CN106683621B - LED backlight driving circuit and method for realizing soft start - Google Patents
LED backlight driving circuit and method for realizing soft start Download PDFInfo
- Publication number
- CN106683621B CN106683621B CN201611255704.9A CN201611255704A CN106683621B CN 106683621 B CN106683621 B CN 106683621B CN 201611255704 A CN201611255704 A CN 201611255704A CN 106683621 B CN106683621 B CN 106683621B
- Authority
- CN
- China
- Prior art keywords
- resistor
- diode
- circuit
- pin
- driving
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000000034 method Methods 0.000 title claims abstract description 10
- 238000007599 discharging Methods 0.000 claims abstract description 15
- 239000003990 capacitor Substances 0.000 claims description 27
- 230000005669 field effect Effects 0.000 claims description 27
- 230000005856 abnormality Effects 0.000 abstract description 3
- 239000004973 liquid crystal related substance Substances 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
Classifications
-
- 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
- G09G3/3406—Control of illumination source
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- General Physics & Mathematics (AREA)
- Theoretical Computer Science (AREA)
- Liquid Crystal Display Device Control (AREA)
- Dc-Dc Converters (AREA)
Abstract
The invention discloses an LED backlight driving circuit and a method for realizing soft start, wherein the driving circuit comprises: a boost circuit for converting the first input voltage into a desired output voltage and providing the desired output voltage to the LED unit; a driving IC circuit for controlling the booster circuit to convert the first input voltage into a desired output voltage to be supplied to the LED unit, the driving IC circuit including a driving chip; a discharging circuit for discharging the electric charges stored in the voltage boosting circuit after the driving IC circuit is turned off; the discharging circuit comprises a first diode, the anode of the first diode is connected to the output pin of the error amplifier of the driving chip, and the cathode of the first diode is connected to the backlight switch output signal of the television main board. The LED backlight driving circuit provided by the invention has the advantages that the impact current of the boost inductor is limited when the whole LED backlight driving circuit is started, the phenomenon of abnormality caused by inductance saturation is avoided, and the soft start is realized.
Description
Technical Field
The invention relates to the field of LED backlight driving, in particular to an LED backlight driving circuit capable of limiting impact current when being started again after being closed and a method for realizing soft start.
Background
With the continuous progress of technology, the backlight technology of the liquid crystal display device is continuously developed. The backlight of the conventional liquid crystal display device employs a Cold Cathode Fluorescent Lamp (CCFL). However, the CCFL backlight has the disadvantages of poor color reduction capability, low luminous efficiency, high discharge voltage, poor discharge characteristics at low temperature, long time for reaching stable gray scale by heating, and the like, so that the backlight technology using the LED backlight has been widely used at present; in a liquid crystal display device, an LED backlight is disposed opposite a liquid crystal display panel such that the LED backlight provides a display light source to the liquid crystal display panel, wherein the LED backlight includes at least one LED string, each LED string including a plurality of LEDs connected in series.
In a boost circuit of a driving circuit of an LED backlight, a boost inductor is generally provided, and the system is very easy to generate impact current due to the boost inductor, so that the working stability of front and rear stage circuits is affected. If the system enters a standby state, the PWM control signal of the main board is pulled down, the output pin of the error amplifier of the driving chip is held by the HOLD, and the output voltage is discharged through a resistor in an overvoltage protection circuit of the driving chip; at this time, the system is restarted, the PWM control signal of the main board is pulled up, and since the output voltage is low at this time and the output current is smaller than the set value, the output pin of the error amplifier of the driving chip is pulled up rapidly on the basis of the previous one, and at this time, the current of the boost inductor is saturated and an abnormal phenomenon may occur.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, and provides an LED backlight driving circuit and a method for realizing soft start.
The technical scheme adopted for solving the technical problems is as follows:
an LED backlight driving circuit, comprising:
a boost circuit for converting the first input voltage into a desired output voltage and providing the desired output voltage to the LED unit;
a driving IC circuit for controlling the booster circuit to convert the first input voltage into a required output voltage and provide the required output voltage to the LED unit; the driving IC circuit comprises a driving chip;
a discharging circuit for discharging the electric charges stored in the voltage boosting circuit after the driving IC circuit is turned off;
the discharging circuit comprises a first diode, the anode of the first diode is connected to the output pin of the error amplifier of the driving chip, and the cathode of the first diode is connected to the backlight switch output signal of the television main board.
The boost circuit comprises a boost inductor, a second diode, a third diode, a first field effect transistor, a first capacitor and a second capacitor; one end of the boost inductor is connected with the first input voltage and used for receiving input direct-current voltage, and the other end of the boost inductor is respectively connected with the drain electrode of the first field effect tube, the anode of the second diode and the anode of the third diode; the source electrode of the first field effect tube is electrically grounded through a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor which are connected in parallel, the source electrode of the first field effect tube is also connected to the driving chip through a sixth resistor, and the grid electrode of the first field effect tube is connected to the driving chip through a seventh variable resistor and an eighth resistor; the second diode and the third diode are connected in parallel, the cathode of the second diode is respectively connected with one end of the first capacitor and the positive end of the LED unit, the cathode of the third diode is respectively connected with one end of the second capacitor and the positive end of the LED unit, and the other ends of the first capacitor and the second capacitor are electrically grounded.
The model of the driving chip is MP4008 and comprises VIN, GND, CS, GATE, OVP, FB, COMP and a PMN pin; wherein the VIN pin is connected with a second input voltage; the GND pin is electrically grounded; the CS pin is connected with the sixth resistor; the GATE pin is connected with the eighth resistor; the OVP pin is connected to the positive end of the LED unit through a ninth resistor, a tenth resistor and an eleventh resistor which are connected in series; the FB pin is connected to the error amplifier output pin COMP through a twelfth resistor, a third capacitor, a thirteenth resistor, and a fourth capacitor; the PMN pin is connected to the PWM control signal output end of the television main board through a fourteenth resistor, and the PMN pin is also connected with the OVP pin; the GATE pin is connected to the negative terminal of the LED unit through a fifteenth resistor, a fourth diode, a sixteenth resistor, and a second field effect transistor.
The drain electrode of the second field effect tube is connected with the negative end of the LED unit; the grid electrode of the second field effect transistor is connected with the sixteenth resistor; the source electrode of the second field effect transistor is connected between the twelve resistors and the third capacitor through a seventeenth resistor, and the source electrode of the second field effect transistor is electrically grounded through an eighteenth resistor, a nineteenth resistor, a twentieth resistor, a twenty first resistor, a twenty second resistor and a twenty third resistor which are connected in parallel.
The LED unit is a plurality of LED strings connected in parallel, wherein each LED string comprises a plurality of LEDs connected in series.
A method for realizing soft start of LED backlight driving circuit includes connecting error amplifier output pin of driving chip to backlight switch output signal of TV set main board through first diode, changing backlight switch output signal to low level after TV set main board enters standby state, discharging error amplifier output pin of driving chip through said first diode; when the television main board is restarted, the voltage of the output pin of the error amplifier rises from zero, so that the duty ratio of the PWM control signal is slowly increased, and the impact current of the boost inductor is restrained.
The technical scheme provided by the invention has the beneficial effects that:
1. according to the invention, the anode of the first diode is connected to the output pin of the error amplifier of the driving chip, and the cathode of the first diode is connected to the backlight switch output signal of the television main board, so that the surge current of the boost inductor is limited when the whole television is started, the phenomenon of abnormality caused by saturated inductor is avoided, the surge current is obviously inhibited, and the soft start is realized;
2. the circuit has the advantages of simple structure, timely response and low cost.
The present invention will be described in further detail with reference to the drawings and embodiments, but the present invention is not limited to the embodiments.
Drawings
FIG. 1 is a block diagram of a connection of an LED backlight driving circuit according to the present invention;
fig. 2 is a circuit diagram of an LED backlight driving circuit according to the present invention.
Detailed Description
Referring to fig. 1 and 2, an LED backlight driving circuit includes: a boost circuit 110 for converting a first input voltage (90V) into a desired output voltage and providing the same to the LED unit 140; a driving IC circuit 120 for controlling the booster circuit 110 to make the booster circuit 110 convert the first input voltage into a desired output voltage and supply the desired output voltage to the LED unit 140; the driving IC circuit 120 includes a driving chip N701; a discharging circuit 130 for discharging the electric charges stored in the booster circuit 110 after the driving IC circuit 120 is turned off; the discharging circuit 130 includes a diode D704, an anode of the diode D704 is connected to an error amplifier output pin (COMP) of the driving chip N701, and a cathode of the diode D704 is connected to a backlight switch output signal (BON) of the television main board.
Further, the boost circuit 110 includes a boost inductor L702, a diode 703, a diode 704, a field effect transistor V703, a first capacitor C711, and a second capacitor C707; one end of the boost inductor L702 is connected to the first input voltage and is used for receiving the input dc voltage, and the other end of the boost inductor L702 is connected to the drain of the fet V703, the anode of the diode 703, and the anode of the diode 704, respectively; the source electrode of the field effect transistor V703 is electrically grounded through a resistor R705, a resistor R706, a resistor R707, a resistor R708 and a resistor R110 which are connected in parallel, the source electrode of the field effect transistor V703 is also connected to the driving chip N701 through a resistor R703, and the grid electrode of the field effect transistor V703 is connected to the driving chip N701 through a variable resistor R701 and a resistor R702; the diode 703 and the diode 704 are connected in parallel, the cathode of the diode 703 is connected to one end of the first capacitor C711 and the positive end led+ of the LED unit 140, the cathode of the diode 704 is connected to one end of the second capacitor C707 and the positive end led+ of the LED unit 140, and the other ends of the first capacitor C711 and the second capacitor C707 are electrically grounded.
Further, the driving chip N701 is MP4008 and comprises a VIN, GND, CS, GATE, OVP, FB, COMP and a PMN which are eight pins; wherein the VIN pin is connected with a second input voltage (12V); the GND pin is electrically grounded; the CS pin is connected with one end of the resistor R703; the GATE pin is connected with the resistor R702; the OVP leg is connected to a positive side led+ of the LED unit 140 through a resistor R728, a resistor R729, and a resistor R730 connected in series; the FB pin is connected to the error amplifier output pin COMP through resistor R713, capacitor C708, resistor R714, and capacitor C709; the PMN pin is connected to a PWM control signal output end (PWM) of the television main board through a resistor R720, and the PMN pin is also connected with the OVP pin; the GATE pin is connected to the negative side LED-of the LED unit 140 through resistor R709, diode D702, resistor R721 and fet V704.
Further, the drain of the field effect transistor V704 is LED-connected to the negative terminal of the LED unit 140; the grid electrode of the field effect transistor V704 is connected with the resistor R721; the source of the field effect transistor V704 is connected between the resistor R714 and the capacitor C709 through the resistor R717, and the source of the field effect transistor V704 is electrically grounded through the resistor R719, the resistor R723, the resistor R724, the resistor R725, the resistor R726 and the resistor R727 which are connected in parallel.
Further, the LED unit 140 is a plurality of LED strings connected in parallel, wherein each LED string includes a plurality of LEDs connected in series.
A method for realizing soft start of LED backlight driving circuit includes connecting output pin of error amplifier of driving chip N701 to backlight switch output signal of TV set mainboard through diode D704, changing backlight switch output signal to low level after TV set mainboard enters standby state, discharging output pin of error amplifier of driving chip N701 through said first diode; when the television main board is restarted, the voltage of the output pin of the error amplifier rises from zero, so that the duty ratio of the PWM control signal is slowly increased, and the impact current of the boost inductor L702 is restrained.
According to the LED backlight driving circuit, the BON control signal of the television main board is utilized, and the COMP amplifying circuit is added, so that the impact current of the boost inductor L702 is limited when the whole machine is switched on and off, and the phenomenon of abnormality caused by inductance saturation is avoided.
The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and scope of the invention are intended to be included within the scope of the invention.
Claims (4)
1. An LED backlight driving circuit, comprising:
a boost circuit for converting the first input voltage into a desired output voltage and providing the desired output voltage to the LED unit;
a driving IC circuit for controlling the booster circuit to convert the first input voltage into a required output voltage and provide the required output voltage to the LED unit; the driving IC circuit comprises a driving chip;
a discharging circuit for discharging the electric charges stored in the voltage boosting circuit after the driving IC circuit is turned off;
the method is characterized in that:
the discharging circuit comprises a first diode, the anode of the first diode is connected to the output pin of the error amplifier of the driving chip, and the cathode of the first diode is connected to the backlight switch output signal of the television main board;
when the television main board enters a standby state, the output signal of the backlight switch becomes low level, and the output pin of the error amplifier of the driving chip discharges through the first diode; when the television main board is restarted, the voltage of the output pin of the error amplifier rises from zero, so that the duty ratio of the PWM control signal is slowly increased, and the impact current of the boost inductor is restrained; the boost circuit comprises a boost inductor, a second diode, a third diode, a first field effect transistor, a first capacitor and a second capacitor; one end of the boost inductor is connected with the first input voltage and used for receiving input direct-current voltage, and the other end of the boost inductor is respectively connected with the drain electrode of the first field effect tube, the anode of the second diode and the anode of the third diode; the source electrode of the first field effect tube is electrically grounded through a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor which are connected in parallel, the source electrode of the first field effect tube is also connected to the driving chip through a sixth resistor, and the grid electrode of the first field effect tube is connected to the driving chip through a seventh variable resistor and an eighth resistor; the second diode and the third diode are connected in parallel, the cathode of the second diode is respectively connected with one end of the first capacitor and the positive end of the LED unit, the cathode of the third diode is respectively connected with one end of the second capacitor and the positive end of the LED unit, and the other ends of the first capacitor and the second capacitor are electrically grounded;
the model of the driving chip is MP4008 and comprises VIN, GND, CS, GATE, OVP, FB, COMP and a PMN pin; wherein the VIN pin is connected with a second input voltage; the GND pin is electrically grounded; the CS pin is connected with the sixth resistor; the GATE pin is connected with the eighth resistor; the OVP pin is connected to the positive end of the LED unit through a ninth resistor, a tenth resistor and an eleventh resistor which are connected in series; the FB pin is connected to the error amplifier output pin COMP through a twelfth resistor, a third capacitor, a thirteenth resistor, and a fourth capacitor; the PMN pin is connected to the PWM control signal output end of the television main board through a fourteenth resistor, and the PMN pin is also connected with the OVP pin; the GATE pin is connected to the negative terminal of the LED unit through a fifteenth resistor, a fourth diode, a sixteenth resistor, and a second field effect transistor.
2. The LED backlight driving circuit of claim 1, wherein the drain of the second fet is connected to the negative terminal of the LED unit; the grid electrode of the second field effect transistor is connected with the sixteenth resistor; the source electrode of the second field effect transistor is connected between the twelve resistors and the third capacitor through a seventeenth resistor, and the source electrode of the second field effect transistor is electrically grounded through an eighteenth resistor, a nineteenth resistor, a twentieth resistor, a twenty first resistor, a twenty second resistor and a twenty third resistor which are connected in parallel.
3. The LED backlight driving circuit of claim 1, wherein the LED units are a plurality of LED strings connected in parallel, wherein each LED string comprises a plurality of LEDs connected in series.
4. A method of implementing soft start of an LED backlight driving circuit, characterized in that it is based on an LED backlight driving circuit according to any one of claims 1-3; the method comprises the following steps: connecting an error amplifier output pin of a driving chip to a backlight switch output signal of a television main board through a first diode, and discharging the error amplifier output pin of the driving chip through the first diode when the television main board enters a standby state and the backlight switch output signal becomes low level; when the television main board is restarted, the voltage of the output pin of the error amplifier rises from zero, so that the duty ratio of the PWM control signal is slowly increased, and the impact current of the boost inductor is restrained.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201611255704.9A CN106683621B (en) | 2016-12-30 | 2016-12-30 | LED backlight driving circuit and method for realizing soft start |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201611255704.9A CN106683621B (en) | 2016-12-30 | 2016-12-30 | LED backlight driving circuit and method for realizing soft start |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN106683621A CN106683621A (en) | 2017-05-17 |
| CN106683621B true CN106683621B (en) | 2024-03-29 |
Family
ID=58873238
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201611255704.9A Active CN106683621B (en) | 2016-12-30 | 2016-12-30 | LED backlight driving circuit and method for realizing soft start |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN106683621B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107527602B (en) * | 2017-09-30 | 2019-07-16 | 深圳市华星光电半导体显示技术有限公司 | Liquid crystal display panel and switching on and shutting down control circuit |
| CN113744695A (en) * | 2021-08-04 | 2021-12-03 | 青岛鼎信通讯股份有限公司 | Low-cost LED backlight control circuit applied to station terminal |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102682714A (en) * | 2012-04-27 | 2012-09-19 | 深圳麦格米特电气股份有限公司 | LED backlight source driving circuit and method for realizing soft startup |
| CN103295538A (en) * | 2013-07-02 | 2013-09-11 | 深圳市华星光电技术有限公司 | Backlight drive circuit and method for shortening soft starting time of backlight drive circuit |
| CN103400560A (en) * | 2013-08-12 | 2013-11-20 | 深圳市华星光电技术有限公司 | Led backlight drive circuit and liquid crystal display |
| CN103747578A (en) * | 2013-12-30 | 2014-04-23 | 深圳市华星光电技术有限公司 | LED (Light-Emitting Diode) backlight driving circuit and liquid crystal display |
| CN206379158U (en) * | 2016-12-30 | 2017-08-04 | 厦门厦华科技有限公司 | A kind of LED backlight drive circuit |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103166458B (en) * | 2013-02-06 | 2014-12-10 | 京东方科技集团股份有限公司 | Boosted circuit, backlight driver circuit and backlight module |
-
2016
- 2016-12-30 CN CN201611255704.9A patent/CN106683621B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102682714A (en) * | 2012-04-27 | 2012-09-19 | 深圳麦格米特电气股份有限公司 | LED backlight source driving circuit and method for realizing soft startup |
| CN103295538A (en) * | 2013-07-02 | 2013-09-11 | 深圳市华星光电技术有限公司 | Backlight drive circuit and method for shortening soft starting time of backlight drive circuit |
| CN103400560A (en) * | 2013-08-12 | 2013-11-20 | 深圳市华星光电技术有限公司 | Led backlight drive circuit and liquid crystal display |
| CN103747578A (en) * | 2013-12-30 | 2014-04-23 | 深圳市华星光电技术有限公司 | LED (Light-Emitting Diode) backlight driving circuit and liquid crystal display |
| CN206379158U (en) * | 2016-12-30 | 2017-08-04 | 厦门厦华科技有限公司 | A kind of LED backlight drive circuit |
Also Published As
| Publication number | Publication date |
|---|---|
| CN106683621A (en) | 2017-05-17 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101569025B (en) | Light emitting diode driving apparatus | |
| CN112233625B (en) | Backlight constant current control circuit and backlight structure | |
| CN202736455U (en) | Drive circuit of light emitting diode, light emitting device using same and electronic equipment | |
| CN103440848A (en) | Backlight driving circuit | |
| CN103198809A (en) | LED (Light Emitting Diode) backlight source and liquid-crystal display equipment | |
| JP2009516923A (en) | Device for driving an LED cell | |
| WO2014187015A1 (en) | Led backlight driving circuit, liquid crystal display apparatus, and driving method | |
| KR20100089432A (en) | Apparatus for driving a light source and light source apparatus having the same | |
| CN105093598B (en) | Array base palte row drives short-circuit protection circuit and liquid crystal panel | |
| TWI390482B (en) | The circuit and method for driving strings of light emitting diode | |
| CN102622986A (en) | Light emitting diode (LED) backlight drive circuit, backlight module, and liquid crystal display device | |
| WO2023124155A1 (en) | Backlight power supply, display apparatus, and electronic device | |
| CN103218976A (en) | Light-emitting diode (LED) backlight driving circuit, LED backlight and liquid crystal display | |
| CN106683621B (en) | LED backlight driving circuit and method for realizing soft start | |
| KR100497393B1 (en) | Apparatus for improving power factor of power supply in a plasma display panel driving system and design method thereof | |
| CN103065589A (en) | Backlight driving circuit and liquid crystal display | |
| CN206379158U (en) | A kind of LED backlight drive circuit | |
| CN106572565A (en) | Two-in-one power supply | |
| KR101932366B1 (en) | Led backlight source for liquid crystal display device and liquid crystal display device | |
| US10278257B2 (en) | Protection circuit and LED driving circuit | |
| CN102354483A (en) | LED (Light Emitting Diode) backlight-source boosting driving circuit, LED backlight source and liquid crystal display device | |
| CN104376816A (en) | LED backlight drive circuit, LED backlight device and display device | |
| CN103247269A (en) | LED backlight and liquid crystal display device | |
| CN204967607U (en) | Supply circuit and LED lighting apparatus based on power tube | |
| US20130293136A1 (en) | Driving method for backlight unit of liquid crystal display and system thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |