CN103151913A - Switching power circuit - Google Patents
Switching power circuit Download PDFInfo
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- CN103151913A CN103151913A CN2013100550026A CN201310055002A CN103151913A CN 103151913 A CN103151913 A CN 103151913A CN 2013100550026 A CN2013100550026 A CN 2013100550026A CN 201310055002 A CN201310055002 A CN 201310055002A CN 103151913 A CN103151913 A CN 103151913A
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- 238000010521 absorption reaction Methods 0.000 claims abstract description 15
- 238000001914 filtration Methods 0.000 claims description 9
- 230000001105 regulatory effect Effects 0.000 description 2
- 230000033228 biological regulation Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 230000002459 sustained effect Effects 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
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Abstract
The invention relates to a switching power circuit which comprises an input rectifier filter module, a resistance-capacitance absorption module, an output rectifier filter module, a voltage feedback module and a switch control chip module, wherein the input rectifier filter module, the resistance-capacitance absorption module, the output rectifier filter module and the voltage feedback module are sequentially connected; the switch control chip module is connected with the resistance-capacitance absorption module; and the voltage feedback module is connected with the switch control chip module. The switching power circuit is low in cost, small in volume, low in loss when alternating current (AC) is converted into direct current (DC), high in efficiency (reaching up to more than 75%), wide in voltage input range and stable in output, and can be used for replacing a transformer and arranged in a product.
Description
Technical field
The present invention relates to automatic field, be specifically related to a kind of switching power circuit.
Background technology
Common Switching Power Supply, be set to the master all, volume is all bigger than normal, be built in product, small product size is increased, and is not very stable and use transformer, when elementary input voltage is higher, the voltage of secondary output also can be higher, the very possible product variety of issue that causes of the height fluctuation of voltage.
Summary of the invention
The object of the present invention is to provide a kind of volume little, the switching power circuit circuit of low-cost high-efficiency.
For achieving the above object, the technical solution adopted in the present invention is: a kind of switching power circuit comprises the input rectifying filtration module, the resistance-capacitance absorption module, the output rectification filter module, Voltage Feedback module and switch control chip module, described input rectifying filtration module, resistance-capacitance absorption module, the output rectification filter module, the Voltage Feedback module connects successively, described switch control chip module access resistance-capacitance absorption module, described Voltage Feedback module connecting valve control chip module.
Adopt LP2705 in described switch control chip module.
Described input rectifying filtration module is converted to direct current stably with alternating current;
The switch of described switch control chip module controls transformer;
The self induction electromotive force that when described resistance-capacitance absorption module is used for absorption and consumes circuit disconnecting, inductive load produces can prevent that the switching tube that overvoltage causes from puncturing.
Described Voltage Feedback module will make the control pin (T point) of TL431 keep 2.5V, by regulating the ratio of R9, R10, can conveniently change output voltage values.During R9=R10, be output as 5V.
Described output rectification filter module makes output voltage stabilization, controls ripple as need, can external LC filtering.
Due to the employing of technique scheme, the present invention compared with prior art has the following advantages: cost is low, volume is little, interchange is converted to that the direct current loss is low, efficient is up to more than 75%, and input voltage range is wide, stable output, can instead of transformers be built in product.
Description of drawings
Fig. 1 is circuit diagram of the present invention.
Wherein: 1. input rectifying filtration module, 2. resistance-capacitance absorption module, 3. output rectification filter module, 4. Voltage Feedback module, 5. switch control chip module.
Embodiment
Switching power circuit as shown in Figure 1, comprise input rectifying filtration module 1, resistance-capacitance absorption module 2, output rectification filter module 3, Voltage Feedback module 4 and switch control chip module 5, described input rectifying filtration module 1, resistance-capacitance absorption module 2, output rectification filter module 3, Voltage Feedback module 4 connect successively, described switch control chip module 5 access resistance-capacitance absorption modules 2, described Voltage Feedback module 4 connecting valve control chip modules 5.Adopt LP2705 in described switch control chip module 5.Voltage Feedback module 4 is connected with load.
Adopt LP2705 in described switch control chip module 5.LP2705 is integrated a high-voltage power switch mosfet and a power-supply controller of electric on a device, and it comes regulated output voltage with simple ON/OFF control mode.This controller has comprised an oscillator, enable circuits, ductility limit state regulator, 5.85V pressurizer, bypass/multi-functional pin is under-voltage and overvoltage circuit, Current Limits stream select circuit, overtemperature protection, current limitation circuit, the disappear power MOSFET tube of equalizing network and a 700V of forward position.In addition, increased also that under-voltage detection, autoboot are moving, self-adjusting switch periods ON time extends and frequency jittering function.
1. overtemperature protection.
Hot breaking circuit detects the temperature of knot.Threshold value setting is at 142 ° of C and possess the sluggish scope of 75 ° of C.Over this threshold value, power MOSFET is closed when junction temperature, 75 ° of C until junction temperature descends, and MOSFET just can reopen.Adopt the sluggishness of 75 ° of C (typical case) can prevent from superheating phenomenon occurring because sustained fault makes pcb board.
2. current limitation.
The electric current of current limitation electric circuit inspection MOS F E T.When electric current surpasses internal threshold (I LIMIT), can switch-off power MOSFET at this cycle Remaining Stages.The current limitation state regulator reduces the current limitation threshold value in discontinuous mode under the mild or moderate loading condition.After power MOSFET was opened, the lead-edge-blanking circuit can suppress a moment (tLEB) with the current limitation comparator.By the lead-edge-blanking time is set, can prevent from causing by mistake turn-offing in advance of switching pulse by the current spike of electric capacity and generation reverse recovery time of secondary commutation pipe.
3. autoboot is moving.
In case break down, for example under output overloading, output short-circuit or open loop case, LP2705 enters the moving operation of autoboot.When the EN/UV pin voltage drags down, an inside register set again of being clocked by oscillator.If the EN/UV pin is not dragged down in 64 ms, power mosfet switch usually be under an embargo 2.5 seconds (except under under-voltage condition, because MOSFET is turned off when under-voltage).The moving circuit of autoboot alternately enables and closes power MOSFET, until fault is got rid of.Under under-voltage condition, the time of forbidding of power mosfet switch has surpassed common 2.5 seconds, until under-voltage condition finishes.
in the present embodiment take the 5V output voltage as example, when the switch control chip conducting, transformer carries out transformation, enter the Voltage Feedback module through the output rectification filter module, when the T point value that the Voltage Feedback module detected is 2.5v, the 5V direct voltage is normally exported, if output voltage is greater than 5 V, be that the T point value is greater than 2.5V, the output stage conducting of TL431, electric current is through R8 resistance, form pressure drop in the above, thereby make optocoupler IC2 conducting, the electric current of pulling out from the EN pin of LP2705 is greater than certain threshold current, MOSFET was turned off in the next cycle, suppress next switch periods, make the lower voltage of transformer secondary output.If output voltage is less than 5 V, namely the T point value is less than 2.5V, and the output stage of TL431 is ended, not conducting of optocoupler, the EN pin no current of LP2705, MOSFET was switched in the next cycle, the voltage of transformer secondary output is raise, add the effect of secondary electric capacity of voltage regulation, realize the Voltage-output of dynamic stability.
Above-described embodiment only is explanation technical conceive of the present invention and characteristics; its purpose is to allow person skilled in the art scholar can understand content of the present invention and implement according to this; can not limit protection scope of the present invention with this; all equivalences that Spirit Essence is done according to the present invention change or modify, within all should being encompassed in protection scope of the present invention.
Claims (2)
1. switching power circuit, it is characterized in that: comprise input rectifying filtration module (1), resistance-capacitance absorption module (2), output rectification filter module (3), Voltage Feedback module (4) and switch control chip module (5), described input rectifying filtration module (1), resistance-capacitance absorption module (2), output rectification filter module (3), Voltage Feedback module (4) connects successively, described switch control chip module (5) access resistance-capacitance absorption module (2), described Voltage Feedback module (4) connecting valve control chip module (5).
2. switching power circuit according to claim 1, is characterized in that: adopt LP2705 in described switch control chip module (5).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2013100550026A CN103151913A (en) | 2013-02-21 | 2013-02-21 | Switching power circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2013100550026A CN103151913A (en) | 2013-02-21 | 2013-02-21 | Switching power circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN103151913A true CN103151913A (en) | 2013-06-12 |
Family
ID=48549836
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2013100550026A Pending CN103151913A (en) | 2013-02-21 | 2013-02-21 | Switching power circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN103151913A (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2772180Y (en) * | 2005-09-29 | 2006-04-12 | 史俊生 | Electronic ballast |
| CN203219174U (en) * | 2013-02-21 | 2013-09-25 | 苏州创泰电子有限公司 | switching power supply circuit |
-
2013
- 2013-02-21 CN CN2013100550026A patent/CN103151913A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2772180Y (en) * | 2005-09-29 | 2006-04-12 | 史俊生 | Electronic ballast |
| CN203219174U (en) * | 2013-02-21 | 2013-09-25 | 苏州创泰电子有限公司 | switching power supply circuit |
Non-Patent Citations (1)
| Title |
|---|
| 联德合微电子有限公司: "LP2705开关电源控制集成电路", 《百度文库》 * |
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| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C05 | Deemed withdrawal (patent law before 1993) | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20130612 |