CN201717623U - Switching power tube protection circuit of LCD TV switching power source - Google Patents
Switching power tube protection circuit of LCD TV switching power source Download PDFInfo
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- CN201717623U CN201717623U CN2010202943905U CN201020294390U CN201717623U CN 201717623 U CN201717623 U CN 201717623U CN 2010202943905 U CN2010202943905 U CN 2010202943905U CN 201020294390 U CN201020294390 U CN 201020294390U CN 201717623 U CN201717623 U CN 201717623U
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Abstract
The utility model relates to the technical field of LCD (liquid crystal display) TV switching power sources, in particular to a switching power tube protection circuit of an LCD TV switching power source, which comprises resistors (R4, R5 and R6), capacitors (C1 and C2), a stabilivolt tube (ZD1), triodes (Q1 and Q2) and a detection unit circuit. The switching power tube protection circuit can control a PFC (Power Factor Correction) driving chip to be supplied power or not through controlling a power source control circuit of the PFC driving chip of the LCD TV switching power source, thereby reducing the instantaneous current flowing through the switching power tube and the overshoot voltage of the switching power tube when a TV set is turned on and off frequently, and enabling the LCD TV switching power source to select a switching power tube with lower withstand voltage and lower withstand current for use.
Description
Technical field
The utility model relates to LCD TV switch power technology field, relates in particular to a kind of switch power tube protective circuit of LCD TV Switching Power Supply.
Background technology
At present, the LCD TV Switching Power Supply generally all is provided with PFC(Power Factor Correction, power factor correction) drive circuit, the power input of PFC drive circuit is connected with power control circuit, power control circuit provides power supply for the PFC drive circuit, the control output end of PFC drive circuit is connected with switching power tube, thereby the PFC drive circuit reaches the purpose of capability correction and output voltage stabilizing by the break-make of control switch power tube.
Because the PFC drive circuit of the LCD TV Switching Power Supply of prior art all is to realize by the PFC chip for driving; and these PFC chip for driving mostly do not have Brown out protection(input under-voltage protection) function is the PFC chip for driving of L6562 as model.The shortcoming of this LCD TV Switching Power Supply is: when LCD TV is shut down, the input AC(of Switching Power Supply exchanges) the voltage disconnection, maintenance effect because of the big electric capacity of PFC chip for driving, for the supply power voltage of PFC chip for driving also exists, so this moment, maximum was arrived in the driving duty ratio exhibitions of PFC chip for driving, to guarantee enough voltage output, if this moment is start (being frequent switching on and shutting down) again immediately, because the driving duty ratio maximum of PFC chip for driving, then flow through big that the immediate current of switching power tube can be very, and can cause very high moment peak voltage (overshoot voltage), and then influence the reliability of switching power tube, even switching power tube may be damaged by super-large current and overshoot voltage at once.
Summary of the invention
The purpose of this utility model is to provide at the deficiencies in the prior art a kind of switch power tube protective circuit of LCD TV Switching Power Supply, and it flows through the immediate current of switching power tube and the overshoot voltage of switching power tube in the time of can reducing frequent switching on and shutting down.
The purpose of this utility model realizes by following technical measures: a kind of switch power tube protective circuit of LCD TV Switching Power Supply, and it includes resistance R 4, R5, R6, capacitor C 1, C2, voltage-stabiliser tube ZD1, triode Q1, Q2, detection cell circuit; The input of described detection cell circuit is used to connect the input AC voltage of LCD TV Switching Power Supply, the output of detection cell circuit and capacitor C 1 one ends, the 3rd pin of voltage-stabiliser tube ZD1 connects, the 1st pin of voltage-stabiliser tube ZD1 and the 2nd pin of voltage-stabiliser tube ZD1, resistance R 4 one ends, triode Q1 base stage connects, triode Q1 collector electrode and resistance R 5 one ends, resistance R 6 one ends, capacitor C 2 one ends, triode Q2 base stage connects, resistance R 5 other ends are used to connect the supply voltage of LCD TV Switching Power Supply, triode Q2 current collection is feedback end very, this feedback end is used to connect the power control circuit of the PFC chip for driving of LCD TV Switching Power Supply, the earth terminal of detection cell circuit, capacitor C 1 other end, resistance R 4 other ends, triode Q1 emitter, resistance R 6 other ends, capacitor C 2 other ends, the equal ground connection of triode Q2 emitter.
Described detection cell circuit comprises resistance R 1, R2, R3, resistance R 1 one ends are the input of detection cell circuit, resistance R 1 other end is connected with resistance R 2 one ends, resistance R 2 other ends are the output of detection cell circuit, and resistance R 2 other ends are connected with resistance R 3 one ends, and resistance R 3 other ends are the earth terminal of detection cell circuit.
Described triode Q1 is a NPN type triode.
Described triode Q2 is a NPN type triode.
The model of described voltage-stabiliser tube ZD1 is BZX84-C6V8.
The utility model beneficial effect is: the utility model includes resistance R 4, R5, R6, capacitor C 1, C2, voltage-stabiliser tube ZD1, triode Q1, Q2, detection cell circuit.The utility model can be by control LCD TV Switching Power Supply the power control circuit of PFC chip for driving control the power supply break-make of PFC chip for driving, thereby flow through the immediate current of switching power tube and the overshoot voltage of switching power tube when reducing frequent switching on and shutting down, make the LCD TV Switching Power Supply can select the switching power tube of lower withstand voltage and lower anti-stream for use simultaneously.
Description of drawings
Fig. 1 is circuit theory diagrams of the present utility model.
Fig. 2 is the circuit theory diagrams that the utility model is applied to the LCD TV Switching Power Supply.
In Fig. 1, Fig. 2, comprise:
11---detection cell circuit 12---power control circuit
13---PFC chip for driving 14---switching power tube.
Embodiment
Below in conjunction with accompanying drawing the utility model is further described, as shown in Figure 1, the switch power tube protective circuit of a kind of LCD TV Switching Power Supply that the utility model provides, it includes resistance R 4, R5, R6, capacitor C 1, C2, voltage-stabiliser tube ZD1, triode Q1, Q2, detection cell circuit 11; The input of detection cell circuit 11 is used to connect the input AC voltage (VAC) of LCD TV Switching Power Supply, the output of detection cell circuit 11 and capacitor C 1 one ends, the 3rd pin of voltage-stabiliser tube ZD1 connects, the 1st pin of voltage-stabiliser tube ZD1 and the 2nd pin of voltage-stabiliser tube ZD1, resistance R 4 one ends, triode Q1 base stage connects, triode Q1 collector electrode and resistance R 5 one ends, resistance R 6 one ends, capacitor C 2 one ends, triode Q2 base stage connects, resistance R 5 other ends are used to connect the supply voltage (VCC) of LCD TV Switching Power Supply, triode Q2 current collection is feedback end (FB) very, this feedback end is used to connect the power control circuit 12 of the PFC chip for driving of LCD TV Switching Power Supply, the earth terminal of detection cell circuit 11, capacitor C 1 other end, resistance R 4 other ends, triode Q1 emitter, resistance R 6 other ends, capacitor C 2 other ends, the equal ground connection of triode Q2 emitter (GND).
The detection cell circuit 11 of present embodiment comprises resistance R 1, R2, R3, resistance R 1 one ends are the input of detection cell circuit 11, resistance R 1 other end is connected with resistance R 2 one ends, resistance R 2 other ends are the output of detection cell circuit 11, and resistance R 2 other ends are connected with resistance R 3 one ends, and resistance R 3 other ends are the earth terminal of detection cell circuit 11.
The triode Q1 of present embodiment is a NPN type triode; Triode Q2 is a NPN type triode; The model of voltage-stabiliser tube ZD1 is BZX84-C6V8.Certainly, the model of above-mentioned electronic devices and components is only for reference, and when specifically implementing the technical program, its model and parameter value can be made amendment according to actual environment.
As shown in Figure 2, when the utility model is applied to the LCD TV Switching Power Supply, its operation principle is as follows: when the LCD TV normal boot-strap, resistance R 1, R2, the detection cell circuit 11 that R3 forms detects the input AC voltage (VAC) of LCD TV Switching Power Supply, after input AC voltage reaches set point, voltage-stabiliser tube ZD1 conducting, this moment, triode Q1 base stage was that high voltage impels triode Q1 conducting ground connection, charge stored has discharged by triode Q1 on the capacitor C 2, triode Q2 base voltage is dragged down and causes triode Q2 to end simultaneously, so the power control circuit 12 of the PFC chip for driving 13 of LCD TV Switching Power Supply is PFC chip for driving 13 normal power supplies, PFC chip for driving 13 operate as normal; When LCD TV is shut down, the input AC voltage that detection cell circuit 11 can detect the LCD TV Switching Power Supply is lower than set point, cause voltage-stabiliser tube ZD1 to end, this moment, triode Q1 ended, so, the supply voltage of LCD TV Switching Power Supply (VCC) is by 2 chargings of 5 pairs of capacitor C of resistance R, after time-delay a little, triode Q2 base stage is that high voltage impels triode Q2 conducting ground connection, power control circuit 12 ground connection that promptly cause the PFC chip for driving 13 of LCD TV Switching Power Supply, thereby the power supply of disconnection PFC chip for driving 13, like this, then the drive waveforms of PFC chip for driving 13 disappears, and drives duty ratio and also can not open up (i.e. expansion) to maximum state; Therefore, if this moment, LCD TV was started shooting again, power control circuit 12 is 13 power supplies of PFC chip for driving again, the soft start that PFC chip for driving 13 inside have forces the driving duty ratio to be changed from small to big, and flows through the immediate current of switching power tube 14 and the overshoot voltage of switching power tube 14 (moment peak voltage) thereby reduce.
In sum, the utility model flows through the immediate current of switching power tube 14 and the overshoot voltage of switching power tube 14 in the time of can reducing frequent switching on and shutting down, make the LCD TV Switching Power Supply can select the switching power tube 14 of lower withstand voltage and low anti-stream for use simultaneously, and the situation that occurs aircraft bombing when preventing the frequent switching on and shutting down of LCD TV has improved the reliability of LCD TV Switching Power Supply.
Should be noted that at last; above embodiment is only in order to the explanation the technical solution of the utility model; but not to the restriction of the utility model protection range; although the utility model has been done to explain with reference to preferred embodiment; those of ordinary skill in the art is to be understood that; can make amendment or be equal to replacement the technical solution of the utility model, and not break away from the essence and the scope of technical solutions of the utility model.
Claims (5)
1. the switch power tube protective circuit of a LCD TV Switching Power Supply, it is characterized in that: it includes resistance R 4, R5, R6, capacitor C 1, C2, voltage-stabiliser tube ZD1, triode Q1, Q2, detection cell circuit; The input of described detection cell circuit is used to connect the input AC voltage of LCD TV Switching Power Supply, the output of detection cell circuit and capacitor C 1 one ends, the 3rd pin of voltage-stabiliser tube ZD1 connects, the 1st pin of voltage-stabiliser tube ZD1 and the 2nd pin of voltage-stabiliser tube ZD1, resistance R 4 one ends, triode Q1 base stage connects, triode Q1 collector electrode and resistance R 5 one ends, resistance R 6 one ends, capacitor C 2 one ends, triode Q2 base stage connects, resistance R 5 other ends are used to connect the supply voltage of LCD TV Switching Power Supply, triode Q2 current collection is feedback end very, this feedback end is used to connect the power control circuit of the PFC chip for driving of LCD TV Switching Power Supply, the earth terminal of detection cell circuit, capacitor C 1 other end, resistance R 4 other ends, triode Q1 emitter, resistance R 6 other ends, capacitor C 2 other ends, the equal ground connection of triode Q2 emitter.
2. the switch power tube protective circuit of LCD TV Switching Power Supply according to claim 1; it is characterized in that: described detection cell circuit comprises resistance R 1, R2, R3; resistance R 1 one ends are the input of detection cell circuit; resistance R 1 other end is connected with resistance R 2 one ends; resistance R 2 other ends are the output of detection cell circuit; and resistance R 2 other ends are connected with resistance R 3 one ends, and resistance R 3 other ends are the earth terminal of detection cell circuit.
3. the switch power tube protective circuit of LCD TV Switching Power Supply according to claim 2 is characterized in that: described triode Q1 is a NPN type triode.
4. the switch power tube protective circuit of LCD TV Switching Power Supply according to claim 2 is characterized in that: described triode Q2 is a NPN type triode.
5. according to the switch power tube protective circuit of any described LCD TV Switching Power Supply of claim 1 to 4, it is characterized in that: the model of described voltage-stabiliser tube ZD1 is BZX84-C6V8.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010202943905U CN201717623U (en) | 2010-08-17 | 2010-08-17 | Switching power tube protection circuit of LCD TV switching power source |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010202943905U CN201717623U (en) | 2010-08-17 | 2010-08-17 | Switching power tube protection circuit of LCD TV switching power source |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201717623U true CN201717623U (en) | 2011-01-19 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2010202943905U Expired - Fee Related CN201717623U (en) | 2010-08-17 | 2010-08-17 | Switching power tube protection circuit of LCD TV switching power source |
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| Country | Link |
|---|---|
| CN (1) | CN201717623U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102646972A (en) * | 2012-04-28 | 2012-08-22 | 山西科泰电气有限公司 | Overvoltage protecting device for coal mine power center |
| CN117639467A (en) * | 2023-12-01 | 2024-03-01 | 深圳市信众科技有限公司 | Soft start circuit of power factor correction circuit |
-
2010
- 2010-08-17 CN CN2010202943905U patent/CN201717623U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102646972A (en) * | 2012-04-28 | 2012-08-22 | 山西科泰电气有限公司 | Overvoltage protecting device for coal mine power center |
| CN117639467A (en) * | 2023-12-01 | 2024-03-01 | 深圳市信众科技有限公司 | Soft start circuit of power factor correction circuit |
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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: 20110119 Termination date: 20150817 |
|
| EXPY | Termination of patent right or utility model |