LED control circuit, method, chip and lighting device

Abstract

The application discloses an LED control circuit, method, chip and lighting device. The LED control circuit comprises an I2C communication module, a digital-analog conversion module and an adjusting module. The I2C communication module receives a clock signal and a data signal, and generates protocol information, wherein the protocol information comprises constant power setting information. The digital-analog conversion module converts the constant power setting information into power adjustment starting point information and a power adjustment coefficient. The adjusting module samples a bus voltage or a voltage at a negative end of an LED lamp string according to the constant power setting information to obtain a sampling voltage, and adjusts a first driving signal generated by the adjusting module according to the sampling voltage, the power adjustment starting point information and the power adjustment coefficient, so as to control the size of a first current on the LED lamp string connected with the adjusting module. The LED control circuit disclosed by the application can perform constant power adjustment on each LED branch to realize constant power control, and can perform over-temperature protection adjustment, so that the circuit is prevented from being burned due to excessive power and excessive temperature, and external constant power adjustment and temperature adjustment resistors are not needed, thereby saving the number of components and improving the integration.

Description

Technical Field

[0001] This disclosure relates to the field of power electronics technology, and more specifically, to an LED control circuit, method, chip, and lighting device. Background Technology

[0002] Because light-emitting diodes (LEDs) offer advantages over traditional light sources, such as high efficiency, energy saving, environmental friendliness, and excellent color rendering, they are increasingly replacing traditional light sources in the lighting field under the global trend of energy conservation and emission reduction. In specific circuit applications, an LED driver circuit provides a stable current to the LED lamp to drive it to work normally. In practical applications, two or more LED loads are usually needed to achieve dimming and color adjustment functions. Dimming is the process of adjusting the brightness of the light emitted by the LED lamp according to the user's needs using a certain control device.

[0003] Currently, many LED lighting products based on LED dimming technology have appeared on the market, mainly used for landscape and architectural decorative lighting. LED linear drive dimming solutions are a relatively simple and direct driving application method, with simple circuitry and compact size, meeting the needs of many applications. Existing LED dimming control chips use external compensation resistors to compensate power or current for each LED branch, occupying many chip pins and exhibiting slow compensation. When the input voltage increases, it often leads to excessive power, chip overheating, and circuit burnout. The over-temperature protection settings are relatively simple and cannot provide adequate protection. Furthermore, problems such as poor dimming accuracy, flickering during dimming, and limited dimming effects exist.

[0004] Therefore, it is necessary to provide improved technical solutions to overcome the above-mentioned technical problems existing in the prior art. Summary of the Invention

[0005] In view of this, the purpose of this disclosure is to provide an LED control circuit, method, chip, and lighting device to solve the problems in the prior art.

[0006] According to a first aspect of this disclosure, an LED control circuit is provided, comprising:

[0007] The I2C communication module receives clock signals and data signals, and generates protocol information, which includes constant power setting information.

[0008] The digital-to-analog conversion module converts the constant power setting information into power adjustment start-point information and power adjustment coefficient;

[0009] The adjustment module obtains a sampled voltage by sampling the bus voltage or the voltage at the negative terminal of the LED string according to the constant power setting information, and adjusts the first drive signal generated by the adjustment module according to the sampled voltage, the power adjustment starting point information and the power adjustment coefficient, so as to control the magnitude of the first current on the LED string connected to the adjustment module.

[0010] Optionally, the adjustment module includes:

[0011] The voltage sampling module obtains the sampled voltage by sampling the bus voltage or the voltage at the negative terminal of the LED string according to the constant power setting information;

[0012] The current control module generates the first driving signal based on the operational amplification result of the first reference voltage and the first sampling voltage, and the current control module adjusts the magnitude of the first reference voltage based on the sampling voltage, the power adjustment start information, and the power adjustment coefficient.

[0013] Optionally, the current control module includes:

[0014] A power transistor is connected to the LED string, and its control electrode receives the first driving signal to control the magnitude of the first current on the LED string.

[0015] An operational amplifier receives the first reference voltage at its positive input terminal, receives the first sampled voltage at its inverting input terminal, and provides a first drive signal to the control electrode of the power transistor at its output terminal.

[0016] A constant power control circuit is connected to the positive input terminal of the operational amplifier. It generates a power adjustment current based on the sampled voltage, the power adjustment start-point information, and the power adjustment coefficient, and adjusts the magnitude of the first reference voltage based on the power adjustment current.

[0017] Optionally, the current control module further includes:

[0018] A current-to-voltage circuit, connected to the positive input of the operational amplifier, generates the first reference voltage based on the reference current provided by the current source and the power adjustment current; and

[0019] A current sampling circuit is connected to the source of the power transistor and the inverting input of the operational amplifier to sample the source voltage of the power transistor to obtain a first sampling voltage.

[0020] Optionally, the constant power control circuit generates the power regulation current based on the product of the difference between the sampled voltage and the power regulation start-up information and the power regulation coefficient.

[0021] Optionally, the protocol information also includes current setting information and brightness setting information. The current control module adjusts the magnitude of the first reference voltage and the first sampling voltage according to the current setting information and the brightness setting information, thereby controlling the magnitude of the first current on the LED string and the grayscale of the LED string.

[0022] Optionally, the voltage sampling module includes:

[0023] The sampling mode selection circuit selects the corresponding sampling branch based on the received constant power setting information;

[0024] The first sampling branch, in the selected state, samples the bus voltage or the voltage at the negative terminal of the LED string through the sample-and-hold circuit to generate the peak sampling voltage.

[0025] The second sampling branch, in the selected state, generates a sampling voltage for instantaneous sampling via the voltage divider unit sampling the bus voltage or the voltage at the negative terminal of the LED string; and

[0026] The third sampling branch, in the selected state, samples the bus voltage or the voltage at the negative terminal of the LED string through the filtering unit to generate the average sampling voltage.

[0027] Optionally, the protocol information also includes over-temperature protection setting information. The digital-to-analog conversion module converts the over-temperature protection setting information into temperature adjustment start-up information and temperature adjustment coefficient. The adjustment module also adjusts the first reference voltage according to the temperature adjustment start-up information and temperature adjustment coefficient to adjust the first drive signal and control the magnitude of the first current.

[0028] Optionally, the current control module further includes:

[0029] An over-temperature protection control circuit is connected to the positive input terminal of the operational amplifier. It generates a temperature regulation current based on the temperature regulation start-up information and the temperature regulation coefficient, and adjusts the magnitude of the first reference voltage based on the temperature regulation current.

[0030] Optionally, the LED control circuit further includes:

[0031] An electrolytic branch adjustment module is connected to the first terminal of an electrolytic capacitor, and the second terminal of the electrolytic capacitor is connected to the positive terminal of an LED string. The electrolytic branch adjustment module generates a second driving signal based on the operational amplification result of a second reference voltage and a second sampling voltage, thereby controlling the magnitude of the second current output by the electrolytic branch adjustment module. The electrolytic branch adjustment module is connected to the digital-to-analog converter module, which converts the constant power setting information into electrolytic power adjustment start-up information and electrolytic power adjustment coefficient, and the over-temperature protection setting information into electrolytic temperature adjustment start-up information and electrolytic temperature adjustment coefficient.

[0032] The electrolysis branch adjustment module generates an electrolysis power adjustment current based on the bus voltage, the electrolysis power adjustment starting point information, and the electrolysis power adjustment coefficient; generates an electrolysis temperature adjustment current based on the electrolysis temperature adjustment starting point information and the electrolysis temperature adjustment coefficient; and adjusts the magnitude of the second reference voltage based on the electrolysis power adjustment current and the electrolysis temperature adjustment current.

[0033] Optionally, the LED control circuit connects multiple LED light strings to adjust the first current on the multiple LED light strings, and each LED light string is connected to one of the adjustment modules.

[0034] According to a second aspect of this disclosure, an LED control method is provided, applied to the aforementioned LED control circuit, the LED control method comprising:

[0035] Receive clock signals and data signals, generate protocol information, the protocol information including constant power setting information;

[0036] The constant power setting information is converted into power adjustment start-up information and power adjustment coefficient;

[0037] The sampling voltage is obtained by sampling the bus voltage or the voltage at the negative terminal of the LED string based on the constant power setting information;

[0038] The first driving signal is adjusted according to the sampling voltage, the power adjustment start information, and the power adjustment coefficient to control the magnitude of the first current on the LED string.

[0039] According to a third aspect of this disclosure, an LED control chip is provided, including the LED control circuit described above, wherein the substrate of the LED control chip is grounded.

[0040] According to a fourth aspect of this disclosure, an LED lighting device is provided, comprising:

[0041] The aforementioned LED control chip;

[0042] The rectifier bridge rectifies the AC power into a bus voltage and supplies it to the LED control chip.

[0043] The microcontroller sends data signals and clock signals to the LED control chip;

[0044] Multiple LED light strings are connected to multiple output pins of the LED control chip.

[0045] According to the LED control circuit, method, chip, and lighting device of this disclosure, the I2C communication module converts data signals and clock signals into protocol information, which includes constant power setting information. Based on this constant power setting information, the input signals are adjusted to control the first drive signal output by the adjustment module, thereby controlling the magnitude of the first current flowing through the LED string and achieving constant power regulation. In other words, constant power control of each LED branch is achieved by using the I2C communication protocol, avoiding overheating and circuit damage caused by excessive power. Furthermore, constant power control of the LED branch is realized through the protocol information generated by the chip's original interface and the I2C communication module, eliminating the need for constant power adjustment resistors outside the circuit or chip. This reduces the number of external components, improves chip integration, reduces chip size, lowers costs, and meets European ERP certification requirements.

[0046] Furthermore, the I2C communication module converts the data signal and clock signal into protocol information with over-temperature protection setting information. Based on the over-temperature protection setting information, the first drive signal output by the adjustment module and the magnitude of the first current flowing through the LED string are controlled. This achieves efficient configuration of the OTP (over-temperature protection) point and the slope of the over-temperature protection point. When the chip temperature exceeds the threshold, the magnitude of the first current of the LED string can be adjusted in time to avoid burning out the chip. This can meet the over-temperature protection requirements in different application scenarios, especially in DOB (Driver on Board) chips.

[0047] Furthermore, by sending protocol information via the I2C bus to adjust the magnitude of the second current in the electrolytic branch, the electrolytic branch is adjusted downwards to achieve efficient charging of the electrolytic capacitor. The chip's COUT pin does not need to have a built-in fixed charging adjustment, making it easier to meet the ERP requirement of a 65° phase angle. Attached Figure Description

[0048] Figure 1 A schematic circuit diagram of a conventional LED lighting device is shown.

[0049] Figure 2 A schematic circuit block diagram of an LED control circuit according to a first embodiment of the present disclosure is shown;

[0050] Figure 3 Show Figure 2 A schematic circuit block diagram of the current control module in the LED control circuit shown.

[0051] Figure 4 Show Figure 3 The diagram shows a schematic circuit of the current-to-voltage conversion circuit in the current control module.

[0052] Figure 5 Show Figure 3 A schematic circuit diagram of the current sampling circuit in the current control module shown.

[0053] Figure 6 Show Figure 2 A schematic circuit block diagram of the voltage sampling module in the LED control circuit shown.

[0054] Figure 7 A schematic circuit block diagram of an LED control circuit according to a second embodiment of the present disclosure is shown;

[0055] Figure 8 A schematic diagram of an LED control chip according to an embodiment of the present disclosure is shown;

[0056] Figure 9 A schematic circuit diagram of an LED lighting device according to an embodiment of the present disclosure is shown. Detailed Implementation

[0057] The preferred embodiments of this disclosure are described in detail below with reference to the accompanying drawings, but this disclosure is not limited to these embodiments. This disclosure covers any alternatives, modifications, equivalent methods, and solutions made within the spirit and scope of this disclosure.

[0058] In order to provide the public with a thorough understanding of this disclosure, specific details are described in detail in the following preferred embodiments of this disclosure, but those skilled in the art can fully understand this disclosure without these details.

[0059] The present disclosure is described in more detail below by way of example with reference to the accompanying drawings. It should be noted that the drawings are in a simplified form and use non-precise scales, and are only used to facilitate and clarify the illustration of the embodiments of the present disclosure.

[0060] Figure 1 A schematic circuit diagram of a conventional LED lighting device is shown.

[0061] like Figure 1As shown, this LED lighting device rectifies the AC power generated by the AC power supply through a rectifier bridge to generate an input voltage or bus voltage HV. The input voltage is filtered by a filter capacitor C1, and the filtered bus voltage HV is provided to the LED dimming chip. The dimming chip has 10 pins (1-10). Pins 2, 1, 10, 9, and 8 correspond to OUT1, OUT2, OUT3, OUT4, and OUT5, respectively, forming 5 output pins connected to 5 LED strings (LED1-LED5). Pin 4 is the SDA pin, and pin 5 is the SCL pin. Pins 4 and 5 are both connected to a microcontroller (MCU). The MCU is connected to the input voltage terminal via an auxiliary power supply. Pins 4 and 5 receive the data signal and clock signal output by the MCU, respectively. Pins 4 and 5 are connected to the auxiliary power supply via pull-up resistors R1 and R2, respectively. The auxiliary power supply provides, for example, approximately 3.3V. A first diode D1 is also placed between each LED string and the input voltage terminal to maintain the minimum voltage required for each LED branch to operate. Pin 3 is the RCAP pin, connected to an external resistor R3, used to provide power regulation for each LED branch. Pin 7 is the HV pin, receiving the bus voltage to power the chip. Pin 6 is the COUT pin, connected to an external electrolytic capacitor C2 and resistor R4, and the ground terminal is connected to pin COUT via the second diode D2 and the third diode D3. This electrolytic branch has a built-in fixed adjustment module through the COUT pin.

[0062] This lighting device controls the current of each LED branch by adjusting the voltage of each output pin through a chip, thus controlling the brightness of each LED string. However, to adjust the power of each branch, a power adjustment resistor needs to be installed outside the chip, which occupies a lot of space. To meet the charging requirements of the electrolytic capacitor, a fixed adjustment needs to be built into the COUT pin, making the circuit complex. Furthermore, with the use of LED chips and changes in the electrolytic capacitor value, it is difficult to achieve the voltage at a 65° phase angle. Moreover, changes in the bus voltage will cause significant changes in the voltage of each LED branch, resulting in significant power fluctuations. Excessive power may cause the chip to overheat and damage the circuit. In addition, the OTP point and OTP slope settings of this circuit are relatively fixed, and the over-temperature protection of the chip is not flexible enough.

[0063] This invention improves the aforementioned lighting device, LED control chip, and its internal LED control circuit, eliminating the need for external adjustment resistors and enabling constant power control and OTP protection for each LED branch. A detailed description follows with reference to the accompanying drawings.

[0064] Figure 2 A schematic circuit block diagram of an LED control circuit according to a first embodiment of the present disclosure is shown.

[0065] like Figure 2As shown, the LED control circuit 100 of the first embodiment of the present invention includes: an I2C communication module 10, a register 20, a digital-to-analog converter (DAC) module 30, and an adjustment module 40. The I2C communication module 10 receives clock signals and data signals through the SCL and SDA pins respectively, and generates and outputs protocol information; the register module 20 is connected to the I2C communication module 10, stores the protocol information, and parses the protocol information into constant power setting information, over-temperature protection setting information, maximum current setting information, and grayscale level setting information according to preset rules; the DAC module 30 is connected to the register module 20, and converts the constant power setting information into power adjustment start-up information V. STA_X and power regulation coefficient V SLO_X The adjustment module 40 is connected to the digital-to-analog converter module 30 and the register module 20. Based on the parsed constant power setting information, the adjustment module 40 samples the bus voltage VBUS via the HV pin or samples the voltage VLE at the negative terminal of the LED string connected to the adjustment module 40 to obtain the sampled voltage V. HV’ And based on the sampled voltage V HV’ Power adjustment start-up information V STA_X and power regulation coefficient V SLO_X The first drive signal generated by the adjustment module 40 controls the magnitude of the first current on the LED string LED1 connected to the adjustment module 40. In this embodiment, the LED control circuit is located within the LED control chip, and taking the chip containing one LED branch as an example, the adjustment module 40 is connected to the LED string LED1 through the OUT1 pin and grounded through the GND pin.

[0066] In this embodiment, the LED control circuit 100 receives data signals and clock signals sent by the microprocessor through the I2C communication module 10, generates protocol information, and this protocol information includes constant power setting information. After passing through the digital-to-analog converter module 30, the constant power setting information is converted into a signal that the adjustment module 40 can receive. Then, the adjustment module 40 adjusts the generated drive signal according to the constant power setting information, thereby adjusting the current of the corresponding LED string. The constant power setting information enables constant power control of the LED string, improving transmission efficiency. Constant power setting information can be generated simply by receiving the I2C bus protocol through the chip's existing pins, thus eliminating the need for external power adjustment resistors to achieve constant power control. This prevents excessive or insufficient power from affecting the circuit, frees up a pin, reduces the number of external components, and lowers costs.

[0067] Furthermore, the adjustment module 40 includes a voltage sampling module 41 and a current control module 42. The voltage sampling module 41 is connected to the register module 20 and obtains the sampling voltage V by sampling the bus voltage or the voltage at the negative terminal of the LED string according to the constant power setting information. HV’The current control module 42 generates a first drive signal based on the amplified result of the first reference voltage Vref1 and the first sampled voltage Vcs1. Specifically, the current control module 42 generates a first drive signal based on the sampled voltage Vref1. HV’ Power adjustment start-up information V STA_X and power regulation coefficient V SLO_X The magnitude of the first reference voltage is adjusted, thereby adjusting the operational amplification result, which in turn adjusts the first drive signal. This first drive signal then controls the magnitude of the first current in the LED string. The structure of the current control module 42 is described in [reference needed]. Figure 3 .

[0068] Figure 3 Show Figure 2 The diagram shows a schematic block diagram of the current control module in the LED control circuit.

[0069] like Figure 3 As shown, the current control module 42 includes a power transistor M0, an operational amplifier U0, and a constant power control circuit 421. The source of the power transistor M0 is grounded, and its drain is connected to the LED string LED1. The control terminal receives a first drive signal to control the first current I on the LED string. LED1 The magnitude of the operational amplifier U0; the positive input terminal receives the first reference voltage Vref1, the inverting input terminal receives the first sampling voltage Vcs1, and the output terminal provides the first drive signal to the control electrode of the power transistor M0; the constant power control circuit 421 is connected to the positive input terminal of the operational amplifier, and according to the sampling voltage V... HV’ Power adjustment start-up information V STA_X and power regulation coefficient V SLO_X Generate power regulation current I LCP Adjust the current I according to the power LCP The magnitude of the first reference voltage Vref1 is adjusted. Specifically, the constant power control circuit 421 adjusts the value based on the sampled voltage Vref1. BUS’ and power regulation start-up information V STA_X The difference (V) BUS’ -V STA_X ) and power regulation coefficient V SLO_X The product of these two factors generates a power regulation current I. LCP Adjust the current I according to the power. LCP The magnitude of the first reference voltage Vref1 can be adjusted, thereby changing the output of the operational amplifier U0, that is, changing the magnitude of the drive signal, controlling the conduction state of the power transistor M0, and thus adjusting the magnitude of the first current.

[0070] Furthermore, the current control module 42 also includes a current-to-voltage circuit 422 and a current sampling circuit 423. Figure 4 Show Figure 3The diagram shown is a schematic of the current-to-voltage conversion circuit in the current control module. Figure 5 Show Figure 3 The diagram shows a schematic of the current sampling circuit in the current control module.

[0071] See Figure 4 The current-to-voltage converter 422 is connected to the positive input terminal of the operational amplifier U0, and operates based on the reference current Iref1 provided by the current source and the power adjustment current I. LCP A first reference voltage Vref1 is generated. Specifically, the current-to-voltage circuit 422 includes multiple identical transistors connected in parallel between the current source and ground, and the first reference voltage Vref1 is the sum of the reference current Iref1 and the power regulation current I. LCP The difference (Ierf1-I) LCP The product of the resistance of the transistors and the equivalent resistance Rref1 of the transistors.

[0072] See Figure 5 The current sampling circuit 423 is connected between the source of the power transistor M0 and the ground terminal, and is also connected to the inverting input terminal of the operational amplifier U0. It samples the source voltage of the power transistor M0 to obtain the first sampling voltage Vcs1. Specifically, the current sampling circuit 423 includes multiple transistors connected in parallel. The resistor corresponding to the current sampling circuit 423 is different depending on the number of transistors selected.

[0073] Furthermore, the protocol information includes current setting information and brightness setting information. The current control module 42 also adjusts the magnitudes of the first reference voltage Vref1 and the first sampling voltage Vcs1 based on the current setting information and brightness setting information to control the first current I. LED1 The size and grayscale of the LED string. For example, the current setting information can adjust the magnitude of the first reference voltage Vref1 via the current-to-voltage circuit 422, and the brightness setting information can adjust the magnitude of the first sampling voltage Vcs1 via the current sampling circuit 423. For example, the grayscale level or grayscale can be divided into 1024 levels from 0 to 1023, and the current corresponding to the highest grayscale level is the maximum current. When the current is at its maximum, the higher the grayscale level, the brighter the LED string. Taking the current setting information containing 8 binary numbers and the brightness setting information containing 10 binary numbers as an example, the current-to-voltage circuit 422 contains 8 transistors, B0-B7, and the current sampling circuit 423 contains 10 transistors, B0-B9.

[0074] In this embodiment, the LED control circuit converts data signals and clock signals into protocol information via the I2C communication module. This protocol information includes constant power setting information. Based on this constant power setting information, the circuit adjusts each input signal to control the first drive signal output by the adjustment module, thereby controlling the magnitude of the first current flowing through the LED string and achieving constant power regulation. In other words, constant power control of each LED branch is achieved by using the I2C protocol, avoiding overheating and circuit damage caused by excessive power. Furthermore, constant power control of the LED branch is achieved through the protocol information generated by the chip's original interface and the I2C communication module, eliminating the need for constant power adjustment resistors outside the circuit or chip. This reduces the number of external components, increases chip integration, reduces chip size, lowers costs, and also meets European ERP certification requirements.

[0075] Furthermore, the protocol information includes over-temperature protection setting information, and the digital-to-analog conversion module 30 is also used to convert the over-temperature protection setting information into temperature regulation start-up information T. OTP and temperature regulation coefficient T SLP Correspondingly, the adjustment module 40 also adjusts the starting point information T based on the temperature. OTP and temperature regulation coefficient T SLP Adjusting the first reference voltage to adjust the first drive signal, and controlling the first current I LED1 Size. See also Figure 3 The current control module 42 also includes an over-temperature protection control circuit 424, which is connected to the positive input terminal of the operational amplifier U0 and adjusts the starting point information T according to the temperature. OTP and temperature regulation coefficient T SLP Generate temperature regulating current I OTP Adjust the current I according to the temperature OTP Adjust the magnitude of the first reference voltage Vref1. Specifically, the current I can also be adjusted based on the reference current Iref1 and the temperature. OTP The difference between the two values ​​is multiplied by the equivalent resistance Rref1 in the current-to-voltage circuit 422 to obtain the first reference voltage Vref1.

[0076] In this embodiment, the I2C communication module converts the data signal and clock signal into protocol information with over-temperature protection setting information. Based on the over-temperature protection setting information, the first drive signal output by the adjustment module and the magnitude of the first current flowing through the LED string are controlled, thereby achieving efficient configuration of the OTP point and the over-temperature protection slope. When the chip temperature exceeds the threshold, the magnitude of the first current of the LED string can be adjusted in time to avoid burning the chip. This can meet the over-temperature protection requirements in different application scenarios, especially in DOB chips.

[0077] Figure 6 Show Figure 2 The diagram shows a schematic block diagram of the voltage sampling module in the LED control circuit.

[0078] like Figure 6 As shown, the voltage sampling module 41 includes: a sampling mode selection circuit 411, a first sampling branch, a second sampling branch, and a third sampling branch. The sampling mode selection circuit 411 selects the corresponding sampling branch according to the received constant power setting information; when the first sampling branch is selected, it samples the bus voltage VBUS or the voltage VLE at the negative terminal of the LED string via the sample-and-hold circuit 412 to generate a peak sampling voltage; when the second sampling branch is selected, it samples the bus voltage VBUS or the voltage VLE at the negative terminal of the LED string via the voltage divider unit 413 to generate an instantaneous sampling voltage; when the third sampling branch is selected, it samples the bus voltage VBUS or the voltage VLE at the negative terminal of the LED string via the filter unit 414 to generate an average sampling voltage.

[0079] Specifically, the first sampling branch includes a transistor M1 connected to the sample-and-hold circuit 412, the second sampling branch includes a transistor M2 connected to the sample and hold circuit 412 and two voltage divider resistors R01 and R02 connected in series (voltage divider unit 413), and the third sampling branch includes a transistor M3, resistors R03, R04, R05 and capacitor C01, wherein resistors R03 and R04 form a voltage divider unit, and resistors R05 and capacitor C01 form a filter unit. Transistors M1, M2, and M3 collectively receive the bus voltage VBUS or the voltage VLE at the negative terminal of the LED string through the HV pin. The control electrodes of transistors M1, M2, and M3 all receive constant power setting information. For example, the constant power setting information received by the control electrode of transistor M1 is 00, that of transistor M2 is 01, and that of transistor M3 is 10. If transistors M1, M2, and M3 are all PMOS transistors, then based on the constant power setting information, transistors M1, M2, or M3 can be selected to conduct, thereby selecting the corresponding sampling branch.

[0080] In this embodiment, the bus voltage VBUS can be the voltage at the positive terminal of the LED string.

[0081] Figure 7 A schematic circuit block diagram of an LED control circuit according to a second embodiment of the present disclosure is shown.

[0082] like Figure 7As shown, the LED control circuit 200 of this embodiment includes multiple adjustment modules 40, and the LED control circuit 200 is used to control the current of multiple LED light strings connected to it. Each adjustment module 40 includes a current control circuit (4201, 4202...420n), and each adjustment module 40 is connected to one LED light string. The multiple adjustment modules 40 adjust the brightness of the multiple LED light strings according to multiple first driving signals, that is, the adjustment module 40 corresponds one-to-one with the LED light strings. Figure 7 As can be seen, the first adjustment module 40 is connected to the first LED string LED1 via pin OUT1, and the second adjustment module is connected to the second LED string LED2 via pin OUT2. Thus, the brightness of multiple LED strings can be adjusted simultaneously according to the protocol information output by the I2C communication module 10.

[0083] Furthermore, the LED control circuit 200 also includes an electrolytic branch adjustment module 50. The electrolytic branch adjustment module 50 is connected to one end of the electrolytic capacitor C4, and the other end of the electrolytic capacitor C4 is connected to the positive terminal of the LED string. The electrolytic branch adjustment module 50 is used to generate a second driving signal based on the operational amplification result of the second reference voltage Vref2 and the second sampling voltage Vcs2, and to control the second current I output by the electrolytic branch adjustment module 50. CAP The value of electrolytic capacitor C4 is adjusted by controlling the magnitude of the voltage. The electrolytic branch adjustment module 50 is connected to the digital-to-analog converter module 30, which converts the constant power setting information into electrolytic power adjustment start-point information V. STA_X and electrolysis power adjustment coefficient V SLO_X The over-temperature protection setting information is converted into electrolysis temperature adjustment start-up information T. OTP_C and the electrolysis temperature adjustment coefficient T SLP_C The electrolysis branch adjustment module 50 adjusts the voltage V based on the sampling voltage. HV’ Electrolysis power adjustment starting point information V STA_X and electrolysis power adjustment coefficient V SLO_X The electrolysis power regulating current is generated, and the starting point information T is adjusted according to the temperature. OTP_C and temperature regulation coefficient T SLP_C An electrolysis temperature regulating current is generated, and the magnitude of the second reference voltage Vref2 is adjusted according to the electrolysis power regulating current and the electrolysis temperature regulating current, thereby regulating the output second current I. CAPThe size of the electrolytic branch adjustment module 50 is as follows. For example, it is connected to the electrolytic capacitor C4 via the COUT pin. In this embodiment, the electrolytic branch is adjusted through protocol information generated by the I2C communication module 10, eliminating the need for a built-in complex fixed adjustment module. That is, the second current of the electrolytic branch is adjusted by sending protocol information through the I2C bus, thereby adjusting the electrolytic branch to achieve efficient charging of the electrolytic capacitor. The COUT pin of the chip does not need to have a built-in fixed charging adjustment, making it easier to meet the ERP requirement of a 65° phase angle.

[0084] Furthermore, the present invention also provides a control method for an LED control circuit, applied to the LED control circuit of any of the above embodiments. The LED control method includes: receiving a clock signal and a data signal, generating protocol information, the protocol information including constant power setting information; converting the constant power setting information into power adjustment start information and power adjustment coefficient; sampling the bus voltage or the voltage at the negative terminal of the LED string according to the constant power setting information to obtain a sampled voltage; adjusting a first driving signal according to the sampled voltage, the power adjustment start information and the power adjustment coefficient to control the magnitude of a first current on the LED string.

[0085] Figure 8 A schematic diagram of an LED control chip according to an embodiment of the present disclosure is shown.

[0086] like Figure 8 The present invention discloses an LED control chip 300, such as JW1859, which includes the LED control circuit of any of the above embodiments, for example including... Figure 7 The LED control circuit 200 has pins 1, 10, 9, 8, and 7 as OUT1-OUT5, connecting to 5 LED strings. Pin 2 is the HV pin, connected to the bus voltage VBUS. Pin 6 is the COUT pin, connected to an external electrolytic capacitor. Pins 4 and 5 are the SDA and SCL pins, receiving data and clock signals respectively. Pin 3 is NC, either unused or grounded, and the substrate of chip 300 is grounded. This LED control circuit eliminates the need for external resistors, saving pin usage, reducing the number of peripheral components, and improving integration. It also enables constant power control of multiple LED branches and allows for flexible setting of the OTP point and OTP slope.

[0087] Figure 9 A schematic circuit diagram of an LED lighting device according to an embodiment of the present disclosure is shown.

[0088] like Figure 9 As shown, an LED lighting device 400 is provided, including... Figure 8The diagram shows an LED control chip 300, a rectifier bridge, a microcontroller, and multiple LED strings. The rectifier bridge rectifies the AC power to a bus voltage VBUS, which is supplied to the LED control chip 300. The microcontroller (MCU) sends data and clock signals to the LED control chip 300. The multiple LED strings are connected to various output pins of the LED control chip 300.

[0089] In summary, the LED control circuit, method, chip, and lighting device according to the embodiments of this disclosure convert data signals and clock signals into protocol information with constant power setting information using an I2C communication module. This constant power setting information is then used to adjust each input signal to control the first drive signal output by the adjustment module, thereby controlling the magnitude of the first current flowing through the LED string and achieving constant power regulation. Specifically, constant power control of each LED branch is achieved by using the I2C protocol, preventing overheating and circuit damage caused by excessive power. Furthermore, the constant power control of the LED branch is realized through the protocol information generated by the chip's existing interface and the I2C communication module, eliminating the need for constant power adjustment resistors outside the circuit or chip. This reduces the number of external components, increases chip integration, reduces chip size, lowers costs, and meets European ERP certification requirements.

[0090] Furthermore, the I2C communication module converts the data signal and clock signal into protocol information with over-temperature protection settings. Based on the over-temperature protection settings, the first drive signal output by the adjustment module and the magnitude of the first current flowing through the LED string are controlled. This enables efficient configuration of the slope of the OTP point and the over-temperature protection point. When the chip temperature exceeds the threshold, the magnitude of the first current of the LED string can be adjusted in time to avoid burning out the chip. This can meet the over-temperature protection requirements in different application scenarios, especially in DOB chips.

[0091] Furthermore, by sending protocol information via the I2C bus to adjust the magnitude of the second current in the electrolytic branch, the electrolytic branch is adjusted downwards to achieve efficient charging of the electrolytic capacitor. The chip's COUT pin does not need to have a built-in fixed charging adjustment, making it easier to meet the ERP requirement of a 65° phase angle.

[0092] The embodiments described above do not constitute a limitation on the scope of protection of this technical solution. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the above embodiments should be included within the scope of protection of this technical solution.

Claims

1. An LED control circuit, comprising: The I2C communication module receives clock signals and data signals, and generates protocol information, which includes constant power setting information. The digital-to-analog conversion module converts the constant power setting information into power adjustment start-point information and power adjustment coefficient; The adjustment module includes: The voltage sampling module obtains the sampled voltage by sampling the bus voltage or the voltage at the negative terminal of the LED string according to the constant power setting information; The current control module includes a constant power control circuit, a power transistor, and an operational amplifier. The positive and negative input terminals of the operational amplifier receive a first reference voltage and a first sampling voltage, respectively, and the output terminal provides a first drive signal to the control electrode of the power transistor. The constant power control circuit calculates the power regulation current based on the sampling voltage, the power regulation start-up information, and the power regulation coefficient. The current control module also adjusts the magnitude of the first reference voltage generated based on the voltage drop across the equivalent resistance of the internal transistor according to the difference between the reference current provided by the current source and the power adjustment current, thereby adjusting the first drive signal to control the magnitude of the first current on the LED string connected to the power transistor.

2. The LED control circuit according to claim 1, wherein, The current control module also includes: A current-to-voltage circuit, connected to the positive input of the operational amplifier, includes multiple transistors connected in parallel. The current-to-voltage circuit generates a first reference voltage based on the product of the difference between the reference current and the power regulation current and the equivalent resistance of the multiple transistors. A current sampling circuit is connected to the source of the power transistor and the inverting input of the operational amplifier to sample the source voltage of the power transistor to obtain a first sampling voltage.

3. The LED control circuit according to claim 1, wherein, The constant power control circuit generates the power regulation current based on the product of the difference between the sampled voltage and the power regulation start-up information and the power regulation coefficient.

4. The LED control circuit according to claim 1, wherein, The protocol information also includes current setting information and brightness setting information. The current control module adjusts the magnitude of the first reference voltage and the first sampling voltage according to the current setting information and the brightness setting information, thereby controlling the magnitude of the first current on the LED string and the grayscale of the LED string.

5. The LED control circuit according to claim 1, wherein, The voltage sampling module includes: The sampling mode selection circuit selects the corresponding sampling branch based on the received constant power setting information; The first sampling branch, in the selected state, samples the bus voltage or the voltage at the negative terminal of the LED string through the sample-and-hold circuit to generate the peak sampling voltage. The second sampling branch, in the selected state, generates a sampling voltage for instantaneous sampling via the voltage divider unit sampling the bus voltage or the voltage at the negative terminal of the LED string; and The third sampling branch, in the selected state, samples the bus voltage or the voltage at the negative terminal of the LED string through the filtering unit to generate the average sampling voltage.

6. The LED control circuit according to claim 1, wherein, The protocol information also includes over-temperature protection setting information. The digital-to-analog conversion module converts the over-temperature protection setting information into temperature adjustment start-point information and temperature adjustment coefficient. The adjustment module also adjusts the first reference voltage according to the temperature adjustment start-point information and temperature adjustment coefficient to adjust the first drive signal and control the magnitude of the first current.

7. The LED control circuit according to claim 6, wherein, The current control module also includes: An over-temperature protection control circuit is connected to the positive input terminal of the operational amplifier. It generates a temperature regulation current based on the temperature regulation start-up information and the temperature regulation coefficient, and adjusts the magnitude of the first reference voltage based on the temperature regulation current.

8. The LED control circuit according to claim 1, further comprising: An electrolytic branch adjustment module is connected to the first terminal of an electrolytic capacitor, and the second terminal of the electrolytic capacitor is connected to the positive terminal of an LED string. The electrolytic branch adjustment module generates a second driving signal based on the operational amplification result of a second reference voltage and a second sampling voltage, thereby controlling the magnitude of the second current output by the electrolytic branch adjustment module. The electrolytic branch adjustment module is connected to the digital-to-analog converter module, which converts the constant power setting information into electrolytic power adjustment start-up information and electrolytic power adjustment coefficient, and the over-temperature protection setting information into electrolytic temperature adjustment start-up information and electrolytic temperature adjustment coefficient. The electrolysis branch adjustment module generates an electrolysis power adjustment current based on the bus voltage, the electrolysis power adjustment starting point information, and the electrolysis power adjustment coefficient; generates an electrolysis temperature adjustment current based on the electrolysis temperature adjustment starting point information and the electrolysis temperature adjustment coefficient; and adjusts the magnitude of the second reference voltage based on the electrolysis power adjustment current and the electrolysis temperature adjustment current.

9. The LED control circuit according to claim 1, wherein, The LED control circuit connects to multiple LED light strings and is used to adjust the first current on the multiple LED light strings. Each LED light string is connected to one of the adjustment modules.

10. An LED control method, applied to the LED control circuit according to any one of claims 1-9, the LED control method comprising: Receive clock signals and data signals, generate protocol information, the protocol information including constant power setting information; The constant power setting information is converted into power adjustment start-up information and power adjustment coefficient; The sampling voltage is obtained by sampling the bus voltage or the voltage at the negative terminal of the LED string based on the constant power setting information; The first driving signal is adjusted according to the sampling voltage, the power adjustment start information, and the power adjustment coefficient to control the magnitude of the first current on the LED string.

11. An LED control chip, comprising an LED control circuit according to any one of claims 1-9, wherein the substrate of the LED control chip is grounded.

12. An LED lighting device, comprising: The LED control chip according to claim 11; The rectifier bridge rectifies the AC power into a bus voltage and supplies it to the LED control chip. The microcontroller sends data signals and clock signals to the LED control chip; Multiple LED light strings are connected to multiple output pins of the LED control chip.

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