CN202167843U - Power supply output overvoltage protective circuit used for LED liquid crystal display television - Google Patents
Power supply output overvoltage protective circuit used for LED liquid crystal display television Download PDFInfo
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- CN202167843U CN202167843U CN 201120210272 CN201120210272U CN202167843U CN 202167843 U CN202167843 U CN 202167843U CN 201120210272 CN201120210272 CN 201120210272 CN 201120210272 U CN201120210272 U CN 201120210272U CN 202167843 U CN202167843 U CN 202167843U
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Abstract
The utility model relates to a power supply output overvoltage protective circuit used for an LED liquid crystal display television, and belongs to the LED switch power supply field of the liquid crystal display television. One end of a resistor R1 is connected with a collector electrode of an NPN triode Q1, and other end of the resistor R1 is connected with a base electrode of the NPN triode Q1 with one end of a capacitor C3 and a cathode of a voltage-stabilizing tube ZD1 together. The other end of the capacitor C3 and an anode of the voltage-stabilizing tube ZD1 are connected with a power supply ground. An emitting electrode of the NPN triode Q1 is connected with one end of a resistor C4, and the other end of the capacitor C4 is connected with the power supply ground. The emitting electrode of the NPN triode Q1 is a power supply terminal of an LED constant current chip. The collector electrode of the NPN triode Q1 is connected with a power supply output terminal of a main topology circuit of the LED liquid crystal display television. The power supply output overvoltage protective circuit can guarantee the safe and damage-free operation of the LED constant current chip even if the voltage given to the chip is much higher while not adopting a complex circuit and not influencing the overall efficiency and cost.
Description
Technical field
The utility model relates to the circuit that LED field of switch power and other LED power supplys in the LCD TV have the output overvoltage risk, at length says it is a kind of a kind of protective circuit to 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 like the NCP1271 of ON and the chips such as LD7575 of Leadtrend in the LED LCD TV, when chip NCP1271 when finding that feedback control loop lost efficacy, need could turn-off output by delay 130ms, the entering guard mode; And LD7575 is 30ms.No matter be 130ms or 30ms, the output voltage in this time is wanted quite a few 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
The purpose of the utility model 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 circuitry; 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.
The utility model 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 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, and 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 beneficial effect of the utility model is, do not adopting complicated circuitry, 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.
Description of drawings
Below in conjunction with accompanying drawing and embodiment the utility model is further specified.
Fig. 1 is the circuit theory diagrams of the utility model.
Q1. NPN triode among the figure, R1. resistance, ZD1. voltage-stabiliser tube, C3. electric capacity, C4. electric capacity.
Embodiment
Below in conjunction with accompanying drawing and specific embodiment the utility model is described further, to help the content of understanding the utility model.
As shown in Figure 1; The collector electrode of the utility model resistance R 1 one termination NPN triode Q1; 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, and 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 utility model is the voltage (A point) of the power output end of main topological circuit in the LED LCD TV, deducts through 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 through 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 preset voltage; The A point voltage rises and when surpassing the puncture voltage of voltage-stabiliser tube ZD1, will have electric current and flow through resistance R 1 from the A point, and 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 let 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 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, and 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 |
|---|---|---|---|
| CN 201120210272 CN202167843U (en) | 2011-06-21 | 2011-06-21 | Power supply output overvoltage protective circuit used for LED liquid crystal display television |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201120210272 CN202167843U (en) | 2011-06-21 | 2011-06-21 | Power supply output overvoltage protective circuit used for LED liquid crystal display television |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN202167843U true CN202167843U (en) | 2012-03-14 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201120210272 Expired - Fee Related CN202167843U (en) | 2011-06-21 | 2011-06-21 | Power supply output overvoltage protective circuit used for LED liquid crystal display television |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN202167843U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102222898A (en) * | 2011-06-21 | 2011-10-19 | 威海东兴电子有限公司 | Power supply output overvoltage protection circuit for LED (light emitting diode) LCD TV (liquid crystal display television) |
| CN108695838A (en) * | 2018-05-18 | 2018-10-23 | 向玲丽 | A kind of power supply or signal transmission plug-in unit |
-
2011
- 2011-06-21 CN CN 201120210272 patent/CN202167843U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102222898A (en) * | 2011-06-21 | 2011-10-19 | 威海东兴电子有限公司 | Power supply output overvoltage protection circuit for LED (light emitting diode) LCD TV (liquid crystal display television) |
| CN108695838A (en) * | 2018-05-18 | 2018-10-23 | 向玲丽 | A kind of power supply or signal transmission plug-in unit |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20120314 Termination date: 20190621 |
|
| CF01 | Termination of patent right due to non-payment of annual fee |