CN210429267U - LED backlight driving circuit - Google Patents
LED backlight driving circuit Download PDFInfo
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- CN210429267U CN210429267U CN201921518661.8U CN201921518661U CN210429267U CN 210429267 U CN210429267 U CN 210429267U CN 201921518661 U CN201921518661 U CN 201921518661U CN 210429267 U CN210429267 U CN 210429267U
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- feedback
- driving chip
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- effect transistor
- field effect
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B20/40—Control techniques providing energy savings, e.g. smart controller or presence detection
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Abstract
The utility model discloses a LED backlight driving circuit, which comprises a driving chip, an LED lamp group, a feedback resistor and a feedback voltage adjusting circuit; one end of the feedback resistor is connected with the feedback end of the driving chip, and the other end of the feedback resistor is grounded; the PWM control pin of the driving chip is connected with the PWM waveform generator; the feedback voltage adjusting circuit comprises a first resistor, an MOS field effect transistor and a voltage input end; one end of the first resistor is connected with the feedback end of the driving chip, and the other end of the first resistor is connected with the MOS field effect transistor; and the voltage input end is used for controlling the on and off of the MOS field effect transistor. According to the utility model discloses a LED drive circuit that is shaded, the resistance of first resistance and the switching on of MOS field effect transistor in the duty cycle through adjusting the PWM waveform, feedback resistance's resistance and the feedback voltage adjusting circuit will export the electric current regulation of LED banks to 0.02-0.04MA for LED banks is in a poor light power saving more, and light is softer when using night simultaneously.
Description
Technical Field
The utility model relates to a LED drive circuit that is shaded.
Background
With the development of electronic and communication technologies, various electronic display devices are in a large number, and some electronic products or some operation panels are provided with a backlight, the minimum current output by the backlight circuit of the backlight at present is between 0.2 and 0.1MA, and the output current of 0.2 to 0.1MA brings unnecessary power consumption, and when the electronic display device is used at night, the backlight is too bright to affect eyes.
The above is only for the purpose of assisting understanding of the technical solutions of the present invention, and does not represent an admission that the above is the prior art.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide an energy-conserving power saving's LED drive circuit that is shaded.
The utility model discloses a following technical scheme realizes: the LED backlight driving circuit comprises a driving chip, an LED lamp group, a feedback resistor and a feedback voltage adjusting circuit;
the positive electrode of the LED lamp group is connected with the power output end of the driving chip, and the negative electrode of the LED lamp group is connected with the feedback end of the driving chip;
one end of the feedback resistor is connected with the feedback end of the driving chip, and the other end of the feedback resistor is grounded;
the PWM control pin of the driving chip is connected with the PWM waveform generator;
the feedback voltage adjusting circuit comprises a first resistor, an MOS field effect transistor and a voltage input end;
one end of the first resistor is connected with the feedback end of the driving chip, and the other end of the first resistor is connected with the drain electrode of the MOS field effect transistor;
the grid electrode of the MOS field effect transistor is connected with the voltage input end, and the source electrode of the MOS field effect transistor is grounded;
the voltage input end is used for inputting a voltage signal so as to control the on and off of the MOS field effect transistor.
As a further improvement of the above technical solution, the duty ratio of the PWM waveform sent by the PWM waveform generator is 1: 255.
As a further improvement of the above technical solution, the LED lamp set includes 8 light emitting diodes connected in series.
As a further improvement of the above technical solution, the LED backlight driving circuit further includes a first capacitor, a second capacitor, an inductor, and a zener diode;
one end of the inductor is connected with the power supply input end of the driving chip, and the other end of the inductor is connected with the power supply output end of the driving chip;
one end of the first capacitor is connected with the power input end of the driving chip, and the other end of the first capacitor is grounded;
the positive electrode of the voltage stabilizing diode is connected with the power output end of the driving chip, the negative electrode of the voltage stabilizing diode is connected with the second capacitor, and the other end of the second capacitor is grounded.
As a further improvement of the above technical solution, the LED backlight driving circuit further includes an overvoltage protection resistor, one end of the overvoltage protection resistor is connected to the anode of the LED lamp set, and the other end of the overvoltage protection resistor is connected to an overvoltage protection pin of the driving chip.
The beneficial effects of the utility model include at least: the utility model discloses a LED drive circuit that is shaded, the resistance of first resistance and the switching on of MOS field effect transistor in duty cycle, feedback resistance and the feedback voltage adjusting circuit through adjusting the PWM waveform, will export the electric current regulation of LED banks to 0.02-0.04MA for LED banks power saving in a poor light is more, and light is softer when using night simultaneously.
Drawings
Fig. 1 is a circuit diagram of an LED backlight driving circuit according to an embodiment of the present invention;
fig. 2 is a circuit diagram of a feedback voltage adjustment circuit according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. The components of embodiments of the present invention, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the accompanying drawings, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiment of the present invention, all other embodiments obtained by the person skilled in the art without creative work belong to the protection scope of the present invention.
As shown in fig. 1 to 2, the LED backlight driving circuit includes a driving chip 10, an LED lamp set 20, a feedback resistor R1, a PWM waveform generator, and a feedback voltage adjusting circuit 30; the anode of the LED lamp set 20 is connected to the power output terminal LX of the driving chip 10, and the cathode of the LED lamp set 20 is connected to the feedback terminal FB of the driving chip 10; one end of the feedback resistor R1 is connected with the feedback end FB of the driving chip 10, and the other end is grounded; the PWM waveform generator is connected to a PWM control pin CE of the driver chip 10; the feedback voltage adjusting circuit 30 is connected to the feedback terminal FB of the driver chip 10.
The PWM waveform generator is configured to send a PWM waveform signal to the driving chip 10 to control the lighting of the LED lamp set 20, the driving chip 10 is rapidly turned on and off by the PWM signal received by the PWM control pin CE, the average current of the LED lamp set 20 is increased in proportion to the duty ratio of the PWM signal, the driving chip 10 is completely turned off at a duty ratio of 0%, the LED has no current at all, and the duty ratio of 100% corresponds to a full current. In the present embodiment, the PWM waveform generator is an 8-bit PWM waveform generator, and its duty ratio can be adjusted between 1:255 to 100%, and in order to make the minimum current of the LED lamp set 20 between 0.04-0.02MA, the duty ratio of the PWM waveform is preferably 1: 255.
The LED light group 20 includes 8 series-connected light emitting diodes (D2-D9). It is understood that the LED lamp set 20 can also be other numbers of LEDs connected in series, or a plurality of LEDs connected in series and then connected in parallel.
The feedback voltage adjusting circuit 30 comprises a first resistor R2, a MOS field effect transistor Q1, a second resistor R3 and a voltage input end LED _ ENG; one end of the first resistor R2 is connected with the feedback end FB of the driving chip 10, and the other end is connected with the drain of the MOS field effect transistor Q1; the grid electrode of the MOS field effect transistor Q1 is connected with the voltage input end LED _ ENG, and the source electrode of the MOS field effect transistor Q1 is grounded; one end of the second resistor R3 is connected with the voltage input end LED _ ENG, and the other end is grounded; the voltage input terminal LED _ ENG is used for inputting a voltage signal to control the switching of the MOS field effect transistor Q1. The MOS fet Q1 is an N-channel MOS fet, and adjusts the electrical signal input from the voltage input terminal LED _ ENG to a high voltage, so as to turn on the MOS fet Q1, and adjust the current of the LED lamp set 20 by adjusting the resistance value of R4 to change the feedback voltage received by the feedback terminal FB of the driver chip 10.
The LED backlight driving circuit further comprises a first capacitor C1, a second capacitor C2, an inductor L1 and a voltage stabilizing diode D1; one end of the inductor L1 is connected to the power input end VIN of the driver chip 10, and the other end is connected to the power output end LX of the driver chip 10; one end of the first capacitor C1 is connected to the power input terminal VIN of the driver chip 10, and the other end is grounded; the anode of the zener diode D1 is connected to the power output terminal LX of the driver chip 10, the cathode of the zener diode D1 is connected to the second capacitor C2, and the other end of the second capacitor C2 is grounded.
The LED backlight driving circuit further includes an overvoltage protection resistor R4, wherein one end of the overvoltage protection resistor R4 is connected to the anode of the LED lamp group 20, and the other end of the overvoltage protection resistor R4 is connected to an overvoltage protection pin OVP of the driving chip 10.
The driving chip 10 is a CP2123ST driving chip, the CP2123ST driving chip is a constant-frequency current-mode controlled BOOST DCDC converter, and can provide excellent voltage and load regulation capability, the CP2123ST driving chip is provided with a built-in 14MHz oscillator, at the beginning of each oscillation period, the RS flip-flop is set, and the switch tube is turned on. A sampling tube samples the current of the switching tube and feeds back a voltage proportional to the current to be superimposed with a ramp voltage generated by a ramp generator, which voltage is then fed to the positive terminal of the comparator. The voltage at the negative input of the comparator is an amplified signal derived from the difference between the feedback voltage FB and the internal reference voltage 300 mV. The error amplifier plays an important role in the stability of the whole loop, if the feedback voltage is lower, the output voltage of the error amplifier is increased, the switching tube is opened for a longer time, more current is transmitted to the output end, if the feedback voltage is higher, the output voltage of the error amplifier is reduced, the opening time of the switching tube is shortened, and less current is transmitted to the output end. Therefore, the value of the feedback voltage can be changed by adjusting the resistance value of the feedback resistor R1 and the resistance value of the first resistor R2, so that the magnitude of the current output to the LED lamp group can be adjusted.
The LED backlight driving circuit adjusts the current output to the LED lamp set 20 to be 0.02-0.04MA by adjusting the duty ratio of the PWM waveform, the resistance value of the feedback resistor R1, the resistance value of the first resistor R2 in the feedback voltage adjusting circuit 30 and the conduction of the MOS field effect transistor Q1, so that the backlight LED lamp set 20 is more power-saving, and meanwhile, the light is softer when the LED backlight driving circuit is used at night.
In the description of the present invention, it is to be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art. In addition, in the description of the present invention, "a plurality" means two or more unless otherwise specified.
In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "connected" and "connected" are to be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate.
In the description of the present specification, reference to the description of the terms "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example" or "some examples" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims (5)
1. The LED backlight driving circuit is characterized by comprising a driving chip, an LED lamp group, a feedback resistor and a feedback voltage adjusting circuit;
the positive electrode of the LED lamp group is connected with the power output end of the driving chip, and the negative electrode of the LED lamp group is connected with the feedback end of the driving chip;
one end of the feedback resistor is connected with the feedback end of the driving chip, and the other end of the feedback resistor is grounded;
the PWM control pin of the driving chip is connected with the PWM waveform generator;
the feedback voltage adjusting circuit comprises a first resistor, an MOS field effect transistor and a voltage input end;
one end of the first resistor is connected with the feedback end of the driving chip, and the other end of the first resistor is connected with the drain electrode of the MOS field effect transistor;
the grid electrode of the MOS field effect transistor is connected with the voltage input end, and the source electrode of the MOS field effect transistor is grounded;
the voltage input end is used for inputting a voltage signal so as to control the on and off of the MOS field effect transistor.
2. The LED backlight driving circuit of claim 1, wherein the PWM waveform generator sends a PWM waveform with a duty cycle of 1: 255.
3. The LED backlight driving circuit of claim 1, wherein the LED lamp set comprises 8 serially connected light emitting diodes.
4. The LED backlight driving circuit according to claim 1, further comprising a first capacitor, a second capacitor, an inductor, and a zener diode;
one end of the inductor is connected with the power supply input end of the driving chip, and the other end of the inductor is connected with the power supply output end of the driving chip;
one end of the first capacitor is connected with the power input end of the driving chip, and the other end of the first capacitor is grounded;
the positive electrode of the voltage stabilizing diode is connected with the power output end of the driving chip, the negative electrode of the voltage stabilizing diode is connected with the second capacitor, and the other end of the second capacitor is grounded.
5. The LED backlight driving circuit of claim 1, further comprising an overvoltage protection resistor, wherein one end of the overvoltage protection resistor is connected to the anode of the LED lamp set, and the other end of the overvoltage protection resistor is connected to an overvoltage protection pin of the driving chip.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921518661.8U CN210429267U (en) | 2019-09-11 | 2019-09-11 | LED backlight driving circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921518661.8U CN210429267U (en) | 2019-09-11 | 2019-09-11 | LED backlight driving circuit |
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| Publication Number | Publication Date |
|---|---|
| CN210429267U true CN210429267U (en) | 2020-04-28 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201921518661.8U Expired - Fee Related CN210429267U (en) | 2019-09-11 | 2019-09-11 | LED backlight driving circuit |
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| CN (1) | CN210429267U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116110352A (en) * | 2023-04-13 | 2023-05-12 | 杭州凡诺电子有限公司 | Backlight driving circuit |
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2019
- 2019-09-11 CN CN201921518661.8U patent/CN210429267U/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116110352A (en) * | 2023-04-13 | 2023-05-12 | 杭州凡诺电子有限公司 | Backlight driving circuit |
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| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20200428 Termination date: 20210911 |