CN102222898A - Power supply output overvoltage protection circuit for LED (light emitting diode) LCD TV (liquid crystal display television) - Google Patents
Power supply output overvoltage protection circuit for LED (light emitting diode) LCD TV (liquid crystal display television) Download PDFInfo
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- CN102222898A CN102222898A CN2011101672623A CN201110167262A CN102222898A CN 102222898 A CN102222898 A CN 102222898A CN 2011101672623 A CN2011101672623 A CN 2011101672623A CN 201110167262 A CN201110167262 A CN 201110167262A CN 102222898 A CN102222898 A CN 102222898A
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Abstract
The invention relates to a power supply output overvoltage protection circuit for an LED (light emitting diode) LCD TV (liquid crystal display television), belonging to the field of an LED switching power supply of an LED TV. One end of a resistance R1 is connected with a collector of an NPN (negative-positive-negative) type triode Q1, the other end of the resistance R1, one end of a capacitance C3, and the cathode of a stabilivolt tube ZD1 are jointly connected with the base of the NPN type triode Q1, the other end of the capacitance C3 and the anode of the stabilivolt tube ZD1 are connected with a power ground, the emitter of the NPN type triode Q1 is connected with one end of a capacitance C4, the other end of the capacitance C4 is connected with the power ground, the emitter of the NPN type triode Q1 is the power supply end of the LED constant current chip, and the collector of the NPN type triode Q1 is connected with the power output end of a main topology circuit of the LED TV. The invention does not need to use a complicated circuit and cannot affect the overall efficiency and cost; and meanwhile, the protection circuit provided by the invention can ensure the chip to work safely without being damaged even if the voltage of the LED constant current chip exceeds too much.
Description
Technical field
The present invention relates to the circuit that LED field of switch power in the LCD TV and other LED power supplys have the output overvoltage risk, at length say it is a kind of a kind of protective circuit the output voltage overrate.
Background technology
As everyone knows: need in the circuit of constant current to the LED power supply at many liquid crystal LED TVs and other, great majority all are to add a LED constant-current circuit again the main topology of Switching Power Supply secondary, and generally the power supply of the chip of this constant-current circuit is that main topology by Switching Power Supply provides.When the feedback control loop of main topology lost efficacy, the output voltage of main topology will raise, if exceed the supply power voltage rated value of chip for the voltage of LED constant-current circuit chip power supply, LED constant-current circuit chip will damage, chip internal short circuit and then cause the damage of other elements.
At present main topological circuit much adopts as the NCP1271 of ON and the chips such as LD7575 of Leadtrend in the LED LCD TV, when chip NCP1271 when finding the feedback control loop inefficacy, need could turn-off output by delay 130ms, enter guard mode; And LD7575 is 30ms.No matter be 130ms or 30ms, the output voltage in this time is wanted several times of overrate.For example the chip used of LED liquid crystal television LED constant-current circuit is the OZ9902 of O2, and its supply power voltage maximum is 20V, if surpass 20V, chip will damage.Generally be that supply power voltage is arranged on about 12V, be easy to surpass 20V, cause the LED constant-current circuit to damage, chip internal short circuit and then cause the damage of other elements with chip.
Summary of the invention
Purpose of the present invention just is to overcome the deficiency that existing electrodeless lamp light modulation exists; a kind of LED liquid crystal display television by using power supply output over-voltage protection circuit is provided; do not adopting complicated circuit; when not influencing overall efficiency and cost; also can guarantee the chip trouble free service even can guarantee to give the voltage of LED constant current chip to exceed a lot, can not damage.
The present invention adopts following technical solution: a kind of LED liquid crystal display television by using power supply output over-voltage protection circuit; the collector electrode that it is characterized in that resistance R 1 one termination NPN triode Q1; the other end of resistance R 1 and capacitor C 3 one ends; the negative electrode of voltage-stabiliser tube ZD1 connects the base stage of NPN triode Q1 jointly; the anode of the other end of capacitor C 3 and voltage-stabiliser tube ZD1 connects power supply ground; the emitter of NPN triode Q1 connects capacitor C 4 one ends; another termination power ground of capacitor C 4; the emission of NPN triode Q1 is the feeder ear of LED constant current chip very, and the collector electrode of NPN triode Q1 connects the power output end of main topological circuit in the LED LCD TV.
The invention has the beneficial effects as follows, do not adopting complicated circuit, when not influencing overall efficiency and cost, also can guarantee the chip trouble free service, can not damage even can guarantee to give the voltage of LED constant current chip to exceed a lot.
Description of drawings
The present invention is further described below in conjunction with drawings and Examples.
Fig. 1 is circuit theory diagrams of the present invention.
Q1. NPN triode among the figure, R1. resistance, ZD1. voltage-stabiliser tube, C3. electric capacity, C4. electric capacity.
Embodiment
The invention will be further described below in conjunction with the drawings and specific embodiments, to help understanding content of the present invention.
As shown in Figure 1, the collector electrode of resistance R 1 one termination NPN triode Q1 of the present invention, the negative electrode of the other end of resistance R 1 and capacitor C 3 one ends, voltage-stabiliser tube ZD1 connects the base stage of NPN triode Q1 jointly, the anode of the other end of capacitor C 3 and voltage-stabiliser tube ZD1 connects power supply ground, the emitter of NPN triode Q1 connects capacitor C 4 one ends, another termination power ground of capacitor C 4, the emission of NPN triode Q1 is the feeder ear of LED constant current chip very, and the collector electrode of NPN triode Q1 connects the power output end of main topological circuit in the LED LCD TV.
The present invention is the voltage (A point) of the power output end of main topological circuit in the LED LCD TV, deducts by the voltage (C point) that is limited in voltage-stabiliser tube ZD1 to the B point behind this circuit in the pressure drop of the be utmost point of NPN triode Q1.At first the A point voltage is delivered to the junction C of the base stage of voltage-stabiliser tube ZD1 and NPN triode by resistance R 1, when the A point voltage does not surpass the puncture voltage of voltage-stabiliser tube ZD1, when not considering the leakage current of voltage-stabiliser tube ZD1 and capacitor C 1, the voltage that C is ordered equals the A point voltage, and the B point voltage equals the C point voltage and deducts the conduction voltage drop of NPN transistor base to emitter.
Main topological circuit in the LED LCD TV is because feedback control loop breaks down, output voltage makes when can not be exported according to default voltage, the A point voltage rises and when surpassing the puncture voltage of voltage-stabiliser tube ZD1, to have electric current and flow through resistance R 1 from the A point, voltage-stabiliser tube ZD1 is to power supply ground, this moment, the C voltage of ordering was the puncture voltage of voltage-stabiliser tube ZD1, and the voltage that B is ordered equals the be pressure drop that voltage that C orders deducts the NPN triode.Need only the suitable of ZD1 choosing like this, the B point voltage when promptly not influencing operate as normal; Can guarantee again when the A point voltage raises, make the B point voltage be no more than the power supply rated value of LED constant current chip IC 1, just can allow the safe and reliable work of LED constant current chip IC 1.
Claims (1)
1. LED liquid crystal display television by using power supply output over-voltage protection circuit; it is characterized in that: the collector electrode of resistance R 1 one termination NPN triode Q1; the other end of resistance R 1 and capacitor C 3 one ends; the negative electrode of voltage-stabiliser tube ZD1 connects the base stage of NPN triode Q1 jointly; the anode of the other end of capacitor C 3 and voltage-stabiliser tube ZD1 connects power supply ground; the emitter of NPN triode Q1 connects capacitor C 4 one ends; another termination power ground of capacitor C 4; the emission of NPN triode Q1 is the feeder ear of LED constant current chip very, and the collector electrode of NPN triode Q1 connects the power output end of main topological circuit in the LED LCD TV.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011101672623A CN102222898A (en) | 2011-06-21 | 2011-06-21 | Power supply output overvoltage protection circuit for LED (light emitting diode) LCD TV (liquid crystal display television) |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011101672623A CN102222898A (en) | 2011-06-21 | 2011-06-21 | Power supply output overvoltage protection circuit for LED (light emitting diode) LCD TV (liquid crystal display television) |
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| Publication Number | Publication Date |
|---|---|
| CN102222898A true CN102222898A (en) | 2011-10-19 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2011101672623A Pending CN102222898A (en) | 2011-06-21 | 2011-06-21 | Power supply output overvoltage protection circuit for LED (light emitting diode) LCD TV (liquid crystal display television) |
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| CN (1) | CN102222898A (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102970500A (en) * | 2012-11-16 | 2013-03-13 | 深圳创维－Rgb电子有限公司 | Liquid crystal display television and power supply circuit thereof |
| CN104362608A (en) * | 2014-12-03 | 2015-02-18 | 中国兵器工业集团第二一四研究所苏州研发中心 | Overvoltage suppression and under-voltage surge detection circuit |
| CN104779694A (en) * | 2011-12-28 | 2015-07-15 | 深圳市金威源科技股份有限公司 | High-energy-efficiency uninterrupted high frequency switching power supply in ATM |
| CN106560958A (en) * | 2016-10-20 | 2017-04-12 | 金卡高科技股份有限公司 | Low-power-consumption voltage protection circuit and gas meter |
| CN106655136A (en) * | 2016-12-12 | 2017-05-10 | 成都航天通信设备有限责任公司 | Airborne station lightning protection circuit |
| CN109103865A (en) * | 2018-10-15 | 2018-12-28 | 南京优倍电气有限公司 | A kind of power supply overvoltage protection circuit of high pressure barricade |
| CN112804793A (en) * | 2021-04-13 | 2021-05-14 | 深圳市安规科技有限公司 | Slow starting circuit and LED power supply device |
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Patent Citations (5)
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| CN201001032Y (en) * | 2006-10-14 | 2008-01-02 | 张幼彬 | AC voltage-limiting and current-limiting safety explosion-proof DC voltage stabilizing power source device |
| CN101267111A (en) * | 2007-12-29 | 2008-09-17 | 成都飞机工业集团电子科技有限公司 | DC over-voltage protection circuit |
| JP2009177865A (en) * | 2008-01-21 | 2009-08-06 | Sony Corp | Overvoltage protection circuit |
| CN201629569U (en) * | 2010-03-18 | 2010-11-10 | 深圳创维－Rgb电子有限公司 | Over-voltage protection circuit of USB interface |
| CN202167843U (en) * | 2011-06-21 | 2012-03-14 | 威海东兴电子有限公司 | Power supply output overvoltage protective circuit used for LED liquid crystal display television |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104779694A (en) * | 2011-12-28 | 2015-07-15 | 深圳市金威源科技股份有限公司 | High-energy-efficiency uninterrupted high frequency switching power supply in ATM |
| CN102970500A (en) * | 2012-11-16 | 2013-03-13 | 深圳创维－Rgb电子有限公司 | Liquid crystal display television and power supply circuit thereof |
| CN102970500B (en) * | 2012-11-16 | 2015-06-03 | 深圳创维－Rgb电子有限公司 | Liquid crystal display television and power supply circuit thereof |
| CN104362608A (en) * | 2014-12-03 | 2015-02-18 | 中国兵器工业集团第二一四研究所苏州研发中心 | Overvoltage suppression and under-voltage surge detection circuit |
| CN104362608B (en) * | 2014-12-03 | 2017-11-14 | 中国兵器工业集团第二一四研究所苏州研发中心 | Over-voltage suppression and under-voltage surge detection circuit |
| CN106560958A (en) * | 2016-10-20 | 2017-04-12 | 金卡高科技股份有限公司 | Low-power-consumption voltage protection circuit and gas meter |
| CN106655136A (en) * | 2016-12-12 | 2017-05-10 | 成都航天通信设备有限责任公司 | Airborne station lightning protection circuit |
| CN109103865A (en) * | 2018-10-15 | 2018-12-28 | 南京优倍电气有限公司 | A kind of power supply overvoltage protection circuit of high pressure barricade |
| CN112804793A (en) * | 2021-04-13 | 2021-05-14 | 深圳市安规科技有限公司 | Slow starting circuit and LED power supply device |
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Application publication date: 20111019 |