The article summarizes power to transmit a process in the changeover in converter circuit, be in in the light of MOSFET of switch parts of an apparatus guide connect and close the instant, produce the problem of voltage and voltaic aiguille, produce electromagnetism to disturb a phenomenon then, pass comparative and traditional planar MOSFET and the structure of MOSFET exceeding a written guarantee and parameter, search the account that uses MOSFET exceeding a written guarantee to produce poorer electromagnetism to disturb, have analysis and improvement.

 

As the ceaseless development of technology of switch power source, power MOSFET regards the core of switch power source as one of electronic parts, switch loss is one of its main loss, act on the economic energy resources, basic idea that reduces loss, power MOSFET technology raises switch rate forward, reduce guide the way of electrify block develops. COOL MOSFET is MOSFET of a kind of new structure power that exceeds a written guarantee, have lower guide electrify block, rapidder switch rate, can realize higher power to change efficiency. However, MOSFET exceeding a written guarantee exceeded fast switch performance to also bring needless secondary action, aiguille of voltage, electric current is for instance taller, electromagnetism interference is poorer wait.

 

The following content stimulates type converter instead with develop attacks (if pursue 1) for exemple, the power that summarizes converter changes transmission course, from planar MOSFET and the structure of MOSFET exceeding a written guarantee and parameter difference, aiguille of discussion voltage, electric current, and the generation mechanism that electromagnetism disturbs, be improved through periphery circuit and reduce aiguille of voltage, electric current, achieve the goal that reduces electromagnetism interference thereby.

 

Graph 1 contain parasitism element stimulate type converter instead develop attacks graph

 

Stimulate principle of type converter job instead

 

Graph 1 it is the simplest stimulate type converter instead develop attacks structure, and contain element of the following parasitism: The knot capacitance of the parasitism capacitance that is like primary leakage inductance, MOSFET and sub diode. This develop attacks come from to rise step-down converter, replace filter wave inductance for coupling inductance, if contain the magnetism core transformer of air gap, when advocate MOSFET of switch parts of an apparatus guides when connecting, energy is with memory of magnetic flux form in transformer, transmit when MOSFET closes to output. Because transformer needs to guide in MOSFET,store energy, magnetism core should leave have air gap, be based on this kind of special power transition, stimulate type converter to be able to change transmission power instead so finite, in just suiting, low power applies, be like batteries charger, adapter and DVD player.

 

Stimulate type converter to be below regular job circumstance instead, when MOSFET closes, primary electric current (the Coss that Id) is MOSFET inside short time (namely Cgd+Cds) charges, when Coss the voltage Vds of two end inputs voltage and the sum of catoptric output voltage more than (when Vin+nVo) , sub diode guides, the voltage of two end of primary inductance Lp by Qian to NVo. Lk of feeling of because this is primary total leakage (resonance happens between Lkp+n2×Lks) and Coss namely, generation is high frequency with high-pressured surge, the exorbitant voltage on MOSFET may cause trouble.

 

It is OK to stimulate type converter instead the job is in guide continuously a mode (CCM) (if pursue 2) and discontinuous guide a mode (DCM) (if pursue 3) below, it is when the job when CCM mode, sub diode maintains guide till MOSFET grid guides,connect, and MOSFET guides when connecting, restore electric current of sub diode to be added to primary electric current reversely, because this is in,guide an instant is primary bigger voltaic surge appears on electric current; It is when the job when DCM mode, because sub electric current is in,a switch dries up before periodic end, resonance happens between the Coss of Lp and MOSFET.

 

Graph 2 guide continuously a mode

 

Graph 3 discontinuous guide a mode  

 

Graph 4 showed job of switch power source is in DCM mode, the MOSFET voltage of actual measurement and voltaic job are undee, besides can see MOSFET is in the process that debut and involves, all produce bigger voltage and voltaic change, and can see MOSFET is in the instant that debut and closes, produce a few concussion and voltaic aiguille.

 

 

Be like what the graph shows 1 times to contain parasitism element stimulate type converter instead develop attacks graph, among them the bar that Cgs, Cgd and Cds part to be in charge of MOSFET for switch source pole, bar leaks extremely with leakage the stray capacitance of source pole, the leakage of the leakage feeling of the primary inductance that Lp, Lkp, Lks and Cp are transformer respectively, primary inductance, sub inductance feels and the stray capacitance of former edge coil, cj is the knot capacitance that outputs diode. Graph 5 to stimulate transformer instead the job is when DCM job mode, switch canal works respectively in (A) enlightened instant, (B) liberal phase, (C) closes to be mixed for an instant (when D) passes level, the equivalent of place correspondence analyses circuit, the leakage source that Rds provides for switch is extremely equivalent resistor.

 

Graph 5 Stimulate transformer to be in charge of the job to analyse circuit in the equivalent of each phase correspondence in DCM mode switch instead

 

In switch the canal opens the instant, as a result of capacitance two upright voltage cannot choppy, two upright voltage begin stray capacitance Cp is to go up lose below, produce discharge electricity, as switch the canal debuts gradually, vin of power source voltage charges to stray capacitance Cp, its two upright voltage are lost to go up to falling, form the voltaic aiguille that sheds classics switch canal and Vin; At the same time Cds capacitance is in charge of discharge to switch, also form voltaic aiguille, but this aiguille electric current does not shed classics Vin, be in charge of interior to form loop in switch only; Additional, if transformer job is when CCM mode, as a result of primary inductance Lp two upright voltage narrow, diode D begins to bear to slant instead voltage closes, cause retrorse extensive telegram in reply to flow, coupling of transformer of classics of this electric current arrives former side side, also can form the voltaic aiguille that sheds classics switch canal and Vin.

 

In switch the canal opens phase, diode D ends, two upright voltage are capacitance Cp Vin, the voltaic index that carries primary inductance Lp rises, approximate linear rises.

 

In switch the canal closes the instant, id of primary electric current charges for Coss, when Coss the voltage of two end exceeds Vin and NVo (the voltage that deputy foul line of the transformer when diode D is enlightened encircles voltage reflex to answer primary foul line to encircle) when the sum, slanting below the voltage effect that diode D produces in follow on current of primary inductance Lp enlightened, lk and Coss produce resonance, produce voltage of high frequency concussion and electricity.

 

In switch the canal passes level, diode D is slanting enlightened, before memory releases laden end in the energy in Lp, right now deputy foul line encircles voltage by Qian be equal to output voltage Vo, via circling the transformer coupling than be N answers former edge, make capacitance Cp voltage is charged to come NVo (going up below polarity negative) , the voltage of two end of primary inductance Lp by Qian to NVo. After discharge of Lp follow on current ends, d slants instead end, lp and Coss, Cp happening is syntonic, bring about the voltage on Cp to reduce.

 

The equivalent of power MOSFET analyses principle scheme

 

MOSFET is voltage control parts of an apparatus, electrode of the source of power MOSFET, leakage is not inside same plane, also call fore-and-aft MOSFET(namely VMOSFET) , its have a lot of characteristics that are different from transverse MOSFET, regard power MOSFET commonly by the fore-and-aft JFET parts of an apparatus of transverse MOSFET drive, graph 6 showed power MOSFET includes parasitism parts of an apparatus or appliance inside equivalent principle graph, among them the down-lead inductance of the grid that Lg, Ld, Ls is MOSFET respectively, leakage pole, source pole, rg is resistor of MOSFET in-house grid, cgd, Cgs, Cds is MOSFET parasitism capacitance, d is parasitism body diode. As a result of the existence of parasitism parts of an apparatus, make power MOSFET works to become complex with the analysis in what stimulate transformer circuit instead, be in especially commutation instant, the analysis of parasitism parameter appears more important.

 

Graph 6 MOSFET includes parasitism parts of an apparatus or appliance inside equivalent principle graph

 

Exceed the distinction of knot MOSFET and planar MOSFET   Graph the 7 sectional structures that showed planar MOSFET and electric field distributing, the puncture tension that can see planar MOSFET from which depends on the adulteration of drift area is spent and ply, the gradient that electric field distributings and drift area adulteration spend direct ratio. Accordingly, if need to obtain taller puncture voltage, need thicker and the denotative layer of light adulteration, but from MOSFET guide electrify block distributings (if pursue 8) in, the resistance that can see denotative layer seizes a body, especially MOSFET of tall puncture voltage.

 

Graph 7 The sectional structure of planar MOSFET and electric field distributing

 

Graph 8 MOSFET guides electrify block distributings

 

The place on put together is narrated, MOSFET of planar high pressure because structural reason, guide electrify block is larger, bring about guide a loss is bigger, and switch speed also is restricted certainly, switch loss is bigger also, before this cannot have satisfied eye apparently, ask increasingly energy-saving with the electronic market demand that improves converter efficiency. Be based on the defect of planar MOSFET, exceed knot MOSFET emerge as the times require, graph the 9 sectional structures that gave out to exceed knot MOSFET and electric field distributing, differ with the sectional structure of planar MOSFET, MOSFET exceeding a written guarantee used structure of deeper P column, the denotative layer of planar MOSFET almost by alternant N model replace with P semiconductor layer, if planar MOSFET and the model of equivalent parts of an apparatus of MOSFET exceeding a written guarantee pursue 10 are shown.

 

Graph the sectional structure that 9 exceed knot MOSFET and electric field distributing

 

Model of equivalent parts of an apparatus of graph 10 MOSFET

 

P area is inserted on perpendicular direction of MOSFET exceeding a written guarantee, the electric conductance electrify that can compensate excessive carries on his shoulder or back, retrorse bias voltage is added in drift layer, will produce a transverse electric field, make PN knot extinct, when voltage reachs fair value, drift layer is completely extinct, the effect that has voltage to support a layer, make the puncture voltage of parts of an apparatus depends on the ply of N- drift area only, and have nothing to do with the impure chroma of N- area and P trap area, and compensation of this kind of charge is more sufficient, puncture voltage is taller. Because impure pH indicator rises considerably, below identical puncture voltage, guide electrify block Ron can be reduced greatly, break through silicon to be restricted even; Same, mix in identical puncture voltage guide electrify block Ron falls identically, can use smaller chip area, reduce bar charge thereby, raise switch rate, reduce drive power and switch loss, the parameter contrast result that expresses the 1 SW Planer set that showed Xi’an core group is the same as model chip and MOSFET of SW Cool series.

 

Express 1 The parameter of MOSFET of SW Planer series and MOSFET of SW Cool series is comparative

 

The reason that stimulates type converter to produce electromagnetism to disturb instead and transmission way

 

Electromagnetism interference basically is conducted interference and faze of spoke blackberry lily, conducted interference is to be in input and output line are genteel the interference noise that pass, originate noise of wrong standard electric current and in all noise of modular electric current; Faze of spoke blackberry lily is to pass dimensional radiant to disturb noise, originate electric field blasts off and magnetic field blasts off, can change each other between them.  

 

The reason that switch power source produces electromagnetism to disturb is more, it is main noise source with power switch parts of an apparatus and transformer among them. Switch parts of an apparatus debuts high frequencily and close, cause the rapid change of electric current and voltage, the change of fast electric current of inductance and parasitism inductance produces magnetic field, produce taller voltage aiguille UL=L×diL/dt thereby; The fast voltage change of capacitance and parasitism capacitance produces electric field, produce taller voltaic aiguille IC=C×duC/dt thereby, and the passageway that the stray inductance of its interior down-lead and parasitism capacitance are noise coupling, but because these parameter are the character with inherent parts of an apparatus, so the electron is designed and applied engineer cannot undertake optimizing to them, can choose the parts of an apparatus that match according to manual of parts of an apparatus only. The equivalent that switch had analysed to be in charge of MOSFET to include parasitism parts of an apparatus or appliance in front analyses principle scheme, exceed the structure of knot MOSFET and planar MOSFET and parameter distinction, electromagnetism disturbs the account of generation, the architect can choose to use and be optimized according to the circumstance.

 

Transformer regards another as main noise source, and the capacitance between primary and sub leakage feeling, simple layer, capacitance between sub layer, primary and sub the passageway that the coupling capacitance between is noise. Be like what the graph shows 11 times to include the transformer model of parasitism capacitance, among them Ca is the outerest winding arrives the capacitance of magnetism core, ct arrives to assist winding the capacitance of sub winding, cs arrives for primary winding the capacitance of sub winding, cp is the capacitance between the layer of primary winding, cm is most primary winding goes to lining the capacitance of magnetism core; Besides, transformer still has magnetism core to arrive the capacitance Cme of the earth, output line arrives the capacitance Coe of the earth, the capacitance between primary or sub layer can be reduced through reducing the number of plies of winding, the breadth that increases transformer framework window can reduce the number of plies of winding. The depart of winding is circled make, if primary winding uses sandwich to wind a way, can reduce simple leakage feeling, but because increased the interface of primary winding and sub winding,accumulate, increased the coupling electric capacity of primary winding and sub winding consequently. Use cupreous skin screen (need to receive primary or sub static point repeatedly) can reduce the coupling electric capacity between primary winding and sub winding, but because screen layer is circled between primary winding and sub winding, make the coupling coefficient of primary winding and sub winding is reduced, increased leakage to feel again thereby.

 

Graph 11 Include the transformer model of parasitism capacitance

 

Wrong standard electric current inputs power supply cord in two (L, N) turn over directional flow, make voltaic return circuit, among them a source line that is wrong standard electric current, criterion another loop-line that is wrong standard electric current, basically arise by the electric current of high frequency switch of switch parts of an apparatus, graph 12 gave out the wrong standard electricity that switch provides enlightened moment flows circumstance, can see IDM=ICp+ NIR−ICin; Graph 13 gave out the wrong standard electric current that switch canal involves the instant flows circumstance, can see IDM= ICds + Ig−ICp −ICin.

 

Graph 12 Switch provides the wrong standard electricity of enlightened instant

 

Graph 13 Switch provides the wrong standard electricity that passes the instant

 

In all modular electric current flows between input line, output line and earth, main by power parts of an apparatus the change of voltage transient state of high frequency job arises, graph 14 gave out in all the circumstance of passageway of going from place to place of modular electric current, basically include to pass Cs and Cde, Cm and Cme, Ca and Cme, Ct and Coe, Coe to arise in all modular electric current, pass Cs and Coe among them in all modular electric current takes dominant effect.

 

Graph 14 In all modular electric current produces a passage

 

Electric field blasts off to arise by Du/dt, dimensional electric capacity is the channel that electric field launchs, electric current of model of its the Communist Party of China can produce quite big electric field to blast off. Graph the positions of 15 emission source of main electric field that gave out to stimulate converter instead, among them the voltage change amplitude of primary winding is big, launch a dominant action to electric field. Additional, like mobile phone charger this kind of belt length outputs a line (1.8m) product, long output lead also is like with an antenna, can will in all enlarge of modular electric current, form thereby bigger in all modular electric field blasts off.

 

Graph 15 Dash the seat of emission source of main electric field of converter instead

 

Magnetic field blasts off to pass generation of inductance of annulus road parasitism by the annulus road of tall Di/dt, graph the 16 main magnetic field that gave out to stimulate converter instead shoot annulus way, magnetic field launchs direction to accord with right hand formula, among them the voltaic change amplitude of sub side is big, launch a dominant action to magnetic field. Additional, the stray magnetic field of transformer also is emission source of a magnetic field, basically arise by the air gap of transformer, for example E magnetism core opens magnetic field of the stray when air gap in two side big, the magnetic field that opens the stray when air gap in newel is small. Require special attention, the parasitism inductance of road of tall Di/dt annulus increases along with annulus road area and increase, because the design of this PCB launchs special key to magnetic field, the voltaic annulus area of sub side wants as far as possible small, wiring wants as far as possible short thick.

 

Graph 16 The main magnetic field that stimulates converter instead shoots annulus way

 

Improvement uses the stimulates transformer instead electromagnetism of MOSFET exceeding a written guarantee to violate measure

 

Adopt the working principle to stimulating transformer instead, the generation account that electromagnetism disturbs, the equivalent principle of MOSFET pursues, and planar MOSFET and the structure of MOSFET exceeding a written guarantee and parameter contrast are analysed, can see be sent on a diplomatic mission although reduced the loss that stimulates transformer instead and drive power,use MOSFET exceeding a written guarantee, but the switch rate that provides as a result of switch rises, increased voltage and voltaic change rate, make the electromagnetism interference that stimulates transformer instead increases.

 

The harm that electromagnetism disturbs is mixed apparently increasingly serious, at present a lot of countries had measured electromagnetism interference the compulsive test project that regards an electron as equipment, in the light of different type product different interference is restricted to be worth a requirement. Power source serves as electrified wire netting and the interface circuit between the equipment that use phone, while the power that finish conveys and contented electric energy alternates, produce electromagnetism inevitably to disturb, but improve and be restricted to be worth a requirement through the standard, also appear particularly important. Set out from the principle that stimulates transformer to produce electromagnetism to disturb instead, the method that reduces electromagnetism interference basically is the metabolic rate that lowers voltage and electric current; Reduce the parasitism inductance that exists in circuit and electric capacity; Optimize PCB design.

 

One, reduce voltage and voltaic change rate

 

Reduce voltage and voltaic change rate, can pass structure of transformer of resistor of change grid drive, change to perhaps increase amortize to absorb circuit to come true.

 

(1) the switch rate that changes grid resistance to be able to change switch to be in charge of, change the metabolic rate of voltage and electric current, if the graph is shown 17 times, the grid that is in charge of in switch is adscititious drive resistor Rg=Rg1+Rg2, increase Rg, lower the enlightened rate that switch provides, accelerate what switch is in charge of to involve rate. Debut for what switch is in charge of and close speed to be reduced, can be like a graph 17 are shown, to Rg2 paralell connection a low pressure falls to restore diode quickly, if receive D1(solid line) direction, resistor of drive of the grid when switch canal is enlightened is Rg, resistor of drive of the grid when closing is Rg1, the speed when switch canal closes does not want when diode relatively slow.

 

Graph 17 Change grid drive resistor

 

(2) in the switch that stimulates transformer instead the canal closes the instant, because the primary leakage of transformer feels,Lk and the parasitism that switch is in charge of outputted capacitance Coss to make circuit of resonance of a series connection, meeting generation is very tall be pressed too and ringing, the Q cost of circuit is higher, ringing voltage is taller. This kind of exorbitant ringing voltage may cause tremendous electromagnetism interference, and lift as a result of what MOSFET leakage of electricity presses, can reduce the reliability that switch runs even.

 

Change the structure of transformer, the primary winding that gives transformer increases to restore winding NR=Np, make two winding are become double stranded, twine side by side go up in magnetism core or bobbin, form is geminate a winding. If the graph is shown 18 times, NR one aspect of the matter and primary ground are linked together, as homonymic as Np one aspect of the matter joins through a diode D1 Vin. This kind of method makes coupling the biggest change, what obtained parasitism capacitance and inductance is strict match, it is so important that the coupling between primary winding and other winding is done not have.

 

Graph 18 Increase restore winding NR and diode D1 to realize passive damper

 

If the graph is shown 19 times, graph (when A) showed switch canal closes, primary electric current (passageway 2, gules weaveform) after charging for Coss, the leakage in MOSFET extremely (Vds, passageway 1, blue is undee) have ringing. Graph (in B) , passageway 1 still be Vds, of Coss charge the sub electric current that makes pass D (passageway 2) defer make an appointment with 100ns. Graph (in C) , restore winding NR to bypass directly parasitism capacitance Coss, guide accumulated leak energy course of wire back cause, and Qian switch voltage (passageway 1) , as a result of Np=NR, vds so limitation is in double of Vin, and the negative surge of primary electric current (passageway 2) is in fact from the electric current that restores winding to pour out of. Graph (in D) , sub diode D turns into to slanting immediately, leak magnetic flux prevented voltaic transmission, sub electric current (passageway 2) reachs a balanced peak value, be restored completely till leakage release capabilities, primary electric current falls for 0.

 

Graph 19 Increase restore winding NR and contrast without the switch voltage that restores winding and electric current

 

(3) the metabolic rate that amortize draws circuit to change high frequency voltage and electric current, if the graph is shown 20 times, the Qian of RCD of primary winding paralell connection in transformer circuit, because transformer is primary,can check the voltage aiguille that leakage feeling provides the generation in involving a process in switch; L1, L2 and L3 can lower rate of change of high frequency electric current, but L1 and L2 act well to specific frequency band only, and L3 is only right the job at CCM mode ability is effective; R1C1, r2C2, r3C3, r4C4 and C5 can reduce corresponding power parts of an apparatus the ratio of change of high frequency voltage of two end. Of special attention is, all these amortize attract circuit to need to consume certain power, generation is additional power loss, reduce systematic efficiency; Also raise dimension of component amount, PCB and systematic cost at the same time, because this needs,fibrous root chooses to use according to real need.

 

Graph 20 Increase amortize to draw circuit

 

2, the inductance that reduces parasitism and capacitance value

 

From wrong standard electric current and in all the generation reason of modular electric current and analysis of direction of going from place to place, the following proposal reduces wrong standard a few kinds electric current and in all the method of modular electric current, the architect can choose to use according to need and actual condition.

 

(1) wrong standard filter is OK filter divides wrong standard electric current, if the graph is shown 21 times, wrong standard filter is comprise by inductance and capacitance 2 rank low connect filter, as a result of its inductance has stray electric capacity, OK to noise of high frequency interference by stray capacitance bypass, make filter cannot have significant effect, use a few to electroanalysis capacitance paralell connection can reduce ESL and ESR, the Gao Cixie wave that reduces switch electric current electroanalysises because of the input the wrong standard electric current that the ESL of capacitance and ESR form.        

 

Graph 21 Reduce the new structure transformer of wrong standard electric current

 

(2) change transformer structure (if pursue 22) the wrong standard electric current that reduces switch to the canal debuts and close the instant.

 

Graph 22 Reduce the new structure transformer of wrong standard electric current

 

(3) capacitance of shunt-wound between L and N line X, can filter is disturbed except wrong standard.

 

(4) MOSFET uses source pole to join chip matrix is used at coming loose to heat up, and do not use leakage pole, and area of skin of copper of leakage polar region is reduced when PCB wiring, the purpose is to reduce Cde, reduce in all modular electric current.

 

(5) change transformer structure is reduced in all modular electric current, if the graph is shown 23 times, the rectification diode that adjusts auxiliary winding and sub winding sets the position, change voltage change way thereby, the change uses bit of position, and notice quiet place is stood by as far as possible, reduce overall in all modular electric current; Additional, cupreous skin is placed in lining, the width of cupreous skin is less than or be equal to the width of primary winding, the midpoint of cupreous skin receives static point repeatedly by lead, can mix in primary winding and sub winding, auxiliary winding at the same time circle between sub winding make screen winding (also can be cupreous skin, method and lining place cupreous skin to agree) , circle full can, one aspect of the matter receives static point repeatedly, one end is impending inside bury, reduce overall in all modular electric current, but the requirement that the use of screen layer must satisfy efficiency, reduce because of the use meeting of screen layer first sub coupling coefficient, reduce changeover efficiency.

 

Graph 23 Reduce in all the new structure transformer of modular electric current

 

(6) in the first time Y electric capacity is added between class, if the graph is shown 24 times, the much that passes Cs in all modular electric current by Y capacitance bypass, return simple land, because the value of Y capacitance is far,be more than Coe. Y capacitance must direct or arrive with short linear join as far as possible primary with sub quiet place, it is the DV/dt when switch canal is enlightened is more than the DV/dt when closing commonly, y capacitance receives simple land repeatedly, receive Vin repeatedly conversely.

 

Convection of capacitance of graph 24 Y passes the first time class in all the action of modular electric current

 

3, optimize PCB design

 

PCB designs special to the generation that electromagnetism disturbs key, suggest a few kinds of PCB that reduce electromagnetism interference devise a method below, the architect can choose to use according to need and actual condition.

 

(1) input end and the foul line that output end should avoid photograph adjacent parallel, lest produce reflection to disturb, should add ground wire segregation when necessary.

 

(2) the position that plans each functional circuit unit according to the flow of circuit, graph the annulus of 25 4 electric current that gave out to stimulate converter interior instead road, it is power switch canal respectively road of road of road of alternating current annulus, annulus of output commutator alternating current, annulus of input source current and road of annulus of output load current, every annulus road wants to part with other annulus road, input annulus road and road of power switch annulus to must receive the two end that input capacitance directly among them; The join that exports annulus road and rectification annulus way must receive the two end that output capacitance directly; Switch of the filter wave capacitance of switch annulus road, power is in charge of and transformer must be stood by as far as possible place; The commutator that exports rectification annulus way, inductance and filter wave capacitance must be stood by as far as possible place, when placing, need to determine direction of good parts of an apparatus, make the voltaic access between its as far as possible short.

 

Graph 25 Stimulate the road of annulus of main electric current of converter interior instead

 

(3) the wiring of two-phase adjacent layer wants mutual and perpendicular, parallel produces parasitism coupling easily.

 

(4) reduce way of tall Di/dt annulus as far as possible, use wide wiring to be helpful for reducing the interference that need a standard.

 

(5) avoid to take a line squarely, walk along a line to be able to make the line of transmission line broad squarely produce change, cause impedance discontinuous, basically reflect to the influence of signal in: Corner is OK and equivalent the load allowing a gender that goes up for transmission line, slow down rise time; Impedance is discontinuous the reflex that can cause signal; The EMI of orthogonal and most advanced generation.

 

(6) the electromagnetism interference that the rationality of ground connection of interior of switch power source affects power source directly affects his to stabilize the job even, graph the 26 ground wire that gave out to stimulate converter instead arrange a condition, among them power source ground is the spur track below voltaic annulus road; Controlling the land is to join control integrated circuit is mixed to it the ground of relevant passive parts of an apparatus. Control land is very sensitive, after wanting to had been decorated in ways of other alternating current annulus consequently, place again, must pass specific feature and a few other join, the communal join of all parts of an apparatus that this join dot is the little tension that place of generation control IC should detect is nodded, include electric current of electric current transformer to detect the communal contact of resistor and the lower end that output upright resistor voltage divider. Besides, the ground wire of every big electric current wants short and wide, the public end that inputs filter wave capacitance should regard other alternating current as the only contact of the ground.

 

Graph 26 Stimulate the ground wire arrangement of converter instead

 

(7) the skin of copper of shop of PCB ground floor in power source or specified amount are extra skin of a copper or odd face plate, can reduce effectively electric field blasts off and in all modular electric current (if pursue 27) .

 

Graph 27 Reduce electric field to blast off