Multi-path constant-current LED drive circuit and backlight structure

Abstract

At least one embodiment of the invention provides a multipath constant current LED driving circuit and a backlight structure, the multipath constant current LED driving circuit comprises a plurality of voltage conversion circuits arranged in parallel and a cascade channel connecting the plurality of voltage conversion circuits, and each voltage conversion circuit comprises a constant current source driving control module, a constant current source power channel module and a lamp area load interface which are connected in sequence, wherein the constant current source driving control module comprises a chip, a cascade signal input circuit and a current feedback circuit; the constant current source power channel module comprises an inductor assembly, an MOS tube, a diode assembly and a filter capacitor array, and the constant current source power channel module comprises a first interface connected with the constant current source drive control module, a second interface connected with a lamp area load interface, and a third interface connected with an external power supply structure; the constant current source drive control module comprises a fourth interface connected with the mainboard interface. The multi-path constant current LED drive circuit has the advantages of being wide in voltage regulation range, simple in power expansion and good in current consistency when multiple modules are compatible.

Description

Multi-channel constant current LED drive circuit and backlight structure Technical Field

[0001] Embodiments of the present disclosure relate to a multi-channel constant-current LED driving circuit and a backlight structure. Background Art

[0002] Light-emitting diodes (LEDs) offer significant advantages, including fast response time, low power consumption, energy efficiency, and long lifespan. Due to their rapid response speed, LEDs are well-suited for use in automotive brake lights, turn signals, traffic lights, and other automotive lighting applications, thereby reducing the likelihood of traffic accidents such as rear-end collisions. With the continuous advancement of semiconductor material and packaging technologies, the luminous flux and light output efficiency of LED light sources have gradually increased. LEDs have been widely used in specialized lighting applications, such as traffic lights, automotive lighting, and billboards. LED driver technology has also evolved alongside the advancement of LED application technology.

[0003] LEDs are light sources whose luminous flux changes with changes in the current flowing through them. Therefore, if a constant LED light source is required, the current flowing through the LED must be controlled to remain constant. Commonly used methods for driving LEDs with constant current include linear regulation and switching regulation. The core technology of linear regulation utilizes a switching transistor operating in its linear region as a dynamically adjustable resistor to control the load. This ensures that the current flowing through the LED load remains essentially constant despite changes in the input voltage, resulting in different power consumption by the switching transistor. However, this driving technology is limited by the input voltage range and the number of LEDs that can be loaded. For automotive lighting, the number of LEDs connected in series is generally less than three due to the vehicle's power supply voltage. When more than three LEDs need to be driven, multiple linear regulation circuits are usually required to drive multiple series-connected LED strings to ensure that the number of LEDs in each string is less than or equal to three.

[0004] Summary of the Invention

[0005] At least one embodiment of the present disclosure provides a multi-channel constant current LED driver circuit and backlight structure. The multi-channel constant current LED driver circuit isolates the constant current source drive control module and the constant current source power channel module, isolating the backlight input voltage from the power supply end of the LED driver management chip, thereby ensuring timing consistency and expanding the input range of the power supply voltage of the LED driver chip. The embodiment of the present disclosure also utilizes the adaptive constant current control of the LED driver chip, cascading the backlight PWM control and switch enable signals to achieve the combined use of multiple modules, and the current feedback and protection feedback between the multiple modules work independently. Even if one of the multiple modules fails, it will not affect the normal operation of other modules unless it causes an abnormality in the input PWM controller channel, thereby simplifying power expansion. In addition, since the current feedback of a single module depends only on the parameters of the hardware device set by the circuit, when the overall consistency of the device is guaranteed and the working environment between the individual board modules is similar, the current output of multiple modules can be basically guaranteed to be consistent when cascaded.

[0006] At least one embodiment of the present disclosure provides a multi-channel constant current LED driving circuit, which includes: multiple voltage conversion circuits arranged in parallel and a cascade channel connecting the multiple voltage conversion circuits, each of the voltage conversion circuits includes a constant current source driving control module, a constant current source power channel module and a lamp area load interface connected in sequence, wherein the constant current source driving control module includes a chip, a cascade signal input circuit and a current feedback circuit; the constant current source power channel module includes an inductor component, a MOS tube, a diode component and a filter capacitor array, and the constant current source power channel module includes a first interface connected to the constant current source driving control module, a second interface connected to the lamp area load interface, and a third interface connected to an external power supply structure; the constant current source driving control module includes a fourth interface connected to the mainboard interface.

[0007] For example, the multi-channel constant current LED driving circuit provided by at least one embodiment of the present disclosure also includes a power supply to the backlight power supply connector, wherein the input end of the power supply to the backlight power supply connector is electrically connected to the external power supply structure, and the output end of the power supply to the backlight power supply connector is electrically connected to the constant current source power channel module.

[0008] For example, in the multi-channel constant current LED driving circuit provided in at least one embodiment of the present disclosure, an isolation circuit formed by a filter capacitor and a voltage conversion circuit is further provided between the output end of the power supply backlight power supply connector and the constant current source power channel module.

[0009] For example, in the multi-channel constant current LED driving circuit provided in at least one embodiment of the present disclosure, the constant current source power channel module further includes a first high-frequency filtering structure and a heat sink interface.

[0010] For example, in the multi-channel constant current LED driving circuit provided in at least one embodiment of the present disclosure, the diode component and the first high-frequency filtering structure are connected in parallel, and the diode component includes at least two diodes connected in series.

[0011] For example, in the multi-channel constant current LED driving circuit provided in at least one embodiment of the present disclosure, the constant current source power channel module also includes an overvoltage protection circuit, which is connected between the MOS tube and the filter capacitor array and connected to the chip of the constant current source driving control module.

[0012] For example, in the multi-channel constant current LED driving circuit provided in at least one embodiment of the present disclosure, the overvoltage protection circuit includes a second high-frequency filtering structure and a protection resistor, and the overvoltage protection circuit is configured to provide a stable sensing signal for the constant current source driving control module.

[0013] For example, in the multi-channel constant current LED driving circuit provided in at least one embodiment of the present disclosure, the constant current source power channel module also includes a third high-frequency filtering structure connected in parallel with the MOS tube, and the third high-frequency filtering structure is configured to filter the MOS tube.

[0014] For example, in the multi-channel constant current LED driving circuit provided in at least one embodiment of the present disclosure, the constant current source power channel module also includes a control loop, which is configured to control the opening and closing of the MOS tube and filter and adjust the GATE2 signal transmitted to the chip.

[0015] For example, in the multi-channel constant current LED driving circuit provided in at least one embodiment of the present disclosure, the constant current source power channel module also includes a current sharing signal input circuit, the first end of the current sharing signal input circuit is connected to the MOS tube, the second end of the current sharing signal input circuit is electrically connected to the fourth pin of the chip, the third end of the current sharing signal input circuit is grounded, and the current sharing signal input circuit includes a resistor array and a transmission resistor, the resistor array is configured to generate a current sharing signal, and the transmission resistor is configured to correct the current sharing signal.

[0016] For example, in the multi-channel constant current LED driver circuit provided by at least one embodiment of the present disclosure, the chip includes a power input pin, a voltage drive control pin, a digital ground pin portion, a current balancing pin, a circuit feedback pin, a boost loop feedback compensation pin, an overvoltage protection pin, and a current control pin;

[0017] The power input pin is connected to the working voltage source; the voltage drive control pin, the current balancing pin, the circuit feedback pin and the overvoltage protection pin are all electrically connected to the constant current source drive control module; the digital ground pin is partially connected to the digital ground; the boost loop feedback compensation pin is an internal calculation pin of the chip, which is grounded after connecting a capacitor; the current control pin is connected to the cascade channel to set the working state of the constant current source power channel module.

[0018] For example, in the multi-channel constant current LED driving circuit provided in at least one embodiment of the present disclosure, the constant current source driving control module includes a voltage stabilizing circuit connected to the circuit feedback pin of the chip.

[0019] For example, in the multi-channel constant current LED driving circuit provided in at least one embodiment of the present disclosure, the constant current source driving control module also includes a dimming circuit connected to the current control pin, and the dimming circuit is configured to input a rectangular wave signal and a switching signal to the current control pin.

[0020] For example, in the multi-channel constant current LED driving circuit provided in at least one embodiment of the present disclosure, the constant current source driving control module further includes a fourth high-frequency filtering structure connected to the boost loop feedback compensation pin.

[0021] For example, in the multi-channel constant current LED driving circuit provided in at least one embodiment of the present disclosure, the constant current source driving control module also includes a voltage buffer circuit connected to the current balancing pin, and the voltage buffer circuit is configured to adjust the voltage of the working voltage source.

[0022] At least one embodiment of the present disclosure further provides a backlight structure, which includes: a power board, an LED lamp, and the multi-channel constant current LED driving circuit described in any of the above embodiments arranged between the power board and the LED lamp.

[0023] For example, in the backlight structure provided in at least one embodiment of the present disclosure, the third interface of the constant current source power channel module included in the multi-channel constant current LED driving circuit is connected to the power interface of the power board, and the second interface of the constant current source power channel module included in the multi-channel constant current LED driving circuit is electrically connected to the LED lamp. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present disclosure, rather than limiting the present disclosure.

[0025] FIG1 is a schematic structural diagram of a multi-channel constant current LED driving circuit provided by at least one embodiment of the present disclosure;

[0026] FIG2 is a circuit diagram of a constant current source power channel module provided by at least one embodiment of the present disclosure;

[0027] FIG3 is a circuit diagram of a constant current source drive control module provided by at least one embodiment of the present disclosure;

[0028] FIG4 is a circuit diagram of an isolation circuit between a constant current source drive control module and a constant current source power channel module provided by at least one embodiment of the present disclosure;

[0029] FIG5 is a circuit diagram of an isolation circuit between a constant current source drive control module and a constant current source power channel module according to at least one embodiment of the present disclosure;

[0030] FIG6 is a circuit diagram of a backlight connector for providing power according to at least one embodiment of the present disclosure;

[0031] FIG7 is a circuit diagram of a power supply connector provided by at least one embodiment of the present disclosure;

[0032] FIG8 is a circuit diagram of a backlight connector provided by at least one embodiment of the present disclosure;

[0033] FIG9 is a circuit diagram of yet another backlight connector provided by at least one embodiment of the present disclosure;

[0034] FIG10 is a block diagram of a backlight structure provided by at least one embodiment of the present disclosure; and

[0035] FIG11 is a simulation diagram of a cascade thermal design of a multi-channel constant current LED driving circuit provided by at least one embodiment of the present disclosure. DETAILED DESCRIPTION

[0036] To make the purpose, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0037] Unless otherwise defined, the technical or scientific terms used in this disclosure should have the usual meanings understood by persons of ordinary skill in the field to which this disclosure belongs. The words "first", "second" and similar terms used in this disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0038] Unless otherwise defined, in the following description of the embodiments of the present disclosure, when the number of a component or element is not specifically indicated, it means that the component or element may be one or more, or may be understood as at least one. "At least one" means one or more, and "more than one" means at least two.

[0039] With growing awareness of environmental protection, restrictions on electronic products containing environmentally hazardous substances and the EU's Restriction of Hazardous Substances (RoHS) directive have emerged. Many liquid crystal display (LCD) panel manufacturers are actively seeking alternative solutions to cold cathode fluorescent lamps (CCFLs). Light-emitting diodes (LEDs) have been widely used in display technology, with LCD backlighting being a rapidly developing application. LEDs are also trending towards replacing CCFLs in medium and large-sized display panels. LED backlights have been widely used in applications requiring higher performance and longer operating times for medium and large-sized displays, such as GPS, P-DVD, DPF, NOTEBOOK, and E-PC devices.

[0040] Since the brightness of an LED is determined by the current flowing through it, to ensure the consistency of the brightness of multiple LEDs, that is, to ensure that the current flowing through all LEDs is exactly the same, this means that when using multiple LEDs in a backlight, connecting them in series is more conducive to ensuring the consistency of the brightness of all LEDs than connecting them in parallel. In this case, controlling the current accuracy of the LED string is very important to ensure the consistency of the brightness of the backlight LED string.

[0041] However, it's not feasible to connect too many LEDs in series within a single LED string. At normal brightness, the voltage drop across a white LED is approximately 3.5V, meaning that the voltage drop across 10 LEDs in series can reach 35V. For a 14-inch display, over 40 LEDs are required. If all were connected in series, the voltage drop would reach approximately 140V or even higher. For larger displays, the voltage drop would be even greater. Therefore, for medium and large displays, connecting multiple LEDs entirely in series is impractical; a combination of series and parallel connections is necessary.

[0042] When the system drives backlight LED strings in a combination of series and parallel connections, even if each current path meets the required accuracy, it still may not guarantee a uniform backlight effect. A current accuracy of ±1% means that the difference between individual LED strings can reach 2%. Unless the current accuracy index is extremely high, the current difference between individual LED strings must be limited. For example, current matching is often used to indicate the level of difference between the output currents of multiple parallel circuits in the same system. It is defined as follows:

[0043] I match =(I max -I min ) / I avg *100%, that is, the current matching degree is equal to the percentage of the difference between the maximum current value and the minimum current value in each current path to the average value of each current path.

[0044] Because of the aforementioned basic requirements for LED backlights in medium- and large-sized displays, specialized LED driver chips are needed to manage the backlight LEDs. This simplifies system design and provides more control and protection features. When the system drives backlight LED strings in a combination of series and parallel connections, the current differences between the parallel circuits must be limited.

[0045] The inventors of the present disclosure have noticed that a system consisting of multiple specialized LED driver chips can be designed to help the system manage the backlight LED driver, so as to simplify the structural design of the system and provide more control functions and protection functions. When multiple LED driver chips are cascaded, it is only necessary to configure the dimming control signal and switch enable signal of the digital dimming method (PWM) at the input end. The adaptive dimming and protection functions of the single chip at the back end are all controlled by the output of the single chip itself, and are adaptively adjusted as the power channel it controls fluctuates. For single-module design, it is necessary to consider the electromagnetic interference (EMI) between the control chip and the power device path. However, for multi-module design, in addition to considering EMI, it is also necessary to consider the thermal design between chips, that is, the components that release heat cannot be too concentrated, otherwise the temperature in the local area will be too high, shortening the life of the device.

[0046] At least one embodiment of the present disclosure provides a multi-channel constant current LED driver circuit, comprising: a plurality of voltage conversion circuits arranged in parallel and a cascade channel connecting the plurality of voltage conversion circuits; each voltage conversion circuit includes a constant current source drive control module, a constant current source power channel module, and a lamp zone load interface connected in sequence; wherein the constant current source drive control module includes a chip, a cascade signal input circuit, and a current feedback circuit; the constant current source power channel module includes an inductor component, a MOS transistor, a diode component, and a filter capacitor array; the constant current source power channel module includes a first interface connected to the constant current source drive control module, a second interface connected to the lamp zone load interface, and a third interface connected to an external power supply structure; and the constant current source drive control module includes a fourth interface connected to a motherboard interface. The embodiments of the present disclosure design a high-power DC voltage-regulated power supply solution to meet the backlight driving requirements of large-size LCD screens. In the embodiments of the present disclosure, a dedicated backlight control chip is used, resulting in the multi-channel constant current LED driver circuit having the characteristics of a wide voltage regulation range, simple power expansion, and good current consistency when compatible with multiple modules.

[0047] For example, the embodiments of the present disclosure provide a dedicated low-power DC conversion circuit and isolate the constant current source drive control module from the constant current source power channel module, isolating the backlight input voltage from the power supply end of the LED driver management chip, thereby ensuring timing consistency and expanding the input range of the LED driver chip's power supply voltage. For example, the frequency of the wide-range PWM dimming is 1kHz to 200kHz. The embodiments of the present disclosure also utilize the adaptive constant current control of the LED driver chip to achieve the combined use of multiple modules by cascading the backlight PWM control and switch enable signals. The current feedback and protection feedback between the multiple modules work independently. Even if one of the multiple modules fails, it will not affect the normal operation of other modules unless it causes an abnormality in the input PWM controller channel, thereby simplifying power expansion. In addition, since the current feedback of a single module depends only on the parameters of the hardware device set by the circuit, when the overall consistency of the device is guaranteed and the working environment between the individual board modules is similar, the current output of multiple modules can be basically guaranteed to be consistent when cascaded.

[0048] For example, Figure 1 is a schematic diagram of the structure of a multi-channel constant current LED driver circuit provided by at least one embodiment of the present disclosure. For ease of illustration, only the portion relevant to the embodiment of the present disclosure is shown. The multi-channel constant current LED driver circuit is connected between an external power supply and multiple LEDs.

[0049] For example, as shown in FIG1 , the multi-channel constant current LED driver circuit 100 includes: a plurality of voltage conversion circuits 101 arranged in parallel and a cascade channel 105 connecting the plurality of voltage conversion circuits 101. Each voltage conversion circuit 101 includes a constant current source drive control module 102, a constant current source power channel module 103, and a lamp area load interface 104, which are connected in sequence. For example, in the structure shown in FIG1 , the multi-channel constant current LED driver circuit 100 includes two voltage conversion circuits 101 arranged in parallel, and the two parallel voltage conversion circuits 101 are connected via the cascade channel 105. The multi-channel constant current LED driver circuit 100 is disposed on a mainboard, and the voltage conversion circuit 101 is connected to a mainboard interface 106 via the cascade channel 105. The voltage conversion circuit 101 is also connected to an external power supply via a power interface 107. It should be noted that although only two voltage conversion circuits 101 arranged in parallel are shown in Figure 1, the embodiments of the present disclosure are not limited to this, and there may be more voltage conversion circuits 101 arranged in parallel, for example, 3, 4, 5, etc.

[0050] For example, the multi-channel constant current LED driving circuit is connected between a constant current source and a plurality of LEDs.

[0051] For example, as shown in FIG1 , the cascade channel 105 receives a PWM dimming control signal outputted by the mainboard and feeds back an enable signal, thereby enabling a plurality of constant current LED driving circuits to achieve unified dimming and switch enablement.

[0052] For example, as shown in FIG1 , the constant current source drive control module 102 is used to ensure that all LEDs operate at a completely consistent current state, monitor the specific electrical parameters of the cascade channel 105, and set protections. Specifically, the constant current source drive control module 102 is used to detect the drive current of any constant current LED drive circuit and, when the drive current fluctuates, perform constant current control on the constant current source, thereby maintaining a constant drive current across multiple constant current LED drive circuits.

[0053] For example, as shown in FIG1 , the constant current source power channel module 103 can realize energy conversion of DC voltage regulation and output a stable current.

[0054] For example, as shown in FIG1 , the connection mode of the lamp zone load interface 104 is two lamp zones connected in series. Since the constant current source only maintains the current consistency of a single channel, the only way to ensure the consistency of light emission is to connect the lamp zones in series.

[0055] For example, as shown in Figure 1, the motherboard, serving as an intermediate stage for power output, requires an external DC voltage regulator and a load light area. The parameters of the external DC voltage regulator are adjustable, and the number of channels in the light strip under test can be expanded by cascading LED driver modules.

[0056] For example, FIG2 is a circuit diagram of a constant current source power channel module provided by at least one embodiment of the present disclosure. In combination with FIG1 and FIG2 , the constant current source power channel module 103 includes an inductor component L2, a MOS transistor Q2, a diode component D201, D205, and a filter capacitor array C205, C206, C207, C217, and C623. For example, the inductor component L2 includes two inductors arranged in parallel, namely, a first inductor composed of end 1 and end 4 corresponding to the inductor component L2 in the figure, and a second inductor composed of end 2 and end 3. The main backlight power supply is input from VBL through the inductor component L2, and the constant current source drive control module 102 controls the MOS transistor Q2 to be short-circuited to the ground to realize inductor energy storage. When the MOS transistor Q2 is turned off, the energy storage inductor voltage and the normal voltage of the inductor channel are superimposed and voltage chopping is realized through the magnetic bead LB2 and the unidirectional power diode D201 included in the diode component to finally form a system boost output.

[0057] For example, as shown in FIG2 , an overcurrent control circuit is implemented by the MOS transistor Q2 and the sampling resistor array R210 , R211 , R212 , R213 , R214 and R215 to achieve smoother voltage fluctuations, and the overcurrent sampling current is isolated and transmitted through R209 .

[0058] For example, as shown in FIG2 , an overvoltage protection acquisition circuit is formed by R205 , R206 , and R207 , and an isolated transmission overvoltage protection signal is implemented through R208 .

[0059] For example, as shown in Figure 2, the output voltage regulation current and power supply filtering are achieved by the filter capacitor array C205, C206, C207, C217 and C623, as well as the magnetic bead FB1. The filter capacitor array C205, C206, C207, C217 and C623, the magnetic bead FB1 and LED1+ constitute a filter unit. One end of the magnetic bead FB1 is the input end of the filter unit. One end of the multiple capacitors in the filter capacitor array is correspondingly connected to the other end of the magnetic bead FB1. The common end of the multiple capacitors is the multiple output ends of the filter unit, and the other ends of the multiple capacitors are grounded. The cathode of the diode connected to the magnetic bead FB1 is correspondingly connected to one end of the magnetic bead FB1, and the anode of the diode is grounded. It should be noted that the magnetic bead FB1 is first connected to the lamp area load interface 104 before connecting to the diode.

[0060] For example, the filter capacitor arrays C205 , C206 , C207 , C217 and C623 include multiple capacitors in order to achieve a better output effect and make the output current more uniform.

[0061] For example, in combination with Figures 1 and 2, the constant current source power channel module 103 includes a first interface OVP2 connected to the constant current source drive control module 102, a second interface connected to the lamp area load interface 104, namely, the dual lamp area series interface LED1+, and a third interface VBL connected to the external power supply structure, namely, the power supply interface.

[0062] For example, as shown in Figure 2, the constant current source power channel module 103 also includes a first high-frequency filtering structure FB8, FB1, C203, C204, R204, and a heat sink interface PHS2. The heat sink interface PHS2, which is connected to the magnetic bead LB2, is the packaging interface of the heat sink. That is, the PHS2 interface is a reserved interface and has no functional structure set up at present. The magnetic beads FB8 and FB1 are also preset structures that can play a role in high-frequency filtering. That is, at high frequencies, the impact signal will be filtered out by the magnetic beads FB8 or FB1, which itself acts as a conductor and can improve EMI.

[0063] For example, as shown in Figure 2, diode assembly D201 / D205 is connected in parallel with the first high-frequency filter structure FB8, FB1, C203, C204, and R204, and diode assembly D201 / D205 includes at least two diodes connected in series. If a single diode cannot meet the thermal effect requirements, two diodes will be used to meet the requirements, which is equivalent to using multiple diodes to expand the capacity. Of course, the number of diodes included in the diode assembly can also be greater than two.

[0064] For example, in combination with Figures 1 and 2, the constant current source power channel module 103 also includes an overvoltage protection circuit, which is connected between the MOS tube Q2 and the filter capacitor array C205, C206, C207, C217 and C623, and is connected to the seventh pin pin7 of the chip of the constant current source drive control module 102 (described later).

[0065] For example, as shown in FIG. 2 , the overvoltage protection circuit includes a second high-frequency filter structure R208 / C208 and protection resistors R205 / R206 / R207 , and the overvoltage protection circuit is configured to provide a stable sensing signal for the constant current source drive control module 102 .

[0066] For example, as shown in FIG2 , capacitor C208 and resistor R207 can make the network signal of the first interface OVP2 more stable when there is no signal input, and no major impact will occur, because it is a sensor signal transmitted to the constant current source drive control module 102, and the sensor signal can theoretically maintain a real and stable signal.

[0067] For example, as shown in FIG2 , OVP2 is fed back by the constant current source drive control module 102 to the constant current source power channel module 103 , and the GATE2 signal is applied by the constant current source drive control module 102 to the constant current source power channel module 103 . It is an applied drive signal that controls the opening and closing of the MOS tube Q2 .

[0068] For example, as shown in FIG2 , the constant current source power channel module 103 further includes a third high-frequency filter structure R203 / C201 / C202 connected in parallel with the MOS transistor Q2. The third high-frequency filter structure is configured to filter the MOS transistor Q2. The MOS transistor Q2 is a controllable diode, i.e., it can be implemented as a controllable switch. When switching, a high-frequency vibration signal is generated. The third high-frequency filter structure R203 / C201 / C202 can ensure that the variable impulse signal has an upper limit at the extreme point of the impulse.

[0069] For example, as shown in Figure 2, the constant current source power channel module 103 also includes a control loop GATE2 / R201 / R202 / D202 / R227. The control loop GATE2 / R201 / R202 / D202 / R227 is configured to control the opening and closing of the MOS tube Q2 and filter and adjust the GATE2 signal transmitted to the chip included in the constant current source drive control module 102.

[0070] For example, the control loop GATE2 / R201 / R202 / D202 / R227 can be unidirectionally controlled or bidirectionally controlled. When bidirectional control is required, D202 can be used to achieve reverse control, that is, to achieve reverse control of MOS transistor Q2 by GATE2.

[0071] For example, as shown in FIG2 , R227 can make the transmission of the GATE2 signal more stable. The GATE2 signal is transmitted to the second pin pin2 of the chip included in the constant current source drive control module 102 .

[0072] For example, as shown in Figure 2, the constant current source power channel module 102 also includes a current sharing signal input circuit CS2, a first end of the current sharing signal input circuit is connected to the MOS tube Q2, a second end of the current sharing signal input circuit is electrically connected to the fourth pin pin4 of the chip included in the constant current source drive control module 102, and a third end of the current sharing signal input circuit is grounded. The current sharing signal input circuit includes a resistor array R210 / R211 / R212 / R213 / R214 / R215 and a transmission resistor R209. The resistor array R210 / R211 / R212 / R213 / R214 / R215 is configured to generate a current sharing signal. The transmission resistor R209 can stabilize the signal on the current sharing signal input circuit CS2, that is, it is configured to correct the current sharing signal and remove some biased signals.

[0073] For example, as shown in Figure 2, the resistor array R210 / R211 / R212 / R213 / R214 / R215 includes 6 independent resistors, which are implemented by grounding a small resistor, and then a voltage signal is generated. This voltage signal is fed back to the current equalizing signal input circuit CS2. The second end of the current equalizing signal input circuit CS2 is electrically connected to the fourth pin pin4 of the chip included in the constant current source drive control module 102 mentioned later. The fourth pin pin4 can achieve current equalization for the current of the entire constant current source power channel module 102, thereby setting the output current value.

[0074] For example, the current sharing signal input circuit CS2 , the GATE2 circuit, and the OVP2 circuit are all connected to the constant current source drive control module 102 .

[0075] For example, in conjunction with Figures 1 and 2, the operating principle of the constant current source power channel module 103 is as follows: an external power supply provides current to the multi-channel constant current LED driver circuit 100 via the power supply connector. The input current flows through the inductor component L2. The constant current source drive control module 102 controls the MOSFET Q2 to short-circuit to ground, thereby storing energy in the inductor. When MOSFET Q2 is off, the voltage of the stored inductor is superimposed with the normal voltage of the inductor channel. Ferrite bead LB2 and unidirectional power diode D201 implement voltage chopping, ultimately forming a system boost output. MOSFET Q2 and resistor array R210 / R211 / R212 / R213 / R214 / R215 implement the overcurrent control circuit to achieve smoother voltage fluctuations. Transmission resistor R209 isolates and transmits the overcurrent sampling current. Protection resistors R205 / R206 / R207 form the overvoltage protection acquisition circuit, and R208 isolates and transmits the overvoltage protection signal. Output voltage regulation and power supply filtering are achieved by C205 / C206 / C207 and magnetic bead FB1.

[0076] For example, FIG3 is a circuit diagram of a constant current source drive control module provided by at least one embodiment of the present disclosure. In combination with FIG1 and FIG3, the constant current source drive control module 102 includes a chip U2, a cascade signal input circuit, and a current feedback circuit. The constant current source drive control module 102 includes a fourth interface connected to the motherboard interface 106, and the fourth interface is the ON / OFF interface and the ADI interface shown in FIG3. The chip U2 constitutes the adjustable constant current source body of the constant current source drive control module 102, the directly connected first diode D203 and the first resistor R220 constitute the cascade signal input circuit, and the current feedback circuit is composed of the second diode D204 and the parallel resistors R223 / R224 / R225 / R226.

[0077] For example, in conjunction with Figures 1 and 3, the chip U2 is designed for an SOP-8 package and has 8 pins, namely, a power input pin 1, a voltage drive control pin 2, a digital ground pin portion 3, a current balancing pin 4, a circuit feedback pin 5, a boost loop feedback compensation pin 6, an overvoltage protection pin 7, and a current control pin 8. The power input pin 1 is connected to the operating voltage source, the voltage drive control pin 2, the current balancing pin 4, the circuit feedback pin 5, and the overvoltage protection pin 7 are all electrically connected to the constant current source drive control module 102, the digital ground pin portion 3 is connected to the digital ground, and the boost loop feedback compensation pin 6 is a chip internal calculation pin that is grounded after connecting a capacitor to stabilize the current. The current control pin 8 is connected to the cascade channel 105 to set the working state of the constant current source power channel module 103.

[0078] For example, the operating voltage source is a component that provides voltage for chip operation.

[0079] For example, as shown in Figure 3, power is introduced to chip U2 through current-limiting resistor R218 and reaches chip U2's power input pin 1. After chip U2 is in operation, it obtains the preset value of the constant current source power channel module 103 through current control pin 8, and drives the related components of the constant current source power channel module 103 through voltage drive control pin 2. At the same time, the current balancing pin 4, circuit feedback pin 5, and overvoltage protection pin 7 are used to sense the working status of the constant current source power channel module 103. The sensing resistor array R223 / R224 / R225 / R226, current-limiting resistor R222, and protection diode D204 realize real-time voltage monitoring and balancing.

[0080] For example, referring to Figures 2 and 3, the signal transmitted from ferrite bead FB1 in constant current source power channel module 103 to LED1+ is further transmitted to LED1- in constant current source driver control module 102, and then to the sensing resistor array R223 / R224 / R225 / R226, current-limiting resistor R222, and protection diode D204. Resistors R223 / R224 / R225 / R226 generate a small voltage, which becomes the FB signal at the circuit feedback pin 5. Current-limiting resistor R222 and protection diode D204 stabilize the FB signal, and protection diode D204 also prevents short circuits between LED1+ and LED1-.

[0081] For example, in conjunction with Figures 2 and 3, the initial external power input is obtained through the VBL network, and then boosted through inductor L2, MOS transistor Q2, and diode D201. By changing the driver level of MOS transistor Q2 (connected to pin 2 of the constant current source drive control module chip), the power operating parameters are updated in real time. The sensing resistor array R210 / R211 / R212 / R213 / R214 / R215 and current-limiting resistor R209 achieve real-time current monitoring and balancing of the power path. The voltage divider resistors R205 / R206 / R207 and current-limiting resistor R208 are connected to the overvoltage protection pin 7 of chip U2 to implement the overvoltage protection function. Capacitor C208 mainly realizes circuit voltage stability.

[0082] For example, in combination with Figure 1 and Figure 3, the voltage enable signal is input through the reverse diode D204 of the single module, the current limiting resistor R220 is connected to the digital dimming signal, and a parallel input is realized on the current control pin pin8 of the chip U2 of the constant current source drive control module 102.

[0083] For example, as shown in FIG3 , the constant current source drive control module 102 includes a voltage stabilization circuit R223 / R224 / R225 / R226 / C214 / R222 / D204 connected to the circuit feedback pin 5 of the chip U2. For example, the diode D204 can prevent a short circuit problem caused by connecting the positive and negative electrodes of the load together.

[0084] For example, as shown in Figure 3, the constant current source drive control module 102 also includes a dimming circuit D203 / R220 / R221 / C213 connected to current control pin 8. The dimming circuit D203 / C213 / R220 / R221 is configured to input a rectangular wave signal ADI and an on / off signal to current control pin 8. The ON / OFF signal on the right side of D203 and the ADI signal on the right side of R220 are both control signals output from the motherboard. The rectangular wave signal ADI is a matrix signal for PWM dimming—that is, it is a rectangular wave signal that can adjust the strength of the input signal and is a continuous digital variable. The ON / OFF signal turns PWM dimming on and off and has only two states: ON and OFF. The ON / OFF signal has a higher priority than the rectangular wave signal ADI. The rectangular wave signal ADI can be connected to the current control pin 8 via R220 / C213, and the rectangular wave signal ADI is filtered. When the OFF signal is transmitted, it is equivalent to a reverse diode, which is externally connected. That is, if the OFF signal is transmitted and the electrical frequency is low, the current control pin pin8 will be pulled low regardless of the input signal of the rectangular wave signal ADI.

[0085] For example, as shown in FIG3 , the constant current source drive control module 102 further includes a fourth high-frequency filter structure C211 / R219 connected to the boost loop feedback compensation pin pin 6 .

[0086] For example, as shown in FIG3 , the constant current source drive control module 102 further includes a voltage buffer circuit connected to the current balancing pin pin4 , and the voltage buffer circuit C209 / CS2 is configured to adjust the voltage of the working voltage source.

[0087] For example, as shown in FIG3 , the digital ground pin portion pin 3 is directly grounded.

[0088] For example, as shown in Figure 3, chip U2 forms the main body of the constant current source drive control module 102, which has an adaptive constant current control function. When the peripheral power channels controlled by a single chip are limited by the parameters of the power device, multiple chips can be cascaded to form a high-power constant current drive circuit. The multiple constant current LED drive circuits are cascaded only through the motherboard control signal. The chip's own protection signals and drive control are all operated with the constant current source drive control module 102, and there is no interference between the constant current source power channel modules 102.

[0089] For example, as shown in Figure 3, diode D203 and resistor R220 form the cascade signal input. The motherboard inputs a PWM dimming signal to control the backlight brightness. When chip U2 malfunctions, the PWM controller is pulled low by chip U2 to turn off the backlight. The cascade signal is a small signal control and requires separate shielded signal traces and connections between components.

[0090] For example, as shown in FIG3 , a current feedback circuit is formed by diode D204 and parallel resistors R223, R224, R225, and R226. The voltage at the upper ends of parallel resistors R223, R224, R225, and R226 in the current feedback circuit is measured and compared with the voltage output by the comparator included in the current loop of the internal controller to provide negative output current feedback. Furthermore, the fourth pin, pin 4 (CS), of chip U2 controls the frequency of the ground switch of MOS transistor Q2 included in the front-end constant current source power channel module 103 to achieve adaptive adjustment of the output channel current. In addition to forming part of the current feedback circuit, diode D204 also protects the cathode of the diode.

[0091] For example, as shown in FIG3 , an isolation series resistor is provided between the fourth pin CS and the constant current source power channel module 103 . The feedback signal itself is connected to the inside of the chip U2 through the series resistor and is not affected. The series resistor also isolates the interference of the power signal on the operation of the chip itself.

[0092] For example, in combination with Figure 1 and Figure 3, when the chip U2 of the constant current source drive control module 102 is cascaded, the backlight PWM dimming control signal needs to be connected through an isolation resistor, and the backlight enable signal is short-circuited through a unidirectional diode to enable the motherboard to pull down the control pin of the chip without pulling down the motherboard integrated enable signal due to abnormality of a single chip.

[0093] For example, an isolation circuit formed by a filter capacitor and a voltage conversion circuit is provided between the output end of the power supply connector for the backlight and the constant current source power channel module.

[0094] For example, FIG4 is a circuit diagram of an isolation circuit between a constant current source drive control module and a constant current source power channel module provided by at least one embodiment of the present disclosure. As shown in FIG4 , the isolation circuit shown in FIG4 is also a circuit diagram of an intermediate voltage output connected between the constant current source drive control module 102 and the constant current source power channel module 103. That is, the VBL interface at one end of the intermediate voltage output circuit diagram is connected to the VBL interface of the constant current source power channel module 103, and the other end is connected to the +12V_Vin port of the constant current source drive control module 102, which is equivalent to isolating the constant current source power channel module 103 from the constant current source drive control module 102 and converting the input of the constant current source power channel module 103 into the input of the constant current source drive control module 102. The intermediate voltage output circuit achieves the output of the intermediate voltage through the action of the resistor boost R629 / R630. The intermediate voltage output circuit plays a key role in powering the chip U2 of the constant current source drive control module 102.

[0095] For example, in combination with Figure 3 and Figure 4, the structure shown in Figure 4 is a module that independently supplies power to the constant current source drive control module 102. It adopts the resistor boost R629 / R630 mode to isolate the power supply of the constant current source drive control module 102 from the constant current source power channel module 103, thereby realizing a higher voltage input to the control module.

[0096] For example, FIG5 is a circuit diagram of an isolation circuit between a constant current source drive control module and a constant current source power channel module provided in at least one embodiment of the present disclosure. As shown in FIG5 , the power supply of the chip of the constant current source drive control module 102 is changed from the original short-circuit at the input end to an intermediate-stage voltage transformation output. Through a separate intermediate-stage voltage transformation circuit, the control chip and the boost power circuit can be completely isolated, and the voltage input range can be expanded from the original chip specification limit of 9 to 30V to a wider range. For example, the implementation of the separate voltage transformation circuit includes resistive voltage division, LDO, or DC / DC.

[0097] For example, the isolation circuit shown in FIG5 , i.e., the circuit diagram for the intermediate voltage output, is connected between the constant current source drive control module 102 and the constant current source power channel module 103. Specifically, the VBL interface at one end of the circuit diagram for the intermediate voltage output is connected to the VBL interface of the constant current source power channel module 103, and the other end is connected to the +12V_Vin port of the constant current source drive control module 102. This is equivalent to isolating the constant current source power channel module 103 from the constant current source drive control module 102, and converting the input of the constant current source power channel module 103 into the input of the constant current source drive control module 102. The intermediate voltage output circuit achieves the output of the intermediate voltage through the action of the resistor booster R633 / R634, and the intermediate voltage output circuit plays a key role in powering the chip U2 of the constant current source drive control module 102.

[0098] For example, in the isolation circuit shown in Figure 5, chip UL1 is located between resistors R633 and R634. This chip includes a first pin, GND; a second pin, OUT1; a third pin, IN; and a fourth pin, OUT2. Pin GND is grounded, pin IN is an input pin, and both pins OUT1 and OUT2 are output pins. Resistor R633 and capacitor C633 also function as low-power voltage converters. Chip UL1 is a solid-state chip that performs voltage conversion.

[0099] For example, resistor R634 and capacitors C632 and C641 filter the input voltage. Capacitor arrays C628, C624, C626, C627, C625, and C629 are capacitor input arrays for the VBL signal.

[0100] For example, in combination with Figure 3 and Figure 5, the structure shown in Figure 5 is a module that independently supplies power to the constant current source drive control module 102. It uses a low-power step-down module UL1 to isolate the power supply of the constant current source drive control module 102 from the constant current source power channel module 103, thereby enabling the control module to input a voltage with a higher amplitude.

[0101] For example, in at least one embodiment of the present disclosure, the multi-channel constant-current LED driver circuit further includes a power supply connector for backlighting. For example, FIG6 is a circuit diagram of a power supply connector for backlighting provided in at least one embodiment of the present disclosure. The input end of the power supply connector for backlighting is electrically connected to an external power supply structure, and the output end of the power supply connector for backlighting is electrically connected to a constant-current source power channel module. The output end of the power supply connector for backlighting serves as a third interface.

[0102] For example, as shown in Figures 2 and 6, the power supply backlight connector is provided with 30 pins, and pins 17 to 30 are the positive terminals of the power input, which are electrically connected to the VBL interface (input terminal) of the constant current source power channel module 103 through the VBL interface. Pins 1, 2, 4 to 14 are the negative terminals of the power input directly grounded, and pin 3 is a sensor, which is connected to resistor R625 and capacitor C617. The sensor adjusts the input fixed voltage on the VBL interface by obtaining the resistance value of resistor R625. In combination with Figures 2 and 6, the power line transmitted from the power board enters the power supply backlight connector, that is, first passes through the input capacitor in the power supply backlight connector, and then reaches the inductor component L2, MOS tube Q2, diode components D201, D205 and filter capacitor array C205, C206, C207, C217 and C623 of the constant current source power channel module 103. The filter capacitor array can be used as an output capacitor.

[0103] For example, FIG7 is a circuit diagram of a power supply connector provided in at least one embodiment of the present disclosure. In conjunction with FIG4 , FIG5 , and FIG7 , the power supply connector is connected between an external power source and the isolation circuit shown in FIG4 or FIG5 . The power supply connector includes 24 interfaces. Interface 1, interface 2, interface 3, interface 4, interface 11, interface 13, interface 16, and interface 18 are all connected to an external 12V positive voltage. Interface 5, interface 6, interface 7, interface 8, interface 9, interface 10, interface 12, interface 14, interface 20, interface 21, and interface 22 are all connected to ground. Interface 15 is connected to the VBL interface, interface 19 is connected to the ON / OFF interface, interface 23 is connected to the AMP_VCC interface, interface 24 is connected to the CWP_VCC2 interface, and interface 17 is not connected to any components. Capacitors C634 and C635 are provided between the VBL interface and the ON / OFF interface.

[0104] For example, Figure 8 is a circuit diagram of a backlight connector provided in at least one embodiment of the present disclosure. As shown in Figure 8, the backlight connector is the output end of the constant current source power channel module 103. The positive electrode of the light-emitting diode is connected to the constant current source power channel module 103. The backlight connector provides power to the output of the light-emitting diode. When power is supplied, it is provided to the positive electrode, and the positive electrode returns to the negative electrode of the light-emitting diode after passing through the load. The backlight connector includes 12 pins, two of which are empty and not connected to external components. Of the remaining 10 pins, 5 are output pins and the other 5 are input pins. The backlight connector shown in Figure 8 corresponds to one voltage conversion circuit among multiple voltage conversion circuits arranged in parallel, corresponding to the first LED to the fifth LED.

[0105] For example, Figure 9 is a circuit diagram of another backlight connector provided by at least one embodiment of the present disclosure. As shown in Figure 9, the backlight connector is the output end of the constant current source power channel module 103. The positive electrode of the light-emitting diode is connected to the constant current source power channel module 103. The backlight connector provides power to the output of the light-emitting diode. When power is supplied, the positive electrode is supplied, and the positive electrode returns to the negative electrode of the light-emitting diode after passing through the load. The backlight connector also includes 12 pins, two of which are empty and not connected to external components. Of the remaining 10 pins, 5 are output pins and the other 5 are input pins. The backlight connector shown in Figure 9 corresponds to another voltage conversion circuit among a plurality of voltage conversion circuits arranged in parallel, corresponding to the sixth to tenth LEDs.

[0106] The embodiments of the present disclosure design a high-power DC voltage-regulated power supply solution to meet the needs of backlight driving of large-size LCD screens. In addition, a dedicated backlight control chip is used in the embodiments of the present disclosure, so that the multi-channel constant-current LED drive circuit has the characteristics of a wide voltage regulation range, simple power expansion, and good current consistency when multiple modules are compatible.

[0107] At least one embodiment of the present disclosure further provides a backlight structure. For example, FIG10 is a block diagram of the backlight structure provided by at least one embodiment of the present disclosure. As shown in FIG10 , the backlight structure 200 includes a power supply board 201, an LED lamp 202, and a multi-channel constant current LED driver circuit 100 according to any of the above embodiments, which is arranged between the power supply board 201 and the LED lamp 202. The multi-channel constant current LED driver circuit isolates the constant current source drive control module from the constant current source power channel module, thereby isolating the backlight input voltage from the power supply end of the LED driver management chip, thereby ensuring timing consistency and expanding the input range of the power supply voltage of the LED driver chip. The embodiment of the present disclosure also utilizes the adaptive constant current control of the LED driver chip, cascades the backlight PWM control and switch enable signals to achieve the combined use of multiple modules, and the current feedback and protection feedback between the multiple modules operate independently. Even if one of the multiple modules fails, it will not affect the normal operation of other modules unless it causes an abnormality in the input PWM controller channel, thereby simplifying power expansion. In addition, since the current feedback of a single module depends only on the parameters of the hardware devices set by the circuit, when the overall consistency of the devices is ensured and the working environment between individual board modules is similar, the current output of multiple modules can basically be guaranteed to be consistent when used in cascade.

[0108] For example, in combination with Figure 10 and Figure 6, the third interface of the constant current source power channel module 103 included in the multi-channel constant current LED driving circuit 100 is connected to the power interface of the power board 201, and the output end of the power supply connector to the backlight is the third interface VBL of the multi-channel constant current LED driving circuit 100. The second interface of the constant current source power channel module 103 included in the multi-channel constant current LED driving circuit 100 is electrically connected to the LED lamp, and the second interface is the dual-lamp zone series interface.

[0109] For example, when designing a single chip, the distribution of the drive control part and the power channel part should be considered, especially the isolation between the digital ground of the control chip and the analog ground of the power acquisition signal, to prevent the power ground fluctuation caused by high-power load changes from causing abnormal fluctuations in the chip reference digital ground, resulting in drive oscillation and loop imbalance.

[0110] FIG11 is a simulation diagram of the cascade thermal design of a multi-channel constant current LED driver circuit provided in at least one embodiment of the present disclosure. As shown in FIG11 , the bright areas A, B, C, D, M, N, and P marked with dotted ovals are the heat-generating areas. FIG11 shows that the heat-generating areas are evenly distributed, avoiding excessive concentration of heat-releasing components, thereby avoiding excessively high temperatures in local areas that shorten the life of the device.

[0111] At least one embodiment of the present disclosure provides a multi-channel constant current LED driver circuit and backlight structure, which has at least the following beneficial technical effects: the multi-channel constant current LED driver circuit isolates the constant current source drive control module and the constant current source power channel module, isolating the backlight input voltage from the power supply end of the LED driver management chip, thereby ensuring timing consistency and expanding the input range of the LED driver chip's power supply voltage. The embodiment of the present disclosure also utilizes the adaptive constant current control of the LED driver chip, cascading the backlight PWM control and switch enable signals to achieve the combined use of multiple modules, and the current feedback and protection feedback between the multiple modules operate independently. Even if one of the multiple modules fails, it will not affect the normal operation of other modules unless it causes an abnormality in the input PWM controller channel, thereby simplifying power expansion. In addition, since the current feedback of a single module depends only on the parameters of the hardware device set by the circuit, when the overall consistency of the device is guaranteed and the working environment between the individual board modules is similar, the current output of multiple modules can be basically guaranteed to be consistent when cascaded.

[0112] There are a few points to note:

[0113] (1) The drawings of the embodiments of the present disclosure only relate to the structures related to the embodiments of the present disclosure. Other structures may refer to conventional designs.

[0114] (2) For the sake of clarity, in the drawings used to describe the embodiments of the present disclosure, the thickness of layers or regions is exaggerated or reduced, that is, these drawings are not drawn according to the actual scale.

[0115] (3) In the absence of conflict, the embodiments of the present disclosure and the features therein may be combined with each other to form new embodiments.

[0116] The above description is only a specific embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto. The protection scope of the present disclosure shall be based on the protection scope of the claims.

Claims

1. A multi-channel constant-current LED driving circuit, comprising: a plurality of voltage conversion circuits arranged in parallel and a cascading channel connecting the plurality of voltage conversion circuits, each of the voltage conversion circuits includes a constant-current source drive control module, a constant-current source power channel module and a lamp area load interface connected in sequence, wherein, the constant-current source drive control module includes a chip, a cascading signal input circuit and a current feedback circuit; the constant-current source power channel module includes an inductor component, a MOS transistor, a diode component and a filter capacitor array, and the constant-current source power channel module includes a first interface connected to the constant-current source drive control module, a second interface connected to the lamp area load interface, and a third interface connected to an external power supply structure; the constant-current source drive control module includes a fourth interface connected to a main board interface.

2. The multi-channel constant-current LED driving circuit according to claim 1, further comprising a power supply for backlight power supply connector, wherein, the input end of the power supply for backlight power supply connector is electrically connected to the external power supply structure, and the output end of the power supply for backlight power supply connector is electrically connected to the constant-current source power channel module.

3. The multi-channel constant-current LED driving circuit according to claim 1 or 2, wherein, an isolation circuit formed by a filter capacitor and a voltage conversion circuit is further provided between the output end of the power supply for backlight power supply connector and the constant-current source power channel module.

4. The multi-channel constant-current LED driving circuit according to any one of claims 1 to 3, wherein, the constant-current source power channel module further includes a first high-frequency filtering structure and a radiator interface.

5. The multi-channel constant-current LED driving circuit according to claim 4, wherein, the diode component is connected in parallel with the first high-frequency filtering structure, and the diode component includes at least two diodes connected in series.

6. The multi-channel constant-current LED driving circuit according to claim 4, wherein, the constant-current source power channel module further includes an overvoltage protection circuit, the overvoltage protection circuit is connected between the MOS transistor and the filter capacitor array, and is connected to the chip of the constant-current source drive control module.

7. The multi-channel constant-current LED driving circuit according to claim 6, wherein, the overvoltage protection circuit includes a second high-frequency filtering structure and a protection resistor, and the overvoltage protection circuit is configured to provide a stable sensing signal for the constant-current source drive control module.

8. The multi-channel constant-current LED driving circuit according to claim 6, wherein, the constant-current source power channel module further includes a third high-frequency filtering structure connected in parallel with the MOS transistor, and the third high-frequency filtering structure is configured to filter the MOS transistor.

9. The multi-channel constant-current LED driving circuit according to any one of claims 5 to 8, wherein, the constant-current source power channel module further includes a control loop, the control loop is configured to control the opening and closing of the MOS transistor, and filter and adjust the GATE2 signal transmitted to the chip.

10. The multi-channel constant-current LED driving circuit according to claim 9, wherein, The constant current source power channel module further includes a current sharing signal input circuit. The first end of the current sharing signal input circuit is connected to the MOS transistor, the second end of the current sharing signal input circuit is electrically connected to the fourth pin of the chip, and the third end of the current sharing signal input circuit is grounded. The current sharing signal input circuit includes a resistor array and a transmission resistor. The resistor array is configured to generate a current sharing signal, and the transmission resistor is configured to correct the current sharing signal.

11. The multi-channel constant current LED driving circuit according to claim 10, wherein, the chip includes a power input pin, a voltage driving control pin, a digital ground pin part, a current balancing pin, a circuit feedback pin, a boost loop feedback compensation pin, an overvoltage protection pin, and a current control pin; the power input pin is connected to a working voltage source; the voltage driving control pin, the current balancing pin, the circuit feedback pin, and the overvoltage protection pin are all electrically connected to the constant current source driving control module; the digital ground pin part is connected to digital ground; the boost loop feedback compensation pin is an internal calculation pin of the chip. After connecting a capacitor, it is grounded; the current control pin is connected to the cascade channel to set the working state of the constant current source power channel module.

12. The multi-channel constant current LED driving circuit according to claim 11, wherein, the constant current source driving control module includes a voltage stabilizing circuit connected to the circuit feedback pin of the chip.

13. The multi-channel constant current LED driving circuit according to claim 12, wherein, the constant current source driving control module further includes a dimming circuit connected to the current control pin. The dimming circuit is configured to input a rectangular wave signal and a switching signal to the current control pin.

14. The multi-channel constant current LED driving circuit according to claim 12, wherein, the constant current source driving control module further includes a fourth high-frequency filtering structure connected to the boost loop feedback compensation pin.

15. The multi-channel constant current LED driving circuit according to claim 11, wherein, the constant current source driving control module further includes a voltage reducing circuit connected to the current balancing pin. The voltage reducing circuit is configured to adjust the magnitude of the voltage of the working voltage source.

16. A backlight structure, comprising: a power supply board, an LED lamp, and the multi-channel constant current LED driving circuit according to any one of claims 1 to 15 provided between the power supply board and the LED lamp.

17. The backlight structure according to claim 16, wherein, the third interface of the constant current source power channel module included in the multi-channel constant current LED driving circuit is connected to the power interface of the power supply board, and the second interface of the constant current source power channel module included in the multi-channel constant current LED driving circuit is electrically connected to the LED lamp.

Images