CN209692617U - A kind of Switching Power Supply and its control circuit - Google Patents
A kind of Switching Power Supply and its control circuit Download PDFInfo
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- CN209692617U CN209692617U CN201920664454.7U CN201920664454U CN209692617U CN 209692617 U CN209692617 U CN 209692617U CN 201920664454 U CN201920664454 U CN 201920664454U CN 209692617 U CN209692617 U CN 209692617U
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- power supply
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- switching power
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Abstract
The utility model discloses a kind of Switching Power Supply and its control circuits, including control chip U5, transformer T3, power tube Q3, rectification filtering module, current detection module, oscillation module and feedback module；The switching power source control circuit further includes division module, and the division module connects the rectification filtering module and ground terminal, and the voltage after rectifying and wave-filtering provides feedback voltage after division module divides, to control the feedback voltage input terminal of chip U5；Control circuit provided by the utility model between the feedback voltage input terminal and DC power supply feeder ear of control chip by increasing a zener diode D4, both it ensure that between the DC power supply feeder ear and feedback voltage input terminal of control chip there is enough voltage differences, the control sensitivity of control chip is improved again, and circuit is simple, at low cost, the speed of response is high.
Description
Technical field
The utility model relates to switch power technology field, in particular to a kind of Switching Power Supply and its control circuit.
Background technique
Switching Power Supply has many advantages, such as small in size, light-weight, high conversion efficiency, using increasingly extensive.Switching Power Supply is logical
It often include switching device, energy-storage travelling wave tube and control circuit；Control circuit be used for output or (and) input sampled signal into
Row processing, according to the duty ratio of the signal intensity regulating switch device of output or input, to realize the stabilization of output.Control electricity
An important component of the road as Switching Power Supply, control precision and stability directly affect the lasting accuracy, total of power supply
Body efficiency and stability.
UC384X series control chip, including model have UC3842, UC3843, UC3844 and UC3845, be switch electricity
The current-control type pulse width modulating chip of the common function admirable in source；Referring to Fig. 1, drawing so that UC3842 controls chip as an example
Foot 2 is feedback voltage input terminal, the 2.5V reference voltage of the voltage of pin 2 and control chip interior error amplifier in-phase end into
Row relatively amplifies, and generates error signal；Pin 3 is current sense input, for acquiring the electricity for flowing through inductance or switching device
Stream.The signal of pin 2 and pin 3 has codetermined the duty ratio of the control square-wave signal of push-pull output end (pin 6) output, from
And the length of control switch device make-and-break time.Feedback voltage input terminal (pin 2) is controlled as outer loop voltag, and it is defeated to be responsible for detection
The variation of voltage out, UC3842 control chip and adjust output duty cycle, therefore, Yao Tigao base according to the voltage variety of pin 2
In the Adjustment precision of the Switching Power Supply of UC3842 control chip, it is necessary to improve feedback voltage input terminal (pin 2) peripheral circuit
Feedback sensitivity and response efficiency.
Fig. 1 is a kind of control circuit of existing Switching Power Supply based on UC3842 control chip, including control chip U1
With transformer T1；The power supply for controlling the DC power supply feeder ear (pin 7) of chip U1 is passed through by the auxiliary winding on transformer T1
It is provided after rectifying and wave-filtering, the power supply of DC power supply feeder ear inputs after resistance R1 and resistance R4 partial pressure as feedback voltage
Hold the power input of (pin 2)；When load voltage variation, the current potential of DC power supply feeder ear generates equidirectional variation, from
And the current potential of feedback voltage input terminal is caused to change proportionally, output side is controlled and adjusted through the error amplifier inside chip U1
The duty ratio of wave, stabilizes the output voltage.Although the control circuit circuit of this Switching Power Supply is simple, at low cost, fast response time,
But its precision is lower；When input voltage fluctuation or load voltage change, the voltage of DC power supply feeder ear also generates variation, if
The voltage variety of DC power supply feeder ear is, the voltage variety of feedback voltage input terminal is, then feed back
The voltage variety of voltage input end are as follows:
(1)
Smaller, the control sensitivity of chip U1 is weaker, and precision is poorer；If the voltage change of feedback voltage input terminal
Amount is less than the voltage change precision that chip U1 can be detected, then chip U1 will be unable to the duty ratio of adjustment switching device, causes whole
The characteristic of a power supply is deteriorated.
Further, another scheme of Fig. 2, including control chip U2, precision voltage source U3 and optocoupler U4, institute are please referred to
State the model UC3842, the model TL431 of precision voltage source, the model TLP521 of optocoupler of control chip U2；Due to using
Precision voltage source improves control precision, and input signal and output signal has been isolated as control reference voltage；But due to
Optocoupler is used, the speed of response is slower, limits the control circuit in the application of high switching frequency, and circuit is complicated, inconvenient
In debugging, product cost is high.
As it can be seen that the prior art could be improved and improve.
Utility model content
Place in view of above-mentioned deficiencies of the prior art, the purpose of this utility model is to provide a kind of Switching Power Supply and its controls
Circuit processed, compared with the control circuit of existing Switching Power Supply, the control of the control circuit of Switching Power Supply provided herein
Chip controls high sensitivity, the speed of response are fast, i.e. the potential change amount of the feedback voltage input terminal of control chip increases, in addition,
The control circuit circuit is simple, cost is relatively low.
In order to achieve the above object, the utility model takes following technical scheme:
A kind of control circuit of Switching Power Supply, including control chip U5, transformer T3, power tube Q3, rectification filtering module,
Current detection module, oscillation module and feedback module；The control circuit of the Switching Power Supply further includes division module, the partial pressure
Module connects the rectification filtering module and ground terminal, and the voltage after rectifying and wave-filtering is after division module divides, to control chip
The feedback voltage input terminal of U5 provides feedback voltage.
In the control circuit of the Switching Power Supply, the division module includes the first partial pressure unit, zener diode D4
With the second partial pressure unit, first partial pressure unit, zener diode D4 and the second partial pressure unit are for limiting control chip U5
Feedback voltage input terminal voltage value；One end connection rectification filtering module of first partial pressure unit is with control chip U5's
DC power supply feeder ear, the other end connect the cathode of zener diode D4, and the second partial pressure of anode connection of zener diode D4 is single
The other end of member, second partial pressure unit connects ground terminal；First partial pressure unit, the partial pressure of zener diode D4 and second
Unit has codetermined the voltage swing of the feedback voltage input terminal of control chip U5 and has controlled the control sensitivity of chip U5.
In the control circuit of the Switching Power Supply, the control chip U5 is the current-control type pulsewidth of UC384X series
Modulate chip.
In the control circuit of the Switching Power Supply, the resistance value of second partial pressure unit is greater than the resistance of the first partial pressure unit
Value.
The utility model also provides a kind of Switching Power Supply, including switching device and energy-storage travelling wave tube, further includes as described above
The control circuit of Switching Power Supply.
Beneficial effect
Compared with prior art, the utility model provides a kind of Switching Power Supply and its control circuit, by control core
Increase a zener diode between the feedback voltage input terminal and DC power supply feeder ear of piece, ensure that the direct current of control chip
There are enough voltage differences between power supply side and feedback voltage input terminal；When load voltage variation, feedback voltage control terminal
Voltage variety account for DC power supply feeder ear voltage variety ratio increase, that is, improve control chip control it is sensitive
Spend and optimize the power supply characteristic of Switching Power Supply；In addition, control circuit circuit provided by the utility model is simple, it is at low cost,
The speed of response is high.
Detailed description of the invention
Fig. 1 is the circuit diagram of the control circuit first embodiment of existing Switching Power Supply；
Fig. 2 is the circuit diagram of the control circuit second embodiment of existing Switching Power Supply；
Fig. 3 is the structural block diagram of control circuit provided by the utility model；
Fig. 4 is the circuit diagram of control circuit provided by the utility model.
Specific embodiment
The utility model provides a kind of Switching Power Supply and its control circuit, to make the purpose of this utility model, technical side
Case and effect are clearer, clear, are described in further detail as follows in conjunction with drawings and embodiments to the utility model.It should
Understand, specific embodiment described herein only to explain the utility model, is not used to limit the utility model.
In the description of the present invention, it should be understood that term " first ", " second " are used for description purposes only, and
It cannot be understood as indicating or implying relative importance or implicitly indicate the quantity of indicated technical characteristic.
Fig. 3 and Fig. 4 are please referred to, the control circuit of Switching Power Supply provided by the utility model includes control chip U5, becomes
Depressor T3, power tube Q3, rectification filtering module 4, current detection module 5, oscillation module 6 and feedback module 7；The Switching Power Supply
Control circuit further include division module 8, division module 8 connects rectification filtering module 4 and ground terminal, rectified filter module are whole
The DC power supply feeder ear and division module for flowing filtered voltage to control chip U5 provide voltage, and division module is to being provided
Voltage divided after, provide feedback voltage to control the feedback voltage input terminal of chip U5, feedback voltage input terminal institute is defeated
The voltage entered is compared with the reference voltage of error amplifier in-phase end, error voltage is generated, to control push-pull output end
The pulse width exported realizes the stabilization of output voltage.
In the present embodiment, the model UC3842 of the control chip U5;The model of the power tube Q3
2SK2654；For controlling chip U5, wherein pin 1 is the output end of error amplifier, and pin 2 is feedback voltage input terminal,
Pin 3 is current sense input, and pin 4 is timing end, and pin 5 is common, and pin 6 is push-pull output end；Pin 7 is
DC power supply feeder ear, pin 8 are benchmark voltage output end.
In addition, in the present embodiment, rectification filtering module includes diode D3 and electrolytic capacitor C7, rectification filtering module is used
After by circuit start, 3. and 4. provided voltage is rectified and is filtered transformer auxiliary winding, is provided just for control chip
Normal operating voltage；Current detection module includes resistance R16, and resistance detection module is for detecting electric current, and by electricity detected
Flow valuve is delivered to the current sense input (pin 3) of control chip, forms current feedback ring, further, since resistance R16 is concatenated
In the source electrode of power tube Q3, current foldback circuit is constituted, when the voltage on resistance R16 is more than 1V, control chip U5 stops defeated
Out, it is effectively protected power tube；Oscillation module includes resistance R14 and capacitor R9, and oscillation module determines determining for control chip
The frequency of oscillation of Shi Duan (pin 4) and reference voltage output end (pin 8), the maximum value of frequency of oscillation is up to 500KHz；Instead
Feedback module includes resistance R13 and capacitor C8, and feedback module is for improving gain and frequency characteristic.
Further, the division module includes the first partial pressure unit 81, zener diode D4 and the second partial pressure unit 82,
The feedback voltage that first partial pressure unit 81, zener diode D4 and the second partial pressure unit 82 are used to limit control chip U5 is defeated
Enter the voltage value at end；One end connection rectification filtering module of first partial pressure unit 81 and the DC power supply power supply for controlling chip U5
End, the other end connect the cathode of zener diode D4, and the anode of zener diode D4 connects one end of the second partial pressure unit 82, the
The other end of two partial pressure units 82 connects ground terminal；First partial pressure unit, zener diode D4 and the second partial pressure unit are total
With the control sensitivity of the voltage swing and control chip U5 of the feedback voltage input terminal for determining control chip U5.
Static drop is big when zener diode has work, the small feature of motional impedance, when load voltage variation, pressure stabilizing
Diode both ensure that be had between the DC power supply feeder ear (pin 7) and feedback voltage input terminal (pin 2) that control chip U5
Enough voltage differences in turn ensure that feedback voltage input terminal can get enough feedback signals；Referring to Fig. 4, in the present embodiment
In, burning voltage when zener diode D4 works is 15V.
Further, referring to Fig. 4, in the present embodiment, first partial pressure unit includes resistance R12, the resistance
The resistance value of R12 is 6.8K.
Further, referring to Fig. 4, in the present embodiment, second partial pressure unit includes resistance R15, the resistance
The resistance value of R15 is 36K.
Preferably, the control chip U5 is the current-control type pulse width modulating chip of UC384X series；UC384X series
Chip is the current-control type pulse width modulating chip of the common function admirable of Switching Power Supply.
Further, the resistance value of second partial pressure unit is greater than the resistance value of the first partial pressure unit.Due to zener diode
Pressure drop when D4 works may be up to 15V, and the resistance value ratio of the resistance value of the second partial pressure unit and the first partial pressure unit can be adjusted significantly
Whole, i.e. the potential change amount of feedback voltage input terminal (pin 2) accounts for the potential change amount ratio of DC power supply feeder ear (pin 7)
Increase, to improve the control sensitivity of control chip U5.
Referring to Fig. 4, in the present embodiment, the resistance value of resistance R12 is 6.8K, the resistance value of resistance R15 is 36K；If direct current
The voltage variety of power supply side (pin 7) is, the voltage variety of feedback voltage input terminal (pin 2) is, then the voltage variety of feedback voltage input terminal are as follows:
(2)
Compare the formula (1) mentioned in background technique, InWithUnder conditions of equal, in the present embodiment
The voltage variety of feedback voltage input terminalGreater than the voltage variety of feedback voltage input terminal in background technique, i.e. the control sensitivity raising of control chip U5, control chip U5 can be according to the potential change of DC power supply feeder ear
The quickly duty ratio of push-pull output end (pin 6) exported square wave of adjustment control chip U5, to realize the stabilization of voltage.
The utility model further correspondingly provides a kind of Switching Power Supply, including switching device, energy-storage travelling wave tube and above-mentioned is mentioned
And the control circuit of Switching Power Supply control that precision is high, and the speed of response is fast using the Switching Power Supply of above-mentioned control circuit.
It is understood that for those of ordinary skills, can with technical solution according to the present utility model and
The design of its utility model is subject to equivalent substitution or change, and all these replacements or change all should belong to appended by the utility model
Claims protection scope in.
Claims (5)
1. a kind of control circuit of Switching Power Supply, including control chip U5, transformer T3, power tube Q3, rectification filtering module, electricity
Flow detection module, oscillation module and feedback module, which is characterized in that further include division module, described in the division module connection
Rectification filtering module and ground terminal, the voltage after rectifying and wave-filtering is after division module divides, for the feedback voltage for controlling chip U5
Input terminal provides feedback voltage.
2. a kind of control circuit of Switching Power Supply according to claim 1, which is characterized in that the division module includes the
One partial pressure unit, zener diode D4 and the second partial pressure unit, first partial pressure unit, the partial pressure of zener diode D4 and second
Unit is used to limit the voltage value of the feedback voltage input terminal of control chip U5；One end of first partial pressure unit connects rectification
The DC power supply feeder ear of filter module and control chip U5, the other end connect the cathode of zener diode D4, zener diode
Anode the second partial pressure unit of connection of D4, the other end of second partial pressure unit connect ground terminal.
3. a kind of control circuit of Switching Power Supply according to claim 1, which is characterized in that the control chip U5 is
The current-control type pulse width modulating chip of UC384X series.
4. a kind of control circuit of Switching Power Supply according to claim 2, which is characterized in that second partial pressure unit
Resistance value is greater than the resistance value of the first partial pressure unit.
5. a kind of Switching Power Supply, including switching device and energy-storage travelling wave tube, which is characterized in that further include any one of claim 1-4
The control circuit of the Switching Power Supply.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920664454.7U CN209692617U (en) | 2019-05-10 | 2019-05-10 | A kind of Switching Power Supply and its control circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920664454.7U CN209692617U (en) | 2019-05-10 | 2019-05-10 | A kind of Switching Power Supply and its control circuit |
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| Publication Number | Publication Date |
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| CN209692617U true CN209692617U (en) | 2019-11-26 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110071642A (en) * | 2019-05-10 | 2019-07-30 | 佛山职业技术学院 | A kind of switching circuit and its control circuit, control method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110071642A (en) * | 2019-05-10 | 2019-07-30 | 佛山职业技术学院 | A kind of switching circuit and its control circuit, control method |
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