CN202395667U - Switch power supply circuit with small voltage output ripple - Google Patents
Switch power supply circuit with small voltage output ripple Download PDFInfo
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- CN202395667U CN202395667U CN 201120408342 CN201120408342U CN202395667U CN 202395667 U CN202395667 U CN 202395667U CN 201120408342 CN201120408342 CN 201120408342 CN 201120408342 U CN201120408342 U CN 201120408342U CN 202395667 U CN202395667 U CN 202395667U
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Abstract
The utility model discloses a switch power supply circuit with small voltage output ripples. The switch power supply circuit comprises a power line, a rectification filter circuit, a switch output circuit, a power supply chip, a power supply chip power supply circuit, and an AC input voltage waveform detection sampling circuit. The input terminal of the AC input voltage waveform detection sampling circuit is connected with the power line, the rectification filter circuit, the switch output circuit and the power supply chip power supply circuit. The output terminal of the AC input voltage waveform detection sampling circuit is connected with the power supply chip. Through detection of the waveform of an input voltage, the frequency of a switch is modulated via the waveform after the waveform of the AC input voltage is detected, the frequency of the switch is at a minimum point when the input voltage is placed at a peak position, and the frequency of the switch is at a maximum point when the input voltage is placed at a trough position. Therefore, the problem that the ripples of an output voltage are large is solved, the capacitance value of an input large electrolytic capacitor can be properly reduced, the size of a switch transformer can be reduced, and the cost is lowered.
Description
[technical field]
The utility model relates to Switching Power Supply, relates in particular to the little switching power circuit of a kind of voltage output ripple.
[background technology]
The early stage power supply chip that uses all is that the fixed-frequency mode is carried out work; Because in the square-wave waveform is to contain a large amount of harmonic componentss; When fixed-frequency time-harmonic wave energy point can be very concentrated; The partial test Frequency point is difficult to be passed through thereby cause when EMI tests, having, and therefore uses the power circuit of this mode to have the difficult problem of passing through of electromagnetic compatibility EMC.
As shown in Figure 5; Present widely used power supply chip major part has all added the frequency jitter technology; The switching frequency that is Switching Power Supply changed in certain cycle (being generally 4mS); The scope of frequency change can effectively suppress the energy of the multiple harmonic of single-point through this kind method about ± 4KHZ, thereby realizes the purpose that EMC is easier to pass through.But the mode of using a fixed cycle realizes the mode of trembling frequency and has a defective; When the frequency of input AC AC voltage when changing; When the AC voltage of the cycle of power supply chip frequency jitter and input is asynchronous; Can appear at input AC voltage and when low-voltage is imported, occur the big problem of output voltage ripple easily, promptly can appear at AC voltage switching frequency when the position of trough and drop to minimum point.At present; One of the solution of this problem is to reduce maximum duty cycle through the design parameter of adjusting anti-sharp power transformer to improve; Another is to reduce output voltage ripple through the big electrochemical capacitor that strengthens input; From early still, these two kinds of schemes all are that the mode that needs to increase cost could realize
[summary of the invention]
The technical problem that the utility model will solve provides a kind of simple in structure, lower-cost, the little switching power circuit of voltage output ripple.
In order to solve the problems of the technologies described above; The technical scheme that the utility model adopts is; The little switching power circuit of a kind of voltage output ripple; Comprise power line, current rectifying and wave filtering circuit, switch output circuit, power supply chip, power supply chip power supply circuits and ac input voltage waveforms detection sample circuit; Described switch output circuit comprises output transformer and switching tube, input termination power line, current rectifying and wave filtering circuit, switch output circuit and the power supply chip power supply circuits of said ac input voltage waveforms detection sample circuit, the output termination power supply chip of said ac input voltage waveforms detection sample circuit.
The little switching power circuit of above-described voltage output ripple; Described ac input voltage waveforms detection sample circuit comprises first divider resistance, second divider resistance and the 3rd divider resistance; One termination power live wire of said first divider resistance, another termination is a sampling end; One termination power zero line of said second divider resistance, the described sampling end of another termination; The described sampling end of one termination of said the 3rd divider resistance, the negative pole end of another termination current rectifying and wave filtering circuit output; The input voltage overvoltage/undervoltage of described sampling termination power supply chip detects pin.
The little switching power circuit of above-described voltage output ripple comprises first filter capacitor, and described first filter capacitor and described three divider resistances also connect.
The little switching power circuit of above-described voltage output ripple, described output transformer comprises auxiliary winding, and described current rectifying and wave filtering circuit comprises filter circuit and rectifier bridge, and the input of said rectifier bridge connects power line through filter circuit; Described power supply chip power supply circuits comprise first current-limiting resistance, second filter capacitor, diode and described auxiliary winding; First termination filter circuit of described first current-limiting resistance and the tie point between the rectifier bridge; The negative electrode of second terminating diode of first current-limiting resistance, the anode of diode connect the negative pole end of current rectifying and wave filtering circuit output; The positive pole of second filter capacitor connects the tie point of the negative electrode of first current-limiting resistance, second end and diode, and negative pole connects the negative pole end of current rectifying and wave filtering circuit output; Auxiliary winding is connected with first current-limiting resistance, diode, and the positive pole of second filter capacitor connects the supply pin of power supply chip.
The little switching power circuit of above-described voltage output ripple, described current rectifying and wave filtering circuit comprises the 3rd filter capacitor and rectifier bridge, the both positive and negative polarity of said the 3rd filter capacitor connects the both positive and negative polarity of rectifier bridge output respectively; Described ac input voltage waveforms detection sample circuit comprises second current-limiting resistance, the positive pole of the termination rectifier bridge output of said second current-limiting resistance, the high voltage startup pin of another termination power supply chip.
The little switching power circuit of above-described voltage output ripple, the former limit winding of said output transformer and switching tube serial connection, described ac input voltage waveforms detection sample circuit comprises sampling resistor; The positive pole of the one termination rectifier bridge output of said switch output circuit; The other end connects the negative pole end of current rectifying and wave filtering circuit output through sampling resistor; The one termination switch output circuit of described ac input voltage waveforms detection sample circuit and the tie point of sampling resistor, the current sample pin of another termination power supply chip.
The switching power circuit that the utility model voltage output ripple is little passes through to detect the waveform of input voltage; After coming out the ac input voltage waveforms detection; Utilize this waveform that switching frequency is modulated again, when input voltage is in crest location, switching frequency is placed minimum point; When input voltage is in wave trough position, switching frequency is placed peak, the big problem of not only soluble output voltage ripple can also suitably reduce to import the appearance value of big electrochemical capacitor and the size of switch transformer, realizes the purpose that reduces cost.
[description of drawings]
Below in conjunction with accompanying drawing and embodiment the utility model is done further detailed explanation.
Fig. 1 is the circuit theory diagrams of the little switching power circuit embodiment 1 of the utility model voltage output ripple.
Fig. 2 is the circuit theory diagrams of the little switching power circuit embodiment 2 of the utility model voltage output ripple.
Fig. 3 is the circuit theory diagrams of the little switching power circuit embodiment 3 of the utility model voltage output ripple.
Fig. 4 is the circuit theory diagrams of the little switching power circuit embodiment 4 of the utility model voltage output ripple.
Fig. 5 is the sketch map of prior art power supply chip frequency jitter.
Fig. 6 is that each embodiment A C input voltage waveform of the utility model detects schematic diagram.
[embodiment]
In the embodiment 1 of the utility model shown in Figure 1; The little switching power circuit of voltage output ripple comprises ac-input power supply, current rectifying and wave filtering circuit, switch output circuit, power supply chip (LD7577 or LD7535, LD7537, LD7750), power supply chip power supply circuits and ac input voltage waveforms detection sample circuit.
Current rectifying and wave filtering circuit comprises filter circuit that is made up of capacitor C X1, inductance L 1 and the rectifier bridge that is made up of 4 rectifier diodes, and the input of rectifier bridge connects the power line of ac-input power supply through filter circuit.
The both positive and negative polarity of big electrochemical capacitor EC1 connects the both positive and negative polarity of rectifier bridge output respectively.The negative pole end ground connection of rectifier bridge output.
The switch output circuit comprises output transformer T1 and switching tube Q1, the positive pole of the termination rectifier bridge output of the former limit winding T1 of output transformer, and the drain electrode of another termination switching tube Q1, the source electrode of switching tube Q1 is through resistance R 7 ground connection.The control signal output ends of power supply chip connects the gate pole of switching tube Q1.
The power supply chip power supply circuits comprise the auxiliary winding of the auxiliary winding T1A of the first current-limiting resistance R4, the second filter capacitor EC2, diode D1 and output transformer T1; The first termination filter circuit inductance L 1 of the first current-limiting resistance R8 and the tie point between the rectifier bridge; The negative electrode of the second terminating diode D1 of the first current-limiting resistance R8, the anode of diode D1 were connected the auxiliary winding earth of the auxiliary winding T1A of transformer.The positive pole of the second filter capacitor EC2 connects the tie point of the negative electrode of the first current-limiting resistance R8, second end and diode D1, minus earth.The positive pole of the second filter capacitor EC2 connects the supply pin of power supply chip.
The ac input voltage waveforms detection sample circuit of present embodiment comprises the first divider resistance R1, the second divider resistance R4 and the 3rd divider resistance R3, the termination power live wire of the first divider resistance R1, and another termination is a sampling end.The termination power zero line of the second divider resistance R4, another termination sampling end.The termination sampling end of the 3rd divider resistance R3, other end ground connection, the first filter capacitor C1 and the 3rd divider resistance R3 also connect.The input voltage overvoltage/undervoltage of the sampling termination power supply chip of ac input voltage waveforms detection sample circuit detects pin (the 1st pin of LD7577 chip); To power supply chip AC is provided the voltage waveform of input; Power supply chip utilizes this waveform that switching frequency is modulated, and is as shown in Figure 6, when input voltage is in crest location, switching frequency placed minimum point; When input voltage is in wave trough position, switching frequency is placed peak; Can solve the big problem of above-mentioned output voltage ripple, can suitably reduce to import the appearance value of big electrochemical capacitor and the size of switch transformer simultaneously, reach the purpose that reduces cost.
The circuit of the embodiment 2 of the utility model is as shown in Figure 2, and different with embodiment 1 is not need independently ac input voltage waveforms detection sample circuit.First end of the first current-limiting resistance R8 of power supply chip power supply circuits directly obtains the voltage waveform of AC input, the supply pin of input power supply chip from filter circuit inductance L 1.
The circuit of the embodiment 3 of the utility model is as shown in Figure 3; Different with embodiment 1 is; Ac input voltage waveforms detection sample circuit comprises the second current-limiting resistance R6; The positive pole of the termination rectifier bridge output of the second current-limiting resistance R6, the high voltage startup pin of another termination power supply chip (the 8th pin of LD7577 chip), the voltage waveform of AC input obtains from the positive terminal of the second filter capacitor EC2.
The circuit of the embodiment 3 of the utility model is as shown in Figure 3; Different with embodiment 1 is; Ac input voltage waveforms detection sample circuit utilizes the emitter resistance R7 of switching tube Q1 as sampling resistor; The emitter of one termination switch switching output circuit pipe Q1 of ac input voltage waveforms detection sample circuit, the current sample pin of another termination power supply chip (the 3rd pin of LD7577 chip).The voltage waveform of AC input obtains from the link of the emitter of sampling resistor and switching tube Q1.
Can see from above embodiment; Ac input voltage waveforms detection mode can directly obtain from the AC input, also can also can be obtained by the current sample end by obtaining on the big electrochemical capacitor; Also can obtain and deliver to power supply chip after the ac input voltage waveforms detection is accomplished by the chip power feeder ear; Power supply chip is handled with detected AC waveform the switching frequency of power supply, makes switching frequency when AC waveform crest, be in minimum, and switching frequency is in peak when AC waveform trough
The big problem of the not only soluble output voltage ripple of the utility model can also suitably reduce to import the appearance value of big electrochemical capacitor and the size of switch transformer, realizes the purpose that reduces cost.
More than the big problem of output voltage ripple is appearred in a kind of switching power source chip that the utility model provided when trembling frequently solution carried out detailed introduction; Used concrete example among this paper the principle and the execution mode of the utility model are set forth, the explanation of above embodiment just is used to help to understand the core concept of the utility model; Simultaneously, for one of ordinary skill in the art, according to the thought of the utility model, the part that on embodiment and range of application, all can change, in sum, this description should not be construed as the restriction to the utility model.
Claims (6)
1. a voltage is exported the little switching power circuit of ripple; Comprise power line, current rectifying and wave filtering circuit, switch output circuit, power supply chip and power supply chip power supply circuits; Described switch output circuit comprises output transformer and switching tube; It is characterized in that; Comprise ac input voltage waveforms detection sample circuit, input termination power line, current rectifying and wave filtering circuit, switch output circuit and the power supply chip power supply circuits of said ac input voltage waveforms detection sample circuit, the output termination power supply chip of said ac input voltage waveforms detection sample circuit.
2. the little switching power circuit of voltage output ripple according to claim 1; It is characterized in that; Described ac input voltage waveforms detection sample circuit comprises first divider resistance, second divider resistance and the 3rd divider resistance; One termination power live wire of said first divider resistance, another termination is a sampling end; One termination power zero line of said second divider resistance, the described sampling end of another termination; The described sampling end of one termination of said the 3rd divider resistance, the negative pole end of another termination current rectifying and wave filtering circuit output; The input voltage overvoltage/undervoltage of described sampling termination power supply chip detects pin.
3. the little switching power circuit of voltage output ripple according to claim 2 is characterized in that comprise first filter capacitor, described first filter capacitor and described three divider resistances also connect.
4. the little switching power circuit of voltage output ripple according to claim 1; It is characterized in that; Described output transformer comprises auxiliary winding, and described current rectifying and wave filtering circuit comprises filter circuit and rectifier bridge, and the input of said rectifier bridge connects power line through filter circuit; Described power supply chip power supply circuits comprise that first current-limiting resistance, second filter capacitor, diode and described auxiliary winding assist winding; First termination filter circuit of described first current-limiting resistance and the tie point between the rectifier bridge; The negative electrode of second terminating diode of first current-limiting resistance, the anode of diode connect the negative pole end of current rectifying and wave filtering circuit output; The positive pole of second filter capacitor connects the tie point of the negative electrode of first current-limiting resistance, second end and diode, and negative pole connects the negative pole end of current rectifying and wave filtering circuit output; Auxiliary winding is connected with first current-limiting resistance, diode, and the positive pole of second filter capacitor connects the supply pin of power supply chip.
5. the little switching power circuit of voltage output ripple according to claim 1 is characterized in that described current rectifying and wave filtering circuit comprises the 3rd filter capacitor and rectifier bridge, and the both positive and negative polarity of said the 3rd filter capacitor connects the both positive and negative polarity of rectifier bridge output respectively; Described ac input voltage waveforms detection sample circuit comprises second current-limiting resistance, the positive pole of the termination rectifier bridge output of said second current-limiting resistance, the high voltage startup pin of another termination power supply chip.
6. the little switching power circuit of voltage output ripple according to claim 1 is characterized in that, the former limit winding of said output transformer and switching tube serial connection, and described ac input voltage waveforms detection sample circuit comprises sampling resistor; The positive pole of the one termination rectifier bridge output of said switch output circuit; The other end connects the negative pole end of current rectifying and wave filtering circuit output through sampling resistor; The one termination switch output circuit of described ac input voltage waveforms detection sample circuit and the tie point of sampling resistor, the current sample pin of another termination power supply chip.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201120408342 CN202395667U (en) | 2011-10-24 | 2011-10-24 | Switch power supply circuit with small voltage output ripple |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201120408342 CN202395667U (en) | 2011-10-24 | 2011-10-24 | Switch power supply circuit with small voltage output ripple |
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| Publication Number | Publication Date |
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| CN202395667U true CN202395667U (en) | 2012-08-22 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN 201120408342 Expired - Fee Related CN202395667U (en) | 2011-10-24 | 2011-10-24 | Switch power supply circuit with small voltage output ripple |
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| CN (1) | CN202395667U (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107070180A (en) * | 2017-04-05 | 2017-08-18 | 广州视源电子科技股份有限公司 | The power supply circuit of power supply chip in Switching Power Supply and Switching Power Supply |
| CN107187419A (en) * | 2017-05-18 | 2017-09-22 | 鞍山科大物联科技有限公司 | A kind of automobile door lock status identification means and recognition methods |
| CN109085500A (en) * | 2018-08-06 | 2018-12-25 | 芜湖莫森泰克汽车科技股份有限公司 | A kind of detection test macro of direct current generator current ripples parameter |
-
2011
- 2011-10-24 CN CN 201120408342 patent/CN202395667U/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107070180A (en) * | 2017-04-05 | 2017-08-18 | 广州视源电子科技股份有限公司 | The power supply circuit of power supply chip in Switching Power Supply and Switching Power Supply |
| CN107187419A (en) * | 2017-05-18 | 2017-09-22 | 鞍山科大物联科技有限公司 | A kind of automobile door lock status identification means and recognition methods |
| CN107187419B (en) * | 2017-05-18 | 2023-08-08 | 辽宁科大物联科技有限公司 | Automobile door lock state identification device and identification method |
| CN109085500A (en) * | 2018-08-06 | 2018-12-25 | 芜湖莫森泰克汽车科技股份有限公司 | A kind of detection test macro of direct current generator current ripples parameter |
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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: 20120822 Termination date: 20201024 |
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| CF01 | Termination of patent right due to non-payment of annual fee |