CN114679812A

CN114679812A - LED driving circuit, driving method thereof and electronic equipment

Info

Publication number: CN114679812A
Application number: CN202210200177.0A
Authority: CN
Inventors: 李育军
Original assignee: Beijing Eswin Computing Technology Co Ltd
Current assignee: Beijing Eswin Computing Technology Co Ltd
Priority date: 2022-03-02
Filing date: 2022-03-02
Publication date: 2022-06-28

Abstract

The embodiment of the application provides an LED driving circuit, a driving method thereof and electronic equipment. The LED drive circuit includes: the LED lamp comprises multiple paths of LED lamp strings, a power supply conversion circuit, a brightness control module and a current source; each path of LED lamp string comprises a first end and a second end; the brightness control module is used for outputting brightness data to the power supply conversion circuit and the current source; the power supply conversion circuit is used for outputting reference voltage according to the brightness data, receiving the voltages of the second ends in real time, and providing stable working voltage to each first end if the minimum voltage in the voltages of the second ends is equal to the reference voltage; otherwise, forming a feedback loop, wherein the feedback loop is used for enabling the minimum voltage to be equal to the reference voltage; the current source comprises a plurality of single-path current sources, one path of single-path current source is connected with the second ends of one path of LED lamp strings in a one-to-one correspondence mode, and each path of single-path current source is used for outputting driving currents with different sizes according to brightness data. The power consumption of the LED driving circuit can be reduced.

Description

LED driving circuit, driving method thereof and electronic equipment

Technical Field

The application relates to the technical field of integrated circuits, in particular to an LED driving circuit, a driving method thereof and electronic equipment.

Background

A conventional LED (Light Emitting Diode) driving circuit generally uses a basic current control circuit as a main part, and a part of the driving circuit is integrated with a power conversion (DC-DC) circuit for providing a power supply for the LED Light string. Whether it is a separate current control circuit or an LED driving circuit of an integrated power conversion circuit, the current of the LED driving circuit needs to be adjustable, and the adjustment usually consists of a maximum current adjustment and a brightness adjustment, which are performed in many ways, among which, PWM (Pulse Width Modulation) dimming is commonly used, that is, the switching of the LED is controlled by a PWM square wave signal, for example: the LED is turned on when the PWM square wave signal is at a high level, and the LED is turned off when the PWM square wave signal is at a low level, so that the brightness of the lamp is changed along with the change of the duty ratio of the PWM signal.

The dimming contrast ratio refers to a ratio of a period of a PWM square wave signal to a high level time of the PWM square wave signal, and under the requirement of higher and higher dimming contrast ratios, a larger driving level may be required for realizing dimming with a smaller duty ratio, which requires a larger driving current.

Disclosure of Invention

The application provides an LED driving circuit, a driving method thereof and electronic equipment, which are used for solving the technical problem of high power consumption when dimming contrast is high in the design of the driving circuit in the prior art.

In a first aspect, an embodiment of the present application provides an LED driving circuit, including: the LED lamp comprises multiple paths of LED lamp strings, a power supply conversion circuit, a brightness control module and a current source;

each path of LED lamp string comprises a first end and a second end;

the brightness control module is used for outputting brightness data to the power supply conversion circuit and the current source;

the power supply conversion circuit is used for outputting reference voltage according to the brightness data, receiving the voltage of the second end in real time, and providing stable working voltage to each first end if the minimum voltage in the voltages of the second ends is equal to the reference voltage; otherwise, forming a feedback loop for equalizing the minimum voltage with the reference voltage;

the current source comprises a plurality of single current sources, one single current source is connected with the second ends of the LED lamp strings in a one-to-one correspondence mode, and each single current source is used for outputting driving currents with different sizes according to the brightness data.

Optionally, the power conversion circuit includes: a feedback receiving circuit and a power supply module;

the feedback receiving circuit is respectively connected with the brightness control module and the second end of each LED lamp string and is used for receiving the voltage of the second end in real time, selecting a minimum voltage from the voltages of the second ends, outputting a reference voltage according to brightness data output by the brightness control module, comparing the minimum voltage with the reference voltage and outputting a comparison result to the power supply module;

the power supply module is respectively connected with a voltage input end, the feedback receiving circuit and the first end of each LED lamp string and is used for providing stable working voltage for each first end when the comparison result shows that the minimum voltage is equal to the reference voltage; and forming a feedback loop when the comparison result shows that the minimum voltage is not equal to the reference voltage.

Optionally, the feedback receiving circuit includes: the output feedback network, the first digital-to-analog conversion circuit and the error amplifier;

the input end of the output feedback network is respectively connected with each second end, the output end of the output feedback network is connected with the inverting input end of the error amplifier, and the output feedback network is used for selecting a minimum voltage from voltages of the second ends and inputting the minimum voltage into the inverting input end;

The input end of the first digital-to-analog conversion circuit is connected with the brightness control module, the output end of the first digital-to-analog conversion circuit is connected with the in-phase input end of the error amplifier, and the first digital-to-analog conversion circuit is used for receiving the brightness data output by the brightness control module, converting the brightness data into corresponding brightness and outputting reference voltage according to the brightness;

and the output end of the error amplifier is connected with the power module and used for receiving the reference voltage and the minimum voltage, comparing the minimum voltage with the reference voltage and outputting a comparison result to the power module.

Optionally, the power module comprises: a switch tube, an inductor and a freewheeling diode;

the control end of the switch tube is connected with the output end of the error amplifier, the first pole of the switch tube is connected with the first end of the inductor, and the second pole of the switch tube is grounded;

the second end of the inductor is connected with the voltage input end;

and the anode of the freewheeling diode is connected with the first end of the inductor, and the cathode of the freewheeling diode is connected with the first end.

Optionally, the current source includes a second digital-to-analog conversion circuit, and each of the single current sources includes an operational amplifier and a multi-stage driving module;

the second digital-to-analog conversion circuit is respectively connected with the brightness control module, the non-inverting input end of each operational amplifier and the other driving modules except the first driving module in each single-path current source, and is used for receiving the brightness data output by the brightness control module, converting the brightness data into corresponding brightness to be input to the non-inverting input end of the operational amplifier, controlling whether the driving module connected with the second digital-to-analog conversion circuit is conducted with the inverting input end of the operational amplifier or not according to the brightness data, and controlling whether the driving module connected with the second digital-to-analog conversion circuit is conducted with the output end of the operational amplifier or not;

The control end of a first-stage driving module in each single-path current source is connected with the output end of the operational amplifier, the first end of the first-stage driving module is connected with the second end of the LED lamp string, the second end of the first-stage driving module is connected with the inverting input end of the operational amplifier, and the third end of the first-stage driving module is grounded;

the control ends of the other driving modules in each single-path current source are connected with the output end of the operational amplifier through a first switch unit, the first end of the single-path current source is connected with the second end of the LED lamp string, the second end of the single-path current source is connected with the inverting input end of the operational amplifier through a second switch unit, and the third end of the single-path current source is grounded; wherein:

the first and second switching units are configured to be turned on or off according to the luminance data.

Optionally, the first stage driving module in each of the single current sources includes a first driving transistor and a first resistor;

the control end of the first driving transistor is connected with the output end of the operational amplifier, the first pole of the first driving transistor is connected with the second end of the LED lamp string, and the second pole of the first driving transistor is connected with the inverting input end of the operational amplifier;

the first end of the first resistor is connected with the second pole of the first driving transistor, and the second end of the first resistor is grounded;

Each stage of driving module in the other stages of driving modules in each single-path current source comprises a second driving transistor and a second resistor;

the control end of the second driving transistor is connected with the output end of the operational amplifier through the first switch unit, the first pole of the second driving transistor is connected with the second end of the LED lamp string, and the second pole of the second driving transistor is connected with the inverting input end of the operational amplifier through the second switch unit;

and the first end of the second resistor is connected with the second pole of the second driving transistor, and the second end of the second resistor is grounded.

Optionally, the first stage driving module in each single current source further includes a first high voltage driving tube and a first driver;

the control end of the first high-voltage driving tube is connected with a power supply, the first pole of the first high-voltage driving tube is connected with the second end of the LED lamp string, and the second pole of the first high-voltage driving tube is connected with the first pole of the first driving transistor;

the first end of the first driver is connected with the output end of the operational amplifier, and the second end of the first driver is connected with the control end of the first driving transistor;

in the other stages of driving modules in each single-path current source, each stage of driving module further comprises a second high-voltage driving tube and a second driver;

The control end of the second high-voltage driving tube is connected with a power supply, the first pole of the second high-voltage driving tube is connected with the second end of the LED lamp string, and the second pole of the second high-voltage driving tube is connected with the first pole of the second driving transistor;

the first end of the second driver is connected with the output end of the operational amplifier through the first switch unit, and the second end of the second driver is connected with the control end of the second driving transistor.

Optionally, each of the single-path current sources further includes a third switching unit;

the first end of the third switching unit is connected with the control end of the first driving transistor and the control end of the second driving transistor respectively, the second end of the third switching unit is grounded, and the control end of the third switching unit is connected with the output end of the pulse adjusting signal and used for being switched on or switched off under the control of the pulse adjusting signal.

Optionally, the LED driving circuit further includes a filter capacitor, a first end of the filter capacitor is connected to the output end of the power conversion circuit, and a second end of the filter capacitor is grounded, and is configured to perform filtering processing on the voltage output by the power conversion circuit.

In a second aspect, an embodiment of the present application provides an electronic device, where the electronic device includes the LED driving circuit provided in the embodiment of the present application.

In a third aspect, an embodiment of the present application provides a driving method of the above LED driving circuit, including:

The power supply conversion circuit receives brightness data output by the brightness control module and provides working voltage for each first end according to the brightness data;

the current source receives the brightness data output by the brightness control module and outputs driving currents with different sizes to the LED lamp string according to the brightness data.

The technical scheme provided by the embodiment of the application at least has the following beneficial effects:

in the LED driving circuit provided in the embodiment of the application, when the minimum voltage of the voltages at the plurality of second ends of the power conversion circuit is equal to the reference voltage, the power conversion circuit provides a working voltage for each first end, that is, provides a working voltage for the LED light string; in addition, each single-path current source in the embodiment of the application can output driving currents with different sizes according to brightness data, so that when the brightness is reduced, a smaller driving current can be output, the power consumption of the current source can be reduced, the power consumption of the LED driving circuit can be further reduced, the voltage of the second end can be reduced after the power consumption is reduced, and the PWM dimming contrast ratio of the LED driving circuit can be further improved.

Additional aspects and advantages of the present application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the present application.

Drawings

The foregoing and/or additional aspects and advantages of the present application will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a schematic structural diagram of an LED driving circuit according to an embodiment of the present disclosure;

fig. 2 is a schematic structural diagram of another LED driving circuit provided in the embodiment of the present application;

fig. 3 is a schematic structural diagram of another LED driving circuit provided in the embodiment of the present application;

fig. 4 is a schematic structural diagram of a first digital-to-analog conversion circuit and a single current source according to an embodiment of the present disclosure;

fig. 5 is a schematic structural diagram of another first digital-to-analog conversion circuit and a single-path current source according to an embodiment of the present disclosure;

fig. 6 is a schematic structural diagram of a first digital-to-analog conversion circuit and a single-path current source according to an embodiment of the present disclosure;

fig. 7 is a schematic structural diagram of a further first digital-to-analog conversion circuit and a single-path current source according to an embodiment of the present disclosure;

fig. 8 is a flowchart of a driving method of an LED driving circuit according to an embodiment of the present disclosure.

Description of reference numerals:

1-LED lamp string; 2-a power conversion circuit; 3-a brightness control module; 4-a current source; 5-a filter capacitor;

41-single current source; 21-a feedback receiving circuit; 22-a power supply module; 211-output feedback network; 212-a first digital-to-analog conversion circuit; 213-error amplifier; 221-a switching tube; 222-an inductor; 223-a freewheeling diode;

411-a second digital-to-analog conversion circuit; 412-an operational amplifier; 413-a drive module; 414 — a first switching unit; 415-a second switching unit; 416-a first high pressure drive tube; 417 — a first driver; 418-a power supply; 419-a second high pressure drive tube; 420-a second driver; 421-third switching unit.

Detailed Description

The present application is described in detail below and examples of embodiments of the present application are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements with the same or similar functionality throughout. In addition, if a detailed description of the known art is not necessary for illustrating the features of the present application, it is omitted. The embodiments described below with reference to the drawings are exemplary only for the purpose of explaining the present application and are not to be construed as limiting the present application.

It will be understood by those within the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. Further, "connected" as used herein may include wirelessly connected. As used herein, the term "and/or" includes all or any element and all combinations of one or more of the associated listed items.

In the related art, in order to reduce power consumption, the LED driving circuit of the integrated power conversion circuit may reduce power consumption through some low power design methods, for example, power consumption is reduced when a notebook computer and a tablet computer are lightly loaded and in standby. With the increase of the screen size, the number of the LED channels in the hardware systems is increased, and with the increase of the screen contrast, the current size change range is very large, which puts higher requirements on the LED driving efficiency. For LED driving, the driving capability of the corresponding driving circuit can be adjusted in real time according to the current or brightness, so that the system efficiency can be obviously improved.

The present application provides a new LED driving circuit and a driving method thereof, which can reduce power consumption while improving the PWM dimming contrast of LED driving, and the following detailed description of the technical solution of the present application is provided in specific embodiments.

As shown in fig. 1, an embodiment of the present application provides an LED driving circuit, including: the LED lighting system comprises a plurality of paths of LED light strings 1 (a first path of LED light string, a second path of LED light string and an N-th path of LED light string in the N paths of LED light strings 1 are shown in the figure), a power supply conversion circuit 2, a brightness control module 3 and a current source 4; each LED string 1 includes a first end (the end connected to VOUT in the figure) and a second end (the ends corresponding to VLED1, VLED2, and VLEDN in the figure); the brightness control module 3 is used for outputting brightness data to the power conversion circuit 2 and the current source 4; the power conversion circuit 2 is used for outputting a reference voltage Vref according to the brightness data, receiving the voltages of the second ends in real time, and providing a stable working voltage VOUT to each first end if the minimum voltage of the voltages of the second ends is equal to the reference voltage Vref; otherwise, forming a feedback loop for making the minimum voltage equal to the reference voltage Vref; the current source 4 includes a plurality of single current sources 41, one single current source 41 is connected to the second end of one LED string 1 in a one-to-one correspondence manner, each single current source 41 is configured to output a driving current of different magnitude according to the brightness data, and the driving current is used to adjust the brightness of the LED.

In the embodiment of the application, when the minimum voltage of the voltages of the plurality of second ends is equal to the reference voltage Vref, the power conversion circuit 2 provides the working voltage VOUT for each first end, that is, provides the working voltage for the LED lamp string 1, because the value of the reference voltage Vref is output according to the brightness data, when the brightness is low, the value of the reference voltage Vref can also be output to be small, so that the power consumption of the power conversion circuit 2 can be reduced, and the power consumption of the LED driving circuit can be further reduced; in addition, each single-path current source 41 in the embodiment of the present application can output driving currents of different magnitudes according to luminance data, so that when luminance is reduced, a smaller driving current can be output, thereby reducing power consumption of the current source 4, further reducing power consumption of the LED driving circuit, and after the power consumption is reduced, voltage at the second end can be reduced, and further improving PWM dimming contrast of LED driving.

It should be noted that, in the embodiment of the present application, the luminance control module 3 is a digital part, that is, the luminance data output by the luminance control module 3 is a digital signal, and the power conversion circuit 2 and the current source 4 are analog parts, that is, the power conversion circuit 2 and the current source 4 need to process an analog signal. Therefore, the power supply conversion circuit 2 and the current source 4 each include a digital-to-analog converter (DAC) to convert the received luminance data into a luminance value.

It should be noted that, because the performance of each LED is not completely the same, the voltage of the second end of each LED string 1 is also not completely the same, and the voltage of the first end of each LED string 1 is the same, in order to ensure that each LED string 1 can normally operate, it is only necessary to ensure that the LED string 1 with the smallest voltage of the second end can normally operate, and therefore, in the embodiment of the present application, the power conversion circuit 2 makes the smallest voltage of the voltages of the second ends equal to the reference voltage Vref, that is, provides the working voltage VOUT for each first end.

In a specific embodiment, as shown in fig. 2, the power conversion circuit 2 in the embodiment of the present application includes: a feedback receiving circuit 21 and a power supply module 22; the feedback receiving circuit 21 is respectively connected with the brightness control module 3 and the second end of each LED lamp string 1, and is configured to receive the voltage of the second end of each LED lamp string 1 in real time, select a minimum voltage from the voltages of the plurality of second ends, output a reference voltage Vref according to the brightness data output by the brightness control module 3, compare the minimum voltage of the voltages of the second ends with the reference voltage Vref, and output a comparison result to the power module 22; the power module 22 is respectively connected to a voltage input terminal (a port for inputting a voltage VIN in the figure), the feedback receiving circuit 21 and the first end of each LED string 1, and is configured to provide a stable working voltage VOUT to each first end when the comparison result is that the minimum voltage is equal to the reference voltage Vref; and forming a feedback loop when the comparison result is that the minimum voltage and the reference voltage Vref are not equal.

Specifically, as shown in fig. 2, in the embodiment of the present application, the feedback receiving circuit 21 includes: an output feedback network 211, a first digital-to-analog conversion circuit 212, and an error amplifier 213; the input end of the output feedback network 211 is connected to the second end of each LED string 1, and the output end is connected to the inverting input end of the error amplifier 213, so as to select a minimum voltage from voltages at the second ends of the LED strings 1, and input the minimum voltage to the inverting input end of the error amplifier 213; the input end of the first digital-to-analog conversion circuit 212 is connected to the brightness control module 3, and the output end is connected to the non-inverting input end of the error amplifier 213, and is configured to receive the brightness data output by the brightness control module 3, convert the brightness data into corresponding brightness, and output a reference voltage Vref according to the brightness; the output end of the error amplifier 213 is connected to the power module 22, and is configured to receive the reference voltage Vref and the voltage output by the output feedback network 211 (i.e., receive the minimum voltage of the voltages at the second ends of the LED strings 1), compare the minimum voltage with the reference voltage Vref, and output the comparison result to the power module 22.

In this embodiment, the power module 22 may adopt a boost circuit or a buck circuit, and the embodiment of this application does not limit the type of the power module 22. In one particular embodiment, as shown in FIG. 2, the power module 22 includes: a switching tube 221, an inductor 222 and a freewheeling diode 223; the control end of the switch tube 22 is connected with the output end of the error amplifier 213, the first pole is connected with the first end of the inductor 222, and the second pole is grounded; a second terminal of the inductor 222 is connected to a voltage input terminal (a port for inputting the voltage VIN); the freewheeling diode 223 has an anode connected to the first end of the inductor 222 and a cathode connected to the first end.

It should be noted that, as shown in fig. 2, the control end of the switch tube 22 and the output end of the error amplifier 213 may not be directly connected, but a logic control circuit is disposed between the control end of the switch tube 22 and the output end of the error amplifier 213, and the switch tube 22 is controlled by the logic control circuit, and the specific implementation manner of the logic control circuit is similar to that of the prior art, and since this portion does not relate to the invention of this application, it is not described here again.

It should be noted that the switch tube 221 in the embodiment of the present application is a Transistor, and specifically may be a thin film Transistor, and may also be a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET), where a first pole of the Transistor may be a source, a second pole may be a drain, a first pole may also be a drain, and a second pole may also be a source; the transistor may be an N-type transistor or a P-type transistor.

It should be noted that the specific method for the output feedback network 211 to select a minimum voltage among the voltages at the second ends of the LED light strings 1 is similar to the prior art, and is not described herein again. In addition, a specific manner in which the first digital-to-analog conversion circuit 212 outputs the reference voltage Vref according to the luminance in the embodiment of the present application will be described below, and will not be described here for the time being.

Further, as shown in fig. 3, the LED driving circuit in this embodiment of the application further includes a filter capacitor 5, a first end of the filter capacitor 5 is connected to the output end of the power conversion circuit 2, and a second end of the filter capacitor is grounded, and is configured to filter the voltage output by the power conversion circuit 2; the filter capacitor 5 can remove noise interference, so that the voltage input to the first end of the LED lamp string 1 is more stable, and the filter capacitor 5 may specifically be a common filter capacitor in the prior art, which is not described herein again.

As shown in fig. 3, since the current source 4 is an analog part and the brightness control module 3 is a digital part, the current source 4 also includes a digital-to-analog converter (DAC), and specifically, in order to save circuit wiring and reduce circuit power consumption, each of the one-way current sources 41 shares one DAC. The switches S1, S2 and SN in fig. 3 are all controlled by a PWM square wave signal, where the switches S1, S2 and SN are closed when the PWM square wave signal is at a high level, and the switches S1, S2 and SN are open when the PWM square wave signal is at a low level. In addition, the DRV in fig. 3 includes an operational amplifier and other devices, and the arrangement of the single-path current sources 41 is the same in the embodiment of the present application, wherein a specific arrangement of one single-path current source 41 will be described in detail below.

In one embodiment, as shown in fig. 4, the current source 4 in the embodiment of the present application includes a second digital-to-analog conversion circuit 411, and each single current source 41 (only one single current source 41 is shown in the figure) includes an operational amplifier 412 and a multi-stage driving module 413; the second digital-to-analog converting circuit 411 is respectively connected to the luminance controlling module 3, the non-inverting input terminal of each operational amplifier 412, and the driving modules 413 of the other stages except the first driving module 413 (the driving module 413 directly connected to the output terminal of the operational amplifier 412) in each single current source 41, for receiving the luminance data output from the luminance controlling module 3, converting the luminance data into the non-inverting input terminal of the corresponding luminance input operational amplifier 412, and controlling whether the driving module 413 connected to the second digital-to-analog converting circuit 411 is conducted to the inverting input terminal of the operational amplifier 412 and whether the driving module 413 connected to the second digital-to-analog converting circuit 411 is conducted to the output terminal of the operational amplifier 412 according to the luminance data.

Specifically, as shown in fig. 4, a control end of the first stage driving module 413 in each single current source 41 is connected to an output end of the operational amplifier 412, a first end of the first stage driving module is connected to a second end of the LED string 1, a second end of the first stage driving module is connected to an inverting input end of the operational amplifier 412, and a third end of the first stage driving module is grounded; the control end of the remaining stage driving module 413 in each single current source 41 is connected to the output end of the operational amplifier 412 through the first switch unit 414, the first end is connected to the second end of the LED light string 1, the second end is connected to the inverting input end of the operational amplifier 412 through the second switch unit 415, and the third end is grounded; wherein: a first switching unit 414 and a second switching unit 415 configured to be turned on or off according to the luminance data.

It should be noted that, a voltage difference exists between the second terminal and the third terminal of the first stage driving module 413, that is, the voltages between the second terminal and the third terminal are different and not the same, and the implementation of the voltage difference between the second terminal and the third terminal will be described below, where, in a conducting wire connecting the first stage driving module 413 to the ground point, a position where a conducting wire connected to the inverting input terminal of the operational amplifier 412 intersects may be used as the second terminal of the first stage driving module 413, and one end connected to the ground point may be used as the third terminal of the first stage driving module 413; similarly, the second and third terminals of the remaining stage driving modules 413 are arranged in the same manner as the first stage driving module 413.

In specific implementation, both the first switch unit 414 and the second switch unit 415 in this embodiment may be transistors or logic gates, and this embodiment does not limit the specific types of the first switch unit 414 and the second switch unit 415; when the first switching unit 414 and the second switching unit 415 are transistors, the first switching unit 414 and the second switching unit 415 may select the same transistor in order to save production costs.

In specific implementation, the first switch unit 414 and the second switch unit 415 in this embodiment are all turned on when the value of the luminance data is high, and when the luminance data is low, part of the first switch unit 414 and the second switch unit 415 are turned off under the control of the luminance data; for example: the brightness represented by the brightness data of 1111 is the highest, and at this time, all the first switch units 414 and all the second switch units 415 can be controlled to be turned on by the brightness data; when the luminance data is 0001, the luminance is low, at this time, all the first switch units 414 and the second switch units 415 can be controlled to be turned off through the luminance data, and at this time, only the first-stage driving module 413 is in a working state; when the luminance data is 0011 or 0101, the luminance represented by the luminance data is between the highest luminance and the lowest luminance, and at this time, part of the first switching unit 414 and the second switching unit 415 may be turned off and part of the first switching unit 414 and the second switching unit 415 may be turned on by controlling the luminance data; according to the embodiment of the application, the first switch unit 414 and the second switch unit 415 are controlled to be turned on or off through the brightness data, so that the power consumption of the LED driving circuit can be reduced.

In an alternative embodiment, as shown in fig. 5, in the embodiment of the present application, the first stage driving module 413 in each single current source 41 includes a first driving transistor T1 and a first resistor R1; the control end of the first driving transistor T1 is connected with the output end of the operational amplifier 412, the first pole is connected with the second end of the LED lamp string 1, and the second pole is connected with the inverting input end of the operational amplifier 412; a first end of the first resistor R1 is connected to the second pole of the first driving transistor T1, and a second end is grounded; in the remaining stages of the driving modules 413 in each of the single current sources 41, each stage of the driving modules 413 includes a second driving transistor T2 and a second resistor R2; the control end of the second driving transistor T2 is connected to the output end of the operational amplifier 412 through the first switch unit 414, the first pole is connected to the second end of the LED string 1, and the second pole is connected to the inverting input end of the operational amplifier 412 through the second switch unit 415; the second resistor R2 has a first terminal connected to the second pole of the second driving transistor T2 and a second terminal connected to ground.

It should be noted that the first driving transistor T1 and the second driving transistor T2 in the embodiment of the present application are the same driving transistor, and the first pole and the second pole of the first driving transistor T1 can be interchanged, specifically, in one embodiment, the first pole of the first driving transistor T1 can be the source, the second pole can be the drain, and in another embodiment, the first pole of the first driving transistor T1 can be the drain, and the second pole can be the source; similarly, the first pole and the second pole of the second driving transistor T2 can be interchanged.

It should be noted that, in the embodiment of the present application, the first resistor R1 and the second resistor R2 may select the same resistor, specifically, the first resistor R1 and the second resistor R2 have the same resistance, and the specific setting manner of the first resistor R1 and the second resistor R2 is set according to actual needs, where the specific resistance of the first resistor R1 and the specific resistance of the second resistor R2 are not limited.

In another alternative embodiment, as shown in fig. 6, the first stage driving module 413 in each single current source 41 further includes a first high voltage driving tube 416 and a first driver 417; the control end of the first high-voltage driving tube 416 is connected with the power supply 418, the first pole is connected with the second end of the LED light string 1, and the second pole is connected with the first pole of the first driving transistor T1; a first terminal of the first driver 417 is connected to the output terminal of the operational amplifier 412, and a second terminal is connected to the control terminal of the first driving transistor T1; in the remaining stage driver modules 413 in each single current source 41, each stage driver module 413 further includes a second high voltage driver tube 419 and a second driver 420; the control end of the second high-voltage driving tube 419 is connected with the power supply 418, the first pole is connected with the second end of the LED light string 1, and the second pole is connected with the first pole of the second driving transistor T2; the second driver 420 has a first terminal connected to the output terminal of the operational amplifier 412 through the first switching unit 414, and a second terminal connected to the control terminal of the second driving transistor T2.

It should be noted that the voltage output by the power supply 418 in the embodiment of the present application is a high-level voltage, and the specific voltage value is set according to actual needs.

It should be noted that, in the embodiment of the present application, the first high-voltage driving transistor 416 and the second high-voltage driving transistor 419 select the same high-voltage driving transistor, the first pole and the second pole of the first high-voltage driving transistor 416 may be interchanged, and the first pole and the second pole of the second high-voltage driving transistor 419 may also be interchanged; the first high voltage driving tube 416 and the second high voltage driving tube 419 are used for buffering the voltage outputted from the second end of the LED string 1 to the first driving transistor T1 and the second driving transistor T2, so that the voltage received by the first driving transistor T1 and the second driving transistor T2 is less than the highest withstand voltage.

It should be noted that the first driver 417 and the second driver 420 in the embodiment of the present application may be selected from the same driver, and the first driver 417 and the second driver 420 have no gain and may play a role of driving enhancement.

Further, as shown in fig. 7, each of the single-path current sources 41 in the embodiment of the present application further includes a third switching unit 421; the third switching unit 421 has a first terminal connected to the control terminal of the first driving transistor T1 and the control terminal of the second driving transistor T2, respectively, a second terminal connected to ground, and a control terminal connected to the output terminal of the pulse adjusting signal (PWM) for turning on or off under the control of the pulse adjusting signal (PWM). Specifically, the third switching unit 421 in this embodiment may be a transistor, and this embodiment does not limit the specific type of the third switching unit 421; in specific implementation, when the PWM square wave signal is at a high level, the third switching unit 421 is turned off, and when the PWM square wave signal is at a low level, the third switching unit 421 is turned on.

As shown in fig. 3 and fig. 7, in the embodiment of the present invention, the reference voltage Vref is generated by the first digital-to-analog conversion circuit 212, and finally, the minimum voltage at the second end of the LED string 1 is equal to the reference voltage Vref through a feedback loop.

Specifically, as shown in fig. 7, the first digital-to-analog conversion circuit 212 in fig. 7 shows a manner of adjusting the reference voltage Vref in a current regulation manner, and the reference voltage Vref can be adjusted by adjusting the value of the resistor in the first digital-to-analog conversion circuit 212; in actual setting, the reference voltage Vref may also be adjusted by other manners, such as: directly adjusting the voltage division ratio, the width-length ratio of a transistor and the like; in specific implementation, when the brightness is high, the adjustable reference voltage Vref value is large, and when the brightness is low, the adjustable reference voltage Vref value is small.

As shown in fig. 3 and 7, the first driving transistor T1 and the second driving transistor T2 usually require relatively large power consumption to drive, and especially when the high-frequency small-duty-ratio PWM driving adjusts the brightness, so that the part consumes a large amount of power consumption.

In addition, in the LED driving circuit, the current source 4 loss determines the loss of the current source 4 according to the voltage value at the second end of the LED string 1, in addition to the loss at the first driving transistor T1 and the second driving transistor T2; because the minimum voltage of the second end of the LED light string 1 is equal to the reference voltage Vref, and the reference voltage Vref in the embodiment of the present application can be set according to the brightness, that is, when the brightness is low, the value of the reference voltage Vref can be made smaller, and correspondingly, the voltage of the second end of the LED light string 1 is made smaller, so that the power consumption of the LED driving circuit can be further reduced.

As shown in fig. 3 and 7, in the embodiment of the present application, each single-channel current source 41 can select drivers and driving tubes with different driving capabilities according to brightness data, and when a driving tube with a smaller driving capability is selected, the duty ratio of PWM can be made lower, so as to improve the PWM dimming contrast of LED driving.

Based on the same inventive concept, the embodiment of the present application further provides an electronic device, which includes the LED driving circuit provided in the embodiment of the present application. Since the electronic device includes the LED driving circuit provided in the embodiment of the present application, the electronic device has the same beneficial effects as the LED driving circuit, and details are not repeated here.

Specifically, the electronic device in the embodiment of the present application may be an electronic device such as a notebook computer, a liquid crystal television, a liquid crystal display, an organic electroluminescence display, and the like.

Based on the same inventive concept, an embodiment of the present application further provides a driving method of the LED driving circuit, as shown in fig. 8, the method includes:

s101, the power supply conversion circuit receives brightness data output by the brightness control module and provides working voltage for each first end according to the brightness data;

s102, the current source receives the brightness data output by the brightness control module, and outputs driving currents with different sizes to the LED lamp string according to the brightness data.

In the embodiment of the application, when the minimum voltage of the voltages of the plurality of second ends is equal to the reference voltage Vref, the power conversion circuit 2 provides the working voltage VOUT for each first end, that is, provides the working voltage for the LED lamp string 1, because the value of the reference voltage Vref is output according to the brightness data, when the brightness is low, the value of the reference voltage Vref can also be output to be small, so that the power consumption of the power conversion circuit 2 can be reduced, and the power consumption of the LED driving circuit can be further reduced; in addition, each single-channel current source 41 in the embodiment of the present application can output driving currents of different magnitudes according to luminance data, so that when luminance is reduced, a smaller driving current can be output, and thus power consumption of the current source 4 can be reduced, and power consumption of the LED driving circuit can be further reduced.

The specific driving method of the LED driving circuit in the embodiment of the present application has been described above, and is not described herein again.

In summary, the application of the embodiment of the present application can at least achieve the following beneficial effects:

in the first LED driving circuit provided in the embodiment of the present application, the power conversion circuit 2 provides the working voltage VOUT for each first end when the minimum voltage of the voltages at the multiple second ends is equal to the reference voltage Vref, that is, provides the working voltage for the LED light string 1, because the value of the reference voltage Vref is output according to the brightness data, when the brightness is low, the value of the reference voltage Vref may also be output to be smaller, so that the power consumption of the power conversion circuit 2 can be reduced, and the power consumption of the LED driving circuit is further reduced; in addition, in the embodiment of the present application, each single current source 41 can select drivers and driving tubes with different driving capabilities according to the brightness data, so that the power consumption of the current source 4 can be reduced, the power consumption of the LED driving circuit can be further reduced, and after the power consumption is reduced, the voltage at the second end can be reduced, and the PWM dimming contrast of LED driving can be further improved.

Secondly, in the embodiment of the present application, the first switch unit 414 and the second switch unit 415 are controlled to be turned on or turned off by the luminance data, and under the condition of low luminance, all driving modules are not required to be in a working state, so that whether the driving modules work or not can be flexibly selected, and further, the power consumption of the LED driving circuit can be reduced.

Third, in the LED driving circuit provided in the embodiment of the present application, since the minimum voltage of the second end of the LED string 1 is equal to the reference voltage Vref, the reference voltage Vref in the embodiment of the present application can be set according to the brightness, that is, when the brightness is low, the value of the reference voltage Vref can be made smaller, so that the power consumption of the LED driving circuit can be further reduced.

The terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless otherwise specified.

The foregoing is only a few embodiments of the present application and it should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present application, and that these improvements and modifications should also be considered as the protection scope of the present application.

Claims

1. An LED driving circuit, comprising: the LED lamp comprises multiple paths of LED lamp strings, a power supply conversion circuit, a brightness control module and a current source;

Each path of LED lamp string comprises a first end and a second end;

2. The LED driving circuit of claim 1, wherein the power conversion circuit comprises: a feedback receiving circuit and a power supply module;

The power supply module is respectively connected with a voltage input end, the feedback receiving circuit and the first end of each path of the LED lamp string and is used for providing stable working voltage for each first end when the comparison result shows that the minimum voltage and the reference voltage are equal; and forming a feedback loop when the comparison result shows that the minimum voltage is not equal to the reference voltage.

3. The LED driving circuit of claim 2, wherein the feedback receiving circuit comprises: the output feedback network, the first digital-to-analog conversion circuit and the error amplifier;

And the output end of the error amplifier is connected with the power supply module and used for receiving the reference voltage and the minimum voltage, comparing the minimum voltage with the reference voltage and outputting a comparison result to the power supply module.

4. The LED driving circuit according to claim 3, wherein the power supply module comprises: a switching tube, an inductor and a freewheeling diode;

the second end of the inductor is connected with the voltage input end;

5. The LED driving circuit according to claim 1, wherein the current source comprises a second digital-to-analog conversion circuit, and each of the single current sources comprises an operational amplifier and a multi-stage driving module;

the second digital-to-analog conversion circuit is respectively connected with the brightness control module, the non-inverting input end of each operational amplifier and the other driving modules except the first driving module in each single current source, and is used for receiving the brightness data output by the brightness control module, converting the brightness data into corresponding brightness to be input to the non-inverting input end of the operational amplifier, controlling whether the driving module connected with the second digital-to-analog conversion circuit is conducted with the inverting input end of the operational amplifier or not according to the brightness data, and controlling whether the driving module connected with the second digital-to-analog conversion circuit is conducted with the output end of the operational amplifier or not;

the control ends of the other driving modules in each single-path current source are connected with the output end of the operational amplifier through a first switch unit, the first end of each single-path current source is connected with the second end of the LED lamp string, the second end of each single-path current source is connected with the inverting input end of the operational amplifier through a second switch unit, and the third end of each single-path current source is grounded; wherein:

6. The LED driving circuit according to claim 5, wherein the first stage driving module in each of the single current sources comprises a first driving transistor and a first resistor;

7. The LED driving circuit according to claim 6, wherein the first stage driving module in each of the single current sources further comprises a first high voltage driving tube and a first driver;

in the other stages of driving modules in each single-path current source, each stage of driving module also comprises a second high-voltage driving tube and a second driver;

8. The LED driving circuit according to claim 6 or 7, wherein each of the one-way current sources further comprises a third switching unit;

the first end of the third switching unit is connected with the control end of the first driving transistor and the control end of the second driving transistor respectively, the second end of the third switching unit is grounded, and the control end of the third switching unit is connected with the output end of the pulse adjusting signal and is used for being switched on or switched off under the control of the pulse adjusting signal.

9. The LED driving circuit according to claim 1, further comprising a filter capacitor, wherein a first end of the filter capacitor is connected to the output end of the power conversion circuit, and a second end of the filter capacitor is grounded, so as to filter the voltage output by the power conversion circuit.

10. An electronic device characterized by comprising the LED driving circuit according to any one of claims 1 to 9.

11. A driving method of the LED driving circuit according to any one of claims 1 to 9, comprising: