CN207490788U - A kind of single-end flyback switching power supply circuit - Google Patents
A kind of single-end flyback switching power supply circuit Download PDFInfo
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- CN207490788U CN207490788U CN201720980632.8U CN201720980632U CN207490788U CN 207490788 U CN207490788 U CN 207490788U CN 201720980632 U CN201720980632 U CN 201720980632U CN 207490788 U CN207490788 U CN 207490788U
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Abstract
The utility model provides a kind of single-end flyback switching power supply circuit, belongs to, field of switch power, including start-up circuit, overcurrent-overvoltage under-voltage protecting circuit, feedback circuit and rectification circuit；The output port of the rectified circuit of output terminal of the start-up circuit is the current output terminal mouth of Switching Power Supply; the output terminal of the overcurrent-overvoltage under-voltage protecting circuit is connect respectively with start-up circuit and rectification circuit; the input terminal of the feedback circuit is connect with rectification circuit, and output terminal is connect with start-up circuit.Start-up circuit includes starting control sub-circuit and activation member sub-circuit, and activation member sub-circuit is connect with starting control sub-circuit, starts control sub-circuit and is connect respectively with overcurrent-overvoltage under-voltage protecting circuit, feedback circuit and rectification circuit.The advantages of there is the utility model output to stablize, and control accuracy is high.
Description
Technical field
The utility model is related to field of switch power, more particularly to a kind of single-end flyback switching power supply circuit.
Background technology
Supply unit is a key areas of power technology application, and wherein high frequency switch type D.C. regulated power supply is due to tool
High efficiency, it is small and light-weight outstanding advantages of, have been widely used.The control circuit of Switching Power Supply can be divided into
Voltage-controlled type and current-control type, voltage-controlled type are a single closed loop voltage control systems, and system low-response is extremely difficult to
Higher LFM signal rate precision.
In order to further adapt to the demand of society, Switching Power Supply is enabled to more to stablize, leads to and improves adjustment
Progress needs to design a kind of novel switching power circuit.
Utility model content
The utility model provides a kind of output supply voltage and stablizes, and the high switching power circuit of control progress solves existing
The problem of switching power circuit is unstable and controls progress not high.
The utility model solves the above problems by the following technical programs：
A kind of single-end flyback switching power supply circuit, including start-up circuit, overcurrent-overvoltage under-voltage protecting circuit, feedback circuit
And rectification circuit；The output port of the rectified circuit of output terminal of the start-up circuit is the current output terminal mouth of Switching Power Supply,
The output terminal of the overcurrent-overvoltage under-voltage protecting circuit is connect respectively with start-up circuit and rectification circuit, the feedback circuit it is defeated
Enter end to connect with rectification circuit, output terminal is connect with start-up circuit；
The start-up circuit includes starting control sub-circuit and activation member sub-circuit, and activation member sub-circuit is controlled with starting
System circuit connects, and starts control sub-circuit and is connect respectively with overcurrent-overvoltage under-voltage protecting circuit, feedback circuit and rectification circuit；
The control sub-circuit that starts compares including error amplifier, attenuator, reference power supply, oscillator, over-current detection
Device, PWM latch, undervoltage lockout circuit and gate circuit output stage；Reference power supply is connect with attenuator, the output terminal of attenuator with
Error amplifier electrode input end connects；The output terminal of error amplifier leads the negative of another attenuator and over-current detection comparator
Pole connects；The output terminal of oscillator and over-current detection comparator is connect with PWM latch；PWM latch and undervoltage lockout circuit
AND gate circuit output stage practices grade.
In said program, preferably activation member sub-circuit includes capacitance C1, C2, C13, C14, C15, C16, inductance L1
With the bridge rectifier ring of diode D1~D4 compositions, capacitance C16 is connected in parallel on power input, and power supply is through inductance L1 and capacitance C15
It is connected in parallel, capacitance C13 is arranged in series with capacitance C14 and capacitance C15 is connected；The connecting pin of capacitance C13 and capacitance C14 be grounded and
It is connect with bridge rectifier ring, bridge rectifier ring is connect respectively with capacitance C1 and capacitance C2 one end, and capacitance C1 and capacitance C2 are another
End is grounded.
In said program, preferably overcurrent-overvoltage under-voltage protecting circuit includes resistance R8, R9, R10, capacitance C9, two poles
Pipe D9 and mos pipe S1, resistance R9 one end are grounded, and source electrode of the other end respectively with resistance R10 one end and mos pipes S1 is connect, capacitance
C9 one end is connect with the resistance R10 other ends, the other end ground connection, mos pipe S1 grids respectively with the input terminal and resistance of diode D9
R8 one end connects, and the resistance R8 other ends are connect with the output terminal of diode D9.
In said program, preferably feedback circuit includes regulator circuit and photoelectric coupled circuit, and the regulator circuit is through optocoupler
Circuit is connect with starting control sub-circuit, and regulator circuit is connect with rectification circuit.
The advantages of the utility model is with effect：
The voltage and current situation of rectification circuit is specifically fed back to start-up circuit by feedback circuit by the utility model,
Start-up circuit controls start-up circuit according to feedback circuit feedback voltage and electric current, so as to be controlled to electric current and voltage
System improves control progress；Due to having Voltage loop, electric current loop bicyclic system in structure, no matter the voltage of Switching Power Supply adjusts
Rate, load regulation and transient response characteristic are all improved, and are that more satisfactory novel controller closes.
Description of the drawings
Fig. 1 is the structure diagram of specific embodiment of the present invention.
Fig. 2 is the schematic diagram of specific embodiment of the present invention.
Specific embodiment
The utility model is described in further detail with reference to embodiments.
A kind of single-end flyback switching power supply circuit is as shown in Figs. 1-2, electric including start-up circuit, overcurrent-overvoltage under-voltage protection
Road, feedback circuit and rectification circuit；The output port of the rectified circuit of output terminal of the start-up circuit is the electricity of Switching Power Supply
Output port is flowed, the output terminal of the overcurrent-overvoltage under-voltage protecting circuit is connect respectively with start-up circuit and rectification circuit, described
The input terminal of feedback circuit is connect with rectification circuit, and output terminal is connect with start-up circuit.
The start-up circuit includes starting control sub-circuit and activation member sub-circuit, and activation member sub-circuit is controlled with starting
System circuit connects, and starts control sub-circuit and is connect respectively with overcurrent-overvoltage under-voltage protecting circuit, feedback circuit and rectification circuit.
The control sub-circuit that starts compares including error amplifier, attenuator, reference power supply, oscillator, over-current detection
Device, PWM latch, undervoltage lockout circuit and gate circuit output stage；Reference power supply is connect with attenuator, the output terminal of attenuator with
Error amplifier electrode input end connects；The output terminal of error amplifier leads the negative of another attenuator and over-current detection comparator
Pole connects；The output terminal of oscillator and over-current detection comparator is connect with PWM latch；PWM latch and undervoltage lockout circuit
AND gate circuit output stage practices grade.
Start-up circuit alternating current as shown in Figure 2 by C16, L1, C15 and C14, C13 carry out low-pass filtering, wherein C16,
C15 forms anti-series mode interference circuit, for inhibiting normal noise；C14, C13, L1 form anti-common mode interference circuit, for inhibiting
Common-mode noise is interfered.Combination thereof, which is applied, is acted on electromagnetic interference by very strong attenuation bypass.Filtered alternating voltage warp
Become the pulsating dc voltage of 3lOV after D1~D4 bridge rectifiers and electrolytic capacitor C1, C2 filtering, this voltage is after R1 is depressured
C8 chargings are given, when the voltage of C8 reaches the startup voltage threshold value of UC3842, UC3842 starts to work and provides driving pulse,
The work of pull switch pipe is exported by foot 6.With the startup of UC3842, the work of R1 also just terminates substantially, and remaining task is given
Feedback winding generates voltage by feedback winding and powers to UC3842.Since input voltage has been more than the work of UC3842, in order to keep away
Exempt from accident, the input voltage of UC3842 is limited with D10 voltage-stabiliser tubes, the impaired situations of UC3842 otherwise will occur.
Overcurrent-overvoltage under-voltage protecting circuit is unstable or some other external due to input voltage as shown in Figure 2
Factor, sometimes result in circuit occur it is short-circuit, over-pressed, under-voltage etc. be unfavorable for the phenomenon that circuit works, therefore, circuit is necessary
With certain defencive function.If as shown in Fig. 2, for some reason, export terminal shortcircuit and generate overcurrent, the leakage of switching tube
Electrode current will significantly rise, and the voltage at R9 both ends rises, and the voltage on the foot 3 of UC3842 also rises.When the voltage of the foot surpasses
When crossing normal value 0.3V and reaching 1V (i.e. electric current be more than 1.5A), the PWM comparators output high level of UC3842 makes PWM latch
It resets, closes output.At this moment, the foot 6 of UC3842 is without output, metal-oxide-semiconductor S1 cut-offs, so as to protect circuit.If supply voltage
Over-pressed (in more than 265V) occurs, UC3842 can not adjust duty ratio, and the primary winding voltage of transformer greatly improves, UC3842
7 supply voltage of foot also steeply rise, the voltage of foot 2 also rises, close output.If the voltage of power grid is less than 85V,
1 voltage of foot of UC3842 also declines, and when declining lV (normal value is 3.4V) below, PWM comparators output high level makes PWM
Latch reset closes output.If artificially will unexpectedly export terminal shortcircuit, at this moment output current will increase exponentially so that from
The dynamic heat restored inside switch RF increases sharply, its disconnecting circuit immediately plays the role of overvoltage protection.Once troubleshooting, automatically
Restore switch RF fast quick-recovery impedances within 5s.Therefore, this circuit has short circuit overcurrent, overvoltage, under-voltage triple protection.
Feedback circuit is as shown in Fig. 2, feedback circuit uses precision voltage regulator TL431 and linear PC817.It can using TL43l
Mode precision voltage-stablizer forms error voltage amplifier, then output is accurately adjusted by linear optical coupling.Such as Fig. 2 institutes
Show, R4, R5 are the external control resistance of precision voltage regulator, they determine that the height of output voltage and TL431 form outside together
Error amplifier.When output voltage increases, sampling voltage VR7 is also increased, and setting voltage is more than reference voltage (TL431
Reference voltage be 2.5V), make the output voltage raising of error amplifier in TL431, cause the output voltage driven in piece
It reduces, also declines output voltage Vo, last Vo tends towards stability；Conversely, output voltage decline causes setting voltage to decline, when defeated
When going out voltage less than setting voltage, the output voltage of error amplifier declines, the output voltage raising of the driving triode in piece,
Finally so that the compensation input current of the foot 1 of UC3842 changes therewith, promote that PWM comparators are adjusted in piece, change accounts for
Empty ratio, achievees the purpose that voltage stabilizing.The resistance value of R7, R8 calculate in this way：The resistance value of R7 is first fixed, then calculates the resistance value of R8.
Rectification circuit influences output electricity as shown in Fig. 2, output rectifier and filter directly influences the size of ripple voltage
The performance of pressure.Influence in switched power output to ripple amplitude mainly has the following aspects.Mainly pass through resistance R3, electricity
Hold C4 and diode D6, D7 realize rectification.
(1) noise of input power refers to alternating component included in input power.The scheme of solution is defeated in power supply
Enter end power-up and hold C5, to filter out this noise jamming.
(2) high-frequency signal noise inputs direct current in Switching Power Supply the copped wave for carrying out high frequency, then passes through the transformation of high frequency
Device is transmitted, and in this process, will necessarily mix the noise jamming of people's high frequency.Also power tube device is during switch
Caused high-frequency noise.Solution for this kind of high-frequency noise be output terminal using π types filtering by the way of.Filter inductance
Using the inductance of 150 μ H, high-frequency noise can be filtered out.
(3) fast quick-recovery D6, D7 rectification is used.The characteristics of based on low pressure, low in energy consumption, high current, is conducive to improve power supply
Efficiency, reverse recovery time is short, advantageously reduces high-frequency noise.
Rectifier diode in parallel reduces peak voltage in powerful rectification circuit, and there are larger for secondary commutation bridge circuit
Stray inductance, output rectifying tube is in the change of current, since, there are unwanted oscillation, rectifying tube can bear larger spike electricity in circuit
Pressure, the presence of peak voltage improve the resistance to pressure request to rectifier diode, will also bring additional circuit loss.Rectifier bridge
Unwanted oscillation results from the leakage inductance (or additional resonant inductance) of transformer and the knot of the winding capacitance of transformer and rectifying tube electricity
Between appearance.
When secondary voltage is zero, 4 diodes all turn in full-bridge rectifier, and output inductor electric current is in
Natural freewheeling state.And when secondary voltage variation is high voltage Vin/K (K is transformer voltage ratio), there are two two in rectifier bridge
Pole pipe will turn off, and two diodes continue to be connected.At this time the leakage inductance (or additional resonant inductance) of transformer begins to and closes
The capacitor resonance of disconnected rectifier diode.Even if using diode can still bear the peak voltage of at least twice, therefore, must
This must be studied there are many document, be summed up 5 kinds of modes using effective buffer circuit：RC buffer circuits, RCD
Buffer circuit, active clamping buffer circuit, third winding add diode clamp buffer circuit, and primary side side adds diode clamp to delay
Rush circuit.Another reduction effective method of diode peak voltage is proposed herein：I.e. rectifier diode is in parallel.
The preferred embodiment created to the utility model above is illustrated, but the utility model is not limited to
Embodiment, those skilled in the art can also make various etc. under the premise of without prejudice to the utility model creative spirit
Same modification or replacement, these equivalent modifications or replacement are all contained in scope of the present application.
Claims (4)
1. a kind of single-end flyback switching power supply circuit, which is characterized in that including start-up circuit, overcurrent-overvoltage under-voltage protection electricity
Road, feedback circuit and rectification circuit；The output port of the rectified circuit of output terminal of the start-up circuit is the electricity of Switching Power Supply
Output port is flowed, the output terminal of the overcurrent-overvoltage under-voltage protecting circuit is connect respectively with start-up circuit and rectification circuit, described
The input terminal of feedback circuit is connect with rectification circuit, and output terminal is connect with start-up circuit；
The start-up circuit includes starting control sub-circuit and activation member sub-circuit, and activation member sub-circuit is with starting control
Circuit connects, and starts control sub-circuit and is connect respectively with overcurrent-overvoltage under-voltage protecting circuit, feedback circuit and rectification circuit；
It is described start control sub-circuit include error amplifier, attenuator, reference power supply, oscillator, over-current detection comparator,
PWM latch, undervoltage lockout circuit and gate circuit output stage；Reference power supply is connect with attenuator, the output terminal and mistake of attenuator
Poor amplifier anode input terminal connection；The output terminal of error amplifier leads the cathode of another attenuator and over-current detection comparator
Connection；The output terminal of oscillator and over-current detection comparator is connect with PWM latch；PWM latch and undervoltage lockout circuit with
Gate circuit output stage practices grade.
2. a kind of single-end flyback switching power supply circuit according to claim 1, it is characterised in that：Activation member
Circuit includes the bridge rectifier ring of capacitance C1, C2, C13, C14, C15, C16, inductance L1 and diode D1~D4 compositions, capacitance
C16 is connected in parallel on power input, and power supply is connected in parallel through inductance L1 and capacitance C15, capacitance C13 and capacitance C14 be arranged in series and
Capacitance C15 connections；The connecting pin of capacitance C13 and capacitance C14 be grounded and connect with bridge rectifier ring, bridge rectifier ring respectively with
Capacitance C1 is connected with capacitance C2 one end, and capacitance C1 and the capacitance C2 other ends are grounded.
3. a kind of single-end flyback switching power supply circuit according to claim 1, it is characterised in that：The overcurrent-overvoltage is owed
Voltage protection circuit includes resistance R8, R9, R10, capacitance C9, diode D9 and mos pipe S1, resistance R9 one end ground connection, the other end point
Source electrode not with resistance R10 one end and mos pipes S1 is connect, and capacitance C9 one end is connect with the resistance R10 other ends, other end ground connection,
Mos pipe S1 grids are connect respectively with the input terminal of diode D9 and resistance R8 one end, and the resistance R8 other ends are defeated with diode D9's
Outlet connects.
4. a kind of single-end flyback switching power supply circuit according to claim 1, it is characterised in that：The feedback circuit packet
Include regulator circuit and photoelectric coupled circuit, the regulator circuit is connect through photoelectric coupled circuit with starting control sub-circuit, regulator circuit with it is whole
Current circuit connects.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201720980632.8U CN207490788U (en) | 2017-08-08 | 2017-08-08 | A kind of single-end flyback switching power supply circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201720980632.8U CN207490788U (en) | 2017-08-08 | 2017-08-08 | A kind of single-end flyback switching power supply circuit |
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| Publication Number | Publication Date |
|---|---|
| CN207490788U true CN207490788U (en) | 2018-06-12 |
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| CN201720980632.8U Expired - Fee Related CN207490788U (en) | 2017-08-08 | 2017-08-08 | A kind of single-end flyback switching power supply circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107276436A (en) * | 2017-08-08 | 2017-10-20 | 广西南宁驰信电子科技有限公司 | A kind of single-end flyback switching power supply circuit |
-
2017
- 2017-08-08 CN CN201720980632.8U patent/CN207490788U/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107276436A (en) * | 2017-08-08 | 2017-10-20 | 广西南宁驰信电子科技有限公司 | A kind of single-end flyback switching power supply circuit |
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| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20180612 Termination date: 20210808 |
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| CF01 | Termination of patent right due to non-payment of annual fee |