CN206259865U - A kind of Switching Power Supply - Google Patents

Abstract

The utility model discloses a kind of Switching Power Supply, belong to power technique fields.The Switching Power Supply includes the input stage filter circuit, current rectifying and wave filtering circuit, TOPSwitch HX, transformer, output voltage stabilizing circuit, feedback circuit and the protection circuit that are connected, and protection circuit is reconnected in TOPSwitch HX, forms circuit loop；The Switching Power Supply also includes clamp absorbing circuit and transformer bias output circuit, and the input of the clamp absorbing circuit is connected with the current rectifying and wave filtering circuit, and the clamp absorbing circuit is connected with each other with the transformer；The output end of the bias output circuit biases winding output end for transformer, and the bias output circuit is connected with the protection circuit.The utility model circuit structure is simple, high frequency transformer small volume, it is only necessary to which minority separates the voltage output performance that original paper can be obtained by needing special chip to realize, efficient and reliable work is obtained with by good design.

Description

A kind of Switching Power Supply

Technical field

The utility model is related to power technique fields, and in particular to a kind of Switching Power Supply.

Background technology

Single-chip switching power supply has the advantages that high integration, high performance-price ratio, peak envelope peripheral circuit, optimal performance index, energy Constitute the isolation type switching power supply and various asc switch power supplys of high efficiency no industrial frequency transformer.Single-chip switching power supply is current As in developing in the world, the preferably integrated circuit of small-power switching power-supply, precision switch power supply and switch power module.It institute Linear stabilized power supply of the Switching Power Supply of composition with equal-wattage on cost is suitable, and power-efficient is significantly improved, volume with Weight is greatly reduced, and is that the popularization of novel switched power supply and popularization create good condition.But current switching power circuit knot Structure is complicated, and goes back Shortcomings at aspects such as filter effects.

Utility model content

Regarding to the issue above, the purpose of this utility model is to provide a kind of Switching Power Supply, the circuit structure of the Switching Power Supply Simply, it is only necessary to which minority separates the voltage output performance that original paper can be obtained by needing special chip to realize, by good Design is obtained with efficient and reliable work.

To achieve these goals, the technical solution adopted in the utility model is：

A kind of Switching Power Supply, including transformer, the Switching Power Supply also include TOPSwitch-HX, input stage filtered electrical Road, current rectifying and wave filtering circuit, clamp absorbing circuit, output voltage stabilizing circuit, feedback circuit and protection circuit；

The input stage filter circuit input incoming transport electricity, the output end of the input stage filter circuit with it is described The input connection of current rectifying and wave filtering circuit, the output end of the current rectifying and wave filtering circuit connects with the input of the TOPSwitch-HX Connect, the output end of the TOPSwitch-HX is connected with the input of the transformer, the input of the output voltage stabilizing circuit It is connected with the transformer, the output end of the output voltage stabilizing circuit is connected with the input of the feedback circuit；The protection The input of circuit is connected with the output end of the feedback circuit, the output end of the protection circuit and the TOPSwitch-HX Connection；The current rectifying and wave filtering circuit also with it is described clamp absorbing circuit input be connected, it is described clamp absorbing circuit with it is described Transformer is connected with each other；The Switching Power Supply also includes that transformer biases output circuit, the output end of the bias output circuit For transformer biases winding output end, the bias output circuit is connected with the protection circuit.

Further, the input stage filter circuit includes electromagnetic interface filter circuit, and the electromagnetic interface filter circuit includes phase The common mode choke of connection, X electric capacity and Y capacitance, the magnetic core of the common mode choke is ferrite, ferrocart core or crystallite.

Further, the input rectification circuit is after alternating current is entered by input interface, by the bridge-type that D1-D4 is constituted Full-bridge rectification is carried out, and is filtered by C1, be direct current convert alternating current.

Further, the clamp absorbing circuit is made up of clamping capacitance C2, clamp resistance R4 and clamp diode D6, institute State clamping capacitance C2 to be connected with the transformer, the clamping capacitance C2 and clamp resistance R4 are in parallel, the clamp diode D6 It is connected with the clamping capacitance C2, clamp resistance R4.

Further, the voltage-stabilizing output circuit include diode D7, output filter capacitor C8, rear class filtering inductance L2 and Rear class filtering electric capacity C9, the diode D7 are connected with the transformer, the output filter capacitor C8 and diode D7 Series connection, the rear class filtering inductance L2 connects with the output filter capacitor C8, the rear class filtering electric capacity C9 and the output Filter capacitor C8 is in parallel, and one end of the output filter capacitor C8 and rear class filtering electric capacity C9 is connected with the feedback circuit, institute The other end for stating output filter capacitor C8 and rear class filtering electric capacity C9 is connected with earth terminal.

Further, the voltage-stabilizing output circuit also include a resistance, the resistance it is in parallel with the diode D7 and with The output filter capacitor C8 series connection.

Further, the diode D7 Schottky barrier diodes, the operating current of the diode D7 is specified electricity 3-4 times of stream.

Further, the feedback circuit includes reference voltage source TL431, photo-coupler PC817, resistance R5, resistance R6, resistance R7 and resistance R8, the resistance R7 and resistance R8 series connection and with the output voltage stabilizing circuit, reference voltage source TL431 Connection, for being sampled to output voltage, sampling voltage is compared with the reference voltage of reference voltage source TL431, and pass through TL431 controls the luminosity of optocoupler；The resistance R5 is connected with output voltage stabilizing circuit and is gone here and there with the reference voltage source TL431 Connection, for limiting by the electric current of optocoupler；The resistance R6 is connected in parallel on PC817 light emitting diodes two ends, for being turned off as PC817 When, output voltage can provide the operating current of stabilization by R5 for TL431, it is to avoid PC817 is operated in critical condition.

Further, the voltage range of the alternating current is 85-265V.

In sum, by adopting the above-described technical solution, the beneficial effects of the utility model are：

(1) the utility model is filtered by input stage filter circuit first, is carried out again by current rectifying and wave filtering circuit Rectifying and wave-filtering, makes filter effect good, and most of leakage inductance energy of transformer can be transferred to pincers in MOSFET pipe shutdown moments Position absorbing circuit, is clamped absorbing circuit consumption, greatly reduces the voltage stress of MOSFET pipes.

(2) circuit structure is simple, high frequency transformer small volume, it is only necessary to which minority separation original paper can be obtained by need to be special The voltage output performance that chip could be realized, efficient and reliable work is obtained with by good design.

Brief description of the drawings

Fig. 1 is the overall structure block diagram of the utility model embodiment；

Fig. 2 is the input stage EMI filter circuit figure in the utility model embodiment；

Fig. 3 is the clamp absorbing circuit in the utility model embodiment；

Fig. 4 is the feedback circuit schematic diagram in the utility model embodiment；

Fig. 5 is the output voltage stabilizing circuit schematic diagram in the utility model embodiment；

Fig. 6 is the protection circuit schematic diagram in the utility model embodiment；

Fig. 7 is transformer characteristic schematic diagram in the utility model embodiment；

Fig. 8 is transformer winding structure chart in the utility model embodiment.

Specific embodiment

Below in conjunction with the accompanying drawing in the utility model embodiment, the technical scheme in the utility model embodiment is carried out Clearly and completely describe, it is clear that described embodiment is only a part of embodiment of the utility model, rather than whole Embodiment.Based on the embodiment in the utility model, those of ordinary skill in the art are not under the premise of creative work is made The every other embodiment for being obtained, belongs to the scope of the utility model protection.

Embodiment

A kind of Switching Power Supply, such as Fig. 1, including transformer, the Switching Power Supply also include that TOPSwitch-HX, input stage are filtered Wave circuit, current rectifying and wave filtering circuit, clamp absorbing circuit, output voltage stabilizing circuit, feedback circuit and protection circuit；

The input stage filter circuit input incoming transport electricity, the output end of the input stage filter circuit with it is described The input connection of current rectifying and wave filtering circuit, the output end of the current rectifying and wave filtering circuit connects with the input of the TOPSwitch-HX Connect, the output end of the TOPSwitch-HX is connected with the input of the transformer, the input of the output voltage stabilizing circuit It is connected with the transformer, the output end of the output voltage stabilizing circuit is connected with the input of the feedback circuit；The protection The input of circuit is connected with the output end of the feedback circuit, the output end of the protection circuit and the TOPSwitch-HX Connection；The current rectifying and wave filtering circuit also with it is described clamp absorbing circuit input be connected, it is described clamp absorbing circuit with it is described Transformer is connected with each other；The Switching Power Supply also includes that transformer biases output circuit, the output end of the bias output circuit For transformer biases winding output end, the bias output circuit is connected with the protection circuit.

Each circuit and its operation principle in the utility model embodiment introduced below：

TOPSwitch-HX is a kind of offline converter IC of high integration monolithic for offline power supply, and it is with economical and efficient Mode by a power MOSFET of 700V, high-voltage switch gear current source, PWM controller, oscillator, Thermal shutdown protection circuit, Fault secure circuit and other control circuits are integrated in a monolithic device.

Input stage EMI filter circuit includes electromagnetic interface filter, and electromagnetic interface filter Main Function has two, and one is to filter extraneous friendship Flow the interference of the high-frequency impulse to power-supply device of power network, two play reduction switch power supply equipment AC network to external world in itself Electromagnetic interference.Actually it is the characteristic of sharp inductance and electric capacity, frequency is passed through filter for the alternating current of 50Hz or so Ripple device, but High-frequency Interference clutter higher than more than 50Hz filtered by wave filter, so electromagnetic interface filter is also called low pass filter, Its meaning is that low frequency can pass through, and high frequency is then filtered out.The schematic circuit of input stage EMI filter circuit as shown in Fig. 2 R1 is protective tube in figure, and C1, C2, C3, C5 are safety electric capacity, and C1, C2, C3, C5 and common mode choke constitute electromagnetic interface filter, Power supply noise is isolated.Protective tube R1 is in parallel with safety electric capacity.The effect of safety electric capacity is, i.e., after capacitor failure, will not lead Send a telegraph and hit, do not jeopardize personal safety.These safety electric capacity include X electric capacity and Y capacitance, wherein C1, and C3 is X electric capacity.X electric capacity is The electric capacity between the line of power line two (L-N) is connected across, otherwise is then Y capacitance, C2 and C5 is Y capacitance.

The selection of filter inductance (i.e. common mode choke)：The value of inductance, the selection principle of material are from the following aspects Consider：First, the frequency range of core material is wide, it is ensured that highest frequency has in 1GHz in frequency range very wide More stable magnetic conductivity；Second, magnetic conductivity is high, but is difficult to meet this requirement in practice, so, magnetic conductivity is often What segmentation considered.Core material is usually ferrite or ferrocart core, more preferable material such as crystallite etc..

EMI power-supply filters must note the installation question of wave filter in application, because if wave filter is mounted so as to It is improper to obtain a worse effect on the contrary, following three points should be noted when in use：One：For the peace of electromagnetic interface filter Full reliably working (radiating and filter effect), in addition to electromagnetic interface filter is necessarily mounted in the frame of equipment or casing, EMI filters The earth point of ripple device should agree with the earth point of equipment shell, and shorten the ground wire of electromagnetic interface filter as far as possible.If earth point Not at one, then the leakage current and noise current of electromagnetic interface filter can be introduced noise into when the approach of two earth points is flowed through Other parts in equipment.Secondly, the ground wire of electromagnetic interface filter can introduce induction reactance, and it can cause electromagnetic interface filter high frequency attenuation special Property degenerates.So, the electromagnetic interface filter of metal shell will be connected directly with equipment shell.As shell is jetted through paint, then must scrape off Coat of paint；If the electromagnetic interface filter of metal shell can not be directly grounded or during using plastic shell electromagnetic interface filter, it and equipment shell Ground wire should may be short.Two：Electromagnetic interface filter will be arranged on device power supply (DPS) line input, and line is as far as possible short；Device interior electricity Source will be arranged on the output end of electromagnetic interface filter.If input line length of the electromagnetic interface filter in equipment, will in front end input line The Conduction Interference being introduced into is coupled to other parts.If device interior power supply is arranged on the input of electromagnetic interface filter, due to line It is long, also result in same result.Three：Ensure that electromagnetic interface filter input line and output line are separated.If electromagnetic interface filter input, it is defeated Enter line tying and installed near together or mutually, then due to the coupling between them, the high frequency attenuation of electromagnetic interface filter may be made Reduce.If input, output line must be close to, then must all use twisted-pair feeder or shielding line.

Civil power enters current rectifying and wave filtering circuit, the alternating current (AC85-265V/ in current rectifying and wave filtering circuit after being filtered by EMI 50Hz) entered by input interface, the bridge-type constituted by D1-D4 carries out full-bridge rectification, and is filtered by C1, is convert alternating current (as input AC electricity 110V, the direct current after rectification is 155V or so to direct current, as input AC electricity 220V, after rectification Direct current is 311V or so).Wherein D1-D4 is bridge rectifier, AC rectification into direct current.Value is mainly and considers it anti- The electric current passed through during to pressure-resistant size and with maximum load.Reversely pressure-resistant the higher the better, and current requirements are than circuit rated current Big 3 accompany the above.C1 is rectification post filtering.Capacitance is bigger, and output DC ripple is smaller, but cost is also higher.This electric capacity Capacity is bigger, connects electric moment, and the electric current by R2 is bigger, and whole machine surge current is bigger；Conversely, capacitance is small, filtering Effect is bad, and the direct current ripple after rectification is larger.

Clamp absorbing circuit is made up of C2, R4 and D6, in TOPSwitch-HX after the cut-off of MOSFET pipes, because transformer is deposited In leakage inductance, and leakage inductance energy can not be by transformer coupled to output stage N_SWinding discharges, if there is no RCD clamp circuits, leakage Energy in sense will be in other stray capacitances during MOSFET pipe shutdown moments are transferred to MOSFET pipes interelectrode capacity and circuit In, now MOSFET drain electrodes will bear switch stress higher, if adding RCD clamp circuits, the most of energy in leakage inductance To be transferred on the clamping capacitance C2 of clamp circuit in MOSFET pipe shutdown moments, then this portion of energy is clamped resistance R4 and disappears Consume, thus the significantly salty voltage stress for having lacked MOSFET pipes.The circuit diagram for clamping absorbing circuit is as shown in Figure 3.

In RCD clamp circuit design processes, because the value of resistance R4 and electric capacity C2 in RCD clamp circuits all compares Greatly, therefore, the voltage on clamping capacitance C2 will not have a greater change in each switch periods, so, can with one it is constant Value V_clampTo represent the voltage at clamping capacitance two ends.RCD clamp circuits are designed by following steps on this basis：

Step one：It is determined that clamp voltage V_clamp

Using V_ORRepresent secondary to primary refraction voltage, V_(BR)DSSThe drain source breakdown voltage of MOSFET pipes is represented, V_inmaxRepresent maximum input direct voltage；

Due to clamp voltage V_clampWith the V of MOSFET pipes_(BR)DSSAnd input ceiling voltage V_inmaxIt is relevant, if it is considered that 0.9 Drop volume coefficient of utilization, V can be determined with following formula_CLAMPSize.

V_CLAMP=0.9V_(BR)DSS-V_INMAX (1)

Step 2：Determine the leakage inductance amount Llk of armature winding

The leakage inductance amount of armature winding can be obtained by testing, and common method is that short-circuit each secondary windings tests this When armature winding sensibility reciprocal, this value is exactly the leakage inductance amount of armature winding.It should be noted that test frequency should be using conversion The working frequency of device.Certainly, the method tested one by one can not possibly be taken during batch production, at this moment, it may be determined that a percentage comes Estimate the leakage inductance value of whole batch, this percentage is typically in 1%--5%.

Step 3：It is determined that clamp resistance R4

Because the voltage at clamping capacitance C2 two ends can use steady state value V_CLAMPRepresent, therefore the power of clamp resistance consumption is：

In formula：P_R-clampRepresent the power of clamp resistance consumption.

On the other hand consider there is following relation from energy conservation principle

In formula：W_R-clampTo clamp the energy of resistance consumption；Wl is the energy of storage in armature winding leakage inductance；V_ORIt is secondary To primary refraction voltage；V_clampIt is clamp voltage；

Then (3) formula can be changed into convert energy into mean power：

In formula：f_sIt is the working frequency of converter, L_lkIt is the leakage inductance amount of armature winding；I_ds-peakIt is the maximum of MOSFET pipes Peak point current (i.e. the peak point current of low pressure full load)；

So can just obtain clamping the computing formula of resistance R4 by (2), (4) formula

Step 4：Determine clamping capacitance C2

The value of clamping capacitance C2 should obtain sufficiently large enough to ensure its pulsating volage of itself when leakage inductance energy is absorbed Small, it is the 5%--10% for clamping voltage generally to take this pulsating volage, so, so that it may the minimum value of C2 is determined by following formula.

In formula：C2 is clamping capacitance；V_clampIt is clamp voltage；△V_clampIt is the pulsating volage on clamping capacitance；Fs is change The working frequency of parallel operation；

In this RCD clamp absorbing circuits：R4=2*100*30/0.00003/0.6/0.6/30000=18518 takes 20K；C2 =100/5/20000/30000=0.033uF takes 0.1uF；△Vclamp：=5V；Vclamp=100V；VOR：=30V；Llk： =0.00003H；Ids-peak：=0.6A；fs：=30000HZ；The power attenuation of R4 is larger, with the resistance of 2W.C2 high frequencies Loss is small, and anti-pulsation ability is strong, long lifespan, the CBB electric capacity of high pressure, due to Vclamp=100V, it is contemplated that other interference and Surplus is left, pressure-resistant 400V is used.D6 it is also noted that pressure-resistant problem, this circuit using pressure-resistant 700V fast diode FR107.

The circuit theory diagrams of output voltage stabilizing circuit are as shown in Figure 4.The voltage-stabilizing output circuit includes diode D7, output filter Ripple electric capacity C8, rear class filtering inductance L2 and rear class filtering electric capacity C9, the diode D7 are connected with the transformer, the output Filter capacitor C8 connects with the diode D7, and the rear class filtering inductance L2 connects with the output filter capacitor C8, described Rear class filtering electric capacity C9 is in parallel with the output filter capacitor C8, and the one of the output filter capacitor C8 and rear class filtering electric capacity C9 End is connected with the feedback circuit, and the other end of the output filter capacitor C8 and rear class filtering electric capacity C9 is connected with earth terminal.

When MOSFET pipes are turned off, the armature winding N of transformer_PBecome lower just upper negative, N_SOn just lower negative, D7 conductings, storage Energy in transformer is supplied to load to be charged to electric capacity C8 simultaneously by D7.Wherein diode D7 is a kind of low-loss Xiao Te Base rectifying tube.C8 and C9 are filter capacitors, make output direct current ripple smaller.C8 and C9 is of different sizes and parallel connection, because Bulky capacitor is different to the ripple filter effect of different frequency with small capacitances, and bulky capacitor is preferable to High frequency filter effect in theory, but Actually there is larger impedance to high frequency because bulky capacitor has inductive effect, the filter effect of the electric capacity of low capacity to high frequency It is better than bulky capacitor.Because control circuit is when MOSFET is turned on, transformer is not powering load, at this moment can only be given by electric capacity Load supplying, C8 is bigger, and the energy of storage is more, supplies same load, and voltage decline is fewer, in other words, output electricity Pressure is more stable, so C8 is the bigger the better.When filter capacitor is chosen, it is also contemplated that its is pressure-resistant, it is pressure-resistant must be than output Voltage is high, preferably leaves certain pressure-resistant leeway.

As further preferred, the present embodiment also in output stage parallel connection a resistance when as fictitious load, for discharging Fall the portion of energy of output filter capacitor C8, play the effect for improving circuit intermittent oscillation.Arrived when MOSFET pipe ON times are small When to a certain degree, due to the charge-storage effect of MOSFET pipes, MOSFET pipes are in itself from the time used by complete switching off that is conducting to The ON time of adjustment circuit needs is greater than, the vibration in so several cycles is more to the energy that output end is provided, more than negative Consumed energy is carried, output voltage is raised, and adjustment circuit just turns off vibration；When load energy is consumed to a certain extent, electricity The voltage reduction of appearance, and control circuit to allow MOSFET pipes to vibrate, so repeat, and there is intermittent oscillation.So adding One small valued resistor, it is relatively good to improving circuit intermittent oscillation effect, but it is too small can increase useless power consumption, reduce circuit effect Rate, its resistance size is general rule of thumb or circuit debugging determines.

Because the working frequency of Switching Power Supply is all higher, so D7 uses response speed than Schottky rectification two faster Pole pipe, when original paper is selected in addition to response speed to be considered, it is also contemplated that its operating current, typically bigger than rated current by 3 More than times, except this it is also contemplated that it pressure-resistant, because when MOSFET pipes are turned in control chip, armature winding N in transformer_POn Voltage (on just lower negative) be substantially input voltage, N_SAlso corresponding ratio-voltage (under just upper negative) has been sensed, along with filter The voltage of ripple electric capacity C8, so the pressure-resistant of Rectifying Schottky diodes have to be larger than both sums, and leaves certain surplus.

The reponse system of power supply is unusual part and parcel in the design of whole power supply, due to the presence power supply that feeds back The output that output voltage could be stablized.The utility model feedback circuit schematic diagram is as shown in Figure 5.Feedback-control circuit work is former Reason：The luminous component that can shunt reference voltage source TL431 and optocoupler PC817 by three ends carries out sampling feedback to output voltage, instead Supply current enters the controlling switch C of TOP253EN.In circuit, D8, C7 be used for the output voltage rectifying and wave-filtering of assists winding and For optocoupler branch road provides power supply；R7, R8 are used to sample output voltage, are compared with sampling power supply TL431 reference voltages, and The luminosity of optocoupler is controlled by TL431；R5 is used to limit by the electric current of optocoupler；R6 is connected in parallel on PC817 light emitting diodes Two ends, are in order to when PC817 is turned off, output voltage can provide the operating current of stabilization by R5 for TL431, it is to avoid PC817 It is operated in critical condition.

Controlling switch C is to provide the low-impedance node of power supply and feedback current.During normal operation, shunt regulator is used Feedback signal is separated from supply current.Controlling switch voltage V_CIt is control circuit (including MOSFET raster data models Including) supply voltage, an external bypass capacitors should be nearby placed between control pole and source lead to provide Instantaneous Grid Driving current.The all electric capacity for being connected to control pin are also used for that setting is automatic to restart timing, while being used for loop compensation.

During startup, the high direct voltage after rectification is added in drain lead, and MOSFET is initially in off state, by connection High-voltage current source between drain electrode and controlling switch charges to control electric capacity.When controlling switch voltage VC is close to 5.8V, control Circuit is activated and starts soft start.Within the time of 17ms or so, soft starting circuit makes drain electrode peak point current and switching frequency Full range maximum drain peak point current is gradually risen to from very low initial value.At the end of soft start, if without external feedback/ Supply current flows into controlling switch, then the shut-off of internal high pressure switched current source, and controlling switch starts to be absorbed according to control circuit Supply current size start electric discharge.If Power Management Design is correct, and during in the absence of failures such as open loop or output short-circuits, When controlling switch is discharged into close to before lower threshold voltage 4.8V (internal electric source is under-voltage latch threshold value), feedback control loop will be closed Close, foreign current is provided to controlling switch.When controlling switch is charged to 5.8V shunt regulator voltages by the outside electric current for flowing into When, source lead will be diverted to by NMOS current mirrors more than the electric current that chip is consumed.The output current control of NMOS current mirrors The dutycycle of power MOSFET processed, realizes that closed circuit is adjusted.

Due to because feedback signal fails, in the case of causing trouble, output voltage is by rapid increase and more than specified electricity Pressure.The increase of output voltage also results in the increase of biasing winding output end voltage simultaneously.When the voltage of biasing winding output end More than rated voltage and the V pins of the Zener voltage-stabiliser tube for being connected to biasing winding output end and V pins (or M pins), (or M draws Pin) voltage summation when, will cause introduce V pins (or M pins) electric current more than IV or IM, so as to trigger overvoltage protection work( Energy.In primary detection OVP protection circuits, be by be significantly increased therefore output voltage (biasing winding voltage therewith increase) come Triggering overvoltage protection.If the protection circuit circuit theory diagrams of the present embodiment as shown in fig. 6, working power heavier loads or Under low pressure input condition, it will open loop occur, output voltage may not significantly rise.When there are these situations, latching will Will not turn off until load or line voltage change.Even so, when on-Line Voltage or load state change, by resistance Only being substantially increased for voltage can still provide required protection.In TOPSwitch-HX typical case's applications, if there is open loop, Its primary side OVP protections will prevent rated output voltage 5V from rising on 20V.

The electrical characteristics of the Transformer structure of PI Expert Expert System Designs can be checked using PIXLS Designer8 Schematic diagram and winding structure figure.User can also be modified using PIXLS Designer8 to the parameter of transformer, join it Number is easy to user to make by oneself or the qualified high frequency transformer of commission manufacturer production mass.The electrical characteristics of transformer in the utility model Schematic diagram and winding structure figure as shown in Figure 7 and Figure 8, according to Fig. 7 and Fig. 8, are described as follows to Transformer Winding respectively：

Cancel 1 winding of shielding：With pin 1,2 as initial pin, the material item of table 2 [4] is used in initiating terminal, reuse table 2 material items [6] around 15 circles (lines of x 2), from a left side to there is just one layer.Edge carries out coiling with armature winding identical direction of rotation. This one end for cancelling shield winding is kept to be not connected to.End is bent 90 degree, wire is cut off in the middle part of skeleton.1 layer of adhesive tape of addition (material item of table 2 [3]) is with by winding fix in position.

Armature winding：Using pin 3 as initial pin, the material item of table 2 [4] is used in initiating terminal, reuse the material of table two [6] around 62 circles (lines of x 1) in 2 layers from left to right.At the end of the 1st layer, continue from right to left around next layer.At last On layer, winding is set to be evenly distributed on whole skeleton.With pin 1,2 as pin is terminated, using material item [4] on this pin Terminate the winding.1 layer of adhesive tape (material item of table 2 [3]) is added to be insulated.Biasing winding using pin 5 as initial pin, Initiating terminal uses the material item of table 2 [4], reuses the material item of table 2 [6] around 9 circles (lines of x 2).Rotated along with armature winding identical Direction carries out coiling.Winding is set to be evenly distributed on whole skeleton.Using pin 4 as pin is terminated, the material item of table 2 [4] is used Terminate the winding on this pin.1 layer of adhesive tape (material item of table 2 [3]) is added to be insulated.

The winding of primary shield 2：With pin 1,2 as initial pin, material item [4] is used in initiating terminal, reuse table two Material item [7] around 4 circles (lines of x 4), from a left side to there is just one layer.Edge carries out coiling with armature winding identical direction of rotation.Make Winding is evenly distributed on whole skeleton.This end of primary shield winding is kept to be not connected to.End is bent 90 degree, in skeleton Portion cuts off wire.3 layers of adhesive tape (material item of table 2 [3]) are added to be insulated.

Secondary windings：Using pin 7 as initial pin, material item [4] is used in initiating terminal, reuse the material of material table 2 [8] Around 3 circles (lines of x 3).Winding is set to be evenly distributed on whole skeleton.Edge carries out coiling with armature winding identical direction of rotation.With Pin 6 terminates the winding using the material of material table 2 [4] as pin is terminated on this pin.2 layers of adhesive tape (material item of table 2 of addition [3]) being insulated.

Magnetic core is assembled：Assemble and fix two halves magnetic core.The material item of table 2 [1].

Dipping：The homogeneous impregnation in the material item of table 2 [5].Vacuum impregnation should not be used.

The transformer of table 1 makes remarks table

The transformer of table 2 makes material therefor table

The electrical characteristics test specification table of table 3

Applicant also 220V input voltage under, to the utility model Switching Power Supply and using 7805 make non-open The linear power supply of pass enters the contrast test of line output voltage in the case of different loads, and test result is as shown in the table：

The test result of table 1

Found by test data in table, the utility model Switching Power Supply is relative to the line using 7805 non-switch for making The carrying load ability of property power supply is stronger, and output voltage stabilization.

The utility model circuit structure is simple, and high frequency transformer volume and printed circuit plate suqare are all smaller, it is only necessary to few Number separates the voltage output performance that original paper can be obtained by needing special chip to realize, is obtained with by good design Efficiently and reliably work.

Described above is directed to the detailed description of the preferable possible embodiments of the utility model, but embodiment is not limited to Patent claim of the present utility model, the equal change or modification completed under the technical spirit suggested by all the utility model Change, all should belong to the utility model and cover the scope of the claims.

Claims (9)

1. a kind of Switching Power Supply, including transformer, it is characterised in that the Switching Power Supply also includes TOPSwitch-HX, input Level filter circuit, current rectifying and wave filtering circuit, clamp absorbing circuit, output voltage stabilizing circuit, feedback circuit and protection circuit；

The input incoming transport electricity of the input stage filter circuit, output end and the rectification of the input stage filter circuit The input connection of filter circuit, the output end of the current rectifying and wave filtering circuit is connected with the input of the TOPSwitch-HX, The output end of the TOPSwitch-HX is connected with the input of the transformer, the input of the output voltage stabilizing circuit and institute Transformer connection is stated, the output end of the output voltage stabilizing circuit is connected with the input of the feedback circuit；The protection circuit Input be connected with the output end of the feedback circuit, the output end of the protection circuit connects with the TOPSwitch-HX Connect；Input of the current rectifying and wave filtering circuit also with the clamp absorbing circuit is connected, the clamp absorbing circuit and the change Depressor is connected with each other；The Switching Power Supply also includes that transformer biases output circuit, and the output end of the bias output circuit is Transformer biases winding output end, and the bias output circuit is connected with the protection circuit.

2. Switching Power Supply according to claim 1, it is characterised in that the input stage filter circuit includes electromagnetic interface filter Circuit, the electromagnetic interface filter circuit includes the common mode choke, X electric capacity and the Y capacitance that are connected.

3. Switching Power Supply according to claim 1, it is characterised in that the input rectification circuit is connect for alternating current by being input into After mouth enters, the bridge-type constituted by D1-D4 carries out full-bridge rectification, and is filtered by C1, is direct current convert alternating current.

4. Switching Power Supply according to claim 1, it is characterised in that the clamp absorbing circuit is by clamping capacitance C2, pincers Position resistance R4 and clamp diode D6 compositions, the clamping capacitance C2 is connected with the transformer, the clamping capacitance C2 and pincers Resistance R4 is in parallel for position, and the clamp diode D6 is connected with the clamping capacitance C2, clamp resistance R4.

5. Switching Power Supply according to claim 1, it is characterised in that the voltage-stabilizing output circuit includes diode D7, defeated Go out filter capacitor C8, rear class filtering inductance L2 and rear class filtering electric capacity C9, the diode D7 is connected with the transformer, described Output filter capacitor C8 connects with the diode D7, and the rear class filtering inductance L2 connects with the output filter capacitor C8, The rear class filtering electric capacity C9 is in parallel with the output filter capacitor C8, the output filter capacitor C8 and rear class filtering electric capacity C9 One end be connected with the feedback circuit, the other end of the output filter capacitor C8 and rear class filtering electric capacity C9 connects with earth terminal Connect.

6. Switching Power Supply according to claim 5, it is characterised in that the voltage-stabilizing output circuit also includes a resistance, institute Resistance is stated to be connected with diode D7 parallel connections and with the output filter capacitor C8.

7. Switching Power Supply according to claim 5, it is characterised in that the diode D7 is Schottky barrier diodes, The operating current of the diode D7 is 3-4 times of rated current.

8. Switching Power Supply according to claim 1, it is characterised in that the feedback circuit includes reference voltage source TL431, photo-coupler PC817, resistance R5, resistance R6, resistance R7 and resistance R8, the resistance R7 and resistance R8 series connection and with institute Output voltage stabilizing circuit, reference voltage source TL431 connections are stated, for being sampled to output voltage, by sampling voltage and reference voltage source The reference voltage of TL431 is compared, and the luminosity of optocoupler is controlled by TL431；The resistance R5 and output voltage stabilizing electricity Road connects and is connected with the reference voltage source TL431, for limiting by the electric current of optocoupler；The resistance R6 is connected in parallel on PC817 light emitting diodes two ends, for when PC817 is turned off, output voltage can to provide the work electricity of stabilization by R5 for TL431 Stream, it is to avoid PC817 is operated in critical condition.

9. Switching Power Supply according to claim 1, it is characterised in that the voltage range of the alternating current is 85-265V.