CN105578652A - Over-temperature protection circuit and system for LED lamp - Google Patents

Over-temperature protection circuit and system for LED lamp Download PDF

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Publication number
CN105578652A
CN105578652A CN201610032268.2A CN201610032268A CN105578652A CN 105578652 A CN105578652 A CN 105578652A CN 201610032268 A CN201610032268 A CN 201610032268A CN 105578652 A CN105578652 A CN 105578652A
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CN
China
Prior art keywords
resistance
led
comparator
input
voltage
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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.)
Pending
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CN201610032268.2A
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Chinese (zh)
Inventor
韦润芝
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KANGNAISI SIGNAL EQUIPMENT CO Ltd SHANGHAI
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KANGNAISI SIGNAL EQUIPMENT CO Ltd SHANGHAI
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Priority to CN201610032268.2A priority Critical patent/CN105578652A/en
Publication of CN105578652A publication Critical patent/CN105578652A/en
Pending legal-status Critical Current

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Classifications

    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05BELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00Circuit arrangements for operating light emitting diodes [LEDs]
    • H05B45/50Circuit arrangements for operating light emitting diodes [LEDs] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02BCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
    • Y02B20/30Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

The invention relates to the field of an LED, and particularly to an over-temperature protection circuit and system for an LED lamp. The input voltage at an inverted input end of a first comparator is changed by a thermistor; meanwhile, the over-temperature protection for the LED lamp is realized by hysteretic characteristics formed by a feedback circuit formed by a fourth resistor that is connected between a first junction point and the output end of the first comparator in series; the invention also provides an over-temperature protection system for the LED lamp; a temperature signal is obtained through a temperature sensor; the input voltage input to a hysteretic temperature control unit is adjusted according to the temperature signal so as to control the operating on-off states of the LED lamp; and meanwhile, when the output voltage of the hysteretic temperature control unit is zero, a trigger signal is generated by a zero voltage trigger unit to trigger an alarm unit to sent out an alarm so as to realize the in-time over-temperature protection for the LED lamp.

Description

A kind of LED thermal-shutdown circuit and system
Technical field
The present invention relates to LED field, particularly relate to a kind of LED thermal-shutdown circuit and system.
Background technology
Work light is mainly used in the light fixture of the working site illuminations such as various Large Construction operation, accident maintenance, rescue and relief work, and volume is little, brightness is high, adopts high light efficiency LED.Because power is large, brightness is high, and light fitting body can be caused to become a thermal source.When LED is under high temperature for a long time, this can be very large injury to LED, has a strong impact on the life-span of LED and causes the light decay of LED.
Existing temperature protection circuit is setting threshold values, when temperature is higher than threshold values time, with regard to the work of halt circuit, closes the output of LED, when temperature is lower than this threshold values time, opens drive circuit, again allows LED normally work.But such design, once temperature detection input signal has a small amount of noise or interference, or the ambient temperature on LED side is just in this threshold values when slightly fluctuating up and down, and LED will be caused between the state that opening and closing two are different to produce saltus step frequently and concussion.This all has a great impact the operating state of light fixture and the life-span of LED., cannot monitor in real time LED meanwhile, LED also may be caused to damage, even cause fire.
Summary of the invention
For the problems referred to above, the present invention proposes a kind of LED thermal-shutdown circuit, it is characterized in that, described circuit comprises:
First resistance of series connection and the second resistance, and first node is provided with between described first resistance and described second resistance;
The thermistor of series connection and the 3rd resistance, and Section Point is provided with between described thermistor and described 3rd resistance;
First comparator, has positive input, reverse input end and output, and described positive input is connected to described first node, and described reverse input end is connected to described Section Point; And
4th resistance, is serially connected between described output and described first node;
Wherein, the output of described first comparator is connected with described LED, to be controlled by the change of described thermistor resistance open or close described LED.
Above-mentioned LED thermal-shutdown circuit, wherein, described thermistor is NTC thermistors.
Above-mentioned LED thermal-shutdown circuit, wherein, described circuit also comprises power supply and grounding ports, described first comparator also comprises power input and earth terminal, described power supply is connected with the described power input of described first resistance, described second resistance and described first comparator respectively, and the described earth terminal of described first comparator, described second resistance are connected with described grounding ports respectively with described 3rd resistance;
The voltage V+=Vc*R2/ (R1+R2) of described first comparator normal phase input end, the voltage V-=Vc*R3/ (RT1+R3) of described first comparator inverting input;
Wherein, R1 is the resistance value of described first resistance, and R2 is the resistance value of described second resistance, and R3 is the resistance value of described 3rd resistance, and RT1 is the resistance value of described thermistor, and Vc is the magnitude of voltage of described power supply.
Above-mentioned LED thermal-shutdown circuit, wherein, described circuit also comprises:
First electric capacity of voltage regulation, with described 3rd resistor coupled in parallel, to prevent the voltage generation saltus step of the inverting input inputting described first comparator.
Above-mentioned LED thermal-shutdown circuit, wherein, described circuit also comprises:
Second electric capacity of voltage regulation, with described second resistor coupled in parallel, to prevent the voltage generation saltus step of the normal phase input end inputting described first comparator.
A kind of LED overheat protector system, is characterized in that, comprising:
Temperature sensor, for the temperature signal detecting described LED;
Hysteresis temperature conditioning unit, is connected with described temperature sensor and described LED respectively, for the break-make controlling described LED according to described temperature signal hysteresis;
Wherein, described hysteresis temperature conditioning unit comprises the LED thermal-shutdown circuit as described in Claims 1 to 5.
Above-mentioned LED overheat protector system, wherein, described system also comprises:
Zero-current transition unit, is connected with described hysteresis temperature conditioning unit, generates and exports triggering signal when described hysteresis temperature conditioning unit output voltage is zero;
Alarm unit, is connected with described zero-current transition unit, reports to the police for generating also output alarm signal according to described triggering signal.
Above-mentioned LED overheat protector system, wherein, described zero-current transition unit comprises:
Second comparator, the end of oppisite phase of described second comparator is connected with described hysteresis temperature conditioning unit, and the positive terminal of described second comparator is connected with described earth terminal, generates and exports triggering signal when described hysteresis temperature conditioning unit output voltage is zero.
In sum, the present invention proposes a kind of LED thermal-shutdown circuit, thermistor is utilized to change the input voltage of the inverting input of the first comparator, utilize the feedback loop being serially connected in the 4th resistance between the first node and the first comparator output terminal and being formed, the hysteretic characteristic formed realizes the overheat protector of LED simultaneously; Also proposed a kind of LED overheat protector system; temperature signal is obtained by temperature sensor; with the input voltage according to this temperature signal adjustment input hysteresis temperature conditioning unit; to control the on off operating mode of LED work; simultaneously when hysteresis temperature conditioning unit output voltage is zero; utilize zero-current transition unit to generate triggering signal, trigger alarm unit is reported to the police, and protects in time with the excess temperature realizing LED.
Accompanying drawing explanation
Fig. 1 is the circuit theory diagrams of embodiment of the present invention LED thermal-shutdown circuit;
Fig. 2 is the structure principle chart of embodiment of the present invention LED overheat protector system;
Fig. 3 is the hysteresis characteristic schematic diagram of embodiment of the present invention hysteresis temperature conditioning unit.
Embodiment
Below in conjunction with accompanying drawing, a specific embodiment of the present invention is further described.
Embodiment one
Fig. 1 is the circuit theory diagrams of embodiment of the present invention LED thermal-shutdown circuit, as shown in Figure 1, present embodiments provides a kind of LED thermal-shutdown circuit, in this circuit:
First resistance R1 of series connection and the second resistance R2, and first node is provided with between the first resistance R1 and the second resistance R2; (circuit that in this embodiment, the 3rd resistance is made up of resistance R31, resistance R32 and resistance R33 forms the thermistor RT1 of series connection and the 3rd resistance R3, but this is a kind of preferred situation just, other equivalent electric circuits are also interpreted as being comprised in the present invention), and Section Point n2 is provided with between thermistor RT1 and the 3rd resistance; First comparator U1A has positive input, reverse input end and output, and positive input is connected to first node n1, and reverse input end is connected to Section Point n2; 4th resistance R4 (in this embodiment, the 4th resistance is composed in parallel by resistance R41, R42, but this is a kind of preferred situation, and other equivalent electric circuits are also interpreted as being comprised in the present invention) is serially connected between output and first node n1; The output of the first comparator U1A is connected with LED, to be controlled by the change of thermistor resistance to open or close LED; Thermistor RT1 is NTC thermistors, and resistance declines when the temperature increases, and resistance rises when the temperature decreases; Power supply Vc is connected with the power input of the first resistance R1, the second resistance R2 and the first comparator U1A respectively, earth terminal, the second resistance R2 of the first comparator U1A are connected with grounding ports respectively with the 3rd resistance R3, the voltage V+=Vc*R2/ (R1+R2) of the first comparator U1A normal phase input end herein, the voltage V-=Vc*R3/ (RT1+R3) of the first comparator U1A inverting input, wherein R3=R31*R32/ (R31+R32)+R33; First electric capacity of voltage regulation C1 is in parallel with the 3rd resistance R3, to prevent the voltage generation saltus step of the inverting input of input first comparator U1A; Second electric capacity of voltage regulation C2 is in parallel with the second resistance R2, to prevent the voltage generation saltus step of the normal phase input end of input first comparator U1A.
When this circuit normally works; LED receives normal working voltage; thermistor RT1 may raise resistance with temperature and constantly diminish; the dividing potential drop of the 3rd resistance R3 constantly raises; first comparator U1A anti-phase input terminal voltage is constantly raised; until when the first comparator U1A anti-phase input terminal voltage exceedes normal phase input end voltage (i.e. the voltage at R2 two ends), the first comparator U1A exports and changes into no-voltage, and LED turns off and forms protection.Now feedback resistance R4 is equivalent in parallel with the second resistance R2, and the second resistance R2 resistance reduces dividing potential drop and reduces, and makes the normal phase input end voltage drop of the first comparator U1A.Therefore; if this circuit needs to return to normal operating conditions; then the 3rd resistance needs than original higher voltage; that is; thermistor RT1 needs the resistance reached than original higher that LED just can be made to reclose; form the temperature protection circuit with hysteresis characteristic, its hysteresis characteristic as shown in Figure 3.
Embodiment two
As shown in Figure 2, the present embodiment proposes a kind of LED overheat protector system, in this protection system:
Temperature sensor 1 is connected with NTC thermistors, for the temperature signal detecting LED, and utilizes this temperature signal to change the resistance of thermistor; Hysteresis temperature conditioning unit 2 is connected with temperature sensor 1, for controlling the break-make of LED according to temperature signal hysteresis; Zero-current transition unit 3 is connected with hysteresis temperature conditioning unit 2, generates and exports triggering signal when hysteresis temperature conditioning unit 2 output voltage is zero; Alarm unit 4 is connected with zero-current transition unit 3, reports to the police for generating also output alarm signal according to triggering signal.
Preferably, zero-current transition unit 4 comprises the second comparator, the inverting input of the second comparator is connected with hysteresis temperature conditioning unit 2, and the normal phase input end of the second comparator is connected with earth terminal, generates and exports triggering signal when hysteresis temperature conditioning unit 2 output voltage is zero.
In sum, the present invention proposes a kind of LED thermal-shutdown circuit, thermistor is utilized to change the input voltage of the inverting input of the first comparator, utilize the feedback loop being serially connected in the 4th resistance between the first node and the first comparator output terminal and being formed, the hysteretic characteristic formed realizes the overheat protector of LED simultaneously; Also proposed a kind of LED overheat protector system; temperature signal is obtained by temperature sensor; with the input voltage according to this temperature signal adjustment input hysteresis temperature conditioning unit; to control the on off operating mode of LED work; simultaneously when hysteresis temperature conditioning unit output voltage is zero; utilize zero-current transition unit to generate triggering signal, trigger alarm unit is reported to the police, and protects in time with the excess temperature realizing LED.
By illustrating and accompanying drawing, giving the exemplary embodiments of embodiment, based on the present invention's spirit, also can do other conversion.Although invention described above provide an embodiment, but these contents are not as limitation.
For a person skilled in the art, after reading above-mentioned explanation, various changes and modifications undoubtedly will be apparent.Therefore, appending claims should regard the whole change and correction of containing true intention of the present invention and scope as.In Claims scope, the scope of any and all equivalences and content, all should think and still belong to the intent and scope of the invention.

Claims (8)

1. a LED thermal-shutdown circuit, is characterized in that, described circuit comprises:
First resistance of series connection and the second resistance, and first node is provided with between described first resistance and described second resistance;
The thermistor of series connection and the 3rd resistance, and Section Point is provided with between described thermistor and described 3rd resistance;
First comparator, has positive input, reverse input end and output, and described positive input is connected to described first node, and described reverse input end is connected to described Section Point; And
4th resistance, is serially connected between described output and described first node;
Wherein, the output of described first comparator is connected with described LED, to be controlled by the change of described thermistor resistance open or close described LED.
2. LED thermal-shutdown circuit according to claim 1, is characterized in that, described thermistor is NTC thermistors.
3. LED thermal-shutdown circuit according to claim 2, it is characterized in that, described circuit also comprises power supply and grounding ports, described first comparator also comprises power input and earth terminal, described power supply is connected with the described power input of described first resistance, described second resistance and described first comparator respectively, and the described earth terminal of described first comparator, described second resistance are connected with described grounding ports respectively with described 3rd resistance;
The voltage V+=Vc*R2/ (R1+R2) of described first comparator normal phase input end, the voltage V-=Vc*R3/ (RT1+R3) of described first comparator inverting input;
Wherein, R1 is the resistance value of described first resistance, and R2 is the resistance value of described second resistance, and R3 is the resistance value of described 3rd resistance, and RT1 is the resistance value of described thermistor, and Vc is the magnitude of voltage of described power supply.
4. LED thermal-shutdown circuit according to claim 3, is characterized in that, described circuit also comprises:
First electric capacity of voltage regulation, with described 3rd resistor coupled in parallel, to prevent the voltage generation saltus step of the inverting input inputting described first comparator.
5. LED thermal-shutdown circuit according to claim 3, is characterized in that, described circuit also comprises:
Second electric capacity of voltage regulation, with described second resistor coupled in parallel, to prevent the voltage generation saltus step of the normal phase input end inputting described first comparator.
6. a LED overheat protector system, is characterized in that, comprising:
Temperature sensor, for the temperature signal detecting described LED;
Hysteresis temperature conditioning unit, is connected with described temperature sensor and described LED respectively, for the break-make controlling described LED according to described temperature signal hysteresis;
Wherein, described hysteresis temperature conditioning unit comprises the LED thermal-shutdown circuit as described in Claims 1 to 5.
7. LED overheat protector system according to claim 6, it is characterized in that, described system also comprises:
Zero-current transition unit, is connected with described hysteresis temperature conditioning unit, generates and exports triggering signal when described hysteresis temperature conditioning unit output voltage is zero;
Alarm unit, is connected with described zero-current transition unit, reports to the police for generating also output alarm signal according to described triggering signal.
8. LED overheat protector system according to claim 7, is characterized in that, described zero-current transition unit comprises:
Second comparator, the inverting input of described second comparator is connected with described hysteresis temperature conditioning unit, and the normal phase input end of described second comparator is connected with described earth terminal, generates and exports triggering signal when described hysteresis temperature conditioning unit output voltage is zero.
CN201610032268.2A 2016-01-18 2016-01-18 Over-temperature protection circuit and system for LED lamp Pending CN105578652A (en)

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Application Number Priority Date Filing Date Title
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Application Number Priority Date Filing Date Title
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106385731A (en) * 2016-08-31 2017-02-08 上海顿格电子贸易有限公司 Lamp and over-temperature protection circuit thereof

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN202335027U (en) * 2011-12-05 2012-07-11 敖志刚 Intelligent light-emitting diode (LED) illuminating system having automatic overheating protection
CN103369770A (en) * 2012-03-31 2013-10-23 海洋王照明科技股份有限公司 Light fixture over-temperature protection circuit and light fixture over-temperature protection device
CN203840609U (en) * 2014-05-05 2014-09-17 长治市华杰光电科技有限公司 LED circuit having overheating protection function
CN204259262U (en) * 2014-07-23 2015-04-08 武汉晶美光电有限公司 A kind of overtemperature protection module of LED actuation temperature warning circuit
CN104735879A (en) * 2015-03-26 2015-06-24 谢晶 Led circuit

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN202335027U (en) * 2011-12-05 2012-07-11 敖志刚 Intelligent light-emitting diode (LED) illuminating system having automatic overheating protection
CN103369770A (en) * 2012-03-31 2013-10-23 海洋王照明科技股份有限公司 Light fixture over-temperature protection circuit and light fixture over-temperature protection device
CN203840609U (en) * 2014-05-05 2014-09-17 长治市华杰光电科技有限公司 LED circuit having overheating protection function
CN204259262U (en) * 2014-07-23 2015-04-08 武汉晶美光电有限公司 A kind of overtemperature protection module of LED actuation temperature warning circuit
CN104735879A (en) * 2015-03-26 2015-06-24 谢晶 Led circuit

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106385731A (en) * 2016-08-31 2017-02-08 上海顿格电子贸易有限公司 Lamp and over-temperature protection circuit thereof

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Application publication date: 20160511