CN205725448U - A kind of switching power circuit with frequency jitter circuit - Google Patents
A kind of switching power circuit with frequency jitter circuit Download PDFInfo
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- CN205725448U CN205725448U CN201620150987.XU CN201620150987U CN205725448U CN 205725448 U CN205725448 U CN 205725448U CN 201620150987 U CN201620150987 U CN 201620150987U CN 205725448 U CN205725448 U CN 205725448U
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Abstract
This utility model is applicable to switch power technology field, provide a kind of switching power circuit with frequency jitter circuit, including rectifier bridge, pulse width modulation circuit, and power output circuit, wherein, described pulse width modulation circuit includes that PWM ripple exports control chip, the FREQUENCY CONTROL pin of described PWM ripple output control chip connects the first resistance and the first electric capacity having input first frequency signal, the FREQUENCY CONTROL pin of the most described PWM ripple output control chip is also associated with inputting the second resistance and second electric capacity of second frequency signal, the input of described second electric capacity connects external ac power source.This utility model embodiment is by connect between FREQUENCY CONTROL pin and the external ac power source at conventional PWM ripple output control chip access the second electric capacity and the second resistance, the output frequency finally obtained is shaken near original frequency, while reducing electromagnetic interference (EMI), circuit the most easily realizes, reduce cost, and highly versatile.
Description
Technical field
This utility model belongs to switch power technology field, particularly relates to a kind of switching power circuit with frequency jitter circuit.
Background technology
Along with communication and the development of control technology, various high frequency digital circuits are more strict to the requirement of Switching Power Supply Electro Magnetic Compatibility (EMC), how to reduce electromagnetic interference (EMI) and become a difficult point in Switching Power Supply design.
Electromagnetic compatibility (EMC) is the generation of the unexpected electromagnetic energy of research in electricity, propagates and receive, and the adverse effect caused by this energy.The target of electromagnetic compatibility is under equivalent environment, and the distinct device relating to electromagnet phenomenon can run well, and any equipment in this environment does not produce the ability of insufferable electromagnetic interference.Saying traditionally, EMC comprises EMI (electromagnetic interference) and two aspects of EMS (electromagnetic susceptibility).
Electromagnetic interference (EMI) refers to any to reduce the performance of certain device, equipment or system at conduction or electromagnetic field along with voltage, the effect of electric current and generation, or produces dysgenic electromagnet phenomenon.
Switching Power Supply uses pulsewidth modulation (PWM) control mode, and switching frequency improves constantly, and its HF switch waveform contains a large amount of harmonic components, is outwards propagated by transmission line and external electromagnetic field, causes conduction and radiation interference.
Frequency jitter (Frequency Jitter) is a kind of new method addressing EMI problem from dispersion harmonic wave interfering energy, refer to that the operating frequency of Switching Power Supply not immobilizes, but periodically become the mode in broadband from arrowband to reduce EMI, the method reducing electromagnetic interference.
Frequency jitter has so many advantages, develop rapidly in Switching Power Supply industry, Ge Jia semiconductor company is proposed many control chips with frequency jitter, utilizes these chips to can be designed that the power supply with frequency jitter, and tests easily by EMI.
But there is a lot of drawback in existing frequency jitter scheme, one is that circuit is complicated, and control chip prevailing price is more expensive, and the benefit brought is not enough to balance the rising of cost, two is that the versatility of these chips is strong, and chip manufacturer often develops for specific application area.
Utility model content
This utility model embodiment provides a kind of switching power circuit with frequency jitter circuit, it is intended to solve in existing frequency jitter scheme, and circuit is complicated, the control chip price of frequency jitter, the problem that versatility is the strongest.
This utility model embodiment is achieved in that a kind of switching power circuit with frequency jitter circuit,
Including rectifier bridge, the pulse width modulation circuit being connected with described rectifier bridge, and power output circuit, described pulse width modulation circuit connects described power output circuit and controls the break-make of described power output circuit, it is characterized in that, described pulse width modulation circuit includes that PWM ripple exports control chip, the FREQUENCY CONTROL pin of described PWM ripple output control chip connects the first resistance and the first electric capacity having input first frequency signal, the FREQUENCY CONTROL pin of the most described PWM ripple output control chip is also associated with inputting the second resistance and second electric capacity of second frequency signal, described second resistance, second capacitances in series, the input of described second electric capacity connects external ac power source.
Further, the model of described PWM ripple output control chip U1 is UC2842 or UC3842, the FREQUENCY CONTROL pin 4 of described PWM ripple output control chip U1 connects one end of the first resistance R1, link one end of the first electric capacity C1 simultaneously, the other end of described first resistance R1 is connected with the pin 8 of described PWM ripple output control chip U1, the other end ground connection GND of described first electric capacity C1；
One end of described second electric capacity C2 connects external ac power source, and the other end of described second electric capacity C2 connects one end of described second resistance R2, and the other end of described second resistance R2 connects the FREQUENCY CONTROL pin 4 of described PWM ripple output control chip U1.
nullFurther，Described pulse width modulation circuit also includes that power-supply circuit is for providing DC source to described PWM ripple output control chip U1，Described power-supply circuit includes resistance R3、Electric capacity C6、Electric capacity C4、Diode D1、Resistance R4、Coil T1，Described resistance R3 connects the output pin 1 of rectifier bridge BD1，One end of described electric capacity C6 connects the pin 7 of described PWM ripple output control chip U1，The other end of described electric capacity C6 connects the pin 8 of described PWM ripple output control chip U1 by electric capacity C5，The minus earth GND of electric capacity C6 and electric capacity C4 simultaneously，Described electric capacity C4 is sequentially connected with diode D1、Resistance R4、Coil T1 forms a loop，One end of described diode D1、One end of electric capacity C6 is connected with one end of resistance R3 simultaneously；
The pin 3 of described PWM ripple output control chip U1 is by electric capacity C3 ground connection GND, and pin 2 and pin 5 are directly grounded GND, and the pin 6 of described PWM ripple output control chip U1 connects described power output circuit；
nullDescribed power output circuit includes resistance R5、Field effect transistor O1、Transformator T2、Resistance R8、Resistance R7、Resistance R6，One end of described resistance R5 connects the pin 6 of described PWM ripple output control chip U1，The other end of described resistance R5 connects the grid 1 of described field effect transistor O1，The error of omission 2 of described field effect transistor O1 connects the pin 3 of described transformator T2，The pin 1 of described transformator T2 connects the pin 1 of described rectifier bridge BD1，The source electrode 3 of described field effect transistor O1 connects resistance R8，The source electrode 3 of the most described field effect transistor O1 connects described resistance R6、One end of resistance R7，The other end ground connection GND of described resistance R8，The other end of described resistance R7 is connected with the grid 1 of described field effect transistor O1，The other end of described resistance R6 is connected with the pin 3 of PWM ripple output control chip U1.
Further, one end that the pin 8 of described resistance R1 and described PWM ripple output control chip U1 is connected is also associated with the other end of resistance R9, described resistance R9 and connects transistor P4, the grounded emitter GND of described transistor P4.
Further, the outfan pin 1 of described rectifier bridge BD1, pin 4 connect the positive pole of electric capacity C7, negative pole respectively, the negative pole of described electric capacity C7 ground connection GND simultaneously.
The switching power circuit with frequency jitter circuit of this utility model embodiment, by connect between FREQUENCY CONTROL pin and the external ac power source at conventional PWM ripple output control chip access the second electric capacity and the second resistance, make FREQUENCY CONTROL pin second input signal of superposition input external power source on the basis of the first input signal that the first resistance and the first electric capacity input, the output frequency finally obtained is shaken near original frequency, while reducing electromagnetic interference (EMI), circuit the most easily realizes, reduce cost, and highly versatile.
Accompanying drawing explanation
Fig. 1 is the module map of the switching power circuit with frequency jitter circuit that this utility model embodiment provides；
Fig. 2 is the schematic diagram of the switching power circuit with frequency jitter circuit that this utility model embodiment provides；
Fig. 3 is the signal conduction test figure of existing switching power circuit；
Fig. 4 is the signal conduction test figure of the switching power circuit with frequency jitter circuit that this utility model embodiment provides；
Fig. 5 is the radiation test figure of existing switching power circuit；
Fig. 6 is the radiation test figure of the switching power circuit with frequency jitter circuit that this utility model embodiment provides.
Detailed description of the invention
In order to make the purpose of this utility model, technical scheme and advantage clearer, below in conjunction with drawings and Examples, this utility model is further elaborated.Should be appreciated that specific embodiment described herein, only in order to explain this utility model, is not used to limit this utility model.
It should be noted that be referred to as " being fixed on " or " being arranged at " another element when element, it can be directly on another element or may be simultaneously present centering elements.When an element is known as " being connected to " another element, and it can be directly to another element or may be simultaneously present centering elements.
With reference to shown in Fig. 1, a kind of switching power circuit with frequency jitter circuit that this utility model embodiment provides,
nullIncluding rectifier bridge 11、The pulse width modulation circuit 12 being connected with described rectifier bridge 11、And power output circuit 13，Described pulse width modulation circuit 12 connects described power output circuit 13 and controls the break-make rectifier bridge 11 of described power output circuit 13 and connect external ac power source，Power being used for after external ac power source rectification to described pulse width modulation circuit 12 and power output circuit 13，Wherein，Described pulse width modulation circuit 12 includes that PWM ripple exports control chip，The FREQUENCY CONTROL pin of described PWM ripple output control chip connects the first resistance and the first electric capacity having input first frequency signal，The frequency of the state modulator PWM ripple output control chip output of the first resistance and the first electric capacity，In actual application，After the first resistance and the first capacitance parameter value are selected，The frequency of PWM ripple output control chip output is fixed，For f1，The FREQUENCY CONTROL pin of the most described PWM ripple output control chip is also associated with inputting the second resistance and second electric capacity of second frequency signal，Described second resistance、Second capacitances in series，The input of described second electric capacity connects external ac power source，Second resistance、Frequency f2 of external ac power source is introduced the FREQUENCY CONTROL pin of PWM ripple output control chip by the second electric capacity，Superpose with fixed frequency f1，Form new frequency f3，New frequency f3 is shaken near original frequency f2，Frequency spectrum is made to tend to continuous in certain band limits，Its electromagnetic interference EMI test curve amplitude is low and becomes smooth，As shown in Figures 3 to 6，
Fig. 3 is the switching power circuit signal conduction test result being not added with the frequency jitter circuit described in this utility model embodiment, Fig. 4 is the signal conduction test result of the switching power circuit increasing the frequency jitter circuit described in this utility model embodiment, Fig. 5 is the switch power supply path radiation test result being not added with the frequency jitter circuit described in this utility model embodiment, Fig. 6 is the switch power supply path radiation test result being not added with the frequency jitter circuit described in this utility model embodiment
Understand from Fig. 4 and Fig. 6, owing to have employed frequency jitter circuit that is this simple and that be easily achieved, by discrete spectrum distribution in certain frequency range, so that frequency spectrum tends to continuous in certain band limits, so EMI test curve amplitude is low and becomes smooth, simultaneously, owing to the switching power circuit with frequency jitter circuit of this utility model embodiment is simply easily achieved, PWM ripple output control chip uses industry universal PWM ripple generation chip, whole circuit realiration is with low cost, versatility simultaneously, strong adaptability, it is not limited to certain specific power circuit.
In this utility model embodiment, as shown in Figure 2, the model of described PWM ripple output control chip U1 is UC2842 or UC3842, the FREQUENCY CONTROL pin 4 of described PWM ripple output control chip U1 connects one end of the first resistance R1, link one end of the first electric capacity C1 simultaneously, the other end of described first resistance R1 is connected with the pin 8 of described PWM ripple output control chip U1, the other end ground connection GND of described first electric capacity C1；
One end of described second electric capacity C2 connects external ac power source, the other end of described second electric capacity C2 connects one end of described second resistance R2, the other end of described second resistance R2 connects the FREQUENCY CONTROL pin 4 of described PWM ripple output control chip U1, first resistance R1, the first electric capacity C1 control the intrinsic first frequency f1 of PWM ripple output control chip U1, second resistance R2, the second electric capacity C2 introduce the second frequency f2 of external ac power source, and the FREQUENCY CONTROL pin 4 at PWM ripple output control chip U1 is overlapped.
nullConcrete，As shown in Figure 2，In this utility model embodiment，Described pulse width modulation circuit also includes that power-supply circuit is for providing DC source to described PWM ripple output control chip U1，Described power-supply circuit includes resistance R3、Electric capacity C6、Electric capacity C4、Diode D1、Resistance R4、Coil T1，Described resistance R3 connects the output pin 1 of rectifier bridge BD1，One end of described electric capacity C6 connects the pin 7 of described PWM ripple output control chip U1，The other end of described electric capacity C6 connects the pin 8 of described PWM ripple output control chip U1 by electric capacity C5，The minus earth GND of electric capacity C6 and electric capacity C4 simultaneously，Described electric capacity C4 is sequentially connected with diode D1、Resistance R4、Coil T1 forms a loop，One end of described diode D1、One end of electric capacity C6 is connected with one end of resistance R3 simultaneously，This loop provides galvanic current source for PWM ripple output control chip U1；
The pin 3 of described PWM ripple output control chip U1 is by electric capacity C3 ground connection GND, and pin 2 and pin 5 are directly grounded GND, and the pin 6 of described PWM ripple output control chip U1 connects described power output circuit；
Described power output circuit includes resistance R5, field effect transistor O1, transformator T2, resistance R8, resistance R7, resistance R6, one end of described resistance R5 connects the pin 6 of described PWM ripple output control chip U1, the other end of described resistance R5 connects the grid 1 of described field effect transistor O1, the error of omission 2 of described field effect transistor O1 connects the pin 3 of described transformator T2, the pin 1 of described transformator T2 connects the pin 1 of described rectifier bridge BD1, the secondary coil of transformator T2 connects load, in this utility model embodiment, the PWM ripple signal of pin 6 output of control chip U1 controls the break-make of field effect transistor O1, thus control to connect described in the secondary coil of transformator T2 the current switching of load, form the effect of Switching Power Supply；
The source electrode 3 of described field effect transistor O1 connects resistance R8, the source electrode 3 of the most described field effect transistor O1 connects described resistance R6, one end of resistance R7, the other end ground connection GND of described resistance R8, the other end of described resistance R7 is connected with the grid 1 of described field effect transistor O1, the other end of described resistance R6 is connected with the pin 3 of PWM ripple output control chip U1, plays the effect of feedback control.
In this utility model embodiment, one end that the pin 8 of described resistance R1 and described PWM ripple output control chip U1 is connected is also associated with resistance R9, the other end of described resistance R9 connects transistor P4, the grounded emitter GND of described transistor P4, for improving the frequency characteristic of PWM ripple output control chip U1.
In this utility model embodiment, the outfan pin 1 of described rectifier bridge BD1, pin 4 connect the positive pole of electric capacity C7, negative pole respectively, the negative pole of described electric capacity C7 ground connection GND simultaneously, are filtered external power source.
The switching power circuit with frequency jitter circuit that this utility model embodiment provides, by connect between FREQUENCY CONTROL pin and the external ac power source at conventional PWM ripple output control chip access the second electric capacity and the second resistance, make FREQUENCY CONTROL pin second input signal of superposition input external power source on the basis of the first input signal that the first resistance and the first electric capacity input, the output frequency finally obtained is shaken near original frequency, reduce electromagnetic interference (EMI), circuit is simply easily achieved simultaneously, control chip uses industry universal PWM ripple generation chip, reduce the cost of whole circuit, versatility simultaneously, strong adaptability.
The foregoing is only preferred embodiment of the present utility model, not in order to limit this utility model, all any amendment, equivalent and improvement etc. made within spirit of the present utility model and principle, within should be included in protection domain of the present utility model.
Claims (5)
1. a switching power circuit with frequency jitter circuit, including rectifier bridge, the pulse width modulation circuit being connected with described rectifier bridge, and power output circuit, described pulse width modulation circuit connects described power output circuit and controls the break-make of described power output circuit, it is characterized in that, described pulse width modulation circuit includes that PWM ripple exports control chip, the FREQUENCY CONTROL pin of described PWM ripple output control chip connects the first resistance and the first electric capacity having input first frequency signal, the FREQUENCY CONTROL pin of the most described PWM ripple output control chip is also associated with inputting the second resistance and second electric capacity of second frequency signal, described second resistance, second capacitances in series, the input of described second electric capacity connects external ac power source.
The switching power circuit with frequency jitter circuit the most according to claim 1, it is characterized in that, the model of described PWM ripple output control chip U1 is UC2842 or UC3842, the FREQUENCY CONTROL pin 4 of described PWM ripple output control chip U1 connects one end of the first resistance R1, link one end of the first electric capacity C1 simultaneously, the other end of described first resistance R1 is connected with the pin 8 of described PWM ripple output control chip U1, the other end ground connection GND of described first electric capacity C1；
One end of described second electric capacity C2 connects external ac power source, and the other end of described second electric capacity C2 connects one end of described second resistance R2, and the other end of described second resistance R2 connects the FREQUENCY CONTROL pin 4 of described PWM ripple output control chip U1.
nullThe switching power circuit with frequency jitter circuit the most according to claim 2，It is characterized in that，Described pulse width modulation circuit also includes that power-supply circuit is for providing DC source to described PWM ripple output control chip U1，Described power-supply circuit includes resistance R3、Electric capacity C6、Electric capacity C4、Diode D1、Resistance R4、Coil T1，Described resistance R3 connects the output pin 1 of rectifier bridge BD1，One end of described electric capacity C6 connects the pin 7 of described PWM ripple output control chip U1，The other end of described electric capacity C6 connects the pin 8 of described PWM ripple output control chip U1 by electric capacity C5，The minus earth GND of electric capacity C6 and electric capacity C4 simultaneously，Described electric capacity C4 is sequentially connected with diode D1、Resistance R4、Coil T1 forms a loop，One end of described diode D1、One end of electric capacity C6 is connected with one end of resistance R3 simultaneously；
The pin 3 of described PWM ripple output control chip U1 is by electric capacity C3 ground connection GND, and pin 2 and pin 5 are directly grounded GND, and the pin 6 of described PWM ripple output control chip U1 connects described power output circuit；
nullDescribed power output circuit includes resistance R5、Field effect transistor O1、Transformator T2、Resistance R8、Resistance R7、Resistance R6，One end of described resistance R5 connects the pin 6 of described PWM ripple output control chip U1，The other end of described resistance R5 connects the grid 1 of described field effect transistor O1，The error of omission 2 of described field effect transistor O1 connects the pin 3 of described transformator T2，The pin 1 of described transformator T2 connects the pin 1 of described rectifier bridge BD1，The source electrode 3 of described field effect transistor O1 connects resistance R8，The source electrode 3 of the most described field effect transistor O1 connects described resistance R6、One end of resistance R7，The other end ground connection GND of described resistance R8，The other end of described resistance R7 is connected with the grid 1 of described field effect transistor O1，The other end of described resistance R6 is connected with the pin 3 of PWM ripple output control chip U1.
The switching power circuit with frequency jitter circuit the most according to claim 3, it is characterized in that, one end that the pin 8 of described resistance R1 and described PWM ripple output control chip U1 is connected is also associated with resistance R9, the other end of described resistance R9 connects transistor P4, the grounded emitter GND of described transistor P4.
The switching power circuit with frequency jitter circuit the most according to claim 4, it is characterised in that the outfan pin 1 of described rectifier bridge BD1, pin 4 connect the positive pole of electric capacity C7, negative pole respectively, the negative pole of described electric capacity C7 ground connection GND simultaneously.
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| CN201620150987.XU CN205725448U (en) | 2016-02-29 | 2016-02-29 | A kind of switching power circuit with frequency jitter circuit |
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| CN201620150987.XU CN205725448U (en) | 2016-02-29 | 2016-02-29 | A kind of switching power circuit with frequency jitter circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108539973A (en) * | 2018-05-18 | 2018-09-14 | 深圳市华星光电技术有限公司 | TFT-LCD displays and its driving circuit, Switching Power Supply |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108539973A (en) * | 2018-05-18 | 2018-09-14 | 深圳市华星光电技术有限公司 | TFT-LCD displays and its driving circuit, Switching Power Supply |
| WO2019218443A1 (en) * | 2018-05-18 | 2019-11-21 | 深圳市华星光电技术有限公司 | Tft-lcd display and drive circuit thereof and switching power supply |
| US11029545B2 (en) | 2018-05-18 | 2021-06-08 | Shenzhen China Star Optoelectronics Technology Co., Ltd. | Thin film transistor liquid crystal display (TFT-LCD) and the driving circuit and switching power supply thereof |
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