CN116744499A - LED control circuit, method, chip and lighting device - Google Patents

Abstract

The application discloses an LED control circuit, an LED control method, a chip and a lighting device, wherein the LED control circuit comprises: the I2C communication module receives the clock signal and the data signal and generates protocol information, wherein the protocol information comprises constant power setting information; the digital-to-analog conversion module is used for converting the constant power setting information into power adjustment starting point information and power adjustment coefficients; and the adjusting module is used for sampling the bus voltage or the voltage of the negative end of the LED lamp string according to the constant power setting information to obtain a sampling voltage, and adjusting a first driving signal generated by the adjusting module according to the sampling voltage, the power adjusting starting point information and the power adjusting coefficient so as to control the magnitude of a first current on the LED lamp string connected with the adjusting module. The LED control circuit can realize constant power control by constant power adjustment on each LED branch, and over-temperature protection adjustment is carried out, so that an over-power temperature overheat burning circuit is avoided, an external constant power adjustment resistor and an external temperature adjustment resistor are not required, the number of elements is saved, and the integration level is improved.

Description

LED control circuit, method, chip and lighting device

Technical Field

The present disclosure relates to the field of power electronics, and more particularly, to an LED control circuit, method, chip, and lighting device.

Background

Because the light-emitting diode (Light Emitting Diode, simply called LED) light source has the advantages of high efficiency, energy conservation, environmental protection, good color rendering property and the like compared with the traditional light source, the LED light source is increasingly used for replacing the traditional light source in the field of illumination under the large background of global energy conservation and emission reduction. In specific circuit applications, the LED lamp is driven to work normally by providing stable current to the LED lamp through the LED driving circuit. In practical use, it is generally necessary to use two or more LED loads to realize Dimming (Dimming) and color mixing functions. Dimming is to adjust the brightness of the light emitted by the LED lamp by a certain control device according to the needs of the user.

At present, many LED illumination products based on LED dimming technology are already on the market, and are mainly used for landscape decoration illumination, building decoration illumination and the like. The LED linear driving dimming scheme is a simpler and direct driving application mode, has a simple circuit and small volume, and can meet more application occasions. The existing LED dimming control chip performs power compensation or current compensation on each LED branch through an external compensation resistor, the occupied chip pins are more, the compensation is slow, the power is usually overhigh when the input voltage is increased, the chip is overheated to burn out a circuit, the setting of an over-temperature protection point is single, the protection effect cannot be well achieved, and the problems of poor dimming precision, flickering in the dimming process, single dimming effect and the like exist.

Accordingly, there is a need to provide an improved solution to overcome the above technical problems in the prior art.

Disclosure of Invention

Accordingly, an objective of the present disclosure is to provide an LED control circuit, method, chip and lighting device, so as to solve the problems in the prior art.

According to a first aspect of the present disclosure, there is provided an LED control circuit comprising:

the I2C communication module receives the clock signal and the data signal and generates protocol information, wherein the protocol information comprises constant power setting information;

the digital-to-analog conversion module is used for converting the constant power setting information into power adjustment starting point information and power adjustment coefficients;

and the adjusting module is used for sampling the bus voltage or the voltage of the negative end of the LED lamp string according to the constant power setting information to obtain a sampling voltage, and adjusting a first driving signal generated by the adjusting module according to the sampling voltage, the power adjusting starting point information and the power adjusting coefficient so as to control the magnitude of a first current on the LED lamp string connected with the adjusting module.

Optionally, the adjustment module includes:

the voltage sampling module is used for sampling bus voltage or the voltage of the negative end of the LED lamp string according to the constant power setting information to obtain sampling voltage;

the current control module generates the first driving signal according to the operational amplification result of the first reference voltage and the first sampling voltage, and adjusts the first reference voltage according to the sampling voltage, the power adjustment starting point information and the power adjustment coefficient.

Optionally, the current control module includes:

the power transistor is connected with the LED lamp string, and the control electrode receives the first driving signal to control the magnitude of the first current on the LED lamp string;

the operational amplifier receives the first reference voltage from a positive input end, receives the first sampling voltage from a negative input end, and provides a first driving signal for a control electrode of the power transistor from an output end;

and the constant power control circuit is connected with the positive input end of the operational amplifier, generates power regulation current according to the sampling voltage, the power regulation starting point information and the power regulation coefficient, and regulates the magnitude of the first reference voltage according to the power regulation current.

Optionally, the current control module further comprises:

the current-to-voltage circuit is connected to the positive input end of the operational amplifier and generates the first reference voltage according to the reference current provided by the current source and the power regulating current; and

and the current sampling circuit is connected with the source electrode of the power transistor and the reverse input end of the operational amplifier and is used for sampling the source electrode voltage of the power transistor to obtain a first sampling voltage.

Optionally, the constant power control circuit generates the power adjustment current according to a product of a difference between the sampling voltage and the power adjustment start point information and the power adjustment coefficient.

Optionally, the protocol information further includes current setting information and brightness setting information, and the current control module adjusts the first reference voltage and the first sampling voltage according to the current setting information and the brightness setting information, and controls the first current on the LED string and the gray scale of the LED string.

Optionally, the voltage sampling module includes:

the sampling mode selection circuit gates a corresponding sampling branch according to the received constant power setting information;

the first sampling branch circuit samples bus voltage or voltage of the negative end of the LED lamp string to generate peak sampled sampling voltage through the sampling hold circuit in a gating state;

the second sampling branch circuit is used for sampling bus voltage or the voltage of the negative end of the LED lamp string to generate instantaneous sampling voltage under the gating state; and

and the third sampling branch is used for sampling the bus voltage or the voltage of the negative end of the LED lamp string to generate a sampling voltage with average value sampling through the filtering unit in the gating state.

Optionally, the protocol information further includes over-temperature protection setting information, the digital-to-analog conversion module converts the over-temperature protection setting information into temperature adjustment starting point information and a temperature adjustment coefficient, and the adjustment module adjusts the first reference voltage according to the temperature adjustment starting point information and the temperature adjustment coefficient to adjust the first driving signal, so as to control the magnitude of the first current.

Optionally, the current control module further comprises:

and the over-temperature protection control circuit is connected with the positive input end of the operational amplifier, generates temperature regulation current according to the temperature regulation starting point information and the temperature regulation coefficient, and regulates the magnitude of the first reference voltage according to the temperature regulation current.

Optionally, the LED control circuit further includes:

the electrolytic branch adjusting module is connected with the first end of the electrolytic capacitor, the second end of the electrolytic capacitor is connected to the positive end of the LED lamp string, the electrolytic branch adjusting module generates a second driving signal according to the operational amplification results of a second reference voltage and a second sampling voltage, and controls the magnitude of a second current output by the electrolytic branch adjusting module, wherein the electrolytic branch adjusting module is connected with the digital-to-analog conversion module, converts the constant power setting information into electrolytic power adjusting starting point information and an electrolytic power adjusting coefficient through the digital-to-analog conversion module, and converts the over-temperature protection setting information into electrolytic temperature adjusting starting point information and an electrolytic temperature adjusting coefficient;

the electrolysis branch regulating module generates electrolysis power regulating current according to the bus voltage, the electrolysis power regulating starting point information and the electrolysis power regulating coefficient, generates electrolysis temperature regulating current according to the electrolysis temperature regulating starting point information and the electrolysis temperature regulating coefficient, and regulates the magnitude of the second reference voltage according to the electrolysis power regulating current and the electrolysis temperature regulating current.

Optionally, the LED control circuit is connected to multiple LED strings, for adjusting a first current on the multiple LED strings, and each LED string is correspondingly connected to one of the adjusting modules.

According to a second aspect of the present disclosure, there is provided an LED control method applied to the above-mentioned LED control circuit, the LED control method including:

receiving a clock signal and a data signal, and generating protocol information, wherein the protocol information comprises constant power setting information;

converting the constant power setting information into power adjustment starting point information and a power adjustment coefficient;

sampling bus voltage or voltage of the negative end of the LED lamp string according to the constant power setting information to obtain sampling voltage;

and adjusting a first driving signal according to the sampling voltage, the power adjustment starting point information and the power adjustment coefficient, and controlling the magnitude of the first current on the LED lamp string.

According to a third aspect of the present disclosure, there is provided an LED control chip including the above-described LED control circuit, the substrate of the LED control chip being grounded.

According to a fourth aspect of the present disclosure, there is provided an LED lighting device comprising:

the LED control chip;

a rectifier bridge for rectifying the alternating current power supply into bus voltage and providing the bus voltage to the LED control chip;

the microcontroller sends a data signal and a clock signal to the LED control chip;

and the multi-path LED lamp strings are respectively connected to a plurality of output pins of the LED control chip.

According to the LED control circuit, the method, the chip and the lighting device, the data signal and the clock signal are converted into the protocol information according to the I2C communication module, the protocol information comprises constant power setting information, so that the first driving signal output by the adjusting module is controlled according to the constant power setting information to adjust each input signal, the first current flowing through the LED lamp string is controlled, constant power adjustment is realized, namely, the I2C communication protocol is used for carrying out constant power control on each LED branch, the overheat damage circuit is avoided, the constant power control of the LED branch is realized by generating the protocol information through the original interface on the chip and the I2C communication module, the number of peripheral devices is reduced, the chip integration level is improved, the chip size is reduced, the cost is reduced, and the European ERP authentication requirement is met.

Further, the data signal and the clock signal are converted into protocol information with over-temperature protection setting information according to the I2C communication module, so that the first driving signal output by the adjusting module and the first current flowing through the LED lamp string are controlled according to the over-temperature protection setting information, the high-efficiency configuration of the slopes of an OTP (over temperature protection) point and an over-temperature protection point is realized, the first current of the LED lamp string can be timely adjusted when the temperature of a chip exceeds a threshold value, the chip is prevented from being burnt, and the requirement of over-temperature protection in different application scenes, especially in a DOB (Driver on Board) chip, can be met.

Further, protocol information is sent through the I2C bus to adjust the second current of the electrolytic branch, the electrolytic branch is subjected to concave adjustment, efficient charging of the electrolytic capacitor is achieved, COUT pins of the chip do not need to be internally provided with fixed charging adjustment, and the requirements of ERP on a phase angle of 65 degrees are met more easily.

Drawings

FIG. 1 shows a schematic circuit diagram of a conventional LED lighting device;

fig. 2 shows a schematic circuit block diagram of an LED control circuit according to a first embodiment of the present disclosure;

FIG. 3 shows a schematic circuit block diagram of a current control module in the LED control circuit shown in FIG. 2;

FIG. 4 shows a schematic circuit diagram of a current-to-voltage circuit in the current control module shown in FIG. 3;

FIG. 5 shows a schematic circuit diagram of a current sampling circuit in the current control module shown in FIG. 3;

FIG. 6 shows a schematic circuit block diagram of a voltage sampling module in the LED control circuit shown in FIG. 2;

fig. 7 shows a schematic circuit block diagram of an LED control circuit according to a second embodiment of the present disclosure;

FIG. 8 shows a schematic diagram of an LED control chip according to an embodiment of the disclosure;

fig. 9 shows a schematic circuit diagram of an LED lighting device according to an embodiment of the present disclosure.

Detailed Description

The preferred embodiments of the present disclosure will be described in detail below with reference to the attached drawings, but the present disclosure is not limited to only these embodiments. The present disclosure is intended to cover any alternatives, modifications, equivalents, and variations that fall within the spirit and scope of the present disclosure.

In the following description of the preferred embodiments of the present disclosure, specific details are set forth in order to provide a thorough understanding of the present disclosure, and the present disclosure will be fully understood to those skilled in the art without such details.

The present disclosure is described more specifically in the following paragraphs by way of example with reference to the accompanying drawings. It should be noted that the drawings are in a simplified form and are not to scale precisely, but rather are merely intended to facilitate a clear and concise description of the embodiments of the present disclosure.

Fig. 1 shows a schematic circuit diagram of a conventional LED lighting device.

As shown in fig. 1, the LED lighting device rectifies an alternating current generated by an alternating current power source AC through a rectifier bridge to generate an input voltage or a bus voltage HV, filters the input voltage through a filter capacitor C1, and provides the filtered bus voltage HV to an LED dimming chip, wherein the dimming chip comprises 1-10 total 10 pins, pins 2, 1, 10, 9 and 8 respectively correspond to OUT1, OUT2, OUT3, OUT4 and OUT5, and are 5 output pins, and are respectively connected with 5 paths of LED light strings LED1-LED5. Pin 4 is the SDA pin, pin 5 is the SCL pin, and pins 4 and 5 are all connected to microcontroller MCU, and microcontroller MCU is connected to the input voltage end through auxiliary power supply again, and pin 4 and pin 5 receive microcontroller MCU output's data signal and clock signal respectively to, pin 4 and pin 5 are connected to auxiliary power supply through pull-up resistor R1 and R2 respectively, and auxiliary power supply provides approximately 3.3V's voltage for example. A first diode D1 is also provided between each LED string and the input voltage terminal for maintaining the minimum voltage required for operation of each LED branch. The pin 3 is an RCAP pin, and is externally connected with a resistor R3 for providing power adjustment for each LED branch, the pin 7 is an HV pin, and the receiving bus voltage supplies power to the chip. The pin 6 is a COUT pin, an external electrolytic capacitor C2 and a resistor R4 are connected, and the grounding end is connected to the pin COUT through a second diode D2 and a third diode D3, and the electrolytic branch is internally provided with a fixed regulating module through the COUT pin.

The lighting device adjusts the voltage of each output pin through the chip, controls the current of each LED branch, namely controls the brightness of each LED string light. However, in the lighting device, for adjusting the power of each branch, a power adjusting resistor is required to be arranged at the periphery of the chip, the periphery occupies more space, and the built-in fixed adjustment of the COUT pins is required to meet the charging requirement of the electrolytic capacitor, so that the circuit is complex, and the voltage at a phase angle of 65 degrees is difficult to reach along with the use of the lamp beads and the change of the electrolytic capacitance value; and the device can lead to the voltage of each LED branch to take place great change when generating the busbar voltage to power produces great change, probably can lead to the chip to overheat because the power is too big, destroys the circuit, and the OTP point of this circuit and the setting of OTP slope are comparatively fixed, and the overtemperature protection to the chip is not nimble enough.

The application improves the lighting device, the LED control chip and the LED control circuit inside the lighting device, so that peripheral adjusting resistors are not required to be arranged, and constant power control and OTP protection of each LED branch can be realized. The following description is made in detail with reference to the accompanying drawings.

Fig. 2 shows a schematic circuit block diagram of an LED control circuit according to a first embodiment of the present disclosure.

As shown in fig. 2, the LED control circuit 100 of the first embodiment of the present application includes: an I2C communication module 10, a register 20, a digital-to-analog conversion module (DAC module) 30, and an adjustment module 40. The I2C communication module 10 receives a clock signal and a data signal through an SCL pin and an SDA pin respectively, and generates and outputs protocol information; the register module 20 is connected with the I2C communication module 10, stores the protocol information and analyzes the protocol information into constant power setting information, over-temperature protection setting information, maximum current setting information, gray level setting information and the like according to preset rules; the digital-to-analog conversion module 30 is connected with the register module 20 and converts the constant power setting information into power adjustment starting point information V _{STA_X} And a power adjustment coefficient V _{SLO_X} The method comprises the steps of carrying out a first treatment on the surface of the The adjusting module 40 is connected with the digital-to-analog conversion module 30 and the register module 20, and the adjusting module 40 samples the busbar voltage VBUS or the voltage VLE of the negative end of the LED lamp string connected with the adjusting module 40 through the HV pin according to the analyzed constant power setting informationObtaining a sampling voltage V _HV’ And according to the sampling voltage V _HV’ Power adjustment start information V _{STA_X} And a power adjustment coefficient V _{SLO_X} The first driving signal generated by the adjusting module 40 is adjusted to control the first current on the LED string light LED1 connected with the adjusting module 40. In this embodiment, the LED control circuit is located in the LED control chip, and the chip includes an LED branch, and the adjustment module 40 is connected to the LED string LED1 through the OUT1 pin and grounded through the GND pin.

The LED control circuit 100 of this embodiment receives the data signal and the clock signal sent by the microprocessor through the I2C communication module 10, generates protocol information, where the protocol information includes constant power setting information, converts the constant power setting information into a signal that can be received by the adjusting module 40 after passing through the digital-to-analog conversion module 30, and then the adjusting module 40 adjusts the generated driving signal according to the constant power setting information, so that the current of the corresponding LED light string can be adjusted, and the LED light string can be controlled in constant power through the constant power setting information, thereby improving the transmission efficiency. The constant power setting information can be generated only by receiving the protocol of the I2C bus through the original pins of the chip, so that constant power control can be realized without arranging a power adjusting resistor at the periphery of the circuit, the influence of excessive or insufficient power on the circuit is prevented, one pin can be also left, the peripheral elements of the circuit are reduced, and the cost is reduced.

Further, the adjusting module 40 includes a voltage sampling module 41 and a current control module 42, the voltage sampling module 41 is connected with the register module 20, and samples the bus voltage or the voltage of the negative terminal of the LED string light according to the constant power setting information to obtain a sampled voltage V _HV’ The method comprises the steps of carrying out a first treatment on the surface of the And the current control module 42 generates the first driving signal according to the operational amplification result of the first reference voltage Vref1 and the first sampling voltage Vcs1. Specifically, the current control module 42 is based on the sampled voltage V _HV’ Power adjustment start information V _{STA_X} And a power adjustment coefficient V _{SLO_X} And adjusting the magnitude of the first reference voltage, thereby adjusting the operational amplification result to adjust a first driving signal, and controlling the magnitude of the first current on the LED lamp string through the first driving signal. Current controlThe structure of the module 42 is seen in fig. 3.

Fig. 3 shows a schematic circuit block diagram of a current control module in the LED control circuit shown in fig. 2.

As shown in fig. 3, the current control module 42 includes a power transistor M0, an operational amplifier U0, and a constant power control circuit 421. The source electrode of the power transistor M0 is grounded, the drain electrode is connected with the LED lamp string LED1, and the control electrode receives a first driving signal to control a first current I on the LED lamp string _LED1 Is of a size of (2); the positive input end of the operational amplifier U0 receives a first reference voltage Vref1, the negative input end receives a first sampling voltage Vcs1, and the output end provides a first driving signal to the control electrode of the power transistor M0; the constant power control circuit 421 is connected with the positive input end of the operational amplifier and is used for controlling the output voltage according to the sampling voltage V _HV’ Power adjustment start information V _{STA_X} And a power adjustment coefficient V _{SLO_X} Generating a power regulating current I _LCP Regulating current I in dependence on power _LCP The magnitude of the first reference voltage Vref1 is adjusted. Specifically, the constant power control circuit 421 is based on the sampling voltage V _BUS’ And power adjustment start point information V _{STA_X} Difference (V) _BUS’ -V _{STA_X} ) And power regulation factor V _{SLO_X} Generates a power regulating current I by the product of (2) _LCP Regulating the current I according to the power _LCP The magnitude of the first reference voltage Vref1 may be adjusted to change the output result of the operational amplifier U0, i.e., change the magnitude of the driving signal, and control the on state of the power transistor M0, thereby adjusting the magnitude of the first current.

Further, the current control module 42 further includes: a current-to-voltage circuit 422 and a current sampling circuit 423. Fig. 4 shows a schematic circuit diagram of a current-to-voltage circuit in the current control module shown in fig. 3, and fig. 5 shows a schematic circuit diagram of a current sampling circuit in the current control module shown in fig. 3.

Referring to FIG. 4, a current-to-voltage circuit 422 is connected to the positive input of the operational amplifier U0 for regulating the current I according to the reference current Iref1 and the power supplied by the current source _LCP A first reference voltage Vref1 is generated. Specifically, the current-to-voltage circuit 422 includes a plurality of current sources connected in parallelThe same transistor as the ground terminal, the first reference voltage Vref1 is the reference current Iref1 and the power regulating current I _LCP Difference (Ierf 1-I) _LCP ) And the equivalent resistance Rref1 of the plurality of transistors.

Referring to fig. 5, a current sampling circuit 423 is connected between the source of the power transistor M0 and the ground terminal, and is connected to the inverting input terminal of the operational amplifier U0, and samples the source voltage of the power transistor M0 to obtain a first sampling voltage Vcs1. Specifically, the current sampling circuit 423 includes a plurality of transistors connected in parallel, different numbers of transistors are turned on, and the resistances of the current sampling circuit 423 are different.

Further, the protocol information includes current setting information and brightness setting information, and the current control module 42 adjusts the magnitudes of the first reference voltage Vref1 and the first sampling voltage Vcs1 according to the current setting information and the brightness setting information to control the first current I _LED1 And the gray scale of the LED string. For example, the current setting information may adjust the magnitude of the first reference voltage Vref1 via the current-to-voltage circuit 422, and the luminance setting information may adjust the magnitude of the first sampling voltage Vcs1 via the current sampling circuit 423. For example, the gray level or gray level may be divided into 1024 levels, and the current corresponding to the highest gray level is the maximum current, and the higher the gray level, the brighter the brightness of the LED string. Taking the example that the current setting information includes an 8-bit binary number and the brightness setting information includes a 10-bit binary number, the current-to-voltage circuit 422 includes 8 transistors, B0-B7, and the current sampling circuit 423 includes 10 transistors, B0-B9.

According to the LED control circuit, the data signal and the clock signal are converted into protocol information according to the I2C communication module, the protocol information comprises constant power setting information, so that the first driving signal output by the adjusting module is controlled according to the constant power setting information to control the first current flowing through the LED lamp string, constant power adjustment is realized, namely, the circuit is prevented from being overheated and damaged due to overlarge power by using the I2C protocol to perform constant power control on each LED branch, and the constant power control of the LED branch is realized by generating protocol information through the original interface on the chip and the I2C communication module, the constant power adjusting resistor is not required to be arranged on the periphery of the circuit or the chip, the number of peripheral devices is reduced, the integration level of the chip is improved, the chip size is reduced, the cost is reduced, and European ERP authentication requirements are also met.

Further, the protocol information includes over-temperature protection setting information, and the digital-to-analog conversion module 30 is further configured to convert the over-temperature protection setting information into temperature adjustment starting point information T _OTP And temperature regulating coefficient T _SLP Correspondingly, the adjusting module 40 adjusts the starting point information T according to the temperature _OTP And temperature regulating coefficient T _SLP Adjusting the first reference voltage to adjust the first driving signal to control the first current I _LED1 Is of a size of (a) and (b). Referring to fig. 3, the current control module 42 further includes: an over-temperature protection control circuit 424 connected to the positive input terminal of the operational amplifier U0 for adjusting the start point information T according to the temperature _OTP And temperature regulating coefficient T _SLP Generating a temperature-regulated current I _OTP Regulating the current I according to the temperature _OTP The magnitude of the first reference voltage Vref1 is adjusted. Specifically, the current I can also be adjusted according to the reference current Iref1 and the temperature _OTP The difference is multiplied by the equivalent resistance Rref1 in the current-to-voltage circuit 422 to obtain the first reference voltage Vref1.

In this embodiment, the data signal and the clock signal are converted into the protocol information with the over-temperature protection setting information according to the I2C communication module, so that the first driving signal output by the adjusting module and the first current flowing through the LED string are controlled according to the over-temperature protection setting information, so that the high-efficiency configuration of the OTP point and the over-temperature protection slope is realized, the first current of the LED string can be timely adjusted when the chip temperature exceeds the threshold value, the chip is prevented from being burnt, and the requirement of over-temperature protection in different application scenarios, especially in the DOB chip, can be met.

Fig. 6 shows a schematic circuit block diagram of a voltage sampling module in the LED control circuit shown in fig. 2.

As shown in fig. 6, the voltage sampling module 41 includes: sampling mode selection circuit 411, first sampling branch, second sampling branch, and third sampling branch. The sampling mode selection circuit 411 gates the corresponding sampling branch according to the received constant power setting information; the first sampling branch samples the bus voltage VBUS or the voltage VLE of the negative terminal of the LED string via the sample-and-hold circuit 412 in the strobe state to generate a peak sampled sampling voltage; the second sampling branch samples the busbar voltage VBUS or the voltage VLE of the negative end of the LED string to generate a sampling voltage which is sampled instantaneously through the voltage dividing unit 413 in the gating state; the third sampling branch samples the bus voltage VBUS or the voltage VLE at the negative terminal of the LED string via the filtering unit 414 in the strobe state to generate a mean sampled sampling voltage.

Specifically, the first sampling branch includes a connected transistor M1 and a sample-and-hold circuit 412, the second sampling branch includes a connected transistor M2 and two voltage dividing resistors R01 and R02 (voltage dividing unit 413) connected in series, the third sampling branch includes a transistor M3, a resistor R03, a resistor R04, a resistor R05, and a capacitor C01, where the resistor R03 and the resistor R04 form the voltage dividing unit, and the resistor R05 and the capacitor C01 form the filter unit. The transistors M1, M2 and M3 commonly receive the bus voltage VBUS or the voltage VLE of the negative terminal of the LED string through the HV pin, and the control electrodes of the transistors M1, M2 and M3 all receive constant power setting information, for example, the constant power setting information received by the control electrode of the transistor M1 is 00, the constant power setting information received by the control electrode of the transistor M2 is 01, the constant power setting information received by the control electrode of the transistor M3 is 10, and the transistors M1, M2 and M3 are PMOS, for example, so that the transistor M1 or the transistor M2 or the transistor M3 can be selectively turned on according to the constant power setting information, and thus the corresponding sampling branch can be gated.

In this embodiment, the bus voltage VBUS may be the voltage of the positive electrode of the LED string.

Fig. 7 shows a schematic circuit block diagram of an LED control circuit according to a second embodiment of the present disclosure.

As shown in fig. 7, the LED control circuit 200 of the present embodiment includes a plurality of adjustment modules 40, and the LED control circuit 200 is configured to control the current of a plurality of LED strings connected thereto, so each adjustment module 40 includes a current control circuit (4201, 4202, … … n), each adjustment module 40 is connected to one LED string, and the plurality of adjustment modules 40 respectively adjust the brightness of the plurality of LED strings according to a plurality of first driving signals, that is, the adjustment modules 40 are in one-to-one correspondence with the LED strings. As can be seen from fig. 7, the first adjusting module 40 is connected to the first string of LED strings LED1 through the pin OUT1, and the second adjusting module is connected to the second string of LED strings LED2 through the pin OUT2, so that the brightness of the multiple LED strings can be simultaneously adjusted according to the protocol information outputted from the I2C communication module 10.

Further, the LED control circuit 200 further includes an electrolytic branch adjusting module 50, the electrolytic branch adjusting module 50 is connected to one end of the electrolytic capacitor C4, the other end of the electrolytic capacitor C4 is connected to the positive end of the LED string, the electrolytic branch adjusting module 50 is configured to generate a second driving signal according to the operational amplification result of the second reference voltage Vref2 and the second sampling voltage Vcs2, and control the second current I output by the electrolytic branch adjusting module 50 _CAP And the capacitance of the electrolytic capacitor C4 is adjusted. Wherein the electrolytic branch adjusting module 50 is connected with the digital-to-analog conversion module 30, and converts the constant power setting information into the electrolytic power adjusting starting point information V via the digital-to-analog conversion module 30 _{STA_X} And an electrolytic power adjustment coefficient V _{SLO_X} Converting the over-temperature protection setting information into electrolysis temperature adjustment starting point information T _{OTP_C} And an electrolysis temperature regulation coefficient T _{SLP_C} The method comprises the steps of carrying out a first treatment on the surface of the The electrolytic branch adjusting module 50 adjusts the voltage according to the sampling voltage V _HV’ And electrolysis power adjustment start point information V _{STA_X} And an electrolytic power adjustment coefficient V _{SLO_X} Generating electrolysis power regulating current according to temperature regulating starting point information T _{OTP_C} And temperature regulating coefficient T _{SLP_C} Generating an electrolysis temperature regulating current, and regulating the magnitude of the second reference voltage Vref2 according to the electrolysis power regulating current and the electrolysis temperature regulating current, thereby regulating the output second current I _CAP Is of a size of (a) and (b). The electrolytic branch adjusting module 50 is connected to the electrolytic capacitor C4, for example, through a COUT pin, and the present embodiment adjusts the electrolytic branch through the protocol information generated by the I2C communication module 10, without a complex fixed adjusting module. Namely, the second current of the electrolytic branch is regulated by sending protocol information through the I2C bus, the electrolytic branch is regulated in a concave manner, the high-efficiency charging of the electrolytic capacitor is realized, the COUT pin of the chip does not need to be internally provided with fixed charging regulation, and the chip is easier to achieveTo the ERP requirement for a 65 ° phase angle.

Further, the application also provides a control method of the LED control circuit, which is applied to the LED control circuit of any embodiment, and the LED control method comprises the following steps: receiving a clock signal and a data signal, and generating protocol information, wherein the protocol information comprises constant power setting information; converting the constant power setting information into power adjustment starting point information and a power adjustment coefficient; sampling bus voltage or the voltage of the negative end of the LED lamp string according to the constant power setting information to obtain sampling voltage; and adjusting the first driving signal according to the sampling voltage, the power adjustment starting point information and the power adjustment coefficient to control the magnitude of the first current on the LED lamp string.

Fig. 8 shows a schematic diagram of an LED control chip according to an embodiment of the present disclosure.

As shown in fig. 8, an LED control chip 300, such as JW1859, is disclosed, the chip 300 includes the LED control circuit of any of the above embodiments, such as LED control circuit 200 of fig. 7, then pins 1, 10, 9, 8 and 7 are respectively OUT1-OUT5, connect 5 LED strings, pin 2 is HV pin, access bus voltage VBUS, pin 6 is COUT pin, external electrolytic capacitor, pins 4 and 5 are SDA and SCL pins respectively, receive data signal and clock signal, and pin 3 is NC, i.e. null pin or ground, and the substrate of the chip 300 is grounded. The LED control circuit of the embodiment does not need to be provided with an external resistor, so that the use amount of pins is saved, the number of peripheral devices is reduced, the integration level is improved, meanwhile, the constant power control of a plurality of paths of LED branches can be realized, and the flexible setting of OTP points and OTP slopes can be realized.

Fig. 9 shows a schematic circuit diagram of an LED lighting device according to an embodiment of the present disclosure.

As shown in fig. 9, an LED lighting device 400 is provided, including the LED control chip 300, rectifier bridge, microcontroller, and multi-channel LED string shown in fig. 8. Wherein the rectifier bridge rectifies the alternating current AC into a bus voltage VBUS and provides the bus voltage VBUS to the LED control chip 300; the microcontroller MCU transmits a data signal and a clock signal to the LED control chip 300; the multiple LED strings are respectively connected to multiple output pins of the LED control chip 300.

In summary, according to the LED control circuit, the method, the chip and the lighting device of the embodiments of the present disclosure, the I2C communication module converts the data signal and the clock signal into the protocol information with the constant power setting information, so as to adjust each input signal according to the constant power setting information to control the first driving signal output by the adjusting module, so as to control the magnitude of the first current flowing through the LED string, and realize constant power adjustment, that is, by using the I2C protocol to perform constant power control on each LED branch, the overheating damage circuit caused by the excessive power is avoided, and the constant power control of the LED branch is realized by generating the protocol information through the original interface on the chip and the I2C communication module, without setting a constant power adjusting resistor on the periphery of the circuit or the chip, thereby reducing the number of peripheral devices, improving the integration level of the chip, reducing the chip volume, reducing the cost, and also meeting the european ERP authentication requirement.

Further, the data signal and the clock signal are converted into protocol information with over-temperature protection setting information according to the I2C communication module, so that the first driving signal output by the adjusting module and the first current flowing through the LED lamp string are controlled according to the over-temperature protection setting information, the high-efficiency configuration of the slope of the OTP point and the over-temperature protection point is realized, the first current of the LED lamp string can be timely adjusted when the chip temperature exceeds a threshold value, the chip is prevented from being burnt, and the requirement of over-temperature protection in different application scenes, especially in a DOB chip, can be met.

Further, protocol information is sent through the I2C bus to adjust the second current of the electrolytic branch, the electrolytic branch is subjected to concave adjustment, efficient charging of the electrolytic capacitor is achieved, COUT pins of the chip do not need to be internally provided with fixed charging adjustment, and the requirements of ERP on a phase angle of 65 degrees are met more easily.

The above-described embodiments do not limit the scope of the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the above embodiments should be included in the scope of the present application.

Claims (14)

1. An LED control circuit comprising:

the I2C communication module receives the clock signal and the data signal and generates protocol information, wherein the protocol information comprises constant power setting information;

the digital-to-analog conversion module is used for converting the constant power setting information into power adjustment starting point information and power adjustment coefficients;

and the adjusting module is used for sampling the bus voltage or the voltage of the negative end of the LED lamp string according to the constant power setting information to obtain a sampling voltage, and adjusting a first driving signal generated by the adjusting module according to the sampling voltage, the power adjusting starting point information and the power adjusting coefficient so as to control the magnitude of a first current on the LED lamp string connected with the adjusting module.

2. The LED control circuit of claim 1, wherein the adjustment module comprises:

the voltage sampling module is used for sampling bus voltage or the voltage of the negative end of the LED lamp string according to the constant power setting information to obtain sampling voltage;

the current control module generates the first driving signal according to the operational amplification result of the first reference voltage and the first sampling voltage, and adjusts the first reference voltage according to the sampling voltage, the power adjustment starting point information and the power adjustment coefficient.

3. The LED control circuit of claim 2, wherein the current control module comprises:

the power transistor is connected with the LED lamp string, and the control electrode receives the first driving signal to control the magnitude of the first current on the LED lamp string;

the operational amplifier receives the first reference voltage from a positive input end, receives the first sampling voltage from a negative input end, and provides a first driving signal for a control electrode of the power transistor from an output end;

and the constant power control circuit is connected with the positive input end of the operational amplifier, generates power regulation current according to the sampling voltage, the power regulation starting point information and the power regulation coefficient, and regulates the magnitude of the first reference voltage according to the power regulation current.

4. The LED control circuit of claim 3, wherein the current control module further comprises:

the current-to-voltage circuit is connected to the positive input end of the operational amplifier and generates the first reference voltage according to the reference current provided by the current source and the power regulating current; and

and the current sampling circuit is connected with the source electrode of the power transistor and the reverse input end of the operational amplifier and is used for sampling the source electrode voltage of the power transistor to obtain a first sampling voltage.

5. The LED control circuit of claim 3, wherein the constant power control circuit generates the power adjustment current according to a product of a difference between the sampling voltage and the power adjustment start point information and the power adjustment coefficient.

6. The LED control circuit of claim 2, wherein the protocol information further comprises current setting information and brightness setting information, the current control module adjusting the magnitudes of the first reference voltage and the first sampled voltage according to the current setting information and the brightness setting information, controlling the magnitude of the first current on the LED string and the gray scale of the LED string.

7. The LED control circuit of claim 2, wherein the voltage sampling module comprises:

the sampling mode selection circuit gates a corresponding sampling branch according to the received constant power setting information;

the first sampling branch circuit samples bus voltage or voltage of the negative end of the LED lamp string to generate peak sampled sampling voltage through the sampling hold circuit in a gating state;

the second sampling branch circuit is used for sampling bus voltage or the voltage of the negative end of the LED lamp string to generate instantaneous sampling voltage under the gating state; and

and the third sampling branch is used for sampling the bus voltage or the voltage of the negative end of the LED lamp string to generate a sampling voltage with average value sampling through the filtering unit in the gating state.

8. The LED control circuit of claim 3, wherein the protocol information further 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 a temperature adjustment coefficient, and the adjustment module adjusts the first reference voltage to adjust the first driving signal according to the temperature adjustment start point information and the temperature adjustment coefficient to control the magnitude of the first current.

9. The LED control circuit of claim 8, wherein the current control module further comprises:

and the over-temperature protection control circuit is connected with the positive input end of the operational amplifier, generates temperature regulation current according to the temperature regulation starting point information and the temperature regulation coefficient, and regulates the magnitude of the first reference voltage according to the temperature regulation current.

10. The LED control circuit of claim 1, further comprising:

the electrolytic branch adjusting module is connected with the first end of the electrolytic capacitor, the second end of the electrolytic capacitor is connected to the positive end of the LED lamp string, the electrolytic branch adjusting module generates a second driving signal according to the operational amplification results of a second reference voltage and a second sampling voltage, and controls the magnitude of a second current output by the electrolytic branch adjusting module, wherein the electrolytic branch adjusting module is connected with the digital-to-analog conversion module, converts the constant power setting information into electrolytic power adjusting starting point information and an electrolytic power adjusting coefficient through the digital-to-analog conversion module, and converts the over-temperature protection setting information into electrolytic temperature adjusting starting point information and an electrolytic temperature adjusting coefficient;

the electrolysis branch regulating module generates electrolysis power regulating current according to the bus voltage, the electrolysis power regulating starting point information and the electrolysis power regulating coefficient, generates electrolysis temperature regulating current according to the electrolysis temperature regulating starting point information and the electrolysis temperature regulating coefficient, and regulates the magnitude of the second reference voltage according to the electrolysis power regulating current and the electrolysis temperature regulating current.

11. The LED control circuit of claim 1, wherein the LED control circuit is connected to a plurality of LED strings for adjusting the first current on the plurality of LED strings, and each LED string is correspondingly connected to one of the adjustment modules.

12. An LED control method applied to the LED control circuit of any one of claims 1 to 11, the LED control method comprising:

receiving a clock signal and a data signal, and generating protocol information, wherein the protocol information comprises constant power setting information;

converting the constant power setting information into power adjustment starting point information and a power adjustment coefficient;

sampling bus voltage or voltage of the negative end of the LED lamp string according to the constant power setting information to obtain sampling voltage;

and adjusting a first driving signal according to the sampling voltage, the power adjustment starting point information and the power adjustment coefficient, and controlling the magnitude of the first current on the LED lamp string.

13. An LED control chip comprising an LED control circuit according to any of claims 1-11, the substrate of the LED control chip being grounded.

14. An LED lighting device, comprising:

the LED control chip of claim 13;

a rectifier bridge for rectifying the alternating current power supply into bus voltage and providing the bus voltage to the LED control chip;

the microcontroller sends a data signal and a clock signal to the LED control chip; and the multi-path LED lamp strings are respectively connected to a plurality of output pins of the LED control chip.