CN112689366B - LED driving system and electronic equipment - Google Patents

LED driving system and electronic equipment Download PDF

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Publication number
CN112689366B
CN112689366B CN202011209435.9A CN202011209435A CN112689366B CN 112689366 B CN112689366 B CN 112689366B CN 202011209435 A CN202011209435 A CN 202011209435A CN 112689366 B CN112689366 B CN 112689366B
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led
circuit
switch
power supply
control
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CN112689366A (en
Inventor
任虎男
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Beijing Xianxin Technology Co ltd
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Beijing Xianxin Technology Co ltd
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Priority to CN202011209435.9A priority Critical patent/CN112689366B/en
Publication of CN112689366A publication Critical patent/CN112689366A/en
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Publication of CN112689366B publication Critical patent/CN112689366B/en
Priority to PCT/CN2021/123116 priority patent/WO2022095664A1/en
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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/10—Controlling the intensity of the light
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
    • H05B45/54—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits in a series array of LEDs

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Circuit Arrangement For Electric Light Sources In General (AREA)

Abstract

The embodiment of the invention provides an LED driving system and electronic equipment, wherein the LED driving system comprises an LED circuit board; the LED circuit board comprises an LED driver and an LED; the LED driver comprises a control circuit and a switch circuit; the switch circuit is used for controlling the brightness of the LED; the control circuit is connected with the control end of the switch circuit and is used for controlling the on-off of the switch circuit; the other ends of the switch circuit except the control end and the grounding end of the control circuit are arranged in the LED driver in a separated mode. The LED driving system and the electronic equipment provided by the embodiment of the invention can reduce the influence of the large current of the LED on the grounding end of the control circuit, so that the grounding bounce of the LED loop does not interfere the voltage of the control circuit as much as possible, thereby reducing the circuit fault caused by the grounding bounce and improving the working stability of the equipment.

Description

LED driving system and electronic equipment
Technical Field
The embodiment of the invention relates to the field of LED display, in particular to an LED driving system and electronic equipment.
Background
With the continuous development of electronic technology, the performance of various electronic devices with image display function, such as liquid crystal display television (LCD TV), etc., is continuously enhanced, and the application is more and more extensive.
Currently, a Light Emitting Diode (LED) or a mini-LED is often used in a liquid crystal television to enhance the display effect. For example, by using a Backlight (Backlight) of LEDs, hundreds or thousands of LEDs can be provided to improve the color expression of lcd television displays.
In the backlight system based on the LED, when the driving current of the LED is large, Ground bounce (Ground bounce) is easily caused, and the Ground bounce easily causes a circuit fault, so that the device cannot normally operate.
Disclosure of Invention
The embodiment of the invention provides an LED driving system and electronic equipment, and aims to solve the technical problem that circuit faults are easily caused when the driving current of an LED is large in the prior art.
In a first aspect, an embodiment of the present invention provides an LED driving system, where the LED driving system includes an LED circuit board;
the LED circuit board comprises an LED driver and an LED;
the LED driver comprises a control circuit and a switch circuit;
the switch circuit is used for controlling the brightness of the LED;
the control circuit is connected with the control end of the switch circuit and is used for controlling the on-off of the switch circuit;
the other ends of the switch circuit except the control end and the grounding end of the control circuit are arranged in the LED driver in a separated mode.
In one possible embodiment, the LED driving system further comprises other circuit boards;
and the grounding end of the switch circuit and the grounding end of the control circuit are connected on the other circuit boards.
In one possible embodiment, the LED driving system further includes a driving circuit board;
the driving circuit board comprises a first power supply circuit for supplying power to the control circuit and a second power supply circuit for supplying power to the LED.
In one possible embodiment, the switching circuit includes a switching tube including a control terminal, a first terminal, and a second terminal;
the first end of the switch tube is connected with one end of the LED controlled by the switch tube, and the second end of the switch tube is connected with the second power supply circuit;
the ground terminal of the control circuit is connected to the ground of the first power supply circuit.
In a possible embodiment, the other end of the switching tube controlled LED is connected to the positive voltage terminal of the second power supply circuit;
and the second end of the switch tube is connected with the ground or negative voltage end of the second power supply circuit.
In a possible embodiment, the number of the switching tubes in the switching circuit is two, and the number of the LEDs controlled by the switching circuit is multiple, wherein some of the LEDs in the multiple LEDs are controlled by a first switching tube of the two switching tubes, and the remaining LEDs are controlled by a second switching tube;
and the second end of the first switching tube and the second end of the second switching tube are both connected with the grounding end of the second power supply circuit.
In a possible embodiment, the first switch controlled LED is connected to the positive voltage terminal of the second power supply circuit, and the second switch controlled LED is connected to the negative voltage terminal of the second power supply circuit;
the voltage of the positive voltage end of the second power supply circuit is equal to the absolute value of the voltage of the negative voltage end.
In a possible implementation, the first switch tube is an NMOS transistor, and the second switch tube is a PMOS transistor; and the signal sent to the control end of the NMOS transistor is the same as or complementary to the signal sent to the control end of the PMOS transistor.
In a possible embodiment, the LED controlled by the switching tube is a single LED, or an LED string formed by connecting a plurality of LEDs in series.
In a second aspect, an embodiment of the present invention provides an electronic device, including the LED driving system according to any one of the first aspects and a liquid crystal panel.
The LED driving system and the electronic equipment provided by the embodiment of the invention comprise an LED circuit board, wherein the LED circuit board comprises an LED driver and an LED, the LED driver comprises a control circuit and a switch circuit, the switch circuit is used for controlling the brightness of the LED, the control circuit is connected with the control end of the switch circuit and is used for controlling the on-off of the switch circuit, and other ends of the switch circuit except the control end are separated from the grounding end of the control circuit in the LED driver, so that the grounding end of the control circuit is far away from an LED loop as much as possible, the influence of large current of the LED on the grounding end of the control circuit is reduced, the grounding bounce of the LED loop does not interfere with the voltage of the control circuit as much as possible, the circuit fault caused by the grounding bounce is reduced, and the working stability of the equipment is improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a schematic view of an application scenario provided in an embodiment of the present invention;
fig. 2 is a schematic structural diagram of an LED driving circuit according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of an LED driver according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of the current-voltage variation of the circuits shown in FIGS. 2 and 3;
fig. 5 is a schematic structural diagram of an LED driving system according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of another LED driving system according to a first embodiment of the present invention;
fig. 7 is a schematic structural diagram of an LED driving system according to a second embodiment of the present invention;
FIG. 8 is a schematic diagram of the current-voltage variation of the LED driving system shown in FIG. 7;
fig. 9 is a schematic structural diagram of an LED driving system according to a third embodiment of the present invention;
FIG. 10 is a schematic diagram of the current-voltage variation of the LED driving system shown in FIG. 9;
fig. 11 is a schematic structural diagram of an LED driving system according to a fourth embodiment of the present invention;
fig. 12 is a schematic diagram of current-voltage variation of the LED driving system shown in fig. 11.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The terminology used in the embodiments of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the embodiments of the present application, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
The words "if", as used herein, may be interpreted as "at … …" or "at … …" or "in response to a determination" or "in response to a detection", depending on the context. Similarly, the phrases "if determined" or "if detected (a stated condition or event)" may be interpreted as "when determined" or "in response to a determination" or "when detected (a stated condition or event)" or "in response to a detection (a stated condition or event)", depending on the context.
It is also noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a good or system that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such good or system. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a commodity or system that includes the element.
Fig. 1 is a schematic view of an application scenario provided in an embodiment of the present invention. As shown in fig. 1, an LED for providing a backlight function and a liquid crystal panel may be provided in the display device, and an arrow in the drawing indicates that light emitted from the LED may act on the liquid crystal panel. The LED driver is connected with the LED and can control the brightness of the LED. The number of the LEDs can be multiple, and the light emitted by the LEDs is matched with the image displayed by the liquid crystal panel, so that the display effect can be improved.
Fig. 2 is a schematic structural diagram of an LED driving circuit according to an embodiment of the present invention. As shown in fig. 2, an LED Driver (LED Driver) and an LED may be disposed on the LED circuit Board (LED Board). The embodiment of the present invention is described by taking an example in which one LED driver drives 2 LEDs. The two LEDs are denoted D1 and D2, respectively. The LEDs are powered by an AC/DC (alternating current to direct current) circuit provided on a Driving Board (Driving Board).
The LED driver may include a control circuit and an NMOS (N-Metal-Oxide-Semiconductor) transistor. The control Circuit may be a Digital & Analog Circuit (Digital Circuit & Analog Circuit).
One end of the transistor is connected with the LED, the other end VSS _ LED is grounded, the LED is connected with the AC/DC circuit, and the power supply voltage V _ LED is provided. When the transistor is turned on, current passes through the LED, namely the current I _ LED passing through the LED is greater than 0; when the transistor is off, I _ LED equals 0.
The control end of the transistor is connected with the control circuit, so that the control circuit can control the on-off of the transistor. The control circuit is powered by a DC/DC (direct current to direct current) circuit on the driving circuit board. Specifically, a power supply terminal VDD of the control circuit is connected to the DC/DC circuit on the driving circuit board, a ground terminal GND of the control circuit is connected to one terminal VSS _ LED of the transistor, which is grounded, and then the VSS _ LED is connected to the ground on the driving circuit board.
Optionally, the LED driver may drive the LED by a PWM (Pulse Width Modulation) signal.
Fig. 3 is a schematic structural diagram of an LED driver according to an embodiment of the present invention. As shown in fig. 3, in the LED driver, the control circuit may include a bandgap reference circuit, a PWM output circuit, resistors R1 and R2, an operational amplifier U1, and the like. The bandgap reference circuit can provide a bandgap reference, and the PWM output circuit can output a PWM signal, so as to control the NMOS transistor and adjust the light emitting states of D1 and D2.
Similarly to fig. 2, the supply voltage and current of the LED are V _ LED and I _ LED, respectively, the LED driver has a supply terminal VDD, and in addition, the ground terminal GND of the control circuit in the LED driver and the ground terminal VSS _ LED of the transistor are connected together inside the LED driver, i.e., VSS _ LED is GND.
In the schemes shown in fig. 2 and 3, when the I _ LED is large, ground bounce may be caused, and the circuit is easy to malfunction.
Fig. 4 is a schematic diagram of current-voltage variation of the circuits shown in fig. 2 and 3. The voltage and current variations in fig. 4 apply to both fig. 2 and fig. 3. As shown in fig. 4, t represents time, and the current I _ LED flowing through the LED varies with the PWM signal. When PWM pulse appears, the transistor is conducted, and the current I _ LED is positive; when the transistor is turned off, the current I _ LED drops to 0.
When the current I _ LED is large, the ground terminal VSS _ LED of the transistor is spaced from the ground of the driving circuit board by a certain distance, and a resistance at the certain distance generates a voltage drop, so that VSS _ LED is larger than 0, and the ground terminal GND of the control circuit is connected to the ground terminal VSS _ LED of the transistor.
When the voltage of VDD of the control circuit is not changed, the voltage change of GND will cause the voltage difference between VDD and GND, i.e. VDD-GND in the figure, to change, which easily causes the control circuit to malfunction, and affects the normal operation of the device.
To solve this problem, embodiments of the present invention provide an LED driving system that separates a ground terminal VSS _ LED of a transistor from a ground terminal GND of a control circuit. VSS _ LED and GND are not connected in the LED circuit board, but are connected together at a place far away from the LED board, so that the grounding bounce of the LED driving circuit can not interfere with the high and low levels of the control circuit, thereby ensuring the normal operation of the circuit.
Example one
The embodiment of the invention provides an LED driving system. Fig. 5 is a schematic structural diagram of an LED driving system according to an embodiment of the present invention. As shown in fig. 5, the LED driving system may include an LED circuit board;
the LED circuit board comprises an LED driver and an LED;
the LED driver comprises a control circuit and a switch circuit;
the switch circuit is used for controlling the brightness of the LED;
the control circuit is connected with the control end of the switch circuit and is used for controlling the on-off of the switch circuit;
the other ends of the switch circuit except the control end and the grounding end of the control circuit are arranged in the LED driver in a separated mode.
The Circuit Board according to the embodiment of the present invention may be a Printed Circuit Board (PCB), Glass (Glass), or a Wafer (Wafer). An LED driver and an LED are arranged on the LED circuit board. The number of the LEDs and the number of the LED drivers can be one or more, and one LED driver can control one LED and can also control a plurality of LEDs. The LED may be a mini-LED or a conventional LED.
In the LED driver, the ground terminal of the control circuit and each terminal of the switching circuit may be separately disposed inside the LED driver. The separate arrangement of the embodiments of the present invention means that the wires are not directly connected together through a wire, and the wire may include a wiring on the PCB.
Specifically, if the switch circuit does not include a ground terminal, then each terminal of the switch circuit need not be directly connected to the ground terminal of the control circuit. If the switch circuit includes a ground terminal, the ground terminal of the switch circuit and the ground terminal of the control circuit may be separately disposed.
One specific implementation scheme of the separated arrangement inside the LED driver is that the separated arrangement is arranged on the LED circuit board. It will be appreciated that since the LED driver is arranged on the LED circuit board, it is arranged separately on the LED circuit board, and naturally also inside the LED driver.
Optionally, in a case that the LED driving system further includes another circuit board, the ground terminal of the switch circuit and the ground terminal of the control circuit may be connected to the other circuit board, and particularly, may be connected to a circuit board for supplying power.
Specifically, the LED driving system may include a plurality of circuit boards, the LED driver and the LEDs may be located on one layer of circuit board, other circuits may be located on other circuit boards, and the ground terminals of the control circuit and the switch circuit in the LED driver may be connected to the other circuit boards.
Of course, the ground terminal of the switch circuit and the ground terminal of the control circuit may be connected at other places apart from the LED circuit board, for example, may be connected on the housing of the LED driving system.
Fig. 6 is a schematic structural diagram of another LED driving system according to a first embodiment of the present invention. The solution shown in fig. 6 differs from the solution shown in fig. 5 in that the ground terminal of the control circuit and the ground terminal of the switching circuit may be connected together on the LED circuit board.
As shown in fig. 6, in the LED driving system, the LED circuit board is provided with the LED driver and the LED, and the ground terminal of the control circuit and the ground terminal of the switching circuit in the LED driver are separately provided inside the LED driver, but are not necessarily separately provided on the LED circuit board.
Specifically, the ground terminal of the control circuit and the ground terminal of the switching circuit may be connected together outside the LED driver and then connected to the ground on the other circuit board. The scheme shown in fig. 6 can be used when the resistance of the LED circuit board is small, and the scheme shown in fig. 5 can be used when the resistance is large, thereby realizing a more flexible circuit design scheme.
The LED driving system provided by the embodiment comprises an LED circuit board, the LED circuit board comprises an LED driver and an LED, the LED driver comprises a control circuit and a switch circuit, the switch circuit is used for controlling the brightness of the LED, the control circuit is connected with the control end of the switch circuit and used for controlling the on-off of the switch circuit, the switch circuit is used for controlling the on-off of the switch circuit, other ends except the control end are all in the grounding end of the control circuit, the grounding end of the control circuit is arranged in the LED driver in a separated mode, so that the grounding end of the control circuit is far away from an LED loop as far as possible, the influence of large current of the LED on the grounding end of the control circuit is reduced, the voltage of the control circuit is not interfered by the grounding bounce as far as possible, the circuit fault caused by the grounding bounce is reduced, and the working stability of equipment is improved.
Example two
The embodiment of the invention provides an LED driving system. In this embodiment, on the basis of the technical solutions provided in the foregoing embodiments, the ground terminal of the control circuit and the ground terminal of the switch circuit are connected to the driving circuit board.
Specifically, the LED driving system may include an LED circuit board; the LED circuit board comprises an LED driver and an LED; the LED driver comprises a control circuit and a switch circuit; the switch circuit is used for controlling the brightness of the LED; the control circuit is connected with the control end of the switch circuit and is used for controlling the on-off of the switch circuit; the other ends of the switch circuit except the control end and the grounding end of the control circuit are arranged in the LED driver in a separated mode.
Further, the LED driving system may include a driving circuit board; the driving circuit board comprises a first power supply circuit for supplying power to the control circuit and a second power supply circuit for supplying power to the LED.
The first power supply circuit can be a direct current to direct current circuit, and the second power supply circuit can be an alternating current to direct current circuit, so that different power supply requirements of the control circuit and the LED are met.
The grounding end of the switch circuit and the grounding end of the control circuit can be connected on the driving circuit board, and the influence of large current of the LED on the grounding end of the control circuit can be effectively reduced on the basis of realizing uniform grounding.
Optionally, the switching circuit may include a switching tube, and the switching tube includes a control end, a first end, and a second end; the first end of the switch tube is connected with one end of the LED controlled by the switch tube, and the second end of the switch tube is connected with the second power supply circuit. The other end of the LED controlled by the switch tube is connected with the positive voltage end of the second power supply circuit; the second end of the switching tube may be specifically used as a ground terminal, and is connected to the ground terminal of the second power supply circuit, so as to form a loop.
Fig. 7 is a schematic structural diagram of an LED driving system according to a second embodiment of the present invention. As shown in fig. 7, the LED circuit board is provided with an LED driver and an LED. The LED driver includes a control circuit and a switching circuit. The switch circuit comprises a switch tube, and the switch tube can be an NMOS transistor in the figure. The driving circuit board is provided with a first power supply circuit and a second power supply circuit.
The port of the LED driver may include a power supply terminal VDD and a ground terminal GND of the control circuit, and further include a second terminal VSS _ LED of the switching tube and a first terminal for connecting with the LED.
Optionally, when the switching tube is an NMOS transistor, a gate of the NMOS transistor is a control end connected to the control circuit, a drain of the NMOS transistor is a first end connected to the LED, and a source of the NMOS transistor is a second end connected to the second power circuit.
In other alternative implementations, the switching circuit may also include other devices capable of performing a switching function, such as PMOS transistors, etc.
In various embodiments of the present invention, the power source terminal may refer to a port for outputting or receiving a positive voltage of a power source, and the ground terminal may refer to a port for grounding. The power supply terminal VDD of the control circuit is connected to the power supply terminal of the first power supply circuit, and the ground terminal GND of the control circuit is connected to the ground of the first power supply circuit. Of course, the LED driver may also comprise other ports not shown, such as communication ports and the like.
The LED controlled by the switch tube is one LED or an LED string formed by connecting a plurality of LEDs in series. Under the condition that the switch tube controls the LEDs, the anodes and the cathodes of the LEDs are connected in sequence and are connected in series to form an LED string, one end of the LED string is the cathode of the first LED, and the other end of the LED string is the anode of the last LED.
In the case where one switching tube controls two LEDs, D1 and D2 of the two LEDs are connected in series. The first end of the switch tube is connected with the negative electrode of the D2, the second end VSS _ LED is connected with the ground of the second power supply circuit, and the positive electrode of the D1 is connected with the positive voltage end of the second power supply circuit, so that a closed loop is formed.
When the switch tube is switched on or off, the loop where the LED is located is switched on or off, so that the LED is controlled to be on or off. The control circuit can control the on-off of the switch tube. Specifically, the control circuit is connected with the control end of the switching tube, and the switching tube is controlled to be switched on or off by sending a PWM signal to the control end.
Of course, the control circuit can be used for other functions besides the control of the switching tube, such as communication with a controller and the like. In the embodiment of the present invention, all or part of the circuits in the LED driver except the switching tube may be referred to as a control circuit.
The other ends of the switch tube except the control end and the grounding end GND of the control circuit are arranged in the LED driver in a separated mode. When a certain end of the switch tube, such as VSS _ LED, needs to be connected to ground, it can be connected to the ground GND of the control circuit on the driving circuit board.
It is understood that the ground of the first power circuit and the ground of the second power circuit are connected together, and therefore, the VSS _ LED of the switching tube and the ground GND of the control circuit are respectively connected to the ground of the first power circuit and the ground GND of the second power circuit, which is equivalent to the VSS _ LED of the switching tube and the ground GND of the control circuit being finally connected together.
Fig. 8 is a schematic diagram of current-voltage variation of the LED driving system shown in fig. 7. As shown in fig. 8, t represents time, and the current I _ LED flowing through the LED varies with the PWM signal, I _ LED is positive during the PWM pulse, and I _ LED is 0 at other times. The voltage of a second end VSS _ LED of the switch circuit changes along with the change of the current I _ LED, and when the I _ LED is 0, the voltage of the VSS _ LED is 0; with I _ LED positive, VSS _ LED rises above 0 by a magnitude related to the resistance of VSS _ LED to ground of the second power supply circuit.
The ground terminal GND of the control circuit is separated from the second terminal VSS _ LED of the switch circuit, so that the voltage of the ground terminal GND of the control circuit is less influenced by the I _ LED, and the voltage fluctuation is not large and is fixed to 0. The voltage of the power supply end VDD of the control circuit basically does not change, so that the voltage difference between the power supply end VDD of the control circuit and the ground end GND basically keeps unchanged, and the working stability of the control circuit can be improved.
The LED driving system provided in this embodiment includes an LED circuit board and a driving circuit board, where the LED circuit board includes an LED driver and an LED, the driving circuit board includes a first power circuit for supplying power to the control circuit and a second power circuit for supplying power to the LED, the switching circuit includes a switching tube, the switching tube includes a control end, a first end and a second end, the first end of the switching tube is connected to one end of the LED controlled by the switching tube, the other end of the LED controlled by the switching tube is connected to a positive voltage end of the second power circuit, the second end of the switching tube is connected to a ground of the second power circuit, and a ground end of the control circuit is connected to the ground of the first power circuit, so that the ground end of the control circuit and the ground end of the switching circuit are connected to the driving circuit board far away from the LED driver, and voltage variation of the ground end of the control circuit can be further reduced, and the grounding bounce is reduced, and the stability of the system is improved.
EXAMPLE III
The third embodiment of the invention provides an LED driving system. Fig. 9 is a schematic structural diagram of an LED driving system according to a third embodiment of the present invention. The difference between this embodiment and the second embodiment is that the second terminal VSS _ LED of the switch tube does not need to be connected to ground, i.e. does not need to be 0.
As shown in fig. 9, the LED circuit board is provided with an LED driver and an LED, and the driving circuit board is provided with a first power supply circuit and a second power supply circuit. The LED driver includes a control circuit and a switching circuit. The port of the LED driver may include a power supply terminal VDD and a ground terminal GND of the control circuit, and further include a second terminal VSS _ LED of the switching tube and a port for connecting with the LED. The power supply terminal VDD of the control circuit is connected to the power supply terminal of the first power supply circuit, and the ground terminal GND of the control circuit is connected to the ground of the first power supply circuit.
The switch tube can be an NMOS transistor, and D1 and D2 in the two LEDs are connected in series. The first end of the switch tube is connected with the negative electrode of the D2, the second end VSS _ LED is connected with the ground of the second power supply circuit, and the positive electrode of the D1 is connected with the positive voltage end of the second power supply circuit, so that a closed loop is formed.
The other ends of the switch tube except the control end and the grounding end GND of the control circuit are arranged in the LED driver in a separated mode.
Alternatively, the second terminal VSS _ LED of the switching tube may not be connected to ground, and thus may have a voltage not equal to 0.
In this embodiment, the second terminal VSS _ LED of the switch tube may be connected to the negative voltage terminal of the second power circuit. In various embodiments of the present invention, the positive voltage terminal may refer to a port where the output voltage is greater than 0, and the negative voltage terminal may refer to a port where the output voltage is less than 0.
Optionally, a difference between the positive voltage output by the positive voltage end of the second power module and the negative voltage output by the negative voltage end of the second power module may be equal to a voltage difference required by the normal operation of the LED, so as to ensure that the LED is driven normally.
Further, the output voltage of the negative voltage end and the output voltage of the positive voltage end can be opposite numbers, the positive voltage output by the second power supply circuit can be V _ LED/2, and the output negative voltage can be-V _ LED/2, so that the power supply circuit can be simplified under the condition of ensuring the pressure difference, and the system performance can be improved.
Fig. 10 is a schematic diagram of current-voltage variation of the LED driving system shown in fig. 9. As shown in fig. 10, t represents time, and the current I _ LED flowing through the LED varies with the PWM signal, I _ LED is positive during the PWM pulse, and I _ LED is 0 at other times.
The voltage of a second end VSS _ LED of the switch circuit changes along with the change of the current I _ LED, and when the I _ LED is 0, the voltage of the VSS _ LED is-V _ LED/2; when I _ LED is positive, the voltage of VSS _ LED is slightly larger than-V _ LED/2 due to the current passing through, and the specific magnitude is related to the resistance value of VSS _ LED to the ground of the second power circuit.
Since the second terminal VSS _ LED of the switch tube is no longer connected to ground, and is naturally no longer connected to the ground terminal GND of the control circuit, the ground terminal GND of the control circuit is not substantially affected when the I _ LED changes, and is fixed to 0. The voltage of the power supply end VDD of the control circuit basically does not change, so that the voltage difference between the power supply end VDD of the control circuit and the ground end GND basically keeps unchanged, and the working stability of the control circuit can be improved.
In the LED driving system provided in this embodiment, except that the voltage of the second terminal VSS _ LED of the switching tube is different from the scheme in the second embodiment, the structure, function, connection relationship, etc. of other devices can be referred to the scheme in the second embodiment.
In the LED driving system provided by this embodiment, the ground terminal of the control circuit is connected to the ground of the first power supply circuit, and the second terminal of the switching tube is connected to the negative voltage terminal of the second power supply circuit, so that the switching circuit does not need to be connected to the ground, i.e., does not need to be 0V, which provides a greater degree of freedom for circuit design, and the second terminal of the switching tube can use any voltage, so that the voltage of the switching tube can be designed according to actual needs on the basis of improving the system stability, and application requirements of different scenes can be met.
Example four
The fourth embodiment of the invention provides an LED driving system. The present embodiment is different from the second and third embodiments in that the switch circuit may include a plurality of switch tubes, and the switch tubes respectively control different LEDs.
Specifically, the number of the switch tubes in the switch circuit is two, and the number of the LEDs controlled by the switch circuit is multiple, wherein part of the LEDs in the multiple LEDs are controlled by a first switch tube of the two switch tubes, and the rest of the LEDs are controlled by a second switch tube; the first end of the first switch tube and the first end of the second switch tube are both connected with the LED, and the second end of the first switch tube and the second end of the second switch tube are both connected with the grounding end of the second power supply circuit.
Further, the LED controlled by the first switching tube is connected to the positive voltage end of the second power supply circuit, and the LED controlled by the second switching tube is connected to the negative voltage end of the second power supply circuit; the voltage of the positive voltage end of the second power supply circuit is equal to the absolute value of the voltage of the negative voltage end.
Fig. 11 is a schematic structural diagram of an LED driving system according to a fourth embodiment of the present invention. As shown in fig. 11, the LED circuit board is provided with an LED driver and an LED, and the driving circuit board is provided with a first power supply circuit and a second power supply circuit. The LED driver includes a control circuit and a switching circuit. The control circuit includes a power terminal VDD connected to a power terminal of the first power circuit and a ground terminal GND connected to a ground of the first power circuit.
The switch circuit includes two switch tubes, optionally, the first switch tube may be an NMOS transistor in the figure, and the second switch tube may be a PMOS (P-Metal-Oxide-Semiconductor) transistor in the figure.
The second end of the first switch tube is connected with the second end of the second switch tube and is marked as VSS _ LED, and the VSS _ LED is connected to the ground of the second power supply circuit.
The first switch tube and the second switch tube control different LEDs, which are respectively marked as D1 and D2. The first end of the first switch tube is connected with the negative electrode of D1, the positive electrode of D1 is connected with the positive voltage end of the second power supply circuit, the first end of the second switch tube is connected with the positive electrode of D2, and the negative electrode of D2 is connected with the negative voltage end of the second power supply circuit, so that a closed loop is formed. The voltages output by the positive voltage end and the negative voltage end of the second power supply circuit are V _ LED/2 and-V _ LED/2 respectively.
When the first switch tube is turned on or off, the loop of the D1 is turned on or off, thereby controlling the on and off of the D1. Similarly, when the second switch tube is turned on or off, the loop of D2 is turned on or off, thereby controlling on/off of D2.
The control circuit can control the on-off of the two switching tubes. Specifically, the control circuit may be connected to the control ends of the two switching tubes, and the switching tubes may be controlled to be turned on or off by sending PWM signals to the control ends of the two switching tubes, respectively.
Optionally, the signal sent to the control terminal of the NMOS transistor is the same as or complementary to the signal sent to the control terminal of the PMOS transistor.
Specifically, when the control ends of the NMOS transistor and the PMOS transistor input the same PWM signal, the brightness changes of the two LEDs are complementary, that is, when one of the LEDs is on, the other LED is not on; when the control ends of the NMOS transistor and the PMOS transistor input complementary PWM signals, the PMOS transistor and the NMOS transistor are conducted at the same time, and the brightness changes of the two LEDs are the same. Where complementary may refer to high-low level complementary, i.e., one signal is high while the other signal is low.
Optionally, the positive voltage output by the second power supply circuit may be V _ LED/2, and the negative voltage output by the second power supply circuit may be-V _ LED/2, so that the two LEDs have the same voltage drop, and the normal operation of each LED is ensured.
Fig. 12 is a schematic diagram of current-voltage variation of the LED driving system shown in fig. 11. As shown in fig. 12, t represents time, and the current I _ LED flowing through the LED varies with the PWM signal, I _ LED is positive during the PWM pulse, and I _ LED is 0 at other times.
The voltage of a second end VSS _ LED of the switching tube changes along with the change of the current I _ LED, and when the I _ LED is 0, the voltage of the VSS _ LED is 0; when the I _ LED is positive, the voltage of the VSS _ LED is slightly larger than 0 due to the passing of current, and the specific magnitude is related to the resistance value from the VSS _ LED to the ground of the second power circuit.
The ground terminal GND of the control circuit is separated from the second terminal VSS _ LED of the switch circuit, so that the voltage of the ground terminal GND of the control circuit is less influenced by the I _ LED, and the voltage fluctuation is not large and is about 0. The voltage of the power supply end VDD of the control circuit basically does not change, so that the voltage difference between the power supply end VDD of the control circuit and the ground end GND basically keeps unchanged, and the working stability of the control circuit can be improved.
In the LED driving system provided in this embodiment, except that the switching circuit includes two switching tubes, the structures, functions, connection relationships, and the like of other devices can be referred to in the schemes of the second and third embodiments.
In the LED driving system provided in this embodiment, the number of the switching tubes in the switching circuit is two, and the number of the LEDs controlled by the switching circuit is multiple, wherein some LEDs in the multiple LEDs are controlled by the first switching tube of the two switching tubes, and the remaining LEDs are controlled by the second switching tube; the first end of the first switch tube and the first end of the second switch tube are both connected with an LED, the second end of the first switch tube and the second end of the second switch tube are both connected with the grounding end of the second power supply circuit, the LED controlled by the first switch tube is connected with the positive voltage end of the second power supply circuit, and the LED controlled by the second switch tube is connected with the negative voltage end of the second power supply circuit; the absolute value of the voltage of the positive voltage end of the second power supply circuit is equal to the absolute value of the voltage of the negative voltage end of the second power supply circuit, so that different LEDs are controlled through different switch tubes, the second ends of the switch tubes do not influence the grounding end GND of the control circuit, and the flexibility of LED control is improved on the basis of reducing misoperation of the circuit.
In practical applications, the voltage and current values of the respective devices of the LED driving system can be designed according to practical requirements. Optionally, the voltage value of the power source terminal VDD of the control circuit may be 1.8V to 5V, V _ LED may be 10V to 80V, VSS _ LED may be designed to be 0V or-V _ LED/2, I _ LED may be 1mA to 120mA, and the frequency of the PWM signal may be 60Hz to 4 khz.
In various embodiments of the present invention, the switching circuit may include one or more switching tubes. It will be appreciated that the respective ends of the switching circuit may comprise respective ends of the one or more switching tubes. For example, the control terminal of the switching circuit may comprise a control terminal of a switching tube. In the case where the switching circuit includes a plurality of switching tubes, there may be a plurality of control terminals of the switching circuit.
The above embodiments show several specific implementations of LED driving. On the basis, the circuit can be properly adjusted according to actual needs, for example, the transistor is adjusted to be a triode, the power circuit is adjusted to be other types of power circuits, more switching tubes are added, and the like. The embodiments of the present invention are not limited in this regard.
The embodiment of the invention also provides electronic equipment which comprises the LED driving system and the liquid crystal panel. The LED driving system is used for providing backlight for the liquid crystal panel.
The electronic device may be any device having a display function, such as a liquid crystal television.
The structure, function, and connection relationship of each component in the electronic device can be referred to the foregoing embodiments, and are not described herein again.
In the embodiments provided in the present invention, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the above-described device embodiments are merely illustrative, and for example, the division of the modules is only one logical division, and other divisions may be realized in practice, for example, a plurality of modules may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or modules, and may be in an electrical, mechanical or other form.
The modules described as separate parts may or may not be physically separate, and parts displayed as modules may or may not be physical units, may be located in one place, or may be distributed on a plurality of units. Some or all of the modules may be selected according to actual needs to implement the solution of the present embodiment.
In addition, functional modules in the embodiments of the present invention may be integrated into one processing unit, or each module may exist alone physically, or two or more modules are integrated into one unit.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (7)

1. An LED driving system, characterized in that the LED driving system comprises an LED circuit board;
the LED circuit board comprises an LED driver and an LED;
the LED driver comprises a control circuit and a switch circuit;
the switch circuit is used for controlling the brightness of the LED;
the control circuit is connected with the control end of the switch circuit and is used for controlling the on-off of the switch circuit;
the other ends of the switch circuit except the control end and the grounding end of the control circuit are arranged in the LED driver in a separated way,
the LED driving system further comprises a driving circuit board;
the driving circuit board comprises a first power supply circuit for supplying power to the control circuit and a second power supply circuit for supplying power to the LED,
the switching circuit comprises a switching tube, and the switching tube comprises a control end, a first end and a second end;
the first end of the switch tube is connected with one end of the LED controlled by the switch tube, and the second end of the switch tube is connected with the second power supply circuit;
the ground terminal of the control circuit is connected to the ground of the first power supply circuit,
the other end of the LED controlled by the switch tube is connected with the positive voltage end of the second power supply circuit;
and the second end of the switch tube is connected with the ground or negative voltage end of the second power supply circuit.
2. The system of claim 1, wherein the LED driving system further comprises other circuit boards;
and the grounding end of the switch circuit and the grounding end of the control circuit are connected on the other circuit boards.
3. The system of claim 1, wherein the number of the switch tubes in the switch circuit is two, and the number of the LEDs controlled by the switch circuit is multiple, wherein a part of the LEDs in the multiple LEDs is controlled by a first switch tube of the two switch tubes, and the rest of the LEDs are controlled by a second switch tube;
and the second end of the first switching tube and the second end of the second switching tube are both connected with the grounding end of the second power supply circuit.
4. The system of claim 3, wherein the first switch controlled LED is connected to a positive voltage terminal of the second power supply circuit and the second switch controlled LED is connected to a negative voltage terminal of the second power supply circuit;
the voltage of the positive voltage end of the second power supply circuit is equal to the absolute value of the voltage of the negative voltage end.
5. The system of claim 4, wherein the first switch is an NMOS transistor and the second switch is a PMOS transistor; and the signal sent to the control end of the NMOS transistor is the same as or complementary to the signal sent to the control end of the PMOS transistor.
6. The system according to any one of claims 1 and 3-5, wherein the LED controlled by the switch tube is one LED or an LED string formed by connecting a plurality of LEDs in series.
7. An electronic device comprising the LED driving system according to any one of claims 1 to 6 and a liquid crystal panel.
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Publication number Priority date Publication date Assignee Title
CN112689366B (en) * 2020-11-03 2021-09-07 北京显芯科技有限公司 LED driving system and electronic equipment
CN114267303B (en) * 2021-12-31 2022-08-09 北京显芯科技有限公司 Method, device and equipment for adjusting brightness

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104835820A (en) * 2014-02-10 2015-08-12 富士电机株式会社 Semiconductor device, control IC for switching power supply, and switching power supply unit
CN111030480A (en) * 2019-12-30 2020-04-17 上海晶丰明源半导体股份有限公司 Switching power supply system and constant voltage control circuit

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006324534A (en) * 2005-05-20 2006-11-30 Seiko Instruments Inc Light emitting diode driving circuit
CN201789662U (en) * 2010-08-17 2011-04-06 深圳市洲明科技股份有限公司 Led control circuit
CN102480819A (en) * 2010-11-24 2012-05-30 海洋王照明科技股份有限公司 LED driving circuit
CN102333402B (en) * 2011-06-02 2013-03-13 张家港市瑞腾科技有限公司 Drive circuit of LED lamp
CN107567144B (en) * 2017-09-26 2023-12-26 上海晶丰明源半导体股份有限公司 Color mixing controller, color mixing control chip and dimming and color mixing LED driving control circuit
CN111083844B (en) * 2019-12-30 2022-03-25 上海晶丰明源半导体股份有限公司 LED color modulation driving circuit and color modulation controller
CN112689366B (en) * 2020-11-03 2021-09-07 北京显芯科技有限公司 LED driving system and electronic equipment

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104835820A (en) * 2014-02-10 2015-08-12 富士电机株式会社 Semiconductor device, control IC for switching power supply, and switching power supply unit
CN111030480A (en) * 2019-12-30 2020-04-17 上海晶丰明源半导体股份有限公司 Switching power supply system and constant voltage control circuit

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
《如何处理AGND和PGND接地的问题》;电子发烧友;《http://www.elecfans.com/d/864463.html》;20190213;第1页-第2页 *

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