CN214847675U - LED backlight driving circuit - Google Patents
LED backlight driving circuit Download PDFInfo
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- CN214847675U CN214847675U CN202120419932.5U CN202120419932U CN214847675U CN 214847675 U CN214847675 U CN 214847675U CN 202120419932 U CN202120419932 U CN 202120419932U CN 214847675 U CN214847675 U CN 214847675U
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Abstract
The utility model relates to a LED drive technical field discloses a stable and higher LED drive circuit in a poor light of security of output drive current possesses: the control circuit (101) is configured in the LED backlight driving circuit and used for generating and outputting an excitation signal; the input end of the booster circuit (103) is coupled to the output end of the control circuit (101) and used for receiving an excitation signal, the other input end of the booster circuit (103) is connected with the power supply output end and used for receiving a low-voltage power supply signal, and the output end of the booster circuit (103) is connected with the anode of the LED lamp bar; the excitation signal is used for adjusting the driving current output by the boost circuit (103) so as to control the LED lamp strip to emit light.
Description
Technical Field
The utility model relates to a LED drive technical field, more specifically say, relate to a LED drive circuit that is shaded.
Background
The LED backlight driving circuit is a commonly used circuit in the lcd, and has the characteristics of light weight, low power consumption and high light emitting efficiency. At present, when a pulse signal output by a driving circuit is unstable, the current passing through an LED is increased, and when the driving circuit is used for a long time, the temperature of the LED is increased, so that the power consumption of the LED is increased or the LED is broken down by a peak current.
Therefore, how to improve the stability of the driving current output by the driving circuit becomes a technical problem that needs to be solved by those skilled in the art.
SUMMERY OF THE UTILITY MODEL
The to-be-solved technical problem of the utility model lies in, when drive circuit output PWM pulse signal is unstable to the aforesaid of prior art, through LED's electric current grow for LED's temperature rises rapidly, causes LED's consumption to increase or by the defect that peak current punctures, provides the LED drive circuit that is shaded that an output drive current is stable and the security is higher.
The utility model provides a technical scheme that its technical problem adopted is: an LED backlight drive circuit is configured to include:
the control circuit is configured in the LED backlight driving circuit and used for generating and outputting an excitation signal;
a boost circuit having an input coupled to the output of the control circuit for receiving the excitation signal,
the other input end of the booster circuit is connected with the power supply output end and used for receiving a low-voltage power supply signal, and the output end of the booster circuit is connected with the anode of the LED lamp strip;
the excitation signal is used for adjusting the driving current output by the booster circuit so as to control the LED lamp strip to emit light.
In some embodiments, the control circuit includes a drive control chip for generating and outputting the excitation signal;
the booster circuit comprises a first field effect transistor, and the grid electrode of the first field effect transistor is coupled to the signal output end of the drive control chip and used for receiving the excitation signal;
the drain electrode of the first field effect tube is connected with the anode of the LED lamp bar,
and the source electrode of the first field effect transistor is connected with one end of the first current sampling circuit.
In some embodiments, the boost circuit further comprises a first triode, a base of the first triode is connected with the signal output end of the drive control chip through a fifteenth resistor,
the emitter of the first triode is coupled with the grid of the first field effect transistor,
and the collector of the first triode is connected with one end of the first current sampling circuit.
In some embodiments, the device further comprises a dimming control circuit, an input end of the dimming control circuit is connected with a PWM signal output end of an external chip, and the dimming control circuit is used for receiving a PWM signal input by the external chip;
the output end of the dimming control circuit is connected with the external dimming control end of the drive control chip, and the drive control chip is used for receiving the PWM signal and controlling the brightness intensity of the LED lamp strip through the dimming control circuit.
In some embodiments, the lighting device further comprises an LED current feedback circuit, wherein a signal input end of the LED current feedback circuit is connected to one end of the LED light bar, and is used for acquiring a current signal of the LED light bar;
the current setting end of the driving control chip is connected with the output end of the LED current feedback circuit, and the driving control chip adjusts the output excitation signal according to the current signal.
In some embodiments, the LED current feedback circuit includes a sixth resistor, and one end of the sixth resistor is connected to one end of the LED light bar, so as to obtain a current signal of the LED light bar;
and the current setting end of the drive control chip is connected with the other end of the sixth resistor.
In some embodiments, the first fet is an N-channel enhancement mode fet.
Among the LED drive circuit that is shaded, including control circuit and a boost circuit that is used for producing and exporting excitation signal, wherein, an input of boost circuit is coupled in control circuit's output for receive excitation signal, this excitation signal is used for adjusting the drive current of boost circuit output, luminous with control LED lamp strip. Compared with the prior art, the booster circuit controls the LED lamp strip to work according to the excitation signal output by the control circuit, and the problem that when the pulse signal output by the driving circuit is unstable, the temperature of the LED rises due to the increase of the current of the LED, so that the power consumption of the LED is increased or the LED is broken down by the peak current can be effectively solved.
Drawings
The invention will be further explained with reference to the drawings and examples, wherein:
fig. 1 is a schematic circuit diagram of an embodiment of an LED backlight driving circuit provided by the present invention.
Detailed Description
In order to clearly understand the technical features, objects, and effects of the present invention, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
As shown in fig. 1, in the first embodiment of the LED backlight driving circuit of the present invention, the LED backlight driving circuit 100 includes a control circuit 101, a dimming control circuit 102 and a voltage boosting circuit 103.
Specifically, the control circuit 101 is configured in the LED backlight driving circuit 100, and is configured to receive a PWM pulse signal output by an external chip, control the output driving end (corresponding to pin 2 of the driving control chip U101) to output an excitation signal (corresponding to GATEI) or a duty ratio of a square wave signal through the internal comparator, and output the excitation signal (corresponding to GATEI) or the square wave signal to the voltage boosting circuit 103, so as to adjust or control the current of the LED light bar.
The boost circuit 103 can boost an input dc voltage (corresponding to 65V) through the first inductor L101 and the first field effect transistor VT101, so that the positive electrode (corresponding to the LED + terminal) of the LED light bar is raised to 120V-160V, thereby driving the LED light bar.
Specifically, an input terminal (corresponding to the GATEI terminal) of the voltage boost circuit 103 is connected to the output terminal of the control circuit 101, and is configured to receive the excitation signal (corresponding to the GATEI) output by the control circuit 101.
The other input end of the boost circuit 103 is connected with a power output end (corresponding to a VBL end) and is used for receiving a low-voltage power signal (corresponding to 65V), and the output end of the boost circuit 103 is connected with the anode (corresponding to an LED + end) of the LED light bar.
The excitation signal (corresponding to GATEI) triggers the boost circuit 103 to operate, so that the boost circuit 103 can boost the input dc voltage, and further adjust the output driving current of the boost circuit 103 to control the LED light bar to emit light.
By using the technical scheme, the boosting circuit 103 controls the LED light bar to work according to the excitation signal (corresponding to GATEI) output by the control circuit 101, and further solves the problem that when the pulse signal output by the driving circuit is unstable, the temperature of the LED rises due to the increase of the current of the LED, so that the power consumption of the LED is increased or the LED is broken down by the current.
In some embodiments, in order to improve the stability of the operation of the LED light bar, a driving control chip U101 may be disposed in the control circuit 101, wherein the driving control chip U101 has functions of generating and outputting an excitation signal, adjusting a pulse signal, protecting against overheating, and protecting against overcurrent.
Specifically, the driving control chip U101 is provided with 8 pins, which correspond to: the device comprises a power input end (VIN end) as a pin 1, a signal output end (GATE end) as a pin 2, a common end (GND end) as a pin 3, an output current monitoring end (CS end) as a pin 4, a current setting end (FB end) as a pin 5, a feedback end (COMP end) as a pin 6, an overvoltage protection monitoring input end (OVP end) as a pin 7 and an external dimming control end (PWM end).
Specifically, a 12V voltage signal is input to pin 1 of the driving control chip U101 through the second resistor R102 to trigger the driving control chip U101 to operate, so as to generate and output an excitation signal, and output the excitation signal to the first fet VT101 (belonging to the voltage boost circuit 103).
The boost circuit 103 includes a first fet VT101, wherein the first fet VT101 is an N-channel enhancement fet, which has a switching function.
Specifically, the GATE of the first fet VT101 is connected to the signal output terminal (corresponding to the GATE terminal) of the driving control chip U101 through the fourteenth resistor R114, and the excitation signal (corresponding to the GATE terminal) is input to the GATE of the first fet VT101 through the fourteenth resistor R114 to control the operating state of the first fet VT 101.
The drain of the first field effect transistor VT101 is connected to the anode of the LED light bar through the fourth diode D104, and the source of the first field effect transistor VT101 is connected to one end of the first current sampling circuit 105 a.
When the first field effect transistor VT101 is triggered and turned on, the input dc voltage (corresponding to 65V) is boosted by the boost inductor (corresponding to the first inductor L101), and then is input to the anode of the LED light bar through the fourth diode D104 to control the LED light bar to emit light.
In some embodiments, in order to improve the stability of the operation of the LED light bar, a first transistor VT103 may be disposed in the boost circuit 103, wherein the first transistor VT103 is a PNP transistor, and has a switching function.
Specifically, the base of the first transistor VT103 is connected to the signal output terminal (corresponding to 2 pins) of the driving control chip U101 through a fifteenth resistor R115, and is configured to receive the driving control chip U101 output excitation signal.
The emitter of the first transistor VT103 is coupled to the gate of the first field effect transistor VT101, and the collector of the first transistor VT103 is connected to one end of the first current sampling circuit 105 a.
In some embodiments, in order to improve the usability of the LED light bar, the dimming control circuit 102 may be disposed in the LED backlight driving circuit 100. The input terminal (corresponding to ADJ-ON) of the dimming control circuit 102 is connected to a PWM signal output terminal of an external chip (not shown in the figure), and is configured to receive a PWM signal input by the external chip (not shown in the figure).
The output end of the dimming control circuit 102 is connected with an external dimming control end (corresponding to 8 pins) of the driving control chip U101, and the driving control chip U101 is used for receiving the PWM signal, adjusting the duty ratio of the PWM signal, and then performing brightness intensity control on the LED light bar through the dimming control circuit 102.
Specifically, the dimming control circuit 102 inputs a pulse signal (corresponding to the PWM signal) to an external dimming control pin (corresponding to 8 pins) of the driving control chip U101, and the driving control chip U101 automatically controls the duty ratio of the output excitation signal (corresponding to GATEI) by adjusting the duty ratio of the pulse signal, thereby changing the lighting time of the LED lamp in a unit time and realizing the control of the intensity of the backlight brightness.
In some embodiments, in order to improve the safety of the operation of the LED light bar, an LED current feedback circuit 104 may be disposed in the LED backlight driving circuit 100, wherein a signal input terminal (corresponding to the LED-FB terminal) of the LED current feedback circuit 104 is connected to one end (corresponding to the LED-FB terminal) of the LED light bar for obtaining a current signal of the LED light bar.
Further, a current setting end (corresponding to the 5 pins) of the driving control chip U101 is connected to an output end of the LED current feedback circuit 104, and when a current signal obtained by the LED current feedback circuit 104 is greater than a preset value of the driving control chip U101, the driving control chip U101 adjusts an output excitation signal according to the fed-back current signal.
In some embodiments, the LED current feedback circuit 104 includes a sixth resistor R106, wherein one end of the sixth resistor R106 is connected to one end (corresponding to the LED-FB end) of the LED light bar for obtaining a current signal of the LED light bar; the current setting end (corresponding to the 5 pins) of the driving control chip U101 is connected to the other end of the sixth resistor R106.
That is, the current signal is input to the current setting end (corresponding to the 5 pins) of the driving control chip U101 through the sixth resistor R106, and the driving control chip U101 adjusts the output excitation signal according to the feedback current signal.
In some embodiments, in order to improve the safety of the operation of the LED light bar, an overcurrent protection circuit may be disposed in the LED backlight driving circuit 100, wherein the overcurrent protection circuit includes a seventh resistor R107, specifically, one end of the seventh resistor R107 is commonly connected to one end of the first current sampling circuit 105a and the source of the first field-effect transistor VT101, and the other end of the seventh resistor R107 is coupled to an output current monitoring end (CS end) of the driving control chip U101.
Specifically, the seventh resistor R107 inputs the obtained overcurrent signal to an output current monitoring terminal (CS terminal) of the driving control chip U101, and when the current of the source of the first field effect transistor VT101 is too large and the overcurrent signal input to the output current monitoring terminal (CS terminal) of the driving control chip U101 is greater than a preset value, the overcurrent signal circuit inside the driving control chip U101 is started, and the excitation signal (corresponding to GATEI) is turned off to be output.
The working principle is as follows: when the LED lamp is turned ON, a lighting signal (corresponding to BL-ON) output by an external chip (not shown in the figure) changes from a low level to a high level during standby, and the third diode D103 is turned off in a reverse bias manner, so that the input of a brightness adjustment signal (corresponding to ADJ-ON) of an external dimming control pin (corresponding to 8 pins) of the driving control chip U101 is not affected, and therefore, a signal output end (corresponding to 2 pins) of the driving control chip U101 can normally output an excitation signal, and the boost circuit 103 can boost a voltage of 65V to provide a normal power supply voltage for the LED lamp strip, so as to light the lamp strip, thereby realizing lighting control.
After the LED lamp is turned off, a lighting signal (corresponding to BL-ON) is changed into a low level, the third diode D103 is conducted, a brightness adjusting signal (corresponding to ADJ-ON) bypasses to the ground through the third diode D103 and the control circuit 101 and cannot be input into an external dimming control pin (corresponding to 8 pins) of the driving control chip U101, an excitation signal is turned off at a signal output end (corresponding to 2 pins) of the driving control chip U101, the boosting circuit 103 cannot boost, the voltage drop provided for the LED lamp bar is lower than 65V, at the moment, the LED lamp bar cannot be lighted, and the LED lamp bar is in an off state.
While the embodiments of the present invention have been described with reference to the accompanying drawings, the present invention is not limited to the above-described embodiments, which are merely illustrative and not restrictive, and many modifications may be made by one skilled in the art without departing from the spirit and scope of the present invention as defined in the appended claims.
Claims (7)
1. An LED backlight drive circuit, comprising:
the control circuit is configured in the LED backlight driving circuit and used for generating and outputting an excitation signal;
a boost circuit having an input coupled to the output of the control circuit for receiving the excitation signal,
the other input end of the booster circuit is connected with the power supply output end and used for receiving a low-voltage power supply signal, and the output end of the booster circuit is connected with the anode of the LED lamp strip;
the excitation signal is used for adjusting the driving current output by the booster circuit so as to control the LED lamp strip to emit light.
2. The LED backlight driver circuit according to claim 1,
the control circuit comprises a drive control chip, and the drive control chip is used for generating and outputting an excitation signal;
the booster circuit comprises a first field effect transistor, and the grid electrode of the first field effect transistor is coupled to the signal output end of the drive control chip and used for receiving the excitation signal;
the drain electrode of the first field effect tube is connected with the anode of the LED lamp bar,
and the source electrode of the first field effect transistor is connected with one end of the first current sampling circuit.
3. The LED backlight driver circuit according to claim 2,
the booster circuit also comprises a first triode, the base electrode of the first triode is connected with the signal output end of the drive control chip through a fifteenth resistor,
the emitter of the first triode is coupled with the grid of the first field effect transistor,
and the collector of the first triode is connected with one end of the first current sampling circuit.
4. The LED backlight driver circuit according to claim 2,
the input end of the dimming control circuit is connected with the PWM signal output end of an external chip and is used for receiving the PWM signal input by the external chip;
the output end of the dimming control circuit is connected with the external dimming control end of the drive control chip, and the drive control chip is used for receiving the PWM signal and controlling the brightness intensity of the LED lamp strip through the dimming control circuit.
5. The LED backlight driver circuit according to claim 2,
the signal input end of the LED current feedback circuit is connected with one end of the LED light bar and used for acquiring a current signal of the LED light bar;
the current setting end of the driving control chip is connected with the output end of the LED current feedback circuit, and the driving control chip adjusts the output excitation signal according to the current signal.
6. The LED backlight driver circuit according to claim 5,
the LED current feedback circuit comprises a sixth resistor, one end of the sixth resistor is connected with one end of the LED light bar, and the sixth resistor is used for acquiring a current signal of the LED light bar;
and the current setting end of the drive control chip is connected with the other end of the sixth resistor.
7. The LED backlight driver circuit according to claim 2 or 3,
the first field effect transistor is an N-channel enhanced field effect transistor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120419932.5U CN214847675U (en) | 2021-02-26 | 2021-02-26 | LED backlight driving circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120419932.5U CN214847675U (en) | 2021-02-26 | 2021-02-26 | LED backlight driving circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN214847675U true CN214847675U (en) | 2021-11-23 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202120419932.5U Expired - Fee Related CN214847675U (en) | 2021-02-26 | 2021-02-26 | LED backlight driving circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN214847675U (en) |
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2021
- 2021-02-26 CN CN202120419932.5U patent/CN214847675U/en not_active Expired - Fee Related
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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: 20211123 |