CN102131324B - Thermal foldback control circuit and control method of light-emitting diode (LED) - Google Patents
Thermal foldback control circuit and control method of light-emitting diode (LED) Download PDFInfo
- Publication number
- CN102131324B CN102131324B CN201010000760.4A CN201010000760A CN102131324B CN 102131324 B CN102131324 B CN 102131324B CN 201010000760 A CN201010000760 A CN 201010000760A CN 102131324 B CN102131324 B CN 102131324B
- Authority
- CN
- China
- Prior art keywords
- hot
- signal
- control circuit
- detection signal
- heat detection
- 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
Abstract
The invention discloses a thermal foldback control circuit and a control method of a light-emitting diode (LED). The thermal foldback control circuit and the control method of the LED are used for sensing the temperature of the LED and the temperature of a control chip of the LED and gradually reducing a driving current of the LED before overheating of the LED or the control chip so as to avoid the twinkle of the LED caused by the startup of an overheating protecting mechanism due to the overheating of the control chip. The thermal foldback control circuit comprises an outside heat-sensing end for receiving an outside heat-sensing signal related to the temperature of the LED, a heat-controllable circuit for sensing the temperature of the control chip so as to determine an inside heat-sensing signal and a multi-path sensing circuit for connecting the outside heat-sensing end and the heat-controllable circuit and triggering a heat-regulating signal to regulate the driving current intelligently and further regulate the temperatures of the LED and the control chip automatically when the outside heat-sensing signal surpasses a first threshold signal or the inside heat-sensing signal surpasses a second threshold signal.
Description
Technical field
The present invention relates to the controller of a kind of light-emitting diode (LED), the heat particularly about a kind of LED is turned back (thermal foldback) control circuit and method.
Background technology
Overtemperature protection mechanism (Over Temperature Protection; OTP) be the technology of protection controller chip, it is when the temperature of controller chip rises to set point, and closing controller chip burns to avoid controller chip.Hot foldback technique is the mechanism of protection LED, and it is when the temperature of LED rises to set point, reduces the drive current of LED, continues to raise to avoid the temperature of LED.The design of existing LED lamp focuses on safety and the heat radiation of LED itself; therefore LED and its drive circuit are provided separately; and be in particular LED retain can supply cross-ventilated space; to reduce the temperature of its surface contact; and drive circuit is arranged in airtight space mostly; heat radiation not easily; therefore; sometimes be the temperature of temperature higher than LED of the controller chip of drive circuit on the contrary; touching OTP makes controller chip enter Thermal protection pattern; cause the drive current of LED to be cut off, thus LED produces the phenomenon of flicker.
Summary of the invention
An object of the present invention, is the hot foldback control circuit and the method that propose a kind of LED, progressively adjusts the drive current of LED according to variations in temperature.
An object of the present invention, is to propose a kind of simple circuit and method, detects the variations in temperature of LED and controller chip, the drive current of Intelligent adjustment LED according to this simultaneously, and then regulate the temperature of LED and controller chip voluntarily.
For reaching above-mentioned purpose, the invention provides a kind of hot foldback control circuit of light-emitting diode, the drive current of the controlled device chip controls of this light-emitting diode is lighted, and this hot foldback control circuit comprises:
External heat sense terminal, receives the external heat detection signal with the temperature correlation of this light-emitting diode;
Hot controlable electric current, detects the temperature of this controller chip, determines internal heat detection signal according to this; And
Multichannel circuit for detecting, connect this external heat sense terminal and this hot controlable electric current, this external heat detection signal more than the first door signal or this internal heat detection signal more than the second door signal time, trigger thermal conditioning signal with this drive current of Intelligent adjustment, and then regulate the temperature of this light-emitting diode and this controller chip voluntarily.
For reaching above-mentioned purpose, the present invention also provides a kind of hot recurving control method of light-emitting diode, and the drive current of the controlled device chip controls of this light-emitting diode is lighted, and this hot recurving control method comprises:
(A) the external heat detection signal with the temperature correlation of this light-emitting diode is received;
(B) temperature of this controller chip is detected to determine internal heat detection signal; And
(C) this external heat detection signal more than the first door signal or this internal heat detection signal more than the second door signal time, this drive current of Intelligent adjustment, and then regulate the temperature of this light-emitting diode and this controller chip voluntarily.
According to the present invention, the control circuit of a kind of LED and method monitor the temperature of this light-emitting diode and the temperature of controller chip thereof simultaneously, judge that whichever is higher, then determine that the position of equalized temperature is accurate.The present invention can detect the temperature of the temperature of this light-emitting diode and the controller chip of this light-emitting diode; this light-emitting diode or this controller chip overheated before; just progressively reduce the drive current of this light-emitting diode, avoid because this controller chip overheated causing starts overtemperature protection mechanism and cause LED flash.
Accompanying drawing explanation
Fig. 1 is schematic diagram according to an embodiment of the invention;
Fig. 2 is the embodiment of hot controlable electric current;
Fig. 3 is the embodiment of hot controlable electric current; And
Fig. 4 is the embodiment using multi-door bank signal.
Specific embodiment
Below in conjunction with Figure of description, the specific embodiment of the present invention is described in detail.Obviously, described embodiment is only a part of embodiment of the present invention, and other embodiment that those skilled in the art obtains under the prerequisite not paying creative work all belongs to protection scope of the present invention.
Fig. 1 is schematic diagram according to an embodiment of the invention, and LED array 10 couples power Vcc through resistance R1, and controller chip 12 connects LED array 10, is used for the drive current Iled of control LED array 10.Controller chip 12 comprises BJT 14 and connects with LED array 10, and therefore the collector current Ic of BJT 14 equals the drive current Iled of LED array 10.Driver 16 connects the base stage of BJT 14, with the collector current Ic of control BJT 14.As prior art, controller chip 12 has light modulation (dimming) pin DIM and connects driver 16, is used for accepting light modulation input, with the brightness of control LED array 10.Controller chip 12 also comprises hot foldback control circuit 18, is used to provide thermal conditioning signal to driver 16, regulates the collector current Ic of BJT 14 according to this.Thermistor NTCR detects the temperature of LED array 10, produces external heat detection signal VTO according to this to controller chip 12.When the temperature increases, the resistance value of thermistor NTCR declines, and external heat detection signal VTO is reduced.Hot foldback control circuit 18 has external heat sense terminal 20, receive external heat detection signal VTO, hot controlable electric current 22 detects the temperature of controller chip 12 itself, produce internal heat detection signal VTI, and multichannel circuit for detecting 24 determines thermal conditioning signal according to external heat detection signal VTO and internal heat detection signal VTI.In multichannel circuit for detecting 24, comparator 26 has two positive input terminals and receives external heat detection signal VTO and internal heat detection signal VTI respectively, it is compared with door signal VTH, generation compares signal to voltage generator 28, produce overheated detecting voltage Vt according to this, hysteresis comparator 30 more overheated detecting voltage Vt produces thermal conditioning signal with the feedback voltage Vf from LED array 10.Because drive current Iled flows through resistance R1, therefore feedback voltage
Vf=Vcc-Iled × R1, formula 1
It is the function of drive current Iled.The door signal VTH of comparator 26 is provided by the voltage source 32 of not temperature influence.Voltage generator 28 comprises current source 34 and determines overheated detecting current It according to comparing signal, and resistance R2 is connected between the positive input terminal of power Vcc and hysteresis comparator 30, overheated detecting current It flows through resistance R2 and produces cross-pressure, thus determines overheated detecting voltage
Vt=Vcc-It × R2, formula 2
It is the function of overheated detecting current It.In one embodiment, the initial value of overheated detecting current It is zero.When the LED array 10 temperature internal temperature that is too high or controller chip 12 of outside is too high, the comparison signal that comparator 26 produces makes current source 34 increase its overheated detecting current It, thus reduce overheated detecting voltage Vt, thus hysteresis comparator 30 triggers thermal conditioning signal, cause driver 16 to reduce the collector current Ic of BJT 22, but still maintaining LED array 10 work.After each thermal conditioning signal is triggered, collector current Ic will be reduced by a predetermined difference by driver 16, unless the temperature of controller chip 12 is elevated to the set point of OTP, just can touch OTP mechanism closing controller chip 12.Therefore, no matter be that the temperature of the temperature of LED array 10 or controller chip 12 is too high, collector current Ic all can be impelled to reduce, but LED array 10 still maintain at work.By comparator 26, can judge that the internal temperature whichever of outside LED array 10 temperature and controller chip 12 is higher, then determine that the position of equalized temperature is accurate.This detecting structure is more flexible, the setting that user can have more grasp lamp temperatures to protect.
Above-mentioned hot controlable electric current 22 can be bipolarity junction transistor, and this bipolarity junction transistor has base-emitter voltage and changes this internal heat detection signal in response to variations in temperature.Fig. 2 is the embodiment of hot controlable electric current 22, and it uses a hot detection signal VTI of simple BJT circuitry produces internal.Base-emitter voltage the VBE of BJT 36 is about 0.7V at a normal temperature, and when the temperature increases, VBE can reduce, and cause its collector current Ic to increase, therefore internal heat detection signal VTI declines.Determine the initial value of internal heat detection signal VTI by adjustment setting resistance Rset, the resistance value of setting resistance Rset is higher, then the initial value of internal heat detection signal VTI is lower, and in other words, the critical temperature of controller chip 12 self is lower.As shown in Figure 3, set up electric capacity C at the output of hot controlable electric current 22, the stability of internal heat detection signal VTI can be improved.For reducing the area of controller chip 12, the setting resistance Rset of hot controlable electric current 10 is arranged on controller chip 12 outside by the embodiment of Fig. 3, but in other embodiments, also setting resistance Rset can be arranged on controller chip 12 inner.
Hot foldback control circuit 18 of the present invention can automatic decision be that the temperature internal temperature that is high or controller chip 12 of LED array 10 is high, and then start the drive current Iled of Intelligent adjustment LED array 10, make it to raise with the internal temperature of controller chip 12 or the temperature of LED array 10 and reduce gradually, to relax the trend that temperature rises, reach the effect of the temperature of conditioning controller chip 12 inside and LED array 10 voluntarily, reduction LED array 10 is the Probability of cease operation because controller chip 12 is overheated.
In the embodiment in figure 1, the temperature monitoring of internal controller chip 12 and the temperature monitoring of external LED array 10 all use same door signal VTH, but in other embodiments, the temperature of the temperature and controller chip 12 that also can be respectively LED array 10 arranges different door signal VTH1 and VTH2, as shown in Figure 4, use two comparators 38 and 40 to compare respectively, the result warp compared or door 42 produce and compare signal to voltage generator 28.
Above; be only preferred embodiment of the present invention, but protection scope of the present invention is not limited thereto, is anyly familiar with those skilled in the art in the technical scope that the present invention discloses; the change that can expect easily or replacement, all should be encompassed within protection scope of the present invention.Therefore, the protection range that protection scope of the present invention should define with claim is as the criterion.
Claims (22)
1. a hot foldback control circuit for light-emitting diode, the drive current of the controlled device chip controls of this light-emitting diode is lighted, and it is characterized in that, this hot foldback control circuit comprises:
External heat sense terminal, receives the external heat detection signal with the temperature correlation of this light-emitting diode;
Hot controlable electric current, detects the temperature of this controller chip, determines internal heat detection signal according to this; And
Multichannel circuit for detecting, connect this external heat sense terminal and this hot controlable electric current, this external heat detection signal more than the first door signal or this internal heat detection signal more than the second door signal time, trigger thermal conditioning signal with this drive current of Intelligent adjustment, and then regulate the temperature of this light-emitting diode and this controller chip voluntarily.
2. hot foldback control circuit as claimed in claim 1, is characterized in that, this external heat sense terminal connects thermistor.
3. hot foldback control circuit as claimed in claim 1, is characterized in that, this hot controlable electric current comprises the second bipolarity junction transistor, has base-emitter voltage and changes this internal heat detection signal in response to variations in temperature.
4. hot foldback control circuit as claimed in claim 1, is characterized in that, this hot controlable electric current connects setting resistance, to determine the initial value of this internal heat detection signal.
5. hot foldback control circuit as claimed in claim 1, is characterized in that, this first door signal and this second door signal are equal to each other.
6. hot foldback control circuit as claimed in claim 5, is characterized in that, this multichannel circuit for detecting comprises:
Comparator, compares this external heat detection signal and this first door signal, and this internal heat detection signal and this second door signal, compares signal to produce;
Voltage generator, connects this comparator, compares signal produce overheated detecting voltage according to this; And
Hysteresis comparator, compares this overheated detecting voltage and the feedback voltage from this light-emitting diode, to produce this thermal conditioning signal.
7. hot foldback control circuit as claimed in claim 6, is characterized in that, this voltage generator comprises:
Current source, compares signal produce overheated detecting current according to this; And
Resistance, connects this current source;
Wherein, this overheated detecting current flows through this resistance and produces this overheated detecting voltage.
8. hot foldback control circuit as claimed in claim 6, is characterized in that, this feedback voltage is the function of this drive current.
9. hot foldback control circuit as claimed in claim 1, is characterized in that, this first door signal and this second door signal unequal each other.
10. hot foldback control circuit as claimed in claim 9, is characterized in that, this multichannel circuit for detecting comprises:
First comparator, compares this external heat detection signal and this first door signal;
Second comparator, compares this internal heat detection signal and this second door signal;
Or door, produce this according to the comparative result of this first comparator and the second comparator and compare signal;
Voltage generator, connect should or door, compare signal produce overheated detecting voltage according to this; And
Hysteresis comparator, compares this overheated detecting voltage and the feedback voltage from this light-emitting diode, to produce this thermal conditioning signal.
11. hot foldback control circuit as claimed in claim 10, it is characterized in that, this voltage generator comprises:
Current source, compares signal produce overheated detecting current according to this; And
Resistance, connects this current source;
Wherein, this overheated detecting current flows through this resistance and produces this overheated detecting voltage.
12. hot foldback control circuit as claimed in claim 10, is characterized in that, this feedback voltage is the function of this drive current.
13. hot foldback control circuit as claimed in claim 1, more comprise voltage source and connect this multichannel circuit for detecting, provide this first door signal and the second door signal.
14. hot foldback control circuit as claimed in claim 1, is characterized in that, this thermal conditioning signal comprises to end this drive current, make the automatic overheated closedown of this light-emitting diode to reduce temperature.
The hot recurving control method of 15. 1 kinds of light-emitting diodes, the drive current of the controlled device chip controls of this light-emitting diode is lighted, and it is characterized in that, this hot recurving control method comprises:
(A) the external heat detection signal with the temperature correlation of this light-emitting diode is received;
(B) temperature of this controller chip is detected to determine internal heat detection signal; And
(C) this external heat detection signal more than the first door signal or this internal heat detection signal more than the second door signal time, this drive current of Intelligent adjustment, and then regulate the temperature of this light-emitting diode and this controller chip voluntarily.
16. hot recurving control methods as claimed in claim 15, is characterized in that, this step B comprises and changes this internal heat detection signal according to the change of the base-emitter voltage of bipolarity junction transistor.
17. hot recurving control methods as claimed in claim 15, more comprise the initial value of this internal heat detection signal of setting.
18. hot recurving control methods as claimed in claim 15, is characterized in that, this first door signal and this second door signal are equal to each other.
19. hot recurving control methods as claimed in claim 15, is characterized in that, this first door signal and this second door signal unequal each other.
20. hot recurving control methods as claimed in claim 15, it is characterized in that, this step C comprises:
Relatively this external heat detection signal and this first door signal, and this internal heat detection signal and this second door signal, produce overheated detecting voltage according to this; And
Relatively this overheated detecting voltage and the feedback voltage from this light-emitting diode, to determine this drive current.
21. hot recurving control methods as claimed in claim 20, it is characterized in that, this feedback voltage is the function of this drive current.
22. hot recurving control methods as claimed in claim 15, is characterized in that, this step C more comprises this drive current of cut-off, makes the automatic overheated closedown of this light-emitting diode to reduce temperature.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201010000760.4A CN102131324B (en) | 2010-01-18 | 2010-01-18 | Thermal foldback control circuit and control method of light-emitting diode (LED) |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201010000760.4A CN102131324B (en) | 2010-01-18 | 2010-01-18 | Thermal foldback control circuit and control method of light-emitting diode (LED) |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN102131324A CN102131324A (en) | 2011-07-20 |
| CN102131324B true CN102131324B (en) | 2015-03-18 |
Family
ID=44269188
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201010000760.4A Active CN102131324B (en) | 2010-01-18 | 2010-01-18 | Thermal foldback control circuit and control method of light-emitting diode (LED) |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN102131324B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9265119B2 (en) | 2013-06-17 | 2016-02-16 | Terralux, Inc. | Systems and methods for providing thermal fold-back to LED lights |
| CN114023739B (en) * | 2022-01-10 | 2022-06-17 | 上海奥简微电子科技有限公司 | Temperature sensing circuit and thermal feedback protection circuit |
| CN114035643A (en) * | 2022-01-10 | 2022-02-11 | 上海奥简微电子科技有限公司 | Temperature control protection circuit |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101164378A (en) * | 2005-04-19 | 2008-04-16 | 电灯专利信托有限公司 | Led module and led lightning unit with a plurality of led modules |
| CN101379889A (en) * | 2006-02-10 | 2009-03-04 | Tir科技公司 | Light source intensity control system and method |
| CN101400942A (en) * | 2005-09-15 | 2009-04-01 | 美光工具公司 | Improved led module |
| CN201374838Y (en) * | 2009-03-11 | 2009-12-30 | 四川九洲铭伟半导体照明有限公司 | LED driving power source |
-
2010
- 2010-01-18 CN CN201010000760.4A patent/CN102131324B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101164378A (en) * | 2005-04-19 | 2008-04-16 | 电灯专利信托有限公司 | Led module and led lightning unit with a plurality of led modules |
| CN101400942A (en) * | 2005-09-15 | 2009-04-01 | 美光工具公司 | Improved led module |
| CN101379889A (en) * | 2006-02-10 | 2009-03-04 | Tir科技公司 | Light source intensity control system and method |
| CN201374838Y (en) * | 2009-03-11 | 2009-12-30 | 四川九洲铭伟半导体照明有限公司 | LED driving power source |
Also Published As
| Publication number | Publication date |
|---|---|
| CN102131324A (en) | 2011-07-20 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| TWI384171B (en) | Thermal foldback control for a light-emitting diode | |
| US11877362B2 (en) | Light emitting diode thermal foldback control device and method | |
| JP5294920B2 (en) | LED light source lighting device and LED lighting apparatus using the same | |
| US9380685B2 (en) | Bypass circuit for neutral-less controller in lighting control system | |
| CN104679089B (en) | Step excess temperature for integrated LED driving chip compensates protection system and circuit | |
| JP2010129612A (en) | Lighting device | |
| US8638038B2 (en) | System for reprogramming power parameters for light emitting diodes | |
| EP2482615A1 (en) | Lighting device and luminaire with failure protection | |
| CN103997811A (en) | Lighting device and lighting fixture | |
| CN104105274A (en) | LED driving device, lighting device, and LED driving method | |
| CN102131324B (en) | Thermal foldback control circuit and control method of light-emitting diode (LED) | |
| CN105075394B (en) | LED converters with frost startup function | |
| JP2017520082A (en) | Emergency lighting system and method for automatic equalization of heating power | |
| JP6114988B2 (en) | Lighting device and lighting apparatus using the same | |
| JP2013161591A (en) | Light source lighting device and illuminating device | |
| CN208690918U (en) | A kind of thermal-shutdown circuit | |
| TWI593313B (en) | Dimming controller, driving circuit and control method for driving light sources | |
| US20190373689A1 (en) | Led arrangement with over-current protection | |
| JP6198812B2 (en) | LED lighting system | |
| CN204362355U (en) | A kind of LED drive circuit with overheat protective function | |
| WO2018149824A1 (en) | Led arrangement with over-current protection | |
| CN105317721A (en) | LED (Light Emitting Diode) control device and LED illumination equipment with same | |
| JP2013137934A (en) | Light-emitting element lighting device and illuminating device having the circuit | |
| JP2020201774A (en) | Lighting power supply and protection circuit for the same | |
| CN108963973A (en) | A kind of thermal-shutdown circuit and mould group |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant |