CN101873735B - LED (light-emitting diode) backlight working circuit - Google Patents
LED (light-emitting diode) backlight working circuit Download PDFInfo
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- CN101873735B CN101873735B CN 200910050004 CN200910050004A CN101873735B CN 101873735 B CN101873735 B CN 101873735B CN 200910050004 CN200910050004 CN 200910050004 CN 200910050004 A CN200910050004 A CN 200910050004A CN 101873735 B CN101873735 B CN 101873735B
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Abstract
The invention discloses an LED backlight working circuit, which greatly improves the working efficiency of a backlight circuit so as to achieve the goal of electricity saving. The invention has the technical scheme that the circuit comprises a backlight chip, a feedback resistor and an LED circuit and also comprises a first divider resistor, a second divider resistor and a switch element, wherein the first end of the first divider resistor is connected with one end of the feedback resistor and one end of the LED circuit; the second end of the first divider resistor is connected with the feedback terminal of the backlight chip; the first end of the second divider resistor is connected with the feedback terminal of the backlight chip; the first end of the switch element is connected with a direct-current power supply, the second end thereof is connected with the GPIO (General Purpose Input/Output) port of external CPU (central processing unit), and the third end thereof is connected with the second end of the second divider resistor. When the LED circuit works, the external CPU enables the switch element to be in an opening state through the GPIO port, and the direct current power supply is started to the power supply path of the second end of the switch element, whereas the first divider resistor and the second divider resistor jointly divide voltage for the feedback resistor. The invention is applied to the field of electronic equipment.
Description
Technical field
The present invention relates to a kind of backlight circuit, relate in particular to a kind of LED-backlit operating circuit that improves backlight efficiency.
Background technology
Used LCD screen needs normally that white light LEDs is luminous to provide backlight on present mobile phone or other electronic installations.Existing liquid crystal LED-backlit circuit circuit structure normally shown in Figure 1.See also Fig. 1, by a backlight chip (also being called the chip that boosts) cell voltage being elevated to can the luminous voltage of driving LED, then control the LED electric current by feedback resistance R1, the FB of backlight chip end is used for input feedback voltage, when the upper electric current of LED changes, control the LED electric current by feedback resistance R1.The FB end (feedback terminal) of chip of boosting is used for input feedback voltage, when the upper electric current of LED changes, electric current by feedback resistance R1 also can change, the voltage of FB end will change, a voltage ratio by the chip internal that boosts just can be regulated the control signal of SW end than control device, keeps constant so that flow through the electric current of LED.
Load power consumption on this circuit comprises two parts: the power consumption on the power consumption on the LED and the feedback resistance R1.During normal operation, the electric current on the LED is a steady state value, so the power consumption on the LED also is constant, the purpose that wants to reach power saving will reduce the power consumption on resistance R 1.
Analyze the efficient of backlight circuit according to circuit shown in Figure 1, calculate according to a white light LEDs 20mA operating current, the LED total current of Fig. 1 parallel connection is 100mA, and feedback voltage is set as 1V at chip internal, then can calculate R1=1V ÷ 100mA=10ohm.Power loss=I*I*R=0.1*0.1*10=0.1W on the R1 this shows that the power consumption loss of this circuit on R1 reaches 0.1W, and large like this power consumption has had a strong impact on the efficient of whole circuit.
About 20 LEDs of large-scale LCD screen needs backlight of digital photo frame and so on for example, electric current needs about 200mA.Because the raising of electric current, traditional backlight circuit exists the excessively low shortcoming of conversion efficiency.
Summary of the invention
The object of the invention is to address the above problem, a kind of LED-backlit operating circuit is provided, greatly improved the operating efficiency of backlight circuit, to reach the purpose of power saving.
Technical scheme of the present invention is: the present invention has disclosed a kind of LED-backlit operating circuit, comprise backlight chip, feedback resistance, led circuit, this feedback resistance is connected between the feedback terminal and earth point of this backlight chip, this led circuit is connected between the control terminal and feedback terminal of this backlight chip, wherein, also comprise the first divider resistance, the second divider resistance and switch element, the first end of this first divider resistance connects the end that this feedback resistance is connected with this led circuit, the second end of this first divider resistance connects the feedback terminal of this backlight chip, the first end of this second divider resistance connects the feedback terminal of this backlight chip, the first end of this switch element connects a direct current power supply, the second end is connected on the universal input and output port of outer CPU, the 3rd end connects the second end of this second divider resistance, when this led circuit work, outer CPU makes this switch element be in open mode by this universal input and output port, open this DC power supply to the supply access of this switch element the second end, and this first divider resistance and this second divider resistance are this feedback resistance dividing potential drop together.
Above-mentioned LED-backlit operating circuit, wherein, this switch element is mos field effect transistor, its first end is source electrode, connects this DC power supply; The second end is grid, is connected to the universal input and output port of outer CPU; The 3rd end is drain electrode, connects the second end of this second divider resistance.
Above-mentioned LED-backlit operating circuit, wherein, the voltage of this DC power supply is 1.8V, the output voltage of the feedback terminal of this backlight chip is 1V.
Above-mentioned LED-backlit operating circuit, wherein, the resistance value of this first divider resistance is 10K ohm～100K ohm.
Above-mentioned LED-backlit operating circuit, wherein, the resistance value of this second divider resistance is 10K ohm～100K ohm.
Above-mentioned LED-backlit operating circuit, wherein, this switch element is the switch that this DC power supply of control is opened or closed.
The present invention contrasts prior art following beneficial effect: technical scheme of the present invention is by mos field effect transistor (MOSFET) and 2 resistance, the voltage at control feedback resistance two ends so that the operating efficiency of whole resistance greatly improve.The contrast prior art, the present invention can improve the conversion efficiency of backlight circuit.
Description of drawings
Fig. 1 is the circuit diagram of existing LED-backlit operating circuit.
Fig. 2 is the circuit diagram of the embodiment of LED-backlit operating circuit of the present invention.
Embodiment
The invention will be further described below in conjunction with drawings and Examples.
Fig. 2 shows the circuit of the embodiment of LED-backlit operating circuit of the present invention.See also Fig. 2, the LED-backlit operating circuit of present embodiment mainly comprises backlight chip 20 (also can be described as the chip that boosts), feedback resistance R1, two divider resistance R2 and R3, a MOSFET (mos field effect transistor) Q1, led circuit 21, and wherein led circuit 21 is by a plurality of LED all-in-one-piece that is connected in parallel afterwards of connecting first.Remainder all is auxiliary circuit, and the CTRL terminal of backlight chip 20 receives LED_Ctrl signal (LED control signal), and the GND_T terminal is connected with the GND terminal and is connected earth point.Capacitor C 1 is connected between the COMP terminal and earth point of backlight chip 20, and capacitor C 2 is connected between the VIN terminal and earth point of backlight chip 20, and inductance L 1 is connected between the VIN terminal and SW terminal of backlight chip 20.Voltage stabilizing didoe D1 is connected between the SW terminal and capacitor C 3 of backlight chip 20, the other end ground connection of capacitor C 3.
Feedback resistance R1 is connected between the FB terminal (feedback terminal) and earth point of backlight chip 20, and led circuit 21 is connected between the SW terminal (control terminal) and FB terminal of backlight chip 20.The first divider resistance R2 is connected between the FB terminal and feedback resistance R1 of backlight chip 20, and the second divider resistance R3 connects a DC power supply by MOSFETQ1, and DC power supply is the 1.8V power supply in the present embodiment.
For MOSFET Q1, be the switch of controlling the 1.8V power supply, grid connects the GPIO port of outer CPU, controls the switch of 1.8V power supply by the height of CPU control GPIO port.When backlight circuit is worked, the time MOSFET Q1 be in open mode, open the 1.8V power supply to the power supply circuits of the drain electrode of MOSFET Q1, backlight chip 20 is so that the voltage of its FB terminal remains on a steady state value (for example 1V) simultaneously.MOSFET Q1 provides the reference voltage of an outside for divider resistance R2 and R3, and divider resistance R2 and R3 provide the dividing potential drop effect for feedback resistance R1 together, certainly this switch element of Q1 can also be triode etc., as long as can reach same or analogous effect, is not to be limited with present embodiment.
For making the power consumption that consumes on divider resistance R2 and R3 smaller, R2 and R3 choose larger resistance value, can select 10K ohm to the resistance value that (comprises 10K ohm and 100K ohm) between 100K ohm.For example choose respectively R2=90K ohm, the resistance of R3=80K ohm calculates.Can calculate first to get electric current I R3=(1.8-1.0) the ÷ 80K=0.01mA on the R3, the FB end is high resistant, so the electric current on the R2 also is 0.01mA, so the voltage on the R2 is the voltage of 0.01mA*90K=0.9V on R1 is 0.1V, and the electric current that flows through on the LED still is 100mA, flow through electric current on the R1 and be that 100mA+0.01mA just can calculate like this in the power loss on the R1 is that P=U*I=0.1V* (100mA+0.01mA)=10mW can find out that the power loss on the R1 at this moment only has 0.01W, circuit before the contrast only has 1/10 power consumption, can greatly improve like this operating efficiency of whole backlight circuit.
Can freely select suitable divider resistance R2 and R3 to come so that the power loss on the feedback resistance R1 reaches the acceptable scope, thereby improve backlight circuit efficient, the operating time of improving whole system.
Above-described embodiment provides to those of ordinary skills and realizes or use of the present utility model; those of ordinary skills can be in the situation that does not break away from invention thought of the present utility model; above-described embodiment is made various modifications or variation; thereby protection range of the present utility model do not limit by above-described embodiment, and should be the maximum magnitude that meets the inventive features that claims mention.
Claims (6)
1. LED-backlit operating circuit, comprise backlight chip, feedback resistance, led circuit, this feedback resistance is connected between the feedback terminal and earth point of this backlight chip, this led circuit is connected between the control terminal and feedback terminal of this backlight chip, it is characterized in that, also comprise the first divider resistance, the second divider resistance and switch element, the first end of this first divider resistance connects the end that this feedback resistance is connected with this led circuit, the second end of this first divider resistance connects the feedback terminal of this backlight chip, the first end of this second divider resistance connects the feedback terminal of this backlight chip, the first end of this switch element connects a direct current power supply, the second end is connected on the universal input and output port of outside central processing unit (CPU), the 3rd end connects the second end of this second divider resistance, when this led circuit work, outside central processing unit makes this switch element be in open mode by this universal input and output port, open this DC power supply to the supply access of this switch element the second end, and this first divider resistance and this second divider resistance are this feedback resistance dividing potential drop together.
2. LED-backlit operating circuit according to claim 1 is characterized in that, this switch element is mos field effect transistor, and its first end is source electrode, connects this DC power supply; The second end is grid, is connected to the universal input and output port of outside central processing unit; The 3rd end is drain electrode, connects the second end of this second divider resistance.
3. LED-backlit operating circuit according to claim 1 is characterized in that, the voltage of this DC power supply is 1.8V, and the output voltage of the feedback terminal of this backlight chip is 1V.
4. LED-backlit operating circuit according to claim 1 is characterized in that, the resistance value of this first divider resistance is 10K ohm～100K ohm.
5. LED-backlit operating circuit according to claim 3 is characterized in that, the resistance value of this second divider resistance is 10K ohm～100K ohm.
6. LED-backlit operating circuit according to claim 1 is characterized in that, this switch element is the switch that this DC power supply of control is opened or closed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200910050004 CN101873735B (en) | 2009-04-24 | 2009-04-24 | LED (light-emitting diode) backlight working circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200910050004 CN101873735B (en) | 2009-04-24 | 2009-04-24 | LED (light-emitting diode) backlight working circuit |
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| Publication Number | Publication Date |
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| CN101873735A CN101873735A (en) | 2010-10-27 |
| CN101873735B true CN101873735B (en) | 2013-10-30 |
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| CN 200910050004 Active CN101873735B (en) | 2009-04-24 | 2009-04-24 | LED (light-emitting diode) backlight working circuit |
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Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102625510A (en) * | 2012-03-14 | 2012-08-01 | 泰州市华强照明器材有限公司 | Adaptive light emitting diode (LED) fluorescent lamp |
| CN110070836B (en) * | 2019-04-19 | 2021-01-26 | 重庆两江联创电子有限公司 | Backlight module driving circuit |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201122423Y (en) * | 2007-12-04 | 2008-09-24 | 英华达(上海)电子有限公司 | Backlight power supply circuit |
| US8304999B2 (en) * | 2009-06-08 | 2012-11-06 | Sunpaltech Co., Ltd. | LED controlling driver and controlling method thereof |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201122423Y (en) * | 2007-12-04 | 2008-09-24 | 英华达(上海)电子有限公司 | Backlight power supply circuit |
| US8304999B2 (en) * | 2009-06-08 | 2012-11-06 | Sunpaltech Co., Ltd. | LED controlling driver and controlling method thereof |
Non-Patent Citations (2)
| Title |
|---|
| "基于单片机的电子时间引信LCD背光控制";崔平、齐杏林;《武器装备自动化》;20051215;第24卷(第6期);全文 * |
| 崔平、齐杏林."基于单片机的电子时间引信LCD背光控制".《武器装备自动化》.2005,第24卷(第6期),全文. |
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| CN101873735A (en) | 2010-10-27 |
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Owner name: BEIJING Z-GOOD TECHNOLOGY SERVICE CO., LTD. Free format text: FORMER OWNER: YINGHUADA (SHANGHAI) ELECTRONICS CO LTD. Effective date: 20140514 |
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Effective date of registration: 20140514 Address after: 100085 Beijing city Haidian District No. 33 Xiaoying Road 1 1FO6 room Patentee after: BEIJING ZHIGU TECHNOLOGY SERVICES CO., LTD. Address before: 200233 Shanghai City Guiqin Road No. 7 Patentee before: Inventec (Shanghai) Electronics Co., Ltd. |