CN201805493U - Output circuit for LED (light-emitting diode) LCDTV (liquid-crystal display television) power supply - Google Patents
Output circuit for LED (light-emitting diode) LCDTV (liquid-crystal display television) power supply Download PDFInfo
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- CN201805493U CN201805493U CN2010205384965U CN201020538496U CN201805493U CN 201805493 U CN201805493 U CN 201805493U CN 2010205384965 U CN2010205384965 U CN 2010205384965U CN 201020538496 U CN201020538496 U CN 201020538496U CN 201805493 U CN201805493 U CN 201805493U
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Abstract
The utility model relates to the technical field of LED (light-emitting diode) LCDTV (liquid-crystal display television) power supply, in particular to an output circuit for the LED LCDTV power supply. The output circuit for the LED LCDTV power supply comprises a transformer T1A, a first output circuit and a second output circuit, wherein a primary part of the transformer T1A is connected with the control end of a PWM (Pulse-Width Modulation) control circuit of the LED LCDTV power supply, and the output end of the first output circuit is connected with the feedback end of the PWM control circuit of the LED LCDTV power supply so that the first output circuit can form principal feedback and the stability of output voltage of the first output circuit can be controlled; and the output end of the second output circuit is provided with a linear voltage regulator circuit capable of ensuring the stability of output voltage of the second output circuit, therefore, by ensuring the stability of output voltage of the first output circuit and that of the second output circuit, the output circuit for the LED LCDTV power supply better improves the cross regulation rate between the first output circuit and the second output circuit.
Description
Technical field
The utility model relates to LED liquid crystal television power supply technical field, relates in particular to a kind of output circuit of LED liquid crystal television power supply.
Background technology
At present, LED(Light Emitting Diode, light-emitting diode) output circuit of the direct voltage of liquid crystal television power supply, four tunnel outputs are set usually, be respectively 5VSB, 5V, 12VA, 24VBL, wherein, 5VSB and the output of 5V two-way are by an anti-sharp framework circuit control, and 12VA and the output of 24VBL two-way are by pwm circuit control, so, 12VA and the output of 24VBL two-way are respectively two secondary winding outputs by a transformer, this situation that can cause is, when the 12VA zero load, and the 24VBL full load, then the output voltage of 12VA can be higher, may reach more than the 14V; Otherwise fully loaded as 12VA, and 24VBL is when unloaded, and then the output voltage of 24VBL also can be higher, i.e. intersection regulation between 12VA and 24VBL two-way output is relatively poor.
The output circuit of LED liquid crystal television power supply of the prior art, usually way is that the method for improving the winding of transformer or two-way feedback is improved the intersection regulation between two-way output, but, the intersection regulation of the output circuit of these ways is still relatively poor, 10% intersection regulation can only be reached, design can not be satisfied the demanding LED liquid crystal television power supply of output voltage stability.
Summary of the invention
The purpose of this utility model is to provide at the deficiencies in the prior art a kind of the improvement to intersect the output circuit of LED liquid crystal television power supply of regulation.
The purpose of this utility model realizes by following technical measures: a kind of output circuit of LED liquid crystal television power supply, it includes transformer T1A, first output circuit that is connected with T1A level of transformer first winding, second output circuit that is connected with T1A level of transformer second winding, the PWM(Pulse Width Modulation of the elementary and LED liquid crystal television power supply of transformer T1A, pulse width modulation) control end of control circuit connects, the output of described first output circuit is connected with the feedback end of the pwm control circuit of LED liquid crystal television power supply, and the output of second output circuit is provided with linear voltage-stabilizing circuit.
Described first output circuit comprises rectifying tube D1, D2, capacitor C 1; The 1st pin of rectifying tube D1 is connected with an end of the 3rd pin, T1A level of transformer first winding, the 2nd pin of rectifying tube D1 is the output of first output circuit, the feedback end of the pwm control circuit of the 2nd pin of the output of first output circuit and rectifying tube D2, the positive pole of capacitor C 1, LED liquid crystal television power supply is connected, the 1st pin of rectifying tube D2 is connected with the other end of the 3rd pin, T1A level of transformer first winding, T1A level of transformer first winding is provided with centre cap, the centre cap of T1A level of transformer first winding, the equal ground connection of negative pole of capacitor C 1.
Described rectifying tube D1, D2 are three end half-bridges cloudy formula rectifying tube altogether.
Described second output circuit comprises rectifying tube D3, capacitor C 2, one end of T1A level of the 1st pin and the transformer of rectifying tube D3 second winding is connected, the 2nd pin of rectifying tube D3 is the output of second output circuit, the other end of T1A level of the 3rd pin and the transformer of rectifying tube D3 second winding is connected, the positive pole of capacitor C 2 is connected with the 2nd pin of rectifying tube D3, T1A level of transformer second winding is provided with centre cap, the centre cap of T1A level of transformer second winding, the equal ground connection of negative pole of capacitor C 1.
Described rectifying tube D3 is three end half-bridges cloudy formula rectifying tubes altogether.
Described linear voltage-stabilizing circuit comprises resistance R 1, R2, R3, R4, capacitor C 3, field effect transistor Q1, voltage stabilizing chip U1; The drain electrode of field effect transistor Q1 is connected with the output of second output circuit, the grid of field effect transistor Q1 and resistance R 1 one ends, resistance R 2 one ends connect, resistance R 1 other end is connected with the supply voltage of LED liquid crystal television power supply, the negative electrode of resistance R 2 other ends and voltage stabilizing chip U1, capacitor C 3 one ends connect, the reference utmost point of capacitor C 3 other ends and voltage stabilizing chip U1, resistance R 3 one ends, resistance R 4 one ends connect, the source electrode of field effect transistor Q1 is the output of linear voltage-stabilizing circuit, resistance R 3 other ends are connected with the source electrode of field effect transistor Q1, the anode of voltage stabilizing chip U1, the equal ground connection of resistance R 4 other ends.
The model of described voltage stabilizing chip U1 is TL431.
Described field effect transistor Q1 is an insulating gate type field effect tube.
The utility model beneficial effect is: the utility model includes transformer T1A, first output circuit that is connected with T1A level of transformer first winding, second output circuit that is connected with T1A level of transformer second winding, the control end of the pwm control circuit of the elementary and LED liquid crystal television power supply of transformer T1A is connected, the output of first output circuit is connected with the feedback end of the pwm control circuit of LED liquid crystal television power supply, make first output circuit form primary feedback, thereby control the output voltage stabilization of first output circuit, the output of second output circuit is provided with linear voltage-stabilizing circuit, linear voltage-stabilizing circuit can guarantee the output voltage stabilization of second output circuit, therefore, the utility model is by guaranteeing the output voltage stabilization of first output circuit and second output circuit, intersects regulation between first output circuit and second output circuit thereby improve preferably.
Description of drawings
Fig. 1 is circuit theory diagrams of the present utility model.
In Fig. 1, comprise:
1---first output circuit 2---, second output circuit
3---pwm control circuit 4---linear voltage-stabilizing circuit.
Embodiment
Below in conjunction with accompanying drawing the utility model is further described, as shown in Figure 1, the output circuit of a kind of LED liquid crystal television power supply that the utility model provides, second output circuit 2 that it includes transformer T1A, first output circuit 1 that is connected with transformer T1A time level first winding, is connected with T1A time grade of second winding of transformer, wherein, first output circuit 1 is the 24VBL output circuit, and second output circuit 2 is the 12VA output circuit; The control end of the pwm control circuit 3 of the elementary and LED liquid crystal television power supply of transformer T1A is connected, the output of first output circuit 1 is connected with the feedback end of the pwm control circuit 3 of LED liquid crystal television power supply, makes first output circuit 1 output voltage can be fed back to pwm control circuit 3; The output of second output circuit 2 is provided with linear voltage-stabilizing circuit 4, and this linear voltage-stabilizing circuit 4 can guarantee the output voltage stabilization of second output circuit 2.
First output circuit 1 comprises rectifying tube D1, D2, capacitor C 1; The 1st pin of rectifying tube D1 is connected with an end of the 3rd pin, T1A level of transformer first winding, the 2nd pin of rectifying tube D1 is the output of first output circuit 1, the feedback end of the pwm control circuit 3 of the 2nd pin of the output of first output circuit 1 and rectifying tube D2, the positive pole of capacitor C 1, LED liquid crystal television power supply is connected, the 1st pin of rectifying tube D2 is connected with the other end of the 3rd pin, T1A level of transformer first winding, T1A level of transformer first winding is provided with centre cap, the centre cap of T1A level of transformer first winding, the equal ground connection of negative pole (GND) of capacitor C 1.
Second output circuit 2 comprises rectifying tube D3, capacitor C 2, one end of T1A level of the 1st pin and the transformer of rectifying tube D3 second winding is connected, the 2nd pin of rectifying tube D3 is the output of second output circuit 2, the other end of T1A level of the 3rd pin and the transformer of rectifying tube D3 second winding is connected, the positive pole of capacitor C 2 is connected with the 2nd pin of rectifying tube D3, T1A level of transformer second winding is provided with centre cap, the centre cap of T1A level of transformer second winding, the equal ground connection of negative pole of capacitor C 1.
Linear voltage-stabilizing circuit 4 comprises resistance R 1, R2, R3, R4, capacitor C 3, field effect transistor Q1, voltage stabilizing chip U1; The drain electrode of field effect transistor Q1 (D) is connected with the output of second output circuit 2, the grid of field effect transistor Q1 (G) and resistance R 1 one ends, resistance R 2 one ends connect, resistance R 1 other end is connected with the supply voltage (VDD) of LED liquid crystal television power supply, the negative electrode (K) of resistance R 2 other ends and voltage stabilizing chip U1, capacitor C 3 one ends connect, the reference utmost point (R) of capacitor C 3 other ends and voltage stabilizing chip U1, resistance R 3 one ends, resistance R 4 one ends connect, the source electrode of field effect transistor Q1 (S) is the output of linear voltage-stabilizing circuit 4, resistance R 3 other ends are connected with the source electrode of field effect transistor Q1, the anode (A) of voltage stabilizing chip U1, the equal ground connection of resistance R 4 other ends.
Wherein, rectifying tube D1, D2, D3 are three end half-bridges cloudy formula rectifying tube altogether, three end half-bridges cloudy formula rectifying tube altogether are made up of two diodes, the negative pole of two diodes is connected, so the negative pole of just very the 1st pin of its first diode, two diodes is just very the 3rd pin of the 2nd pin, second diode; The model of voltage stabilizing chip U1 is TL431; Field effect transistor Q1 is an insulating gate type field effect tube.Certainly, the model and the parameter of above-mentioned electronic devices and components are only for reference, and when specifically implementing the technical program, its model and parameter value can be made amendment according to actual environment.
Operation principle of the present utility model is as follows: because the output of first output circuit 1 is connected with the feedback end of the pwm control circuit 3 of LED liquid crystal television power supply, promptly first output circuit 1 adopts the primary feedback structure, when the output voltage of first output circuit 1 because second output circuit 2 is fully loaded or unloaded when higher or on the low side, the meeting immediate feedback is to the pwm control circuit 3 of LED liquid crystal television power supply, the pwm control circuit 3 of LED liquid crystal television power supply is adjusted the output voltage of first output circuit 1 again according to feedback signal, make the output voltage stabilization of first output circuit 1, as remain 24V, first output circuit 1 of this employing primary feedback structure, its intersection regulation can reach 5%; When the output voltage of second output circuit 2 because first output circuit 1 when fully loaded and higher, voltage stabilizing chip U1 can detect by resistance R 3 and R4, voltage on the resistance R 4 is higher than the internal reference voltage of voltage stabilizing chip U1, so, voltage stabilizing chip U1 is by dragging down the voltage of field effect transistor Q1 grid, the conducting state of control field effect transistor Q1 makes the output voltage (being the voltage of field effect pipe Q1 source electrode) of second output circuit 2 keep stable, as remains 12V; Otherwise, when the output voltage of second output circuit 2 because first output circuit 1 is unloaded when on the low side, voltage stabilizing chip U1 can detect by resistance R 3 and R4, voltage on the resistance R 4 is lower than the internal reference voltage of voltage stabilizing chip U1, so, voltage stabilizing chip U1 can discharge fully, the voltage of field effect transistor Q1 grid is provided by the supply voltage of LED liquid crystal television power supply fully, the complete conducting of control field effect transistor Q1, make the output voltage (being the voltage of field effect pipe Q1 source electrode) of second output circuit 2 keep stable, as remaining 12V, this linear voltage-stabilizing circuit 4 can make the intersection regulation of second output circuit 2 reach 5%.
In sum, the utility model is by guaranteeing the output voltage stabilization of first output circuit 1 and second output circuit 2, thereby improve first output circuit 1 and 2 of second output circuits preferably and intersect regulation, make the intersection regulation of second output circuit 2 of T1A time grade of second winding of first output circuit 1, transformer of transformer T1A time level first winding all can reach 5%, improved the reliability of LED liquid crystal television 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 (8)
1. the output circuit of a LED liquid crystal television power supply, second output circuit that it includes transformer T1A, first output circuit that is connected with transformer T1A time level first winding, is connected with T1A time grade of second winding of transformer, the control end of the pwm control circuit of the elementary and LED liquid crystal television power supply of transformer T1A is connected, it is characterized in that: the output of described first output circuit is connected with the feedback end of the pwm control circuit of LED liquid crystal television power supply, and the output of second output circuit is provided with linear voltage-stabilizing circuit.
2. the output circuit of LED liquid crystal television power supply according to claim 1 is characterized in that: described first output circuit comprises rectifying tube D1, D2, capacitor C 1; The 1st pin of rectifying tube D1 is connected with an end of the 3rd pin, T1A level of transformer first winding, the 2nd pin of rectifying tube D1 is the output of first output circuit, the feedback end of the pwm control circuit of the 2nd pin of the output of first output circuit and rectifying tube D2, the positive pole of capacitor C 1, LED liquid crystal television power supply is connected, the 1st pin of rectifying tube D2 is connected with the other end of the 3rd pin, T1A level of transformer first winding, T1A level of transformer first winding is provided with centre cap, the centre cap of T1A level of transformer first winding, the equal ground connection of negative pole of capacitor C 1.
3. the output circuit of LED liquid crystal television power supply according to claim 2 is characterized in that: described rectifying tube D1, D2 are three end half-bridges cloudy formula rectifying tube altogether.
4. the output circuit of LED liquid crystal television power supply according to claim 1 and 2, it is characterized in that: described second output circuit comprises rectifying tube D3, capacitor C 2, one end of T1A level of the 1st pin and the transformer of rectifying tube D3 second winding is connected, the 2nd pin of rectifying tube D3 is the output of second output circuit, the other end of T1A level of the 3rd pin and the transformer of rectifying tube D3 second winding is connected, the positive pole of capacitor C 2 is connected with the 2nd pin of rectifying tube D3, T1A level of transformer second winding is provided with centre cap, the centre cap of T1A level of transformer second winding, the equal ground connection of the negative pole of capacitor C 1.
5. the output circuit of LED liquid crystal television power supply according to claim 4 is characterized in that: described rectifying tube D3 is three end half-bridges cloudy formula rectifying tubes altogether.
6. the output circuit of LED liquid crystal television power supply according to claim 4 is characterized in that: described linear voltage-stabilizing circuit comprises resistance R 1, R2, R3, R4, capacitor C 3, field effect transistor Q1, voltage stabilizing chip U1; The drain electrode of field effect transistor Q1 is connected with the output of second output circuit, the grid of field effect transistor Q1 and resistance R 1 one ends, resistance R 2 one ends connect, resistance R 1 other end is connected with the supply voltage of LED liquid crystal television power supply, the negative electrode of resistance R 2 other ends and voltage stabilizing chip U1, capacitor C 3 one ends connect, the reference utmost point of capacitor C 3 other ends and voltage stabilizing chip U1, resistance R 3 one ends, resistance R 4 one ends connect, the source electrode of field effect transistor Q1 is the output of linear voltage-stabilizing circuit, resistance R 3 other ends are connected with the source electrode of field effect transistor Q1, the anode of voltage stabilizing chip U1, the equal ground connection of resistance R 4 other ends.
7. the output circuit of LED liquid crystal television power supply according to claim 6 is characterized in that: the model of described voltage stabilizing chip U1 is TL431.
8. the output circuit of LED liquid crystal television power supply according to claim 6 is characterized in that: described field effect transistor Q1 is an insulating gate type field effect tube.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010205384965U CN201805493U (en) | 2010-09-21 | 2010-09-21 | Output circuit for LED (light-emitting diode) LCDTV (liquid-crystal display television) power supply |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010205384965U CN201805493U (en) | 2010-09-21 | 2010-09-21 | Output circuit for LED (light-emitting diode) LCDTV (liquid-crystal display television) power supply |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201805493U true CN201805493U (en) | 2011-04-20 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2010205384965U Expired - Fee Related CN201805493U (en) | 2010-09-21 | 2010-09-21 | Output circuit for LED (light-emitting diode) LCDTV (liquid-crystal display television) power supply |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN201805493U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102412746A (en) * | 2011-11-30 | 2012-04-11 | 康佳集团股份有限公司 | Flyback switching power supply circuit for improving cross regulation |
| CN104242630A (en) * | 2013-06-21 | 2014-12-24 | 全汉企业股份有限公司 | Power supply apparatus |
-
2010
- 2010-09-21 CN CN2010205384965U patent/CN201805493U/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102412746A (en) * | 2011-11-30 | 2012-04-11 | 康佳集团股份有限公司 | Flyback switching power supply circuit for improving cross regulation |
| CN102412746B (en) * | 2011-11-30 | 2015-07-29 | 康佳集团股份有限公司 | A kind of inverse-excitation type switch power-supply circuit improving cross regulation rate |
| CN104242630A (en) * | 2013-06-21 | 2014-12-24 | 全汉企业股份有限公司 | Power supply apparatus |
| CN104242630B (en) * | 2013-06-21 | 2017-04-12 | 全汉企业股份有限公司 | Power supply apparatus |
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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: 20110420 Termination date: 20150921 |
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| EXPY | Termination of patent right or utility model |