CN2631184Y - LED drive circuit - Google Patents
LED drive circuit Download PDFInfo
- Publication number
- CN2631184Y CN2631184Y CN 03255691 CN03255691U CN2631184Y CN 2631184 Y CN2631184 Y CN 2631184Y CN 03255691 CN03255691 CN 03255691 CN 03255691 U CN03255691 U CN 03255691U CN 2631184 Y CN2631184 Y CN 2631184Y
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- resistance
- triode
- led
- emitter
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- Expired - Fee Related
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Abstract
The utility model provides a luminescent diode driving circuit, the characteristics are that: the utility model comprises resistances (R1)-(R8), dynatrons (Q1)-(Q3), a calculation amplifier (A) and a luminescence diode (LED), in which the other end of the resistance (R1) is connected with the I/O interface of the single chip (CPU), the emitter of the dynatrons (Q3) is connected with the driving voltage (Vcc), in which the resistances (R4), (R5), (R6), (R7), (R8) use precise resistance with the same temperature coefficient. The utility model can be applied in physical optic instrument with the luminescent diode as the light source, such as used to determine the concentration and refraction ratio of the solutions of hand hold refraction instrument, and has the advantages of low cost, stable light source and automatic opening and closing.
Description
Technical field
The utility model relates to light source driving circuit, particularly a kind of LED driving circuit.
Background technology
With light-emitting diode (LED) is the physico-optical instrument of light source, as be used to measure the hand-hold refractometer of solution concentration, refractive index, require light source very stable, just require the drive current of LED very stable, also require the light source can automatic switch in some cases.But common led drive circuit is serially connected in LED and resistance R as shown in Figure 1 and makes in the circuit of power supply Vcc that LED is luminous to get final product.Or triode Q of serial connection in circuit more as shown in Figure 2, its base stage is connected with the I/O interface of singlechip CPU, control the conducting of triode Q or end, even sequential circuit open or turn-off, thereby control the LED automatic switch.These circuit all can not be realized the stable of led light source.Though the integrated circuit (IC)-components that designs for driving LED is specially arranged on the market, and cost is higher.
Summary of the invention
The utility model is in order to solve the unstable existing technical problem of led light source, and a kind of LED driving circuit of light stability is provided.
According to above-mentioned purpose, the utility model provides a kind of LED driving circuit, is characterized in: be made up of resistance R 1～R8, triode Q1～Q3, operational amplifier A and LED; Wherein resistance R 2 is connected with triode Q2 base stage, and resistance R 3 is connected with triode Q2 emitter, and the other end of resistance R 2, R3 is connected with the collector electrode of triode Q1; Wherein LED is anodal is connected with triode Q2 collector electrode, resistance R 5, and resistance R 5 other ends are connected with resistance R 4, operational amplifier A in-phase input end (+), and the LED negative pole is connected with triode Q3 collector electrode; Wherein operational amplifier A inverting input (-) is connected with emitter, the resistance R 8 of triode Q3 through resistance R 7, and the output of operational amplifier A is connected with triode Q3 base stage through resistance R 6; Wherein, the other end ground connection of triode Q1 emitter, resistance R 4 and R8; Wherein, resistance R 1 other end is connected with the I/O interface of singlechip CPU, and the emitter of triode Q2 is connected with driving voltage Vcc.
Said apparatus, wherein resistance R 4, R5, R6, R7, R8 adopt the identical precision resistance of temperature coefficient.
The utility model is compared with common led drive circuit owing to adopted above technical measures, has that cost is low, an advantage of light stability and automatic switch.
Description of drawings
Fig. 1 is common led drive circuit figure.
Fig. 2 is the led drive circuit figure that possesses switch control.
Fig. 3 is a circuit diagram of the present utility model.
Embodiment
As shown in Figure 3: the utility model is actually a V-I change-over circuit, converts a fixing voltage V to corresponding electric current I.
Q1, Q2 are switch triodes, and Q3 is a follower, electrify and banish big effect.R1, R2 are current-limiting resistances, R3 is the pull-up resistor of triode Q1, R4, R5 constitute potential-divider network, for the in-phase input end of operational amplifier A (+end) provides a suitable voltage Vp, R6 is a current-limiting resistance, R7 realizes negative feedback, and R8 realizes the V-I conversion, and the size of the electric current that flows through on the R8 just equals the size of the drive current I of LED.Stable for guaranteeing the LED drive current, R4, R5, R6, R7, R8 must be the identical precision resistances of temperature coefficient.
CPU is the I/O mouth of single-chip microcomputer, the switch of control LED.When the I/O of CPU mouth was output as low level, Q1, Q2 were in cut-off state, and LED does not have drive current, and LED is not luminous, is in off state.When the I/O of CPU mouth was output as high level, Q1, Q2 were in the saturation conduction state, and the voltage that appears at the LED positive pole is about Vcc.Principle according to operational amplifier under the degree of depth negative feedback condition " empty short " and " empty disconnected ":
Vp＝Vcc×R4÷(R4+R5)
Vn=Vp is about zero because operational amplifier input electric current is minimum, therefore, and Vn ≈ Vr8.Flow through the drive current I of the as many as LED of electric current of R8.Therefore,
I=Vcc * R4 ÷ (R4+R5) ÷ R8; The careful resistance value of selecting R4, R5, R8 can obtain a suitable LED drive current.
Claims (2)
1, a kind of LED driving circuit is characterized in that: be made up of resistance (R1)～(R8), triode (Q1)～(Q3), operational amplifier (A) and light-emitting diode (LED); Wherein resistance (R2) is connected with triode (Q2) base stage, and resistance (R3) is connected with triode (Q2) emitter, and the other end of resistance (R2), (R3) is connected with the collector electrode of triode (Q1); Wherein light-emitting diode (LED) is anodal is connected with triode (Q2) collector electrode, resistance (R5), resistance (R5) other end is connected with resistance (R4), operational amplifier (A) in-phase input end (+), and light-emitting diode (LED) negative pole is connected with triode (Q3) collector electrode; Wherein operational amplifier (A) inverting input (-) is connected with emitter, the resistance (R8) of triode (Q3) through resistance (R7), and the output of operational amplifier (A) is connected with triode (Q3) base stage through resistance (R6); Wherein, triode (Q1) emitter, resistance (R4) and other end ground connection (R8); Wherein, resistance (R1) other end is connected with the I/O interface of single-chip microcomputer (CPU), and the emitter of triode (Q2) is connected with driving voltage (Vcc).
2, LED driving circuit according to claim 1 is characterized in that: wherein resistance (R4), (R5), (R6), (R7), (R8) adopt the identical precision resistance of temperature coefficient.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 03255691 CN2631184Y (en) | 2003-07-17 | 2003-07-17 | LED drive circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 03255691 CN2631184Y (en) | 2003-07-17 | 2003-07-17 | LED drive circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN2631184Y true CN2631184Y (en) | 2004-08-04 |
Family
ID=34295067
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 03255691 Expired - Fee Related CN2631184Y (en) | 2003-07-17 | 2003-07-17 | LED drive circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN2631184Y (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101063517B (en) * | 2006-04-28 | 2010-05-12 | 长春吉大·小天鹅仪器有限公司 | Hand-held refractometer light source and illuminating system |
| US7812794B2 (en) | 2004-12-06 | 2010-10-12 | Semiconductor Energy Laboratory Co., Ltd. | Display device and driving method thereof |
| CN101379879B (en) * | 2006-01-31 | 2011-08-17 | 皇家飞利浦电子股份有限公司 | Led driver circuit |
| CN1952838B (en) * | 2005-10-21 | 2012-03-14 | 鸿富锦精密工业（深圳）有限公司 | Overheat indicating circuit for mainboard |
-
2003
- 2003-07-17 CN CN 03255691 patent/CN2631184Y/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7812794B2 (en) | 2004-12-06 | 2010-10-12 | Semiconductor Energy Laboratory Co., Ltd. | Display device and driving method thereof |
| US7978158B2 (en) | 2004-12-06 | 2011-07-12 | Semiconductor Energy Laboratory Co., Ltd. | Display device and driving method thereof |
| CN101593487B (en) * | 2004-12-06 | 2013-01-02 | 株式会社半导体能源研究所 | Device, electric equipment and the device driving method |
| CN1952838B (en) * | 2005-10-21 | 2012-03-14 | 鸿富锦精密工业（深圳）有限公司 | Overheat indicating circuit for mainboard |
| CN101379879B (en) * | 2006-01-31 | 2011-08-17 | 皇家飞利浦电子股份有限公司 | Led driver circuit |
| CN101063517B (en) * | 2006-04-28 | 2010-05-12 | 长春吉大·小天鹅仪器有限公司 | Hand-held refractometer light source and illuminating system |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C19 | Lapse of patent right due to non-payment of the annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |