LED driving circuit and driving method thereof, and electronic device

Abstract

The embodiments of the present application provide an LED driving circuit, a driving method thereof, and an electronic device. The LED driving circuit includes: multiple LED light strings, a power conversion circuit, a brightness control module, and a current source; each LED light string includes a first end and a second end; the brightness control module is used to output brightness data to the power conversion circuit and the current source; the power conversion circuit is used to output a reference voltage based on the brightness data and receive the voltage of the second end in real time. If the minimum voltage among the multiple second end voltages is equal to the reference voltage, a stable operating voltage is provided to each first end; otherwise, a feedback loop is used to form a feedback loop for making the minimum voltage equal to the reference voltage; the current source includes a plurality of single current sources, each single current source is connected to the second end of an LED light string in a one-to-one correspondence, and each single current source is used to output a driving current of different sizes based on the brightness data. The embodiments of the present application can reduce the power consumption of the LED driving circuit.

Description

Technical Field

[0001] The present application relates to the field of integrated circuit technology. Specifically, the present application relates to an LED driving circuit and a driving method thereof, and an electronic device. Background Art

[0002] Common LED (Light Emitting Diode) driver circuits typically utilize a basic current control circuit as their primary component. Some driver circuits also incorporate a power conversion (DC-DC) circuit to power the LED light string. Whether using a standalone current control circuit or an LED driver circuit with an integrated power conversion circuit, the current in the LED driver circuit must be adjustable. This adjustment typically involves adjusting the maximum current and dimming. There are many different ways to adjust dimming, with PWM (Pulse Width Modulation) dimming being a common method. This involves controlling the on / off state of the LED using a PWM square wave signal. For example, when the PWM square wave signal is high, the LED turns on; when it is low, the LED turns off. This allows the brightness of the light to vary with the duty cycle of the PWM signal.

[0003] Dimming contrast refers to the ratio of the PWM square wave signal period to the high-level time of the PWM square wave signal. Under the increasingly higher dimming contrast requirements, it may be necessary to achieve a relatively small duty cycle dimming with a large driver stage, which requires a relatively large drive current. In battery-powered systems such as laptops and tablets, reducing the overall system power consumption and improving power supply efficiency are very important. Summary of the Invention

[0004] The present application proposes an LED driving circuit and a driving method thereof, and an electronic device, to solve the technical problem of high power consumption when the dimming contrast is high in the existing driving circuit design.

[0005] In a first aspect, an embodiment of the present application provides an LED driving circuit, comprising: a multi-channel LED light string, a power conversion circuit, a brightness control module, and a current source;

[0006] Each of the LED light strings includes a first end and a second end;

[0007] The brightness control module is used to output brightness data to the power conversion circuit and the current source;

[0008] a power conversion circuit, configured to output a reference voltage based on the brightness data and receive the voltage of the second terminal in real time, and to provide a stable operating voltage to each of the first terminals if a minimum voltage among the plurality of voltages of the second terminals is equal to the reference voltage; otherwise, to form a feedback loop for ensuring that the minimum voltage is equal to the reference voltage;

[0009] The current source includes a plurality of single-channel current sources, each of which is connected to the second end of one of the LED light strings in a one-to-one correspondence, and each of the single-channel current sources is used to output a driving current of different magnitude according to the brightness data.

[0010] Optionally, the power conversion circuit includes: a feedback receiving circuit and a power module;

[0011] The feedback receiving circuit is connected to the brightness control module and the second end of each LED light string, respectively, and is used to receive the voltage of the second end in real time, select a minimum voltage from a plurality of voltages of the second end, output a reference voltage according to the brightness data output by the brightness control module, and compare the minimum voltage with the reference voltage, and output the comparison result to the power supply module;

[0012] The power supply module is respectively connected to the voltage input end, the feedback receiving circuit and the first end of each LED light string, and is used to provide a stable operating voltage to each first end when the comparison result shows that the minimum voltage and the reference voltage are equal; and to form a feedback loop when the comparison result shows that the minimum voltage and the reference voltage are not equal.

[0013] Optionally, the feedback receiving circuit includes: an output feedback network, a first digital-to-analog conversion circuit, and an error amplifier;

[0014] The input end of the output feedback network is connected to each of the second ends respectively, and the output end is connected to the inverting input end of the error amplifier, for selecting a minimum voltage among the voltages of the plurality of second ends and inputting the minimum voltage into the inverting input end;

[0015] The input end of the first digital-to-analog conversion circuit is connected to the brightness control module, and the output end is connected to the non-inverting input end of the error amplifier, and is used to receive the brightness data output by the brightness control module, convert the brightness data into corresponding brightness, and output a reference voltage according to the brightness;

[0016] The output end of the error amplifier is connected to the power module, and is used for receiving the reference voltage and the minimum voltage, comparing the minimum voltage with the reference voltage, and outputting the comparison result to the power module.

[0017] Optionally, the power module includes: a switch tube, an inductor and a freewheeling diode;

[0018] The control terminal of the switch tube is connected to the output terminal of the error amplifier, the first terminal is connected to the first terminal of the inductor, and the second terminal is grounded;

[0019] The second end of the inductor is connected to the voltage input end;

[0020] The anode of the freewheeling diode is connected to the first end of the inductor, and the cathode is connected to the first end.

[0021] Optionally, the current source includes a second digital-to-analog conversion circuit, and each of the single-channel current sources includes an operational amplifier and a multi-stage driving module;

[0022] The second digital-to-analog conversion circuit is respectively connected to the brightness control module, the non-inverting input terminal of each of the operational amplifiers, and the remaining stage driving modules except the first stage driving module in each of the single current sources, and is used to receive brightness data output by the brightness control module, convert the brightness data into corresponding brightness data and input it into the non-inverting input terminal of the operational amplifier, and control whether the driving module connected to the second digital-to-analog conversion circuit is connected to the inverting input terminal of the operational amplifier, and control whether the driving module connected to the second digital-to-analog conversion circuit is connected to the output terminal of the operational amplifier according to the brightness data;

[0023] The control end of the first-stage driving module in each of the single-channel current sources is connected to the output end of the operational amplifier, the first end is connected to the second end of the LED light string, the second end is connected to the inverting input end of the operational amplifier, and the third end is grounded;

[0024] The control end of the remaining stage driving modules in each of the single current sources is connected to the output end of the operational amplifier through a first switch unit, the first end is connected to the second end of the LED light string, the second end is connected to the inverting input end of the operational amplifier through a second switch unit, and the third end is grounded; wherein:

[0025] The first switch unit and the second switch unit are configured to be turned on or off according to the brightness data.

[0026] Optionally, the first-stage driving module in each of the single-channel current sources includes a first driving transistor and a first resistor;

[0027] The control terminal of the first driving transistor is connected to the output terminal of the operational amplifier, the first terminal is connected to the second terminal of the LED light string, and the second terminal is connected to the inverting input terminal of the operational amplifier;

[0028] A first end of the first resistor is connected to the second electrode of the first driving transistor, and a second end thereof is grounded;

[0029] In the remaining driving modules of each of the single current sources, each driving module includes a second driving transistor and a second resistor;

[0030] The control terminal of the second driving transistor is connected to the output terminal of the operational amplifier through the first switching unit, the first terminal is connected to the second terminal of the LED light string, and the second terminal is connected to the inverting input terminal of the operational amplifier through the second switching unit;

[0031] A first end of the second resistor is connected to the second electrode of the second driving transistor, and a second end of the second resistor is grounded.

[0032] Optionally, the first-stage driving module in each of the single-channel current sources further includes a first high-voltage driving tube and a first driver;

[0033] The control end of the first high-voltage driving tube is connected to the power supply, the first electrode is connected to the second end of the LED light string, and the second electrode is connected to the first electrode of the first driving transistor;

[0034] A first terminal of the first driver is connected to the output terminal of the operational amplifier, and a second terminal of the first driver is connected to the control terminal of the first driving transistor;

[0035] In the remaining stage driving modules of each of the single current sources, each stage driving module further includes a second high-voltage driving tube and a second driver;

[0036] The control end of the second high-voltage driving tube is connected to the power supply, the first electrode is connected to the second end of the LED light string, and the second electrode is connected to the first electrode of the second driving transistor;

[0037] A first end of the second driver is connected to the output end of the operational amplifier through the first switch unit, and a second end of the second driver is connected to the control end of the second driving transistor.

[0038] Optionally, each of the single-channel current sources further includes a third switching unit;

[0039] The first end of the third switch unit is respectively connected to the control end of the first driving transistor and the control end of the second driving transistor, the second end is grounded, and the control end is connected to the output end of the pulse adjustment signal, and is used to be turned on or off under the control of the pulse adjustment signal.

[0040] Optionally, the LED driving circuit further includes a filter capacitor, a first end of which is connected to the output end of the power conversion circuit, and a second end of which is grounded, for filtering the voltage output by the power conversion circuit.

[0041] In a second aspect, an embodiment of the present application provides an electronic device, which includes the above-mentioned LED driving circuit provided by an embodiment of the present application.

[0042] In a third aspect, an embodiment of the present application provides a driving method for the above-mentioned LED driving circuit, including:

[0043] The power conversion circuit receives the brightness data output by the brightness control module and provides a working voltage to each of the first terminals according to the brightness data;

[0044] The current source receives the brightness data output by the brightness control module, and outputs driving currents of different magnitudes to the LED light string according to the brightness data.

[0045] The technical solutions provided by the embodiments of the present application bring at least the following beneficial effects:

[0046] In the LED driving circuit provided in the embodiment of the present application, when the minimum voltage among the voltages at multiple second ends of the power conversion circuit is equal to the reference voltage, the power conversion circuit provides an operating voltage to each first end, that is, provides an operating voltage to the LED light string. Since the value of the reference voltage is output according to the brightness data, when the brightness is low, the value of the reference voltage can also be output smaller, which can reduce the power consumption of the power conversion circuit and further reduce the power consumption of the LED driving circuit; in addition, since each single current source in the embodiment of the present application can output driving currents of different sizes according to the brightness data, when the brightness is reduced, a smaller driving current can be output, thereby reducing the power consumption of the current source and further reducing the power consumption of the LED driving circuit. After the power consumption is reduced, the voltage at the second end can be reduced, which can further improve the LED driving PWM dimming contrast.

[0047] Additional aspects and advantages of the present application will be given in part in the following description, which will become apparent from the following description, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0049] Figure 1 A schematic diagram of the structure of an LED driving circuit provided in an embodiment of the present application;

[0050] Figure 2 A schematic structural diagram of another LED driving circuit provided in an embodiment of the present application;

[0051] Figure 3 A schematic structural diagram of another LED driving circuit provided in an embodiment of the present application;

[0052] Figure 4 A schematic structural diagram of a first digital-to-analog conversion circuit and a single current source provided in an embodiment of the present application;

[0053] Figure 5 A schematic structural diagram of another first digital-to-analog conversion circuit and a single current source provided in an embodiment of the present application;

[0054] Figure 6 A schematic structural diagram of another first digital-to-analog conversion circuit and a single current source provided in an embodiment of the present application;

[0055] Figure 7 A schematic structural diagram of another first digital-to-analog conversion circuit and a single current source provided in an embodiment of the present application;

[0056] Figure 8 A flow chart of a driving method for an LED driving circuit provided in an embodiment of the present application.

[0057] Description of reference numerals:

[0058] 1-LED light string; 2-power conversion circuit; 3-brightness control module; 4-current source; 5-filter capacitor;

[0059] 41 - single current source; 21 - feedback receiving circuit; 22 - power supply module; 211 - output feedback network; 212 - first digital-to-analog conversion circuit; 213 - error amplifier; 221 - switch tube; 222 - inductor; 223 - freewheeling diode;

[0060] 411 - second digital-to-analog conversion circuit; 412 - operational amplifier; 413 - drive module; 414 - first switch unit; 415 - second switch unit; 416 - first high-voltage drive tube; 417 - first driver; 418 - power supply; 419 - second high-voltage drive tube; 420 - second driver; 421 - third switch unit. DETAILED DESCRIPTION

[0061] The present application is described in detail below. Examples of embodiments of the present application are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar components or components having the same or similar functions. In addition, if the detailed description of the known technology is not necessary for the features of the present application shown, it will be omitted. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and are not to be construed as limiting the present application.

[0062] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0063] It will be understood by those skilled in the art that, unless expressly stated otherwise, the singular forms "a", "an", "said" and "the" used herein may also include the plural forms. It should be further understood that the term "comprising" used in the specification of the present application refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we refer to an element as being "connected" to another element, it may be directly connected to the other element, or there may be intermediate elements. In addition, the "connection" used here may include wireless connection. The term "and / or" used here includes all or any unit and all combinations of one or more associated listed items.

[0064] To reduce power consumption, LED driver circuits with integrated power conversion circuits often employ low-power design methods. This is particularly true for laptops and tablets, where power consumption is reduced during light loads and standby mode. As screen sizes increase, the number of LED channels in these hardware systems also increases. Furthermore, as screen contrast increases, the current range also increases, placing higher demands on LED driver efficiency. For LED drivers, real-time adjustment of the driver circuit's driving capability based on current or brightness can significantly improve system efficiency.

[0065] The present application provides a new LED driving circuit and driving method thereof, which can improve the contrast of LED driving PWM dimming while reducing power consumption. The technical solution of the present application is described in detail with specific embodiments below.

[0066] like Figure 1As shown, the embodiment of the present application provides an LED driving circuit, comprising: a plurality of LED light strings 1 (the figure shows the first LED light string, the second LED light string and the Nth LED light string in the N-way LED light string 1), a power conversion circuit 2, a brightness control module 3 and a current source 4; each LED light string 1 includes a first end (an end connected to VOUT in the figure) and a second end (an end corresponding to VLED1, VLED2 and VLEDN in the figure); the brightness control module 3 is used to output brightness data to the power conversion circuit 2 and the current source 4; the power conversion circuit 2 is used to adjust the brightness according to the brightness. The current source 4 outputs a reference voltage Vref based on the brightness data and receives the voltage of the second end in real time. If the minimum voltage among the multiple second-end voltages is equal to the reference voltage Vref, a stable operating voltage VOUT is provided to each first end; otherwise, it is used to form a feedback loop, which is used to make the minimum voltage equal to the reference voltage Vref; the current source 4 includes a plurality of single-channel current sources 41, and each single-channel current source 41 is connected to the second end of a LED light string 1 in a one-to-one correspondence. Each single-channel current source 41 is used to output a driving current of different sizes according to the brightness data, and the driving current is used to adjust the LED brightness.

[0067] In an embodiment of the present application, when the minimum voltage among the voltages at multiple second ends of the power conversion circuit 2 is equal to the reference voltage Vref, the power conversion circuit 2 provides an operating voltage VOUT to each first end, that is, provides an operating voltage for the LED light string 1. Since 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 smaller, which can reduce the power consumption of the power conversion circuit 2 and further reduce the power consumption of the LED driving circuit; in addition, since each single current source 41 in the embodiment of the present application can output driving currents of different sizes according to the brightness data, when the brightness is reduced, a smaller driving current can be output, thereby reducing the power consumption of the current source 4 and further reducing the power consumption of the LED driving circuit. After the power consumption is reduced, the voltage at the second end can be reduced, which can further improve the LED driving PWM dimming contrast.

[0068] It should be noted that in the embodiment of the present application, the brightness control module 3 is a digital component, that is, the brightness data output by the brightness control module 3 is a digital signal, while the power conversion circuit 2 and the current source 4 are analog components, that is, the power conversion circuit 2 and the current source 4 need to process the analog signals. Therefore, the power conversion circuit 2 and the current source 4 both include a digital-to-analog converter (DAC) to convert the received brightness data into a brightness value.

[0069] It should be noted that, since the performance of each LED is not exactly the same, the voltage at the second end of each LED light string 1 is also not exactly the same, while the voltage at the first end of each LED light string 1 is the same. In order to ensure that each LED light string 1 can work normally, it is necessary to ensure that the LED light string 1 with the smallest voltage at the second end can work normally. Therefore, in the embodiment of the present application, the power conversion circuit 2 makes the minimum voltage among the multiple second end voltages equal to the reference voltage Vref, and thus provides the operating voltage VOUT for each first end.

[0070] In a specific embodiment, Figure 2 As shown, the power conversion circuit 2 in the embodiment of the present application includes: a feedback receiving circuit 21 and a power module 22; the feedback receiving circuit 21 is respectively connected to the brightness control module 3 and the second end of each LED light string 1, and is used to receive the voltage of the second end of each LED light string 1 in real time, select a minimum voltage from the voltages of multiple second ends, and output a reference voltage Vref according to the brightness data output by the brightness control module 3, and is used to compare the minimum voltage among the voltages of the second ends with the reference voltage Vref, and output the comparison result to the power module 22; the power module 22 is respectively connected to the voltage input end (the port of the input voltage VIN in the figure), the feedback receiving circuit 21 and the first end of each LED light string 1, and is used to provide a stable operating voltage VOUT to each first end when the comparison result is that the minimum voltage and the reference voltage Vref are equal; and when the comparison result is that the minimum voltage and the reference voltage Vref are not equal, a feedback loop is formed.

[0071] Specifically, if Figure 2 As shown, 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 respectively connected to the second end of each LED light string 1, and the output end is connected to the inverting input end of the error amplifier 213, for selecting a minimum voltage from the voltages at the second ends of the multiple LED light strings 1, and inputting the minimum voltage into 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, for receiving the brightness data output by the brightness control module 3, converting the brightness data into corresponding brightness, and outputting a reference voltage Vref according to the brightness; the output end of the error amplifier 213 is connected to the power supply module 22, for receiving the reference voltage Vref and the voltage output by the output feedback network 211 (that is, receiving the minimum voltage among the voltages at the second ends of each LED light string 1), comparing the minimum voltage with the reference voltage Vref, and outputting the comparison result to the power supply module 22.

[0072] In the embodiment of the present application, the power module 22 can adopt a boost circuit or a buck circuit, and the embodiment of the present application does not limit the type of the power module 22. In a specific embodiment, Figure 2 As shown, the power supply module 22 includes: a switch tube 221, an inductor 222 and a freewheeling diode 223; the control end of the switch tube 22 is connected to the output end of the error amplifier 213, the first pole is connected to the first end of the inductor 222, and the second pole is grounded; the second end of the inductor 222 is connected to the voltage input end (the port of the input voltage VIN in the figure); the positive pole of the freewheeling diode 223 is connected to the first end of the inductor 222, and the negative pole is connected to the first end.

[0073] It should be noted that if Figure 2 As shown, 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 set 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. The specific implementation method of the logic control circuit is similar to the prior art. Since this part does not involve the invention point of this application, it will not be repeated here.

[0074] It should be noted that the switch tube 221 in the embodiment of the present application is a transistor, which can be a thin film transistor or a metal oxide semiconductor field effect transistor (MOSFET). The first electrode of the transistor can be a source electrode, and the second electrode can be a drain electrode, or the first electrode can be a drain electrode, and the second electrode can be a source electrode; the transistor can be an N-type transistor or a P-type transistor.

[0075] It should be noted that the specific method by which the output feedback network 211 selects a minimum voltage among the voltages at the second terminals of the plurality of LED light strings 1 is similar to that of the prior art and will not be further described here. Furthermore, the specific method by which the first digital-to-analog conversion circuit 212 outputs the reference voltage Vref based on the brightness in the embodiment of the present application will be described below and will not be described here for the time being.

[0076] Furthermore, if Figure 3 As shown, the LED driving circuit in the embodiment of the present application also 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 is grounded, for filtering the voltage output by the power conversion circuit 2; the setting of the filter capacitor 5 can remove noise interference, so that the voltage input to the first end of the LED light string 1 is more stable. The filter capacitor 5 can specifically select the filter capacitor commonly used in the prior art, which will not be repeated here.

[0077] It should be noted that if Figure 3As shown, 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). Specifically, in order to save circuit wiring and reduce circuit power consumption, each single current source 41 shares a digital-to-analog converter. Figure 3 The switches S1, S2 and SN in the circuit are all controlled by the PWM square wave signal. When the PWM square wave signal is high, the switches S1, S2 and SN are closed. When the PWM square wave signal is low, the switches S1, S2 and SN are open. Figure 3 The DRV includes an operational amplifier and other devices. The configuration of each single current source 41 in the embodiment of the present application is the same. The specific configuration of one single current source 41 will be described in detail below.

[0078] In a specific embodiment, Figure 4 As shown, 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 conversion circuit 411 is respectively connected to the brightness control module 3, the non-inverting input terminal of each operational amplifier 412, and the remaining stage driving modules 413 except the first stage driving module 413 in each single current source 41 (the driving module 413 directly connected to the output terminal of the operational amplifier 412), and is used to receive the brightness data output by the brightness control module 3, convert the brightness data into the corresponding brightness input to the non-inverting input terminal of the operational amplifier 412, and control whether the driving module 413 connected to the second digital-to-analog conversion circuit 411 is connected to the inverting input terminal of the operational amplifier 412 according to the brightness data, and control whether the driving module 413 connected to the second digital-to-analog conversion circuit 411 is connected to the output terminal of the operational amplifier 412.

[0079] Specifically, if Figure 4 As shown, the control end of the first-stage driving module 413 in each single-channel current source 41 is connected to the output end of the operational amplifier 412, 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, and the third end is grounded; the control ends of the remaining stage driving modules 413 in each single-channel current source 41 are 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: the first switch unit 414 and the second switch unit 415 are configured to be turned on or off according to brightness data.

[0080] It should be noted that there is a voltage difference between the second end and the third end of the first-stage driver module 413, that is, the voltages between the second end and the third end are different, and the two are not at the same point. The implementation method of the voltage difference between the second end and the third end will be introduced below. Here, among the wires connected to the ground point of the first-stage driver module 413, the position where the wire connected to the inverting input terminal of the operational amplifier 412 intersects can be used as the second end of the first-stage driver module 413, and the end connected to the ground point is used as the third end of the first-stage driver module 413; similarly, the setting method of the second end and the third end of the remaining stage driver modules 413 is the same as the setting method of the first-stage driver module 413.

[0081] In specific implementation, the first switch unit 414 and the second switch unit 415 in the embodiment of the present application can both be transistors or logic gate circuits. The embodiment of the present application does not limit the specific types of the first switch unit 414 and the second switch unit 415; when the first switch unit 414 and the second switch unit 415 are transistors, in order to save production costs, the first switch unit 414 and the second switch unit 415 can select the same transistors.

[0082] In a specific implementation, the first switch unit 414 and the second switch unit 415 in the embodiment of the present application are all turned on when the value of the brightness data is high, and when the brightness data is low, some of the first switch units 414 and the second switch units 415 are turned off under the control of the brightness data; for example, when the brightness data is 1111, the brightness is the highest. At this time, all the first switch units 414 and the second switch units 415 can be controlled to be turned on by the brightness data; when the brightness data is 0001, the brightness is low. At this time, all the first switch units 414 and the second switch units 415 can be controlled to be turned off by the brightness data, and only the first-stage driving module 413 is in the working state; when the brightness data is 0011 or 0101, the brightness is between the highest brightness and the lowest brightness. At this time, some of the first switch units 414 and the second switch units 415 can be controlled to be turned off by the brightness data, and some of the first switch units 414 and the second switch units 415 can be turned on; the embodiment of the present application controls the conduction or disconnection of the first switch unit 414 and the second switch unit 415 by the brightness data, which can reduce the power consumption of the LED driving circuit.

[0083] In an optional embodiment, as Figure 5As shown, in the embodiment of the present application, the first-stage driving module 413 in each single-channel 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 to the output end of the operational amplifier 412, the first electrode is connected to the second end of the LED light string 1, and the second electrode is connected to the inverting input end of the operational amplifier 412; the first end of the first resistor R1 is connected to the second electrode of the first driving transistor T1, and the second end is grounded; in the remaining stage driving modules 413 in each single-channel current source 41, each stage driving module 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 switching unit 414, the first electrode is connected to the second end of the LED light string 1, and the second electrode is connected to the inverting input end of the operational amplifier 412 through the second switching unit 415; the first end of the second resistor R2 is connected to the second electrode of the second driving transistor T2, and the second end is grounded.

[0084] It should be noted that, in the embodiment of the present application, the first driving transistor T1 and the second driving transistor T2 are the same driving transistors, and the first electrode and the second electrode of the first driving transistor T1 can be interchangeable. Specifically, in one embodiment, the first electrode of the first driving transistor T1 can be a source electrode, and the second electrode can be a drain electrode. In another embodiment, the first electrode of the first driving transistor T1 can be a drain electrode, and the second electrode can be a source electrode; similarly, the first electrode and the second electrode of the second driving transistor T2 can also be interchangeable.

[0085] It should be noted that the first resistor R1 and the second resistor R2 in the embodiment of the present application can be selected to have the same resistance. Specifically, the resistance values ​​of the first resistor R1 and the second resistor R2 are equal. The specific setting method of the first resistor R1 and the second resistor R2 is set according to actual needs. The specific resistance values ​​of the first resistor R1 and the second resistor R2 are not limited here.

[0086] In another optional embodiment, as Figure 6As shown, the first-stage driving module 413 in each single-channel current source 41 also 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 to the power supply 418, the first electrode is connected to the second end of the LED light string 1, and the second electrode is connected to the first electrode of the first driving transistor T1; the first end of the first driver 417 is connected to the output end of the operational amplifier 412, and the second end is connected to the control end of the first driving transistor T1; in the remaining stage driving modules 413 in each single-channel current source 41, each stage driving module 413 also includes a second high-voltage driving tube 419 and a second driver 420; the control end of the second high-voltage driving tube 419 is connected to the power supply 418, the first electrode is connected to the second end of the LED light string 1, and the second electrode is connected to the first electrode of the second driving transistor T2; the first end of the second driver 420 is connected to the output end of the operational amplifier 412 through the first switch unit 414, and the second end is connected to the control end of the second driving transistor T2.

[0087] 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.

[0088] It should be noted that the first high-voltage driving tube 416 and the second high-voltage driving tube 419 in the embodiment of the present application select the same high-voltage driving transistor, the first pole and the second pole of the first high-voltage driving tube 416 can be interchanged, and the first pole and the second pole of the second high-voltage driving tube 419 can also be interchanged; the first high-voltage driving tube 416 and the second high-voltage driving tube 419 are used to buffer the voltage output from the second end of the LED light 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 their maximum tolerance voltage.

[0089] It should be noted that the first driver 417 and the second driver 420 in the embodiment of the present application can select the same driver. The first driver 417 and the second driver 420 have no gain and can play a role in driving enhancement.

[0090] Furthermore, if Figure 7As shown, each single-channel current source 41 in the embodiment of the present application further includes a third switch unit 421; the first terminal of the third switch unit 421 is respectively connected to the control terminal of the first driving transistor T1 and the control terminal of the second driving transistor T2, the second terminal is grounded, and the control terminal is connected to the output terminal of the pulse adjustment signal (PWM), and is configured to be turned on or off under the control of the pulse adjustment signal (PWM). Specifically, the third switch unit 421 in the embodiment of the present application can be a transistor, and the embodiment of the present application does not limit the specific type of the third switch unit 421; in a specific implementation, when the PWM square wave signal is at a high level, the third switch unit 421 is disconnected, and when the PWM square wave signal is at a low level, the third switch unit 421 is turned on.

[0091] like Figure 3 and Figure 7 As shown, in the embodiment of the present application, the reference voltage Vref is generated by the first digital-to-analog conversion circuit 212, and ultimately the minimum voltage at the second end of the LED light string 1 is equal to the reference voltage Vref through the feedback loop.

[0092] Specifically, if Figure 7 As shown, Figure 7 The first digital-to-analog conversion circuit 212 provides a method for adjusting the reference voltage Vref by current regulation. 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 settings, the reference voltage Vref can also be adjusted by other methods, such as: directly adjusting the voltage divider ratio, adjusting the width-to-length ratio of the transistor, etc.; in specific implementation, when the brightness is high, the reference voltage Vref value that can be adjusted is larger, and when the brightness is low, the reference voltage Vref value that can be adjusted is smaller.

[0093] like Figure 3 and Figure 7 As shown, the first driving transistor T1 and the second driving transistor T2 usually require relatively large power consumption to drive, especially when the high-frequency and small duty cycle PWM drive is used to adjust the brightness. Therefore, this part will consume a lot of power. The embodiment of the present application controls the conduction or disconnection of the first switch unit 414 and the second switch unit 415 through brightness data. When the brightness is low, it is not necessary for all levels of driving modules to be in a working state. The driving module can be flexibly selected to work, thereby reducing the power consumption of the LED driving circuit.

[0094] In addition, in the LED driving circuit, in addition to the loss in the first driving transistor T1 and the second driving transistor T2, the voltage value at the second end of the LED light string 1 also determines the amount of loss in the current source 4; since the minimum voltage at 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 at the second end of the LED light string 1 is made smaller, which can further reduce the power consumption of the LED driving circuit.

[0095] like Figure 3 and Figure 7 As shown, 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. When a driving tube with smaller driving capability is selected, the PWM duty cycle can be made lower, thereby improving the LED drive PWM dimming contrast.

[0096] Based on the same inventive concept, embodiments of the present application further provide an electronic device, comprising the aforementioned LED driver circuit provided in embodiments of the present application. Since the electronic device comprises the aforementioned LED driver circuit provided in embodiments of the present application, the electronic device has the same beneficial effects as the aforementioned LED driver circuit, and details thereof will not be repeated here.

[0097] Specifically, the electronic device in the embodiment of the present application may be a laptop computer, a liquid crystal television, a liquid crystal display, an organic electroluminescent display, or other electronic device.

[0098] Based on the same inventive concept, the embodiment of the present application further provides a driving method of the above-mentioned LED driving circuit, such as Figure 8 As shown, the method includes:

[0099] S101, a power conversion circuit receives brightness data output by a brightness control module, and provides a working voltage to each first terminal according to the brightness data;

[0100] S102 : The current source receives brightness data output by the brightness control module, and outputs driving currents of different magnitudes to the LED light string according to the brightness data.

[0101] In an embodiment of the present application, when the minimum voltage among the voltages at multiple second ends of the power conversion circuit 2 is equal to the reference voltage Vref, the power conversion circuit 2 provides an operating voltage VOUT to each first end, that is, provides an operating voltage for the LED light string 1. Since 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 smaller, which can reduce the power consumption of the power conversion circuit 2 and further reduce the power consumption of the LED driving circuit; in addition, since each single current source 41 in the embodiment of the present application can output driving currents of different sizes according to the brightness data, when the brightness is reduced, a smaller driving current can be output, thereby reducing the power consumption of the current source 4 and further reducing the power consumption of the LED driving circuit.

[0102] The specific driving method of the LED driving circuit in the embodiment of the present application has been introduced above and will not be repeated here.

[0103] In summary, the application of the embodiments of the present application can achieve at least the following beneficial effects:

[0104] First, in the LED driving circuit provided in the embodiment of the present application, when the minimum voltage among the voltages at multiple second ends of the power conversion circuit 2 is equal to the reference voltage Vref, the power conversion circuit 2 provides an operating voltage VOUT to each first end, that is, provides an operating voltage for the LED light string 1. Since 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 as a smaller value, which can reduce the power consumption of the power conversion circuit 2 and further reduce the power consumption of the LED driving circuit; in addition, since each single current source 41 in the embodiment of the present application can select drivers and driving tubes with different driving capabilities according to the brightness data, the power consumption of the current source 4 can be reduced, and the power consumption of the LED driving circuit can be further reduced. After the power consumption is reduced, the voltage at the second end can be reduced, and the LED driving PWM dimming contrast can be further improved.

[0105] Second, the embodiment of the present application controls the on or off of the first switch unit 414 and the second switch unit 415 through brightness data. When the brightness is low, it is not necessary for all levels of driving modules to be in a working state. The driving module can be flexibly selected to be working, thereby reducing the power consumption of the LED driving circuit.

[0106] Third, in the LED driving circuit provided in the embodiment of the present application, since the minimum voltage at the second end of the LED lamp 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, which can further reduce the power consumption of the LED driving circuit.

[0107] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. Throughout this application, unless otherwise specified, "plurality" means two or more.

[0108] The above description is only part of the implementation methods of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. An LED driving circuit, characterized in that: include: Multiple LED light strings, power conversion circuit, brightness control module and current source; Each of the LED light strings includes a first end and a second end; The brightness control module is used to output brightness data to the power conversion circuit and the current source; the brightness data is a digital signal; a power conversion circuit, configured to output a reference voltage based on the brightness data and receive the voltage of the second terminal in real time, and to provide a stable operating voltage to each of the first terminals if a minimum voltage among the plurality of voltages of the second terminals is equal to the reference voltage; otherwise, to form a feedback loop for ensuring that the minimum voltage is equal to the reference voltage; The current source includes a plurality of single-channel current sources, each of the single-channel current sources being connected to the second end of one of the LED light strings in a one-to-one correspondence, and each of the single-channel current sources being configured to output a driving current of different magnitudes according to the brightness data; 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 to the brightness control module, the non-inverting input terminal of each of the operational amplifiers, and the remaining stage driving modules except the first stage driving module in each of the single current sources, and is used to receive brightness data output by the brightness control module, convert the brightness data into corresponding brightness data and input it into the non-inverting input terminal of the operational amplifier, and control whether the driving module connected to the second digital-to-analog conversion circuit is connected to the inverting input terminal of the operational amplifier, and control whether the driving module connected to the second digital-to-analog conversion circuit is connected to the output terminal of the operational amplifier according to the brightness data; The control end of the remaining stage driving modules in each of the single current sources is connected to the output end of the operational amplifier through a first switch unit, the first end is connected to the second end of the LED light string, the second end is connected to the inverting input end of the operational amplifier through a second switch unit, and the third end is grounded; wherein: The first switch unit and the second switch unit are configured to be turned on or off according to the brightness data.

2. The LED driving circuit according to claim 1, wherein: The power conversion circuit includes: a feedback receiving circuit and a power module; The feedback receiving circuit is connected to the brightness control module and the second end of each LED light string, respectively, and is used to receive the voltage of the second end in real time, select a minimum voltage from a plurality of voltages of the second end, output a reference voltage according to the brightness data output by the brightness control module, and compare the minimum voltage with the reference voltage, and output the comparison result to the power supply module; The power supply module is respectively connected to the voltage input end, the feedback receiving circuit and the first end of each LED light string, and is used to provide a stable operating voltage to each first end when the comparison result shows that the minimum voltage and the reference voltage are equal; and to form a feedback loop when the comparison result shows that the minimum voltage and the reference voltage are not equal.

3. The LED driving circuit according to claim 2, wherein: The feedback receiving circuit includes: an output feedback network, a first digital-to-analog conversion circuit and an error amplifier; The input end of the output feedback network is connected to each second end respectively, and the output end is connected to the inverting input end of the error amplifier, for selecting a minimum voltage among the voltages of the plurality of 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 to the brightness control module, and the output end is connected to the non-inverting input end of the error amplifier, and is used to receive the brightness data output by the brightness control module, convert the brightness data into corresponding brightness, and output a reference voltage according to the brightness; The output end of the error amplifier is connected to the power module, and is used for receiving the reference voltage and the minimum voltage, comparing the minimum voltage with the reference voltage, and outputting the comparison result to the power module.

4. The LED driving circuit according to claim 3, characterized in that: The power supply module includes: a switch tube, an inductor and a freewheeling diode; The control terminal of the switch tube is connected to the output terminal of the error amplifier, the first terminal is connected to the first terminal of the inductor, and the second terminal is grounded; The second end of the inductor is connected to the voltage input end; The anode of the freewheeling diode is connected to the first end of the inductor, and the cathode is connected to the first end.

5. The LED driving circuit according to claim 1, wherein: The control end of the first-stage driving module in each single current source is connected to the output end of the operational amplifier, the first end is connected to the second end of the LED light string, the second end is connected to the inverting input end of the operational amplifier, and the third end is grounded.

6. The LED driving circuit according to claim 5, characterized in that: The first-stage driving module in each of the single-channel current sources includes a first driving transistor and a first resistor; The control terminal of the first driving transistor is connected to the output terminal of the operational amplifier, the first terminal is connected to the second terminal of the LED light string, and the second terminal is connected to the inverting input terminal of the operational amplifier; A first end of the first resistor is connected to the second electrode of the first driving transistor, and a second end thereof is grounded; In the remaining driving modules of each of the single current sources, each driving module includes a second driving transistor and a second resistor; The control terminal of the second driving transistor is connected to the output terminal of the operational amplifier through the first switching unit, the first terminal is connected to the second terminal of the LED light string, and the second terminal is connected to the inverting input terminal of the operational amplifier through the second switching unit; A first end of the second resistor is connected to the second electrode of the second driving transistor, and a second end of the second resistor is grounded.

7. The LED driving circuit according to claim 6, characterized in that: The first-stage driving module in each of the single-channel current sources further includes a first high-voltage driving tube and a first driver; The control end of the first high-voltage driving tube is connected to the power supply, the first electrode is connected to the second end of the LED light string, and the second electrode is connected to the first electrode of the first driving transistor; A first terminal of the first driver is connected to the output terminal of the operational amplifier, and a second terminal of the first driver is connected to the control terminal of the first driving transistor; In the remaining stage driving modules of each of the single current sources, each stage driving module further includes a second high-voltage driving tube and a second driver; The control end of the second high-voltage driving tube is connected to the power supply, the first electrode is connected to the second end of the LED light string, and the second electrode is connected to the first electrode of the second driving transistor; A first end of the second driver is connected to the output end of the operational amplifier through the first switch unit, and a second end of the second driver is connected to the control end of the second driving transistor.

8. The LED driving circuit according to claim 6 or 7, characterized in that: Each of the single-channel current sources further includes a third switching unit; The first end of the third switch unit is respectively connected to the control end of the first driving transistor and the control end of the second driving transistor, the second end is grounded, and the control end is connected to the output end of the pulse adjustment signal, and is used to be turned on or off under the control of the pulse adjustment signal.

9. The LED driving circuit according to claim 1, wherein: It also includes a filter capacitor, a first end of which is connected to the output end of the power conversion circuit, and a second end of which is grounded, for filtering the voltage output by the power conversion circuit.

10. An electronic device, characterized in that: The LED driving circuit comprises 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, characterized in that: include: The power conversion circuit receives the brightness data output by the brightness control module and provides a working voltage to each of the first terminals according to the brightness data; The current source receives the brightness data output by the brightness control module, and outputs driving currents of different magnitudes to the LED light string according to the brightness data.

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