CN205232030U - Input undervoltage protection circuit and switching power supply - Google Patents
Input undervoltage protection circuit and switching power supply Download PDFInfo
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- CN205232030U CN205232030U CN201521071589.0U CN201521071589U CN205232030U CN 205232030 U CN205232030 U CN 205232030U CN 201521071589 U CN201521071589 U CN 201521071589U CN 205232030 U CN205232030 U CN 205232030U
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Abstract
The utility model discloses an input undervoltage protection circuit has utilized main control unit IC1's starting voltage to be greater than the characteristics of closing voltage, is the voltage of main control unit IC1 power supply through the input undervoltage protection circuit regulation who comprises input voltage sampling circuit, bleeder circuit, switch tube to input undervoltage protection and hysteresis loop function have been realized, the utility model discloses need not to use components such as operational amplifier, extra auxiliary electrical power source, a plurality of triode, special IC, the circuit is simple, low cost, owing to have the hysteresis loop function, can avoid the power frequently to start at protection point in practical application, and the power performance is better. The utility model discloses still disclose a switching power supply who uses above -mentioned input undervoltage protection circuit.
Description
Technical field
The utility model relates to switch power technology field, particularly relates to a kind of input undervoltage protection circuit and Switching Power Supply.
Background technology
Switching Power Supply is normal in actual applications to be damaged because of the exception of environment for use, and input undervoltage is wherein a kind of more common destructive factor.Input undervoltage can cause power source internal to occur the abnormal conditions such as control loop is unstable, power device is overheated, magnetic device is saturated, easily causes power supply to damage, and in order to solve this problem, common scheme increases under-voltage protecting circuit.
Chinese utility model patent CN202334295U discloses a kind of input undervoltage protection circuit device, and its focus, in IC design itself, realizes input undervoltage protection by the inside ena-bung function controlling application-specific integrated circuit.Chinese utility model patent CN202488832U discloses a kind of input undervoltage protection circuit, and what it adopted is also a kind of application-specific integrated circuit having internal under-pressure protective circuit.Some products are also had to use Brownout (brownout) the function pin of application-specific integrated circuit to realize under-voltage protection on the market.Adopt the scheme of application-specific integrated circuit, general cost is high, and selectable device is less, and without substitute materials.
Chinese utility model patent CN201846066U discloses a kind of under-voltage protecting circuit with lag function, and its control circuit is more complicated, needs to use operational amplifier, realizes under-voltage protection by on-off switching tube.Also have some product needed to use operational amplifier on the market, need extra accessory power supply owing to powering to operational amplifier, therefore, the circuit of this type of scheme is general more complicated, and cost is higher.In addition, also have some to control the scheme of under-voltage protection point by multiple triode, voltage-stabiliser tube, because the device used is more, therefore circuit is also more complicated, and voltage-stabiliser tube is comparatively large by the impact of temperature and On current, and precision is poor.
Chinese utility model patent CN201937238U discloses a kind of input undervoltage protection circuit; under-voltage protection is realized by " enable " pin of IC; error is larger; and without " stagnant ring " design, (namely the input voltage of Switching Power Supply must comparatively higher than under-voltage protection setting voltage; just Switching Power Supply can be reopened; thus the frequent unlatching of Switching Power Supply or shutoff when avoiding the input voltage of Switching Power Supply to fluctuate near under-voltage protection setting voltage), easily cause power supply at a protection point frequent starting.
Utility model content
The technical problem that the utility model solves is to provide a kind of without the need to using application-specific integrated circuit, circuit simple and can realizing the input undervoltage protection circuit of stagnant ring function.
For solving the problems of the technologies described above, the utility model adopts technical scheme as described below.
A kind of input undervoltage protection circuit, in Switching Power Supply, comprises input voltage sample circuit, bleeder circuit, switching tube, wherein:
Described input voltage sample circuit is connected with power input, also keeps input crest voltage for sampled input voltage;
Described bleeder circuit comprises the divider resistance of two series connection, and described bleeder circuit is in parallel with described input voltage sample circuit;
The control end of described switching tube is connected to the tie point of described two divider resistances, and the output of described switching tube is connected to the energization pins of the master controller IC1 of Switching Power Supply.
Further, described input voltage sample circuit comprises electric capacity C1, and the two ends of electric capacity C1 are connected between power input positive pole and ground.
Further, described input voltage sample circuit comprises diode D1, the electric capacity C1 of series connection, and the anode of diode D1 is connected to power input positive pole, and the negative electrode of diode D1 is connected to one end of electric capacity C1, the other end ground connection of electric capacity C1.
Further, described bleeder circuit is in parallel with electric capacity C1, described bleeder circuit comprises divider resistance R1, the divider resistance R2 of series connection, the other end of divider resistance R1 is connected to the negative electrode of diode D1, the other end ground connection of divider resistance R2, the control end of described switching tube is connected to divider resistance R1 and divider resistance R2 tie point.
Further, the input of described switching tube respectively with the auxiliary winding switching of power input positive pole, Switching Power Supply.
Further, described switching tube is NMOS tube, and its grid is connected to the tie point of divider resistance R1 and divider resistance R2, and its source electrode is connected to the energization pins of master controller IC1, and its drain electrode is connected with power input positive pole by a current-limiting resistance R3.
Further, the control end of described switching tube is by a high-frequency filter capacitor C2 ground connection.
Further, the control end of described switching tube is also connected with the negative electrode of a voltage stabilizing didoe ZD, and the anode of this voltage stabilizing didoe ZD is connected to ground.
The technical problem that the utility model solves also is to provide a kind of Switching Power Supply using above-mentioned input undervoltage protection circuit; it comprises main transformer T1; be positioned at the power input of main transformer T1 primary side; the input undervoltage protection circuit be connected with power input; the primary control circuit be connected with input undervoltage protection circuit; be positioned at the secondary control circuit of transformer T1 primary side, and for the feedback signal of secondary control circuit being delivered to the isolating device of primary control circuit.
Further, the input undervoltage of this Switching Power Supply protects stagnant ring △ Vac to be:
Wherein, Von represents the cut-in voltage of master controller IC1, and Voff represents the closedown voltage of master controller IC1, and R1 is the resistance of the divider resistance being connected to described input voltage sample circuit positive pole, R2 is the resistance of another divider resistance.
Advantageous Effects of the present utility model is: the starting resistor that the utility model make use of master controller IC1 is greater than the feature of closing voltage, by by input voltage sample circuit, bleeder circuit, the input undervoltage protection circuit that switching tube forms is adjusted to the voltage that master controller IC1 powers, thus achieve input undervoltage protection and stagnant ring function, the utility model is without the need to using operational amplifier, extra accessory power supply, multiple triode, the elements such as application-specific integrated circuit, circuit is simple, with low cost, owing to having stagnant ring function, power supply can be avoided in actual applications at protection point frequent starting, power source performance is better.
Accompanying drawing explanation
Fig. 1 is a kind of circuit diagram of Switching Power Supply.
Fig. 2 is the circuit diagram of input undervoltage protection circuit in certain embodiments.
Embodiment
For making those of ordinary skill in the art clearly understand the purpose of this utility model, technical scheme and advantage, below in conjunction with drawings and Examples, the utility model is further elaborated.
Shown in figure 1, a kind of Switching Power Supply comprises main transformer T1, is positioned at the power input 10 of main transformer T1 primary side, the input undervoltage protection circuit 20 be connected with power input 10, the primary control circuit 30 be connected with input undervoltage protection circuit 20, be positioned at the secondary control circuit 40 of transformer T1 primary side and the feedback signal (current sampling signal, voltage sampling signal) of secondary control circuit 40 be delivered to the photoelectrical coupler OC1 of primary control circuit 30.
In certain embodiments, the alternating current of power input 10 is by exporting after rectifier bridge BR1.
Main transformer T1 comprises armature winding N1, auxiliary winding N3 and secondary winding N2, armature winding N1 comprise first end N11 and the second end N12, and auxiliary winding N3 comprises the 3rd end N31 and the 4th end N32, secondary winding N2 comprise five terminal N21 and the 6th end N22.
This input undervoltage protection circuit 20 comprises input voltage sample circuit, bleeder circuit, switching tube, and wherein switching tube can be switch MOS pipe, triode etc.
Input voltage sample circuit is connected with power input 10, and also keep input crest voltage for sampled input voltage, it comprises electric capacity C1, and the two ends of electric capacity C1 are connected between power input 10 positive pole and ground, and described bleeder circuit is in parallel with electric capacity C1.In order to prevent reversal connection and electric current from pouring in down a chimney, preferably the anode of a diode D1 is connected to power input 10 positive pole, the negative electrode of diode D1 is connected to one end of electric capacity C1, the other end ground connection of electric capacity C1.Bleeder circuit comprises divider resistance R1, divider resistance R2, switching tube Q1 is preferably NMOS tube, its grid is connected to the tie point of divider resistance R1 and divider resistance R2, its source electrode is connected to the energization pins Pvcc of master controller IC1, and its drain electrode is connected with power input 10 positive pole by a current-limiting resistance R3.The grid of switching tube Q1, by a high-frequency filter capacitor C2 ground connection, for filtering High-frequency Interference, avoids false triggering.The grid of switching tube Q1 is also connected with the negative electrode of a voltage stabilizing didoe ZD, and the anode of this voltage stabilizing didoe ZD is connected to ground, and with the grid voltage of stable switch pipe Q1, avoids grid voltage too high damage switching tube Q1.The drain electrode of switching tube Q1 is also connected with the 3rd end N31 of auxiliary winding N3 by a diode D2, for auxiliary winding power and master controller IC1 power between switch.The drain electrode of switching tube Q1 and source electrode are also connected to filter capacitor C4, filter capacitor C3.
Primary control circuit 30 comprises master controller IC1, switching tube Q2 and some peripheral circuits, master controller IC1 is a kind of pwm chip, its energization pins Pvcc is connected with the output of switching tube Q1, the feedback signal pin FB of master controller IC1 is connected to 3 pin (the 4 pin ground connection of photoelectrical coupler OC1) of photoelectrical coupler OC1, the control end of the output pin Out connecting valve pipe Q2 of master controller IC1.The input of switching tube Q2 connects the second end N12 of armature winding N1, the output head grounding of switching tube Q2.An absorbing circuit is also connected with between the first end N11 of armature winding N1 and the second end N12.
Secondary control circuit 40 comprises output rectifier and filter, secondary controller IC2, the energization pins Svcc of secondary controller IC2 is connected with the five terminal N21 of secondary winding N2, and voltage sample pin Vsen, the current sample pin Isen of secondary controller IC2 are connected with five terminal N21, the 6th end N22 of secondary winding N2 respectively.The output pin Vc of secondary controller IC2 is connected with 1 pin of photoelectrical coupler OC1 (2 pin of photoelectrical coupler OC1 are connected with the five terminal N21 of secondary winding N2) by a current-limiting resistance R4.
This Switching Power Supply operationally, the result of electric current, voltage sample is fed back to the master controller IC1 of primary control circuit 30 by secondary control circuit 40 by photoelectrical coupler OC1, master controller IC1 according to the operating state of this sampled result control switch pipe Q2, thus realizes the control to output current or voltage.Because this master controller IC1 is also connected with input undervoltage protection circuit 20; master controller IC1 is also according to the operating state of the working condition control switch pipe Q2 of input undervoltage protection circuit 20; therefore this Switching Power Supply can close output when input voltage is under-voltage; with protection power source, its detailed operation principle is as follows:
Shown in figure 2, Fig. 2 is the basic block diagram of input undervoltage protection circuit 20 in certain embodiments, compared to Figure 1, eliminates filter capacitor C4, filter capacitor C3, current-limiting resistance R3, voltage stabilizing didoe ZD.
The output end voltage Vcc_ic of switching tube Q1 powers to master controller IC1, and the value of output end voltage Vcc_ic is the difference of this switching tube Q1 control end voltage Vac_sen and this switching tube Q1 threshold voltage vt h, namely obtains expression formula (1):
Vcc_ic＝Vac_sen-Vth(1)
The value of Vac_sen equals the voltage at divider resistance R2 two ends, and the voltage at divider resistance R2 two ends is relevant with power input 10 voltage.Concrete, if the alternating voltage of input is Vac, this peak values of ac magnitude of voltage is Vac_peak, wherein:
Vac_peak＝√2×Vac(2)
According to bleeder circuit principle:
In formula (3), R1 is the resistance of divider resistance R1, and R2 is the resistance of divider resistance R2.
Visible; for different master controller IC1; when master controller IC1 open and close voltage determine, the ratio of the resistance value of divider resistance R1, divider resistance R2 directly determines the cut-in voltage Vac_on of this Switching Power Supply and the closedown voltage Vac_off (i.e. under-voltage protection voltage) of Switching Power Supply.Concrete:
When input voltage Vac does not reach Vac_on, the cut-in voltage Von that the value of output end voltage Vcc_ic does not reach master controller IC1 represents;
When input voltage Vac reaches Vac_on, when the value of output end voltage Vcc_ic reaches master controller IC1 cut-in voltage Von, i.e. Von=Vcc_ic, master controller IC1 start output PWM, this Switching Power Supply starts normal work, derives the starting resistor effective value Vac_on of this Switching Power Supply to be:
When input voltage Vac drops to lower than Vac_off; during closedown voltage Voff lower than master controller IC1 of the value of output end voltage Vcc_ic; master controller IC1 closes PWM and exports, and Switching Power Supply enters under-voltage protection state, derives the closedown voltage effective value Vac_off of this Switching Power Supply to be:
Starting resistor due to master controller IC1 is greater than closedown voltage, so the input voltage value that Switching Power Supply is opened also is greater than the input voltage value of closedown, also namely open input voltage value and close between input voltage value and have stagnant ring, avoid the shutdown again that causes of input voltage bust that this Switching Power Supply opens moment, thus boot failure.Concrete, from formula (4), formula (5), input undervoltage protects stagnant ring △ Vac to be:
The starting resistor that the utility model make use of master controller IC1 is greater than the feature of closing voltage; be adjusted to by the input undervoltage protection circuit be made up of input voltage sample circuit, bleeder circuit, switching tube the voltage that master controller IC1 powers, thus achieve input undervoltage protection and stagnant ring function.The utility model is without the need to using the elements such as operational amplifier, extra accessory power supply, multiple triode, application-specific integrated circuit; circuit is simple, with low cost; owing to having stagnant ring function, power supply can be avoided in actual applications at protection point frequent starting, and power source performance is better.
These are only preferred embodiment of the present utility model, but not any pro forma restriction is done to the utility model.Those skilled in the art can impose various equivalent change and improvement on the basis of above-described embodiment, and all equivalent variations of doing in right or modification, all should fall within protection range of the present utility model.
Claims (10)
1. an input undervoltage protection circuit, in Switching Power Supply, is characterized in that, described under-voltage protecting circuit comprises input voltage sample circuit, bleeder circuit, switching tube, wherein:
Described input voltage sample circuit is connected with power input, also keeps input crest voltage for sampled input voltage;
Described bleeder circuit comprises the divider resistance of two series connection, and described bleeder circuit is in parallel with described input voltage sample circuit;
The control end of described switching tube is connected to the tie point of described two divider resistances, and the output of described switching tube is connected to the energization pins of the master controller IC1 of Switching Power Supply.
2. input undervoltage protection circuit as claimed in claim 1, it is characterized in that, described input voltage sample circuit comprises electric capacity C1, and the two ends of electric capacity C1 are connected between power input positive pole and ground.
3. input undervoltage protection circuit as claimed in claim 1; it is characterized in that; described input voltage sample circuit comprises diode D1, the electric capacity C1 of series connection; the anode of diode D1 is connected to power input positive pole; the negative electrode of diode D1 is connected to one end of electric capacity C1, the other end ground connection of electric capacity C1.
4. input undervoltage protection circuit as claimed in claim 1; it is characterized in that; described bleeder circuit is in parallel with electric capacity C1; described bleeder circuit comprises divider resistance R1, the divider resistance R2 of series connection; the other end of divider resistance R1 is connected to the negative electrode of diode D1; the other end ground connection of divider resistance R2, the control end of described switching tube is connected to divider resistance R1 and divider resistance R2 tie point.
5. input undervoltage protection circuit as claimed in claim 1, is characterized in that, the input of described switching tube respectively with the auxiliary winding switching of power input positive pole, Switching Power Supply.
6. input undervoltage protection circuit as claimed in claim 4; it is characterized in that; described switching tube is NMOS tube; its grid is connected to the tie point of divider resistance R1 and divider resistance R2; its source electrode is connected to the energization pins of master controller, and its drain electrode is connected with power input positive pole by a current-limiting resistance R3.
7. input undervoltage protection circuit as claimed in claim 1, is characterized in that, the control end of described switching tube is by a high-frequency filter capacitor C2 ground connection.
8. input undervoltage protection circuit as claimed in claim 1, it is characterized in that, the control end of described switching tube is connected with the negative electrode of a voltage stabilizing didoe ZD, and the anode of this voltage stabilizing didoe ZD is connected to ground.
9. a Switching Power Supply; it is characterized in that; described Switching Power Supply comprises main transformer T1, is positioned at the power input of main transformer T1 primary side, the input undervoltage protection circuit as described in claim 1 ~ 8 be connected with power input, the primary control circuit be connected with input undervoltage protection circuit, be positioned at the secondary control circuit of transformer T1 primary side, and for the feedback signal of secondary control circuit being delivered to the isolating device of primary control circuit.
10. Switching Power Supply as claimed in claim 9, it is characterized in that, this Switching Power Supply has input undervoltage and protects stagnant ring △ Vac, and its value is:
Wherein, Von represents the cut-in voltage of master controller IC1, and Voff represents the closedown voltage of master controller IC1, and R1 is the resistance of the divider resistance being connected to described input voltage sample circuit positive pole, R2 is the resistance of another divider resistance.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201521071589.0U CN205232030U (en) | 2015-12-18 | 2015-12-18 | Input undervoltage protection circuit and switching power supply |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201521071589.0U CN205232030U (en) | 2015-12-18 | 2015-12-18 | Input undervoltage protection circuit and switching power supply |
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| CN205232030U true CN205232030U (en) | 2016-05-11 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105406721A (en) * | 2015-12-18 | 2016-03-16 | 深圳市赢新光电发展有限公司 | Input under-voltage protection circuit and switching power supply |
| CN110416973A (en) * | 2019-07-25 | 2019-11-05 | 珠海格力电器股份有限公司 | Motor overvoltages protect circuit, under-voltage protecting circuit, voltage protection circuit and motor |
-
2015
- 2015-12-18 CN CN201521071589.0U patent/CN205232030U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105406721A (en) * | 2015-12-18 | 2016-03-16 | 深圳市赢新光电发展有限公司 | Input under-voltage protection circuit and switching power supply |
| CN110416973A (en) * | 2019-07-25 | 2019-11-05 | 珠海格力电器股份有限公司 | Motor overvoltages protect circuit, under-voltage protecting circuit, voltage protection circuit and motor |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
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Effective date of registration: 20170527 Address after: 518000 Guangdong city of Shenzhen province Nanshan District West Road No. 1061 white Rayson Patentee after: Shenzhen Moso Power Electronics Technology Co., Ltd. Address before: 518000, Shiyan City, Guangdong, Baoan District Province, on the north side of the high-speed overpass, on the west side of the highway, the 2 floor of the 6 floor, the east side of the building on the east side of Shenzhen Patentee before: Wintek Electronics Technology Limited |