CN101896028B - Double-end current source and LED driver comprising same - Google Patents
Double-end current source and LED driver comprising same Download PDFInfo
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- CN101896028B CN101896028B CN 201010229096 CN201010229096A CN101896028B CN 101896028 B CN101896028 B CN 101896028B CN 201010229096 CN201010229096 CN 201010229096 CN 201010229096 A CN201010229096 A CN 201010229096A CN 101896028 B CN101896028 B CN 101896028B
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Abstract
The invention discloses a double-end current source and an LED driver comprising the same. The double-end current source is used for driving a light emitting diode, and comprises a constant-current offset unit, an internal voltage generation unit and a function control unit, wherein the constant-current offset unit comprises a boosting current mirror consisting of a first N-channel metal oxide semiconductor (NMOS) transistor and a second NMOS transistor, and a current reference circuit connected with the boosting current mirror, and the gates of the first and second NMOS transistors are connected with each other; the internal voltage generation unit is connected with the current reference circuit; and the function control unit comprises a luminance adjustment module which is connected with the current reference circuit. The double-end current source and the LED driver comprising the same can save more cost and realize smaller chip sizes.
Description
Technical field
The present invention relates to a kind of LED driver, particularly relate to a kind of both-end current source of LED driver.
Background technology
Easy and low-cost due to LED, thereby be widely used in portable product, when using more than one LED to be used as power supply, the brightness that must control each LED is consistent, the brightness of LED is proportional to the electric current that passes through again, therefore control the size of current that is supplied to each LED, namely control the brightness of each LED.In general, the current source that LED arranges in pairs or groups must be considered its Cost Problems, affects the quantity that key factor is external component of cost.
Existing LED driver is commonly used two kinds of voltage-dropping type and booster types, referring to Fig. 1 and Fig. 2.Figure 1 shows that BUCK type LED driver, namely the voltage-dropping type LED driver, Figure 2 shows that BOOST type LED driver, i.e. the booster type LED driver.But these two kinds of drivers all have some external components, and the voltage that the quantity of LED can be born by power supply limits.
Summary of the invention
The object of the invention is to overcome the deficiencies in the prior art, a kind of both-end current source is provided, this both-end current source external component is few, and the quantity of the LED limiting voltage that not can bear by power supply.
For achieving the above object, the present invention adopts following technical scheme:
A kind of both-end current source be used for to drive light-emitting diode, comprises: the constant biasing unit comprises the boost current mirror that is made of the interconnective NMOS pipe of grid and the 2nd NMOS pipe, with the current reference circuit that is connected with this boost current mirror; The builtin voltage generation unit connects described current reference circuit; And function control unit, comprising the brightness regulation module, this brightness regulation module is connected with described current reference circuit.
Preferably; described function control unit also comprises the protection module that is connected with described current reference circuit; this protection module comprises short circuit protection module, the voltage between this short circuit protection module two terminals detected according to internal inspection device, corresponding reduction output current.
Preferably, described protection module also comprises the overheat protector module that is connected with described current reference circuit, this overheat protector module junction temperature detected according to the internal temperature detector, corresponding regulation output electric current.
Preferably, described builtin voltage generation unit, comprise the resistance and the 3rd NMODS pipe that are connected with voltage stabilizing didoe, the grid of the 3rd NMOS pipe is connected with described voltage stabilizing didoe, the source electrode of the 3rd NMOS pipe is connected with described current reference circuit, and the drain electrode of the 3rd NMOS pipe is connected with power positive end.
Preferably, described constant biasing unit also comprises operational amplifier, the in-phase input end of this operational amplifier connects the drain electrode of a NMOS pipe, inverting input connects the drain electrode of the 2nd NMOS pipe, output connects the grid of the 4th NMOS pipe, and the source electrode of the 4th NMOS pipe connects the drain electrode of the 2nd NMOS pipe.
Preferably, the input voltage range of described LED drive at 85V between 265V.
Preferably, the present invention also provides a kind of LED drive, and it comprises aforesaid both-end current source.
Preferably, the present invention provides a kind of electronic equipment in addition, and it also comprises aforesaid both-end current source.
The advantage of the technical solution adopted in the present invention is:
(1) both-end current source of the present invention is only relevant with the both-end voltage difference, and when connect application with the LED load, the voltage that total input voltage deducts LED load two ends is the voltage difference at device two ends.The present invention passes through at the built-in builtin voltage generation unit of driver, and when the voltage difference of installing two ends changed between minimum voltage difference and puncture voltage, builtin voltage remained unchanged relatively, and internal current source is stablized constant.When changing, the LED load voltage only need the voltage difference at assurance device two ends just can work between minimum voltage difference and puncture voltage, so install the quantity of the LED that drives is not subjected to total input voltage that device bears in certain scope restriction.
(2) both-end current source of the present invention is only relevant with the both-end voltage difference, and when the voltage difference of installing two ends changed between minimum voltage difference and puncture voltage, builtin voltage remained unchanged relatively, and internal current source is stablized constant, guarantees the LED normal operation.The present invention has omitted external component, and this has not only reduced bill of materials cost, places the more required extra production cost of multicompartment but also reduced, and has realized dwindling of solution size.
(3) the present invention passes through at the built-in builtin voltage generation unit of driver, when the both-end voltage difference changes between poor and puncture voltage at minimum input voltage, builtin voltage remains unchanged relatively, internal current source is stable, the voltage that can make by the quantity that changes LED total input voltage deduct LED load two ends remains between the poor and device puncture voltage of the minimum input voltage of device, this device can provide stable electric current for LED in wider input voltage range, the present invention can be applied to most of LED, comprise the family expenses ac equipment, its voltage range at 85V between 265V.
(4) the built-in short circuit protection module of the present invention, the voltage between two terminals detected according to internal inspection device comes corresponding reduction output current, can effectively reduce total power consumption, avoids system to break down, and for example is short-circuited.
(5) the present invention connects with the LED load when using, and constant electric current flows through device and load, and the efficient of device can be only by regulating the voltage drop ratio realization between LED load and device, and it can be designed as and surpasses 98%.
Below in conjunction with accompanying drawing, the embodiment and advantages of the present invention are further explained.
Description of drawings
Fig. 1 is existing a kind of voltage-dropping type LED driver;
Fig. 2 is existing a kind of booster type LED driver;
Fig. 3 shows that the brightness of LED is directly proportional to the current deviation value;
Fig. 4 shows according to a kind of both-end current source of the present invention;
Fig. 5 shows according to another kind of both-end current source of the present invention;
Fig. 6 shows that when in-phase voltage of the present invention in very large range changed, the analogue value of output current remained unchanged.
Embodiment
Fig. 3 shows that the brightness of LED is directly proportional to the current deviation value, and it is directly to be provided to LED by power supply that the constant the most simple and efficient mode in current deviation value ground is provided.When as shown being junction temperature and being 25 ℃, the relation between relative discharge and usefulness and forward current, abscissa is forward current, ordinate is typical case's flux and typical relative efficiency relatively.
With reference to figure 4, both-end current source 100 for driving light-emitting diode provided by the present invention, comprise: constant biasing unit 10, it comprises by interconnective NMOS pipe the 101 and the 2nd NMOS pipe 102 boost current mirrors that consist of of grid, with the current reference circuit 103 that is connected with this boost current mirror; Builtin voltage generation unit 20 connects described current reference circuit 103; With function control unit 30, comprise brightness regulation module 301, this brightness regulation module 301 is connected with described current reference circuit 103.
In described constant biasing unit 10, electric current provides parts 104 and NMOS pipe 101 to form the bias current generation module, as the accurate current reference circuit 103 in inside, for generation of bias current, produce amplified current through the 2nd NMOS pipe 102 mirror images, electric current is risen to desired value.
Described builtin voltage generation unit 20, comprise the resistance 202 and the 3rd NMOS pipe 203 that are connected with voltage stabilizing didoe 201, the grid of the 3rd NMOS pipe 203 is connected with described voltage stabilizing didoe 202, the source electrode of the 3rd NMOS pipe 203 provides parts 104 to be connected with described electric current, and the drain electrode of the 3rd NMOS pipe 203 is connected with power positive end.
In another embodiment of the present invention; described function control unit 20 also comprises the protection module 302 that is connected with described current reference circuit; this protection module can comprise short circuit protection module; this short circuit protection module is according to the voltage difference between internal inspection device two ends 303 and 304, corresponding reduction output current.Like this, as a LED during by short circuit, the voltage by device is also by the expansion of same degree.When more LED were arranged by short circuit, voltage just may exceed the puncture voltage of device.Internal comparator is used to detect input voltage.When input voltage surpassed a setting limit, the current value of LED just was reduced, such as, reduce to 10mA from 20mA.In this case, it has effectively reduced half with the power consumption of system.By way of caution, the brightness of LED also is lowered.
The overheat protector module that provides parts 104 to be connected with described electric current can also be provided described protection module, this overheat protector module junction temperature detected according to the internal temperature detector, corresponding regulation output electric current.
As shown in Figure 4, LED drive circuit of the present invention, builtin voltage Vinternal raises with the rising of input voltage, and its value is Vin-Vt.And when input voltage during greater than a threshold value, builtin voltage Vinternal does not change with input voltage and keeps stablizing.The internal reference current circuit is started working when voltage reaches a threshold value.Pass through the extended N of current mirroring circuit after this reference current doubly, for example, if internal reference electric current I ref=10uA, ratio n=2000, the electric current I power=20mA after amplifying.Because the drain voltage of NMOS pipe the 101 and the 2nd a NMOS pipe 102 can not guarantee to equate fully, this has just reduced the current copy precision of common-source common-gate current mirror, and current ratio may be not according to the variation of expectation.For improving this problem, the invention provides an improved technical scheme, embodiment is as shown in Figure 5.
With reference to figure 5, the present invention further arranges operational amplifier 105 in constant biasing unit 10, the in-phase input end of this operational amplifier 105 connects the drain electrode of a NMOS pipe 101, inverting input connects the drain electrode of the 2nd NMOS pipe 102, output connects the grid of the 4th NMOS pipe 104, and the source electrode of the 4th NMOS pipe 104 connects the drain electrode of the 2nd NMOS pipe 102.
Described operational amplifier 105 is used to make the drain voltage of a NMOS pipe 101 identical with the drain voltage of the 2nd NMOS pipe 102.Like this, no matter how the homophase input voltage changes, current ratio n can remain unchanged.
Fig. 6 shows that when in-phase voltage in very large range changed, the analogue value of output current all remained unchanged.Since it is identical with the electric current that flows through device to flow through the electric current of LED, any variation of therefore flowing through the electric current of device all can affect the electric current that flows through LED.This flows through the electric current of LED, according to Fig. 4, for
I
LED＝Id+Iref+Ipower+I1+Idim
Iref wherein, Ipower, I1 and Idim are produced by fixing builtin voltage Vinternal, and voltage Vinternal can control by the precision and the fault-tolerance that improve circuit.Id is unique electric current that changes with input voltage wherein, and the variation of input voltage changes because of the variation of diode current.A kind of mode that obtains better stabling current deviate is to adopt the depletion type NMOS with stepping brake voltage.Another kind of mode is first to adopt a start-up circuit, then utilizes the complete voltage afterwards of startup to produce a constant-current source and replaces the branch road that in start-up circuit, electric current changes with input voltage.Yet as shown in Figure 4, adopt 3,000,000 resistance 202 in builtin voltage generation unit of the present invention, series zener diode 201, this moment, the excursion of electric current and voltage was respectively 1uA to 10uA, and 8V is to 35V.The electric current of 10uA is only 0.5% of 20mA, concerning most of practical applications, can ignore.Therefore, this device can be for LED provides stable electric current in wider input voltage range, and input voltage range can at 85V between 265V, can be applied to most of LED.
Certainly, above is only concrete exemplary applications of the present invention, and protection scope of the present invention is not constituted any limitation.In addition to the implementation, the present invention can also have other execution mode.All employings are equal to the technical scheme of replacement or equivalent transformation formation, within all dropping on the present invention's scope required for protection.
Claims (7)
1. a both-end current source, be used for driving light-emitting diode, comprises:
The constant biasing unit comprises the boost current mirror that is made of the interconnective NMOS pipe of grid and the 2nd NMOS pipe, with the current reference circuit that is connected with this boost current mirror;
The builtin voltage generation unit connects described current reference circuit; And
Function control unit comprises the brightness regulation module, and this brightness regulation module is connected with described current reference circuit;
It is characterized in that, described constant biasing unit also comprises operational amplifier, the in-phase input end of this operational amplifier connects the drain electrode of a NMOS pipe, inverting input connects the drain electrode of the 2nd NMOS pipe, output connects the grid of the 4th NMOS pipe, and the source electrode of the 4th NMOS pipe connects the drain electrode of the 2nd NMOS pipe; Described operational amplifier is used for making the drain voltage of a NMOS pipe identical with the drain voltage of the 2nd NMOS pipe.
2. both-end current source according to claim 1; it is characterized in that; described function control unit also comprises the protection module that is connected with described current reference circuit; this protection module comprises short circuit protection module; voltage between this short circuit protection module two terminals detected according to internal inspection device, corresponding reduction output current.
3. both-end current source according to claim 2; it is characterized in that; described protection module also comprises the overheat protector module that is connected with described current reference circuit, this overheat protector module junction temperature detected according to the internal temperature detector, corresponding regulation output electric current.
4. both-end current source according to claim 1, it is characterized in that, described builtin voltage generation unit, comprise the resistance and the 3rd NMOS pipe that are connected with voltage stabilizing didoe, the grid of the 3rd NMOS pipe is connected with described voltage stabilizing didoe, the source electrode of the 3rd NMOS pipe is connected with described current reference circuit, and the drain electrode of the 3rd NMOS pipe is connected with power positive end.
5. both-end current source according to claim 1, is characterized in that, the input voltage range of described LED drive at 85V between 265V.
6. a LED drive, comprise both-end current source as described in any one in claim 1-5.
7. an electronic equipment, comprise both-end current source as described in any one in claim 1-5.
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| CN 201010229096 CN101896028B (en) | 2010-07-16 | 2010-07-16 | Double-end current source and LED driver comprising same |
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| CN 201010229096 CN101896028B (en) | 2010-07-16 | 2010-07-16 | Double-end current source and LED driver comprising same |
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| CN101896028B true CN101896028B (en) | 2013-05-15 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| TWI469686B (en) * | 2011-05-10 | 2015-01-11 | Richtek Technology Corp | Light emitting device current regulator circuit and control method thereof |
| CN110784100B (en) * | 2018-07-30 | 2022-11-29 | 上海雷舞照明技术有限公司 | Power conversion device and power management method |
| CN111900617B (en) * | 2020-07-20 | 2024-01-09 | 索尔思光电（成都）有限公司 | Laser drive circuit and optical module |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101069339A (en) * | 2004-12-03 | 2007-11-07 | 罗姆股份有限公司 | Power supply device, light emitting device using such power supply device, and electronic device |
| CN101267705A (en) * | 2007-03-14 | 2008-09-17 | 株式会社理光 | Constant current circuit and light emitting diode drive circuit |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101069339A (en) * | 2004-12-03 | 2007-11-07 | 罗姆股份有限公司 | Power supply device, light emitting device using such power supply device, and electronic device |
| CN101267705A (en) * | 2007-03-14 | 2008-09-17 | 株式会社理光 | Constant current circuit and light emitting diode drive circuit |
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Effective date of registration: 20200927 Address after: Room a1102, Xinhui building, No. 33, Gaoxin Road, hi tech Zone, Xi'an City, Shaanxi Province Patentee after: CHANGXIN (XI'AN) INTEGRATED CIRCUIT TECHNOLOGY Co.,Ltd. Patentee after: SHENZHEN TAIDE SEMICONDUCTOR CO.,LTD. Address before: 710071 Shaanxi Province, Xi'an City Xinhui High Road No. 33 Building No. A2402 Patentee before: CHANGXIN (XI'AN) INTEGRATED CIRCUIT TECHNOLOGY Co.,Ltd. Patentee before: Shenzhen Techcode Industrial Product Design Co.,Ltd. |
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Effective date of registration: 20231007 Address after: A-115-14, iChuangtu Zhongchuang Park, No.14 Gaoxin Second Road, Gaoxin District, Xi'an City, Shaanxi Province, 710075 Patentee after: CHANGXIN (XI'AN) INTEGRATED CIRCUIT TECHNOLOGY Co.,Ltd. Address before: Room A1102, Xinhui Building, No. 33 Gaoxin Road, High tech Zone, Xi'an City, Shaanxi Province, 710000 Patentee before: CHANGXIN (XI'AN) INTEGRATED CIRCUIT TECHNOLOGY Co.,Ltd. Patentee before: SHENZHEN TAIDE SEMICONDUCTOR CO.,LTD. |
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Effective date of registration: 20231204 Address after: 101200 floors 1-5, building 5, yard 32, Mafang street, Mafang Town, Pinggu District, Beijing Patentee after: BEIJING QIXING HUACHUANG MICROELECTRONICS CO.,LTD. Address before: A-115-14, iChuangtu Zhongchuang Park, No.14 Gaoxin Second Road, Gaoxin District, Xi'an City, Shaanxi Province, 710075 Patentee before: CHANGXIN (XI'AN) INTEGRATED CIRCUIT TECHNOLOGY Co.,Ltd. |