.

[0067] It is understandable that if the difference between the voltage value of the voltage sampling signal and the voltage value of the voltage reference signal is within a preset range, it can be determined that the voltage value of the voltage sampling signal is infinitely close to the voltage value of the voltage reference signal, that is, the voltage sampling signal and the voltage reference signal have reached dynamic equilibrium. The relevant signal information of the PWM signal in the dynamic equilibrium state and the voltage value corresponding to the voltage reference signal are written into the above memory for storage.

[0068] It should be noted that the above-mentioned preset multiplier can be set according to actual needs, such as 50 times, 100 times, etc., and this application embodiment does not impose specific limitations on this.

[0069] It should also be noted that the above-mentioned preset range can be a very small fluctuation range. When the voltage difference is within this range, it can be considered that the voltage sampling signal and the voltage reference signal have reached a dynamic balance. The preset range can be set according to the control accuracy requirements of the driven lamp. This application does not impose any specific restrictions on this.

[0070] It should be noted that, Figure 4 This is merely a schematic diagram of the circuit implementation of a constant current control unit for an LED driving circuit provided in an embodiment of this application; otherwise... Figure 4 In addition to the example shown, the constant current control unit can also be implemented based on other circuits. For example, the low-pass filter component mentioned above may include a second-order RC filter or a first-order RC filter (without an operational amplifier). The voltage acquisition component mentioned above can also be implemented using other circuit structures that can achieve voltage acquisition, such as using a voltage sensor, etc. The embodiments of this application do not impose specific limitations on this.

[0071] It should be noted that when the current flowing through the load reaches its maximum value, Vcs = V / FB / mV.

[0072] In the embodiments of this application, the aforementioned memory can be any type of memory, such as FLASH memory.

[0073] Understandably, as long as the load or power remains unchanged, the data written to the memory does not need to be modified or adjusted. If the power or load changes, then it is necessary to redetermine the reference voltage value V / FB (i.e., the voltage value V / FB corresponding to the voltage reference signal), and write this voltage reference signal into the main control chip 21 via an external controller, so as to readjust the voltage value Vcs of a certain detection voltage to the voltage value corresponding to the voltage reference signal. That is, when the load current reaches its maximum, Vcs = V / FB / mV = V / FB.

[0074] In this embodiment, it is necessary to pre-determine the correspondence between the voltage reference signal and the PWM signal, that is, to determine the relationship between different voltage values ​​and the PWM signal value (specifically, the duty cycle relationship), and write this correspondence into the main control chip 21 so that the main control chip 21 can determine the corresponding initial PWM signal based on the voltage reference signal. The process of pre-determining the correspondence between the voltage reference signal and the PWM signal can be as follows:

[0075] First, the frequency of the PWM_VCS signal needs to be determined. Generally speaking, such as... Figure 4In the circuit example shown, the frequency range of the PWM_VCS signal can be determined after first determining the first-order RC parameters. Due to the non-abrupt nature of the voltage across the capacitor, the capacitance value of the capacitor in the low-pass filter cannot be too large; otherwise, the PWM_VCS signal will be completely diluted by the capacitor. Therefore, a capacitor with an appropriate capacitance value can be selected as needed, for example, a 0.1uF capacitor. The resistor selection can be set according to circuit requirements; for example, a 100KΩ resistor can be selected. The cutoff frequency of the RC filter can be obtained as 16Hz using f=1 / (2π√RC). Empirically, the relationship between the frequency of the PWM signal and the cutoff frequency of the RC filter is approximately 100:1. Therefore, in this example, the frequency of the PWM_VCS signal can be selected as 2KHz.

[0076] Then, based on the bit depth of the analog-to-digital converter (ADC), the duty cycle of the PWM_VCS is divided into multiple levels. For example, the conversion accuracy of an ADC is generally 12 bits, meaning that PWM is needed to simulate a 12-bit ADC. Therefore, the PWM signal value is selected from 0-4095 (a total of 4096 discrete values). By actually testing logic voltages from 0-0.600mV, the matching PWM value is obtained. Through this, we can obtain a correspondence between the PWM signal and the voltage value.

[0077] It is understandable that the PWM signal controls the average output voltage based on the duty cycle. Therefore, the duty cycle of the PWM signal needs to be matched with the numerical range of the 12-bit DAC. That is, the duty cycle of the PWM signal from 0% to 100% is divided into 4096 levels (corresponding to 0-4095 of the 12-bit DAC), so that the adjustment accuracy of the PWM is comparable to that of the 12-bit DAC.

[0078] Finally, the voltage value corresponding to the duty cycle level of each PWM signal is obtained from the hardware.

[0079] In practical applications, each PWM signal value (PWM(X)) corresponds to a voltage value (V / FB(X)). This correspondence for each power supply / lamp can be directly obtained through the actual hardware. However, due to differences in hardware parameters, this correspondence may deviate slightly from that of different products, but the actual deviation will not be significant. Therefore, the same correspondence (i.e., basic data) can be pre-written, and the actual deviation generated by the product is compensated for by dynamically adjusting the duty cycle of the initial PWM signal.

[0080] For example, the correspondence between PWM_VCS and V / FB can be shown in Table 1:

[0081] Table 1:

[0082]

[0083] It should be noted that if the digital-to-analog converter has higher precision, such as a 16-bit digital-to-analog converter, the duty cycle of the PWM signal can be divided into 65,536 levels, and the voltage value (V / FB value) corresponding to each level can be determined. The above is only an example and not a limitation.

[0084] The following explains how to determine the voltage value of the voltage reference signal:

[0085] In practical applications, the voltage reference signal can be determined by actual testing of the LED load actually driven by the LED driver circuit.

[0086] In practical applications, the power allocated to each LED string can be determined based on the rated power and voltage of the connected LED load, as well as the number of LED strings. Then, the current for each string is determined based on the power value and the voltage of each string. For example, assuming the connected LED load is a four-color smart light fixture with a rated power of 100W and a rated DC voltage of 24V, the power allocated to each string should be 25W. Assuming each string has 6 LEDs connected in series, the maximum voltage should be 18V, resulting in a current of 1.39A (Vcs / Rcs) for each string.

[0087] Assuming the factory default setting for the detection voltage Vcs is 0.2mV, then the resistance value of the sampling adjustment resistor can be Rcs = 0.2mV / 1.39A = 0.14Ω.

[0088] Taking a luminaire load with 6 series and 6 parallel LEDs of four colors (red, green, blue, and white, RGBW) as an example, assuming the rated power of the luminaire is 100W, then the power of each circuit is 25W. It can be distributed according to the voltage of 18V for each circuit. However, due to the inconsistency of the voltage of different colored LED beads, the voltage of each circuit will actually be different. For example, the voltage of the circuit with red LEDs may be 11V (assuming the voltage of a red LED is 1.83V), the voltage of the circuit with green LEDs may be 19.2V (assuming the voltage of a green LED is 3.2V), the voltage of the circuit with blue LEDs may be 19.8V (assuming the voltage of a blue LED is 3.3V), and the voltage of the circuit with white LEDs may be 18.6V (assuming the voltage of a red LED is 3.1V).

[0089] Therefore, the power of the circuit containing the red LED is 15.3W (P_R=11X1.39=15.3W). The power of the circuit containing the green LED is 26.6W (P_G=19.2X1.39=26.6W). The power of the circuit containing the blue LED is 27.5W (P_B=19.8X1.39=27.5W). The power of the circuit containing the white LED is 25.8W (P_W=18.6X1.39=25.8W).

[0090] Because LED beads are current-sensitive devices, directly adjusting the current of the red LED bead will cause inconsistencies in the RGBW currents, leading to mixed light and preventing white balance, which is unacceptable. Therefore, this application proposes determining the theoretical current value for each channel based on the total power and the voltage value of each channel. Then, based on the fixed resistance value of the sampling adjustment resistor, the voltage value (V / FB) corresponding to the voltage reference signal can be determined.

[0091] For example, taking the rated power of the aforementioned lamp as 100W, the voltage of the circuit containing the red LED as 11V, the voltage of the circuit containing the green LED as 19.2V, the voltage of the circuit containing the blue LED as 19.8V, and the voltage of the circuit containing the white LED as 18.6V as an example, the following formula can be obtained:

[0092] P total=P_R+P_G+P_B+P_W=11V*I+19.2V*I+19.8V*I+18.6V*I=100W;

[0093] We can calculate I = 1.45A, and then obtain Vcs using I = Vcs / Rcs.

[0094] For example, assuming the sampling adjustment resistor Rcs is fixed at 0.14Ω, the voltage value Vcs corresponding to the voltage reference signal can be calculated as 0.203mV (1.45A * 0.14Ω = 0.203mV).

[0095] Here, the voltage of each LED can be obtained through actual testing.

[0096] The structure and working principle of the LED driving circuit provided in the embodiments of this application have been illustrated above. The working process of the LED driving circuit provided in the embodiments of this application will be described by way of example below:

[0097] 1. Select a power supply that matches the operating conditions required for the lamps that need power balancing and connect it to the actual LED load.

[0098] 2. The actual power of the lamp is measured using a power testing device.

[0099] 3. Determine the voltage value of each LED load using voltage detection equipment, and calculate the voltage deviation of each load.

[0100] 4. Calculate the current value after deviation based on the voltage and actual power of each load, substitute it into I=Vcs / Rcs to obtain Vcs, and determine the voltage reference signal corresponding to Vcs.

[0101] 5. The voltage reference signal is written into the main control chip mentioned above through the Mini controller.

[0102] 6. The main control chip obtains the initial PWM signal corresponding to the voltage reference signal by the correspondence between the PWM signal and the voltage value.

[0103] 7. The constant current control unit converts the initial PWM signal into a control signal for driving the connected LED (specifically, it can be the driving voltage, i.e., the analog voltage output by the constant current control unit), and acquires the voltage sampling signal corresponding to the control signal.

[0104] 8. The main control chip dynamically adjusts the initial PWM signal based on the voltage reference signal and the voltage sampling signal to obtain the target PWM signal.

[0105] 9. Write the target PWM signal and voltage reference signal into the FLASH memory.

[0106] In one embodiment of this application, the main control chip dynamically adjusts the initial PWM signal according to the voltage reference signal and the voltage sampling signal to obtain the target PWM signal. Specifically, it can determine the adjustment amplitude of the PWM signal according to the difference between the voltage value of the voltage reference signal and the voltage value of the voltage sampling signal, and adjust the PWM signal based on the determined adjustment amplitude.

[0107] Understandably, if the difference between the voltage value of the voltage reference signal and the voltage value of the voltage sampling signal is large, the value of the PWM signal can be adjusted significantly; if the difference is small, the value of the PWM signal can be adjusted slightly to improve the efficiency of achieving dynamic balance.

[0108] Of course, the PWM signal value can also be adjusted according to a preset level. For example, if the voltage value of the voltage reference signal is greater than the voltage value of the voltage sampling signal, the value of the PWM signal can be increased by a preset level; if the voltage value of the voltage reference signal is less than the voltage value of the voltage sampling signal, the value of the PWM signal can be decreased by a preset level.

[0109] In some embodiments of this application, if the difference between the voltage value of the voltage reference signal and the voltage value of the voltage sampling signal is within a preset range, it can be determined that the voltage value of the voltage sampling signal is infinitely close to the voltage value of the voltage reference signal, that is, the voltage sampling signal and the voltage reference signal have reached dynamic equilibrium. The relevant signal information of the PWM signal in the dynamic equilibrium state and the voltage value corresponding to the voltage reference signal are written into the above-mentioned memory for storage.

[0110] For example, assuming the voltage reference signal corresponds to a voltage value of 0.092mV, according to the correspondence shown in Table 1, the initial PWM signal value can be determined to be 500. Based on this initial PWM signal driving the LED load, assuming the voltage sampling signal corresponds to a voltage value of 0.09mV, the actual voltage value (i.e., the voltage value of the voltage sampling signal) is less than the set voltage value (i.e., the voltage value of the voltage reference signal). The main control chip will then adjust the PWM amplitude based on the difference between the voltage sampling signal and the voltage reference signal. For example, a difference of approximately 0.001mV will be adjusted by a factor of 1, and a difference of approximately 0.01mV will be adjusted by a factor of 10. The LED load is then controlled according to the adjusted PWM signal. If the adjusted voltage sampling signal corresponds to a voltage value of 0.093mV, the main control chip can determine that the current PWM signal value is too high and can reduce the PWM signal value; conversely, it can increase the PWM signal value. This adjustment continues until the voltage sampling signal value is infinitely close to 0.092mV.

[0111] When the value of the PWM signal is adjusted to increase or decrease by one, for example, in the case of PWM+1, the voltage value corresponding to the voltage sampling signal is 0.093mV; in the case of PWM-1, the voltage value corresponding to the voltage sampling signal is 0.091mV. Then PWM-1 can be determined as the target PWM signal. After repeated internal operation, output and feedback sampling comparison, the most reasonable PWM value will be obtained, that is, the so-called dynamic balance is achieved.

[0112] It is understandable that the constant current control unit in the LED driver circuit mentioned above will only output PWM_VSC to the constant current control unit through the main control chip when it is necessary to adjust the characteristic parameters such as the detection voltage of the load circuit.

[0113] For example, Figure 5 A schematic diagram of the structure of an LED driving circuit according to another embodiment of this application is shown, as follows: Figure 5 As shown, the LED driving circuit described above may also include a PWM dimming unit 24, which can enable the constant current control unit to operate in dimming mode according to an external PWM signal.

[0114] When the constant current control unit is working in dimming mode, it can directly convert the PWM signal corresponding to the external dimming into a control signal to control the LED to turn on and off.

[0115] In specific applications, the aforementioned constant current control unit may also include a MOS driving circuit, which controls the LED to emit light.

[0116] Understandably, the aforementioned constant current control unit may also include a control chip and a MOS drive circuit 25. When the internal control chip recognizes that the received PWM signal is a PWM_VCS signal issued by the internal main control chip, it can determine that the current signal is an abnormal dimming signal. To reduce abnormal flickering of the light, the control chip of the constant current control unit can turn off the output of the MOS drive circuit of the constant current section, for example, turn off the output of the MOS transistor, and then restore the output of the MOS transistor after receiving all data packets. Specifically, the MOS drive circuit can be connected to the constant current control unit and is configured to turn off the power supply line between the constant current control unit and the LED load according to the turn-off control signal of the constant current control unit; the constant current control unit is also configured to output a turn-off control signal to the MOS drive circuit during the process of the main control chip receiving the voltage reference signal.

[0117] Understandably, the external controller can write data packets with voltage reference signals according to the communication protocol corresponding to the communication link with the main control chip. The main control chip can parse the received data packets. If the parsed data carries a command to change electrical parameters (for example, the value of a certain flag bit is the value of the electrical parameter that needs to be changed), and the parsed data is within the normal parameter range, then the process of adjusting the detection voltage according to the reference voltage signal can be executed to determine the target PWM signal. Then, the target PWM signal and the voltage reference signal are written into the FLASH. In this way, the lamp can control the detection voltage of each channel based on the target PWM signal, so that the lamp can achieve power balance, improve the life of the lamp, and reduce safety hazards.

[0118] It is understood that, in some embodiments, the LED driving circuit described above can be set in a chip. The chip has the original program embedded in it at the factory. The program embedded in the chip can also be upgraded via PWM signal. When the connected load changes or the power changes, or when the program is modified, the external Mini controller can be used to perform one-to-many firmware burning.

[0119] It should be noted that LED driver circuits are set with a fixed current output at the factory, assuming a default of 600mA. The chip also has internal overcurrent protection, and an overcurrent protection circuit can also be configured (e.g., Figure 6As shown in the figure, if the maximum operating current of the chip is 3A, then the upper limit of the hardware protection is 3A. If the current exceeds 3A, the MOS output will be directly shut off, and the chip will also activate overcurrent protection. When the value of the PWM signal written by human error is 4000, assuming that the corresponding V / FB exceeds the 0.6mV defined internally by the chip, the LED driver circuit can retain the original PWM signal and voltage reference signal without modification.

[0120] As can be seen from the above, the LED driving circuit provided in this application embodiment can determine the corresponding voltage reference signal for the load and power, and determine the initial PWM signal corresponding to the voltage reference signal according to the correspondence between the voltage reference signal and the PWM signal. Then, the initial PWM signal is dynamically adjusted according to the voltage sampling signal and the voltage reference signal so that the voltage sampling signal is infinitely close to the voltage reference signal, and the PWM signal under dynamic balance, i.e., the target PWM signal, is determined. The final PWM signal and voltage reference signal are saved in the memory, so that the corresponding Vcs (voltage reference signal) can be set for the LED load, thereby realizing the power balance setting of the LED lamp. In this way, the resistance value of the sampling adjustment resistor can be fixed, and the resistance value of the sampling adjustment resistor does not need to be manually adjusted, and the power balance of each circuit of the LED lamp can be achieved. In this way, even if the smart lamp has been potted or installed in the place of use, the power balance adjustment can be achieved simply by writing the voltage reference signal parameter to the main control chip through the external controller, which can greatly simplify the debugging process and save labor costs.

[0121] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0122] Based on the LED driving circuit provided in the above embodiments, this application also provides an LED driving power supply, which includes the above LED driving circuit.

[0123] This application also provides a lighting fixture, which includes an LED load and the aforementioned LED driving circuit or LED driving power supply.

[0124] It is understood that the lighting fixture provided in this application embodiment can also determine the corresponding voltage reference signal for the load and power through the LED driving circuit described above, and determine the initial PWM signal corresponding to the voltage reference signal based on the correspondence between the voltage reference signal and the PWM signal. Then, the initial PWM signal is dynamically adjusted according to the voltage sampling signal and the voltage reference signal so that the voltage sampling signal is infinitely close to the voltage reference signal, and the PWM signal under dynamic balance, i.e., the target PWM signal, is determined. By storing the final PWM signal and voltage reference signal in the memory, the corresponding Vcs (voltage reference signal) setting for the LED load can be realized, thereby achieving the power balance setting of the LED lighting fixture. In this way, the resistance value of the sampling adjustment resistor can be fixed, eliminating the need for manual adjustment of the resistance value of the sampling adjustment resistor, and the power balance of each circuit of the LED lighting fixture can be achieved. Thus, even if the smart lighting fixture has been potted or installed in the place of use, power balance adjustment can be achieved simply by writing the voltage reference signal parameter to the main control chip through an external controller, which can greatly simplify the debugging process and save labor costs.

[0125] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the terminal device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0126] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, refer to the relevant descriptions of other embodiments.

[0127] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0128] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. An LED driving circuit, characterized in that, include: The main control chip is configured to determine an initial PWM signal corresponding to the voltage reference signal upon receiving the voltage reference signal; wherein the voltage reference signal is calculated based on the measured voltage value of each LED load, the measured power value of the LED load, and the resistance value of the sampling adjustment resistor; the correspondence between the voltage reference signal and the initial PWM signal is predetermined and written into the main control chip, and different voltage values ​​of the voltage reference signal correspond to different duty cycle PWM signal values; The pre-determined correspondence between the voltage reference signal and the PWM signal includes: Determine the frequency positioning of the PWM_VCS signal; Based on the number of bits in the analog-to-digital converter, the duty cycle of the PWM_VCS signal is divided into multiple duty cycle levels; Determine the voltage value corresponding to each duty cycle level of the PWM_VCS signal; A constant current control unit, connected to the main control chip, is used to connect to the LED load and is configured to convert the initial PWM signal into a control signal to control the LED load to emit light; The main control chip is also configured to dynamically adjust the initial PWM signal according to the voltage sampling signal and the voltage reference signal to obtain the target PWM signal; wherein, the voltage sampling signal is the sampling signal corresponding to the detection voltage generated on the sampling resistor when the constant current control unit outputs current to the LED load; The memory, connected to the main control chip, is configured to store the target PWM signal and the voltage reference signal.

2. The LED driving circuit according to claim 1, characterized in that, The constant current control unit includes: A low-pass filter component, wherein the input terminal of the low-pass filter component is the input terminal of the constant current control unit, and the output terminal of the low-pass filter component is the output terminal of the constant current control unit, is configured to filter out the high-frequency AC component of the input PWM signal and output an analog voltage corresponding to the duty cycle of the input PWM signal; The voltage sampling component is configured to acquire the sampling signal corresponding to the detection voltage generated on the sampling resistor when the constant current control unit outputs current to the load.

3. The LED driving circuit according to claim 2, characterized in that, The low-pass filter component includes a low-pass RC filter and an operational amplifier.

4. The LED driving circuit according to claim 2, characterized in that, The voltage sampling component includes a sampling resistor and a signal amplifier.

5. The LED driving circuit according to claim 1, characterized in that, The LED driving circuit also includes a PWM dimming unit; The PWM dimming unit is connected to the constant current control unit and is configured to output a corresponding PWM dimming signal to the constant current control unit according to the external PWM signal. The constant current control unit is also configured to convert the PWM dimming signal into a control signal that controls the LED load to emit light.

6. The LED driving circuit according to claim 1, characterized in that, The LED driving circuit also includes a MOS driving circuit. The MOS driving circuit is connected to the constant current control unit and is configured to turn off the power supply line between the constant current control unit and the LED load according to the turn-off control signal of the constant current control unit. The constant current control unit is further configured to output the shutdown control signal to the MOS drive circuit during the process of the main control chip receiving the voltage reference signal.

7. The LED driving circuit according to claim 1, characterized in that, The LED driving circuit also includes an overcurrent protection circuit; The overcurrent protection circuit is configured to perform overcurrent protection action when the current of the LED driving circuit is greater than a preset current.

8. The LED driving circuit according to claim 1, characterized in that, The main control chip is further configured to determine the adjustment amplitude of the initial PWM signal based on the difference between the voltage value of the voltage reference signal and the voltage value of the voltage sampling signal, and to adjust the initial PWM signal based on the determined adjustment amplitude.

9. An LED driver power supply, characterized in that, The LED driver power supply includes the LED driver circuit as described in any one of claims 1 to 8.

10. A lamp, characterized in that, The luminaire includes an LED load, an LED driving circuit as described in any one of claims 1 to 8, or an LED driving power supply as described in claim 9.

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