CN109818493A - A kind of RCD absorbing circuit and switching power circuit - Google Patents
A kind of RCD absorbing circuit and switching power circuit Download PDFInfo
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- CN109818493A CN109818493A CN201910126780.7A CN201910126780A CN109818493A CN 109818493 A CN109818493 A CN 109818493A CN 201910126780 A CN201910126780 A CN 201910126780A CN 109818493 A CN109818493 A CN 109818493A
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Abstract
It includes: peak voltage input terminal, power connector end, RC series arm, first resistor, first diode and the second diode that the present invention, which discloses a kind of RCD absorbing circuit and switching power circuit, RCD absorbing circuit,；Power connector end connects the first end of RC series arm and the first end of first resistor, the second end of the second end connection first resistor of RC series arm and the cathode of the first diode；The anode of first diode connects the peak voltage input terminal；RC series arm includes: first capacitor and second resistance, and first capacitor and second resistance are connected in series；The first end of the cathode connection second resistance of second diode, the second end of the anode connection second resistance of the second diode.Resistance power consumption and temperature rise can be reduced in RCD absorbing circuit when absorption diode short circuit, so that circuit be avoided to damage and cause dangerous possibility, guarantee the safety of entire RCD circuit.
Description
Technical field
The present invention designs electronic technology field more particularly to a kind of RCD absorbing circuit and switching power circuit.
Background technique
In switching power circuit, in order to avoid switching tube produces in switching process since transformer leakage inductance and capacitor shake
Raw due to voltage spikes and lead to component wear, it will usually a RCD absorbing circuit is added, for absorbing big due to voltage spikes, with
Protective switch pipe.
Existing RCD absorbing circuit is as shown in Figure 1, when switching tube S1 cut-off, the energy that is accumulated in parasitic inductance L1
It is charged by the parasitic capacitance of switching tube S1, increase the voltage of switching tube S1, when its voltage rises to a certain extent, inhaled
Diode D1 conducting is received, the energy accumulated in parasitic inductance L1 also charges to Absorption Capacitance C1；When switching tube S1 conducting, absorb
Capacitor C1 passes through the conductive discharge in circuit.Wherein, resistance R2 can be used for reducing electromagnetic interference.
However, inventor application above-mentioned RCD absorbing circuit during, discovery the prior art at least exist it is following not
Foot: when carrying out the test of safety safety to RCD absorbing circuit, short-circuit absorption diode D1 will lead to the electric current for flowing through resistance R2
It is very big, it will usually more than resistance R2 can tolerance range, therefore the power consumption of resistance R2 is excessive, and temperature will be increased significantly, be discontented with
Sufficient safety standard, or even have risk on fire.
Summary of the invention
The present invention provides a kind of RCD absorbing circuit and switching power circuits, to solve in switching power circuit
When RCD carries out safety test, the temperature rise of resistance is excessively high, circuit is easily caused to damage and cause dangerous problem, and realizing reduces resistance
Power consumption and temperature rise, guarantee test safety.
In a first aspect, the present invention provides a kind of RCD absorbing circuits, comprising: peak voltage input terminal, power connector end,
RC series arm, first resistor, first diode and the second diode；
The power connector end connects the first end of the RC series arm and the first end of the first resistor, described
The second end of RC series arm connects the second end of the first resistor and the cathode of the first diode；Described 1st
The anode of pole pipe connects the peak voltage input terminal；
The RC series arm includes: first capacitor and second resistance, and the first capacitor and the second resistance are connected
Connection；
The cathode of second diode connects the first end of the second resistance, the anode connection of second diode
The second end of the second resistance, wherein the second end of the second resistance is that peak voltage inputs the one of the second resistance
End.
Further, the first end of the second resistance is the first end of the RC series arm, the second resistance
Second end connects the first end of the first capacitor, and the second end of the first capacitor is the second end of the RC series arm.
Further, the RC series arm further includes 3rd resistor；
The 3rd resistor is in parallel with the second resistance.
Further, the first end of the first capacitor is the first end of the RC series arm, the first capacitor
Second end connects the first end of the second resistance, and the second end of the second resistance is the second end of the RC series arm.
Further, the RC series arm further includes the 4th resistance；
4th resistance is in parallel with the second resistance.
Further, the first diode is fast recovery diode or supper-fast recovery diode.
Further, the conduction voltage drop of second diode is 0.7V.
Second aspect, the present invention also provides a kind of switching power circuits, comprising: voltage input end, is opened power control circuit
Guan Guan, transformer, over-current detection circuit and above-mentioned RCD absorbing circuit；
The voltage input end, respectively with the power connector end of the RCD absorbing circuit, the transformer it is first primary
Winding connecting pin is connected；
The peak voltage input terminal of the RCD absorbing circuit, respectively with the drain electrode of the switching tube, the transformer second
Armature winding connecting pin is connected；
The grid of the switching tube is connected with the power control terminal of the power control circuit；
The first end of the over-current detection circuit is connected with the source electrode of the switching tube, second end ground connection.
Further, the switching power circuit further include: electromagnetic interference EMI and current rectifying and wave filtering circuit, flyback sourse master
Loop of power circuit and feedback control loop；
The first end of the EMI and current rectifying and wave filtering circuit is connected across between zero curve and firewire, the EMI and rectifying and wave-filtering electricity
The second end on road is connected with the power connector end of the RCD absorbing circuit, for filtering difference mode signal and by the alternating current of input
Be converted to Rectified alternating current；
The voltage input end of the main loop of power circuit of flyback sourse is connected with the voltage output end of the power control circuit,
The voltage output end of the main loop of power circuit of flyback sourse is grounded after being connected with load, for powering to the load；
The external circuit that the feedback control loop passes through the photoelectric coupling triode and the power control circuit that include compensates
End connection regulates and controls the power control circuit output constant voltage.
The embodiment of the invention provides a kind of RCD absorbing circuit and switching power circuits, by RCD absorbing circuit
The both ends of second resistance the second diode in parallel, the cathode of second diode connect the first end of the second resistance, institute
The anode for stating the second diode connects the second end of the second resistance, wherein the second end of the second resistance is spike electricity
Pressure inputs one end of the second resistance, generates when can be to avoid absorption diode short circuit in RCD absorbing circuit, realizing reduces
The power consumption and temperature rise of resistance ensure that the safety of entire RCD circuit so that circuit be avoided to damage and cause dangerous possibility.
Detailed description of the invention
Fig. 1 is the schematic diagram of RCD absorbing circuit in the prior art；
Fig. 2 is a kind of schematic diagram for RCD absorbing circuit that the embodiment of the present invention one provides；
Fig. 3 is a kind of another schematic diagram for RCD absorbing circuit that the embodiment of the present invention one provides；
Fig. 4 is a kind of another schematic diagram for RCD absorbing circuit that the embodiment of the present invention one provides；
Fig. 5 is a kind of another schematic diagram for RCD absorbing circuit that the embodiment of the present invention one provides；
Fig. 6 is a kind of structural schematic diagram of switching power circuit provided by Embodiment 2 of the present invention；
Fig. 7 is a kind of EMI of switching power circuit provided by Embodiment 2 of the present invention and the structure of current rectifying and wave filtering circuit is shown
It is intended to；
Fig. 8 is that a kind of structure of the main loop of power circuit of the flyback sourse of switching power circuit provided by Embodiment 2 of the present invention is shown
It is intended to；
Fig. 9 is a kind of structural schematic diagram of the feedback control loop of switching power circuit provided by Embodiment 2 of the present invention.
Specific embodiment
The present invention is described in further detail with reference to the accompanying drawings and examples.It is understood that this place is retouched
The specific embodiment stated is used only for explaining the present invention rather than limiting the invention.It also should be noted that in order to just
Only the parts related to the present invention are shown in description, attached drawing rather than entire infrastructure.
Embodiment one
It should be noted that usually needing to carry out safety test, the purpose is to pass through before circuit product launch
Artificially perhaps open circuit predicts product during the work time just in case short circuit occurs or opens a way to will appear to manufacture shorted devices in advance
What consequence, such as catching fire, specifically, circuit board usually have fixed temperature specification, if the Current Temperatures of circuit board
More than temperature specification, i.e., power consumption is excessive causes temperature rise excessively high, is unsatisfactory for safety standard, it is likely that the wind of carbonization burning occurs
Danger.
Fig. 2 is the schematic diagram for the RCD absorbing circuit 100 that the embodiment of the present invention one provides.As shown in Fig. 2, the RCD absorbs electricity
Road 100 includes: peak voltage input terminal V1, power connector end V2, RC series arm 101, first resistor R1, first diode D1
With the second diode D2；
The first end (not shown) of power connector end V2 connection RC series arm 101 and the first end of first resistor R1
(not shown), the second end (not shown) and first of the second end (not shown) connection first resistor R1 of RC series arm 101
The cathode of diode D1；The anode of first diode D1 connects peak voltage input terminal V1；
RC series arm 101 includes: first capacitor C1 and second resistance R2, the first capacitor C1 and second resistance R2 string
Connection connection；
The first end (not shown) of the cathode connection second resistance R2 of second diode D2, the anode of the second diode D2 connect
Connect the second end (not shown) of second resistance R2, wherein the second end of second resistance R2 is that peak voltage inputs second resistance R2
One end.
Specifically, peak voltage input terminal V1 is used to connect the device in circuit there are peak voltage, power connector end V2
For accessing power supply signal.For example, when RCD absorbing circuit 100 provided by the present embodiment is applied to switching power circuit,
Drain electrode of the peak voltage input terminal V1 for the switching tube in connection switch power circuit 200, power connector end V2 is for connecting
The voltage input end of switching power circuit 200 is connect, i.e. access bus power supply signal.In switching power circuit, when switching tube is led
When logical, primary side magnetizing inductance and leakage inductance energy storage, when switching tube shutdown, magnetizing inductance energy transmission is to pair side, and in leakage inductance
Energy can not be transmitted to secondary side, can be superimposed upon switching tube together with input voltage, secondary side refraction voltage in the form of peak voltage
Drain electrode, there are the danger of breakdown.It can reach the purpose for inhibiting peak voltage by using RCD absorbing circuit 100.Specifically,
When the switching tube cut-off in switching power circuit, the voltage reversal of transformer, the in RCD absorbing circuit 100
One diode D1 conducting, leakage inductance release energy and directly charge to the first capacitor C1 in RC series arm 101, first capacitor
The voltage of C1 rises rapidly, and when switching tube conducting, first diode D1 cut-off, first capacitor C1 is carried out by first resistor R1
Electric discharge, inhibits the due to voltage spikes of switching tube with this.
In RC series arm, the second diode D2 is connected in parallel on the both ends of second resistance R2, and the yin of the second diode D2
Pole connects second resistance R2 close to one end of power connector end V2, the anode connection peak voltage input second of the second diode D2
One end of resistance R2.Second diode D2 is for protecting second resistance R2, to reduce the power consumption of second resistance R2 and 3rd resistor,
Solve its problem of temperature rise generated in first diode short circuit.
Further, the first end of second resistance R2 is the first end of RC series arm 101, the second end of second resistance R2
The first end of first capacitor C1 is connected, the second end of first capacitor C1 is the second end of RC series arm 101.
Specifically, peak voltage inputs direction when RC series arm 101 with reference to Fig. 2 are as follows: first capacitor C1 is first passed through,
Using second resistance R2.Wherein, second resistance R2 is used to reduce by the first electricity when switching tube cut-off, first capacitor C1 charging
The dI/dt for holding C1, to reduce the electromagnetic interference (Electromagnetic Interference, EMI) of circuit；First capacitor
C1 is used to absorb the energy of peak voltage；First resistor R1 is used for when closing pipe conducting, the energy that release first capacitor C1 is absorbed
Amount.
RCD absorbing circuit 100 provided in this embodiment solves the working principle that second resistance R2 power consumption is excessive, temperature rise is excessively high
It is as follows:
When short circuit occurs for first diode D1, the second diode D2 forward conduction is unidirectionally led using the second diode D2
Characteristic (such as: when one-way conduction pressure drop is 0.7V) is fixed in logical pressure drop, limits the both ends second resistance R2 during switching tube shutdown
Voltage, to solve power consumption and problem of temperature rise.
Specifically, can be illustrated by following calculated examples to above-mentioned working principle:
Assuming that the resistance value of second resistance R2 is 10 Ω, the voltage of peak voltage input terminal V1 (switching tube drain electrode) is 600V,
The voltage of power connector end V2 is 380V, and the voltage through actual test first capacitor C1 is 120V, I1And I2Respectively switching tube turns off
With the electric current for flowing through second resistance R2 when conducting.Before not connected second diode D2 (such as Fig. 1), second resistance R2 is in switching tube
Power consumption when shutdown isIt is switching off and on the total power consumption of periodAnd after the second diode D2 of increase protects second resistance R2,
Second resistance R2 switching tube turn off when power consumption beThis power consumption very little, substantially may be used
It ignores, the total power consumption during switching off and on isBy
This is as it can be seen that increase after the second diode D2 protects second resistance R2, when short-circuit first diode D1 carries out safety survey
When examination, the power consumption of second resistance R2 can be greatly lowered, flow through the electric current very little of second resistance R2, asked to solve temperature rise
Topic protects circuit element, while guaranteeing the safety of test.
It should be noted that, due to the one-way conduction characteristic of the second diode D2, only being opened when carrying out safety test
When pass pipe disconnects, the voltage of peak voltage input terminal V1 is higher than the voltage of power connector end V2, the second diode D2 is just connected；When
When switching tube is connected, the second diode D2 is the state disconnected, therefore will not influence RCD absorbing circuit 100 and Switching Power Supply
The normal work on road.
A kind of RCD absorbing circuit 100 is present embodiments provided, by the both ends of second resistance R2 the second diode in parallel
The cathode of D2, the second diode D2 connect the first end of the second resistance R2, and the anode of the second diode D2 connects
Connect the second end of the second resistance R2, wherein the second end of the second resistance R2 is peak voltage input second electricity
The one end for hindering R2, may be implemented to drop low-resistance power consumption and temperature rise, guarantee the safety of test.
Fig. 3 is another schematic diagram for the RCD absorbing circuit 100 that the embodiment of the present invention one provides.Embodiment shown in Fig. 2
On the basis of, the RC series arm 101 in RCD absorbing circuit 100 provided by the present embodiment further include: 3rd resistor R3；
3rd resistor R3 is in parallel with second resistance R2.
Specifically, as shown in figure 3,3rd resistor R3 is in parallel with second resistance R2, all in first capacitor C1 charging,
The dI/dt of first capacitor C1 is reduced, to reduce the EMI interference of circuit；First capacitor C1 is used to absorb the energy of peak voltage.
In addition, by the 3rd resistor R3 power consumption that further decreases resistance in parallel with second resistance R2.Peak voltage inputs RC series connection branch
Direction when road 101 are as follows: first capacitor C1 is first passed through, using second resistance R2 and 3rd resistor R3.Second diode D2 is used
In protection second resistance R2 and 3rd resistor R3.
Fig. 4 is another schematic diagram for the RCD absorbing circuit 100 that the embodiment of the present invention one provides.As shown in figure 4, described
The first end of one capacitor C1 is the first end of the RC series arm 101, the second end connection described the of the first capacitor C1
The first end of two resistance R2, the second end of the second resistance R2 are the second end of the RC series arm 101.
Specifically, direction when peak voltage inputs RC series arm 101 are as follows: second resistance R2 is first passed through, using the
One capacitor C1.Second diode D2 is for protecting second resistance R2.
Fig. 5 is another schematic diagram for the RCD absorbing circuit 100 that the embodiment of the present invention one provides.Embodiment shown in Fig. 4
On the basis of, the RC series arm 101 in RCD absorbing circuit 100 provided by the present embodiment further include: the 4th resistance R4；
The 4th resistance R4 is in parallel with the second resistance R2.
Specifically, as shown in figure 5, the 4th resistance R4 is in parallel with second resistance R2, it is all anti-for reducing first diode D1
To the current spike generated when restoring, first capacitor C1 is for consuming peak voltage, to reduce the EMI interference of circuit.Also,
By the 4th resistance R4 power consumption that further decreases resistance in parallel with second resistance R2.Peak voltage inputs RC series arm 101
When direction are as follows: second resistance R2 and the 4th resistance R4 are first passed through, using first capacitor C1.Second diode D2 is for protecting
Second resistance R2 and the 4th resistance R4.
Further, first diode D1 is fast recovery diode or supper-fast recovery diode.
Fast recovery diode or supper-fast recovery diode have preferable switching characteristic, belong to PIN junction type diode,
Because base area is very thin, reverse recovery charge very little, so recovery time is shorter, forward voltage drop is lower, breakdown reverse voltage (pressure resistance
Value) it is higher, therefore, using fast recovery diode or supper-fast recovery diode as first diode D1, it is ensured that circuit
Good switch performance and safety.
Further, the conduction voltage drop of the second diode D2 is that 0.7V makes to flow to limit the voltage at the both ends second resistance R2
Electric current very little through second resistance R2 protects circuit element to solve problem of temperature rise, while guaranteeing the safety of test.
A kind of RCD absorbing circuit provided in an embodiment of the present invention, passes through the both ends of the second resistance in RCD absorbing circuit
Second diode in parallel, the cathode of the second diode connect the first end of the second resistance, the anode connection of the second diode
The second end of second resistance, wherein the second end of second resistance is one end that peak voltage inputs second resistance, to limit second
The voltage at resistance both ends guarantees the safety of test to drop low-resistance power consumption and temperature rise.
Embodiment two
Fig. 6 is a kind of structural schematic diagram of switching power circuit 200 provided by Embodiment 2 of the present invention.The present embodiment is in reality
On the basis of applying example one, a kind of switching power circuit 200 is provided, which includes a kind of institute of embodiment
Any RCD absorbing circuit 100 provided, by adding the second diode D2 in RCD absorbing circuit 100 to protect second resistance
Low-resistance power consumption and temperature rise can drop in R2, convenient for carrying out safety test to switching power circuit, guarantee the safety of test.
As shown in fig. 6, switching power circuit 200 provided in this embodiment includes: voltage input end Vin, power supply control electricity
Any RCD absorbing circuit provided by road 230, switching tube QM, transformer TB1, over-current detection circuit 240 and above-described embodiment
100 (Fig. 6 only show with the embodiment in Fig. 3 for basis the case where)；
Voltage input end Vin respectively with the power connector end V2 of RCD absorbing circuit 100, transformer TB1 first it is primary around
Group connecting pin (not shown) is connected；
The voltage input end Vin peak voltage input terminal V1 of RCD absorbing circuit 100 (schemes with the drain electrode of switching tube QM respectively
Do not show), transformer TB1 the second armature winding connecting pin (not shown) be connected；
The grid (not shown) of switching tube QM is connected with the power control terminal (not shown) of power control circuit 230；
The first end (not shown) of over-current detection circuit 240 is connected with the source electrode (not shown) of the switching tube QM, and second
End ground connection.
Specifically, as shown in fig. 6, voltage input end Vin access bus power supply signal, respectively with RCD absorbing circuit 100
Power connector end V2, the first armature winding connecting pin of transformer TB1 are connected.Power control circuit 230 includes that power supply controls core
Piece and its peripheral circuit, are mainly used for the on and off of control switch pipe QM based on the feedback signal, and topological structure can have
Multiple choices are not specifically limited herein.It include sampling resistor R10 in over-current detection circuit 240, when the existing short circuit of output or overcurrent
The case where when, the primary current of transformer TB1 increases, and the pressure drop at the both ends R10 increases, and the pin of power supply control chip is caused to receive
To voltage increase, output duty cycle be gradually increased, increase to a certain extent when, power supply control chip close, no longer export, because
This plays the role of over-current detection and protection.In addition, transformer TB1, switching tube QM and over-current detection circuit 240 function and
Connection relationship between them is the prior art, is not added and repeats herein.
RCD absorbing circuit 100 plays the purpose for inhibiting peak voltage in switching power circuit 200.Specifically, when switch
When switching tube QM cut-off in power circuit 200, the voltage reversal of transformer TB1 primary coil, in RCD absorbing circuit 100
First diode D1 conducting, leakage inductance release energy and directly charge to first capacitor C1, when switching tube QM conducting, the one or two
Pole pipe D1 cut-off, first capacitor C1 are discharged by first resistor R1, inhibit the due to voltage spikes of switching tube QM with this.
A kind of switching power circuit 200 provided in an embodiment of the present invention, comprising: voltage input end Vin, power control circuit
230, switching tube QM, transformer TB1, over-current detection circuit 240 and RCD absorbing circuit 100；By in RCD absorbing circuit 100
In add the second diode D2, and it is it is in parallel with second resistance R2, when first diode D1 short circuit, switching tube QM shutdown,
Second diode D2 conducting, to drop low-resistance power consumption and temperature rise, protects circuit to limit the voltage at the both ends second resistance R2
Element guarantees the safety of test convenient for carrying out safety test to switching power circuit 200.
On the basis of the above embodiments, switching power circuit 200 further include: EMI and current rectifying and wave filtering circuit 230, flyback
The main loop of power circuit 240 of power supply and feedback control loop 250；
The first end (not shown) of EMI and current rectifying and wave filtering circuit is connected across between zero curve and firewire, EMI and rectifying and wave-filtering electricity
The second end (not shown) on road is connected with the power connector end V2 of RCD absorbing circuit 100, for filtering difference mode signal and will input
Alternating current be converted to Rectified alternating current.
The voltage input end (not shown) of the main loop of power circuit 240 of flyback sourse and the voltage output of power control circuit 230
Hold (not shown) to be connected, the voltage output end (not shown) of the main loop of power circuit of flyback sourse is grounded after being connected with load, be used for
Load supplying；
Feedback control loop 250 passes through the external circuit of the photoelectric coupling triode PC1 and the power control circuit 230 that include
The connection of compensating end (not shown), regulation power control circuit 230 export constant voltage.
Specifically, Fig. 7 is the EMI and rectifying and wave-filtering electricity of a kind of switching power circuit 200 provided by Embodiment 2 of the present invention
The structural schematic diagram on road 230.As shown in fig. 7, the first end of EMI and current rectifying and wave filtering circuit 230 be connected across zero curve N and firewire L it
Between, second end is connected with the power connector end V2 of RCD absorbing circuit 100, for filtering difference mode signal and by the alternating current of input
Be converted to Rectified alternating current.Wherein, EMI filter circuit essence is a LC low-pass filter, can make the low frequency of 50-400Hz
Signal passes through, and has inhibiting effect to high-frequency signal.EMI filter circuit is by common mode inductance TB2, the tenth capacitor C10, the 11st capacitor
C11 and the 12nd capacitor C12 composition.Wherein, the tenth capacitor C10 is connected across between zero curve N and firewire L, is carried out to difference mode signal
Filtering.Current rectifying and wave filtering circuit is made of tetra- diodes of D10-D13, and the alternating current for alternating current to be inputted becomes the direct current of pulsation
Electricity.Other topological structures in EMI and current rectifying and wave filtering circuit 230 are the prior art, and this embodiment is not repeated.
Fig. 8 is the structure of the main loop of power circuit 240 of flyback sourse of switching power circuit 200 provided by Embodiment 2 of the present invention
Schematic diagram.As shown in figure 8, the voltage of the voltage input end of the main loop of power circuit 240 of flyback sourse and the power control circuit 230
Output end (the VCC foot of power supply control chip) is connected, voltage output end and the load phase of the main loop of power circuit 230 of flyback sourse
It is grounded after even, for powering to the load.
Specifically, output rectifier diode D7 and output rectifier diode D8 reversely end when switching tube QM conducting, this
When there is no electricity to pass to transformer TB1 secondary end, therefore powered to the load by output capacitance C8.At this point, flowing through the electricity of inductance
Cleanliness increases, and transformer TB1 is equivalent to pure inductance.When switching tube QM shutdown, all winding voltages are reversed, rectify output
Diode D7 and output rectifier diode D8 enters on state, the energy transmission of transformer TB1 primary side storage to secondary end,
It is powered to the load by secondary end by C9.Other topological structures in the main loop of power circuit 240 of flyback sourse are the prior art, this
Embodiment repeats no more.
Fig. 9 is the structural schematic diagram of the feedback control loop 250 of switching power circuit 200 provided by Embodiment 2 of the present invention.Such as
Shown in Fig. 9, feedback control loop 250 passes through the external circuit of the photoelectric coupling triode PC1 and the power control circuit 230 that include
Compensating end (the COMP foot of power supply control chip) connection regulates and controls the power control circuit 230 and exports constant voltage.
Specifically, including voltage-stabiliser tube UB1 and photoelectric coupling triode PC1 in feedback control loop 250, output voltage passes through electricity
Resistance partial pressure, can be defeated using the isolation transmission characteristic of photoelectric coupling triode PC1 compared with the reference voltage that voltage-stabiliser tube UB1 is constituted
The fluctuation of voltage out, by the output error voltage compared with reference voltage, error voltage controls optocoupler diode PC2 (such as Fig. 6 institute
Show, connect the COMP foot in power supply control chip) electric current, will lead to the curent change of photoelectric coupling triode PC1.And photoelectricity coupling
Conjunction triode PC1 connects the pwm pulse width in the changeable output of COMP foot of controller by pull-up resistor R20, to reach
The purpose stabilized the output voltage.Other topological structures in feedback control loop 250 are the prior art, and this embodiment is not repeated.
A kind of switching power circuit provided in an embodiment of the present invention, comprising: voltage input end, power control circuit, switch
Pipe QM, transformer, over-current detection circuit, RCD absorbing circuit, EMI and the main loop of power circuit of current rectifying and wave filtering circuit, flyback sourse and
Feedback control loop；By adding the second diode in RCD absorbing circuit, and it is in parallel with second resistance, work as first diode
When short circuit, switching tube QM shutdown, the second diode current flow, to limit the voltage at second resistance both ends, to drop low-resistance function
Circuit element is protected in consumption and temperature rise, convenient for carrying out safety test to switching power circuit, guarantees the safety of test.
The above are the preferred embodiment of the present invention, it is noted that for those skilled in the art,
Without departing from the principle of the present invention, several improvement and deformations can also be made, these improvement and deformations are also considered as this hair
Bright protection scope.
Claims (9)
1. a kind of RCD absorbing circuit characterized by comprising peak voltage input terminal, power connector end, RC series arm,
One resistance, first diode and the second diode；
The power connector end connects the first end of the RC series arm and the first end of the first resistor, the RC string
The second end of connection branch connects the second end of the first resistor and the cathode of the first diode；The first diode
Anode connect the peak voltage input terminal；
The RC series arm includes: first capacitor and second resistance, and the first capacitor and the second resistance are connected in series；
The cathode of second diode connects the first end of the second resistance, described in the anode connection of second diode
The second end of second resistance, wherein the second end of the second resistance is one end that peak voltage inputs the second resistance.
2. RCD absorbing circuit according to claim 1, which is characterized in that the first end of the second resistance is the RC
The first end of series arm, the second end of the second resistance connect the first end of the first capacitor, the first capacitor
Second end is the second end of the RC series arm.
3. RCD absorbing circuit according to claim 2, which is characterized in that the RC series arm further includes 3rd resistor；
The 3rd resistor is in parallel with the second resistance.
4. RCD absorbing circuit according to claim 1, which is characterized in that the first end of the first capacitor is the RC
The first end of series arm, the second end of the first capacitor connect the first end of the second resistance, the second resistance
Second end is the second end of the RC series arm.
5. RCD absorbing circuit according to claim 4, which is characterized in that the RC series arm further includes the 4th resistance；
4th resistance is in parallel with the second resistance.
6. RCD absorbing circuit according to claim 1, the first diode is fast recovery diode or supper-fast extensive
Multiple diode.
7. RCD absorbing circuit according to claim 1-6, the conduction voltage drop of second diode is 0.7V.
8. a kind of switching power circuit characterized by comprising voltage input end, power control circuit, switching tube, transformer,
Over-current detection circuit and the described in any item RCD absorbing circuits of claim 1-7；
The voltage input end, respectively with the first armature winding of the power connector end of the RCD absorbing circuit, the transformer
Connecting pin is connected；
The peak voltage input terminal of the RCD absorbing circuit, it is primary with the drain electrode of the switching tube, the transformer second respectively
Winding connecting pin is connected；
The grid of the switching tube is connected with the power control terminal of the power control circuit；
The first end of the over-current detection circuit is connected with the source electrode of the switching tube, second end ground connection.
9. switching power circuit according to claim 8, which is characterized in that further include: electromagnetic interference EMI and rectifying and wave-filtering
The main loop of power circuit of circuit, flyback sourse and feedback control loop；
The first end of the EMI and current rectifying and wave filtering circuit is connected across between zero curve and firewire, the EMI and current rectifying and wave filtering circuit
Second end is connected with the power connector end of the RCD absorbing circuit, for filtering difference mode signal and converting the alternating current of input
For Rectified alternating current；
The voltage input end of the main loop of power circuit of flyback sourse is connected with the voltage output end of the power control circuit, described
The voltage output end of the main loop of power circuit of flyback sourse is grounded after being connected with load, for powering to the load；
The external circuit compensating end that the feedback control loop passes through the photoelectric coupling triode and the power control circuit that include connects
It connects, regulates and controls the power control circuit output constant voltage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910126780.7A CN109818493A (en) | 2019-02-20 | 2019-02-20 | A kind of RCD absorbing circuit and switching power circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201910126780.7A CN109818493A (en) | 2019-02-20 | 2019-02-20 | A kind of RCD absorbing circuit and switching power circuit |
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| CN109818493A true CN109818493A (en) | 2019-05-28 |
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| CN201910126780.7A Pending CN109818493A (en) | 2019-02-20 | 2019-02-20 | A kind of RCD absorbing circuit and switching power circuit |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110138229A (en) * | 2019-06-20 | 2019-08-16 | 浙江万胜智能科技股份有限公司 | A kind of double-transistor flyback formula Switching Power Supply with clamper protection |
| CN110250580A (en) * | 2019-06-26 | 2019-09-20 | 西安拓尔微电子有限责任公司 | A kind of High Accuracy Constant Temperature electronic cigarette based on dual power supply |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1302113A (en) * | 1999-12-27 | 2001-07-04 | 三垦电气株式会社 | DC-AC exchanger |
| CN104009644A (en) * | 2014-05-30 | 2014-08-27 | 广州视源电子科技股份有限公司 | Fly-back power circuit |
| CN206820646U (en) * | 2017-05-23 | 2017-12-29 | 广州视源电子科技股份有限公司 | RCD absorbing circuits and switching power circuit |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1302113A (en) * | 1999-12-27 | 2001-07-04 | 三垦电气株式会社 | DC-AC exchanger |
| CN104009644A (en) * | 2014-05-30 | 2014-08-27 | 广州视源电子科技股份有限公司 | Fly-back power circuit |
| CN206820646U (en) * | 2017-05-23 | 2017-12-29 | 广州视源电子科技股份有限公司 | RCD absorbing circuits and switching power circuit |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110138229A (en) * | 2019-06-20 | 2019-08-16 | 浙江万胜智能科技股份有限公司 | A kind of double-transistor flyback formula Switching Power Supply with clamper protection |
| CN110138229B (en) * | 2019-06-20 | 2024-04-05 | 浙江万胜智能科技股份有限公司 | Double-tube flyback switching power supply with clamp protection |
| CN110250580A (en) * | 2019-06-26 | 2019-09-20 | 西安拓尔微电子有限责任公司 | A kind of High Accuracy Constant Temperature electronic cigarette based on dual power supply |
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Application publication date: 20190528 |