Gepraat van die moeilike probleem van die skakelaar se kragtoevoer, PCB cloth plate problems is not very difficult, but if want to cloth up a refined PCB must be one of the difficulties in switching power supply (PCB design is not good, may cause no matter how to debug parameter debugging cloth out of the situation, so not scaremongering) when reason was the PCB board consideration or a lot of, such as: Elektriese werkverrigting, prosesroete, veiligheidsvereistes, EMC -impak, ens .; Onder die faktore wat oorweeg moet word, is elektries die basiesste, maar EMC is die moeilikste om te verstaan, en die knelpunt van baie projekte lê by EMC. Die volgende uit 22 rigtings om die PCB -bord en EMC te deel.

1, ‘n volwasse stroombaan kan rustig wees met ‘n PCB -ontwerp -EMI -kring

Die impak van die bogenoemde stroombaan op EMC kan voorgestel word; die insetfilters is hier; Lightning-proof pressure sensitivity; Weerstand R102 om skokstroom te voorkom (met relais om verlies te verminder); Key error mode X capacitance and Y capacitance with inductor filtering; Daar is sekuriteite wat die veiligheidsbord beïnvloed; Elkeen van hierdie toestelle is van kardinale belang, en die funksie en werking van elke toestel moet deeglik waardeer word. The EMC severity level should be considered when designing the circuit, such as the number of filters to be set, the number and location of the y-capacitor quantity. The choice of pressure-sensitive size and quantity is closely related to our requirements for EMC. Welcome to discuss the seemingly simple EMI circuit that actually contains profound truths for each component.

2. Kring en EMC: (die mees bekende terugvloei -hooftopologie, kyk watter sleuteldele van die stroombaan EMC -meganisme bevat)

The circled parts in the circuit in the figure above are very important for EMC (note that the green part is not), such as radiation. It is known that electromagnetic field radiation is spatial, but the basic principle is the change of magnetic flux, which involves the effective cross-sectional area of magnetic field, namely the corresponding loop in the circuit. The electric current can produce a magnetic field, which is stable and cannot be converted into an electric field. Maar ‘n veranderende elektriese stroom produseer ‘n veranderende magnetiese veld, en ‘n veranderende magnetiese veld kan ‘n elektriese veld produseer (dit is eintlik die beroemde Maxwell -vergelyking en ek gebruik gewone taal), en ‘n veranderende elektriese veld kan ook ‘n magnetiese veld produseer veld. Maak dus seker dat u aandag gee aan die plekke waar daar aan/af toestande is, dit is een van die bronne van die EMC, en dit is een van die bronne van die EMC. For example, the dotted line loop in the circuit is the opening and closing loop of the switch tube. Not only the switching speed can be adjusted during the design of the circuit, but also the area of the wiring loop of the layout board has an important influence on EMC! Die ander twee lusse is absorpsielusse en regstellende lusse, verstaan ​​eers vooraf en praat dan!

3. Vereniging tussen PCB -ontwerp en EMC

1.PCB loop has a very important influence on EMC, such as flyback main power loop. If it is too large, the radiation will be poor.

2. Filter wiring effect, filter is used to filter out interference, but if PCB wiring is not good, filter may lose the effect it should have.

3. The structure part, the radiator design grounding is not good will affect the grounding of the shielded version;

4. As die sensitiewe deel te naby aan die steuringsbron is, soos EMI -stroombaan en skakelbuis, sal dit noodwendig lei tot swak EMC, en ‘n duidelike isolasiegebied is nodig.

5. Bedrading van RC -absorpsielus.

6.Y capacitor grounding and wiring, and the position of Y capacitor is also critical!

I’m going to talk about this, and I’m going to talk about it more, but I’m going to give you a lead.

Here’s a quick example:

Soos in die gestippelde boks in die bostaande figuur getoon, is die bedrading van die X -kondensatorpen ingespan. U kan leer hoe u die bedrading van die kondensatorpen ekstern kan maak (met behulp van die persstroombedrading). Op hierdie manier kan die filtereffek van X -kondensator die beste toestand bereik.

4. Voorbereiding vir PCB -ontwerp: (as u volledig voorbereid is, kan die ontwerp stap vir stap stabiel wees om te voorkom dat die ontwerp omval en weer begin)

There are roughly the following aspects, are their own design process to consider, all the content has nothing to do with other tutorials, are just their own experience summary.

1. Appearance structure size, including positioning hole, air channel flow direction, input and output socket, need to match with the customer system, also need to communicate with the customer assembly problems, height limit and so on.

2. Safety certification, products do what kind of certification, where do the basic insulation creepage distance to leave enough, where do strengthen the insulation to leave enough distance or slot.

3. Packaging design: there is no special period, such as preparation for customized packaging.

4. Proses roete keuse: enkel paneel dubbel paneel seleksie, of multi-laag bord, volgens die skematiese diagram en bord grootte, koste en ander omvattende evaluering.

5. Other special requirements of customers.

The structure and process will be relatively more flexible, safety regulations or relatively fixed part, what certification to do, what safety standards, of course, there are some safety regulations are common in many standards, but there are also some special products such as medical treatment will be more stringent.

For the new entry engineer friends are not dazzled;

Next list some general products general, the following is summarized for IEC60065 specific cloth requirements, for safety needs to keep in mind, encounter specific products will be targeted processing:

1. Die afstand van die ingangskerm is groter as 3.0 mm soos vereis deur veiligheidsvoorskrifte, en die werklike plaat is 3.5 mm (eenvoudigweg, die kruipafstand van die lont is 3.5 mm voor en 3.0 mm daarna).

2. Before and after the rectifier bridge, the safety requirements are 2.0MM, and the plate layout is 2.5MM.

3. After rectification, safety regulations generally do not require, but the distance between high and low voltage is left according to the actual voltage, and 400V high voltage is left above 2.0mm.

4. Die veiligheidsvoorskrifte vir die eerste fase vereis 6.4 mm (elektriese gaping), en die kruipafstand moet 7.6 mm wees. (Let daarop dat dit verband hou met die werklike ingangsspanning; verwys na die tabel vir ‘n spesifieke berekening, die gegewens is slegs ter verwysing, onderhewig aan die werklike situasie)

5. Cold ground and hot ground are clearly marked for the first stage; L, N merk, INPUT AC INPUT merk, lont waarskuwing punt ensovoorts moet duidelik gemerk wees;

It is reiterated that the actual safety distance is related to the actual input voltage and the working environment, so it is necessary to refer to the table for specific calculation. The data provided is for reference only and shall prevail in the actual situation.

5. Consider other factors for PCB design safety

1. Understand what certification their products do and what product categories they belong to. For example, medical treatment, communication, electricity, TV and so on are different, but there are also many similarities.

2. In veiligheidsvoorskrifte, verstaan ​​die isolasie -eienskappe van die nabye plek met PCB -bord, die basiese isolasie, die plek is versterkte isolasie, verskillende standaard isolasie -afstand is nie dieselfde nie. Dit is die beste om die standaarde na te gaan en die elektriese afstand en kruipafstand te bereken.

3. Focus on the safety devices of the product, such as the relationship between the magnetism of the transformer and the original side;

4. Radiator and surrounding distance problem, radiator insulation is not the same as the ground is not the same, the ground is cold, hot insulation is the same cloth.

5. Special attention should be paid to the distance of insurance, requiring the strictest place. The distance between front and rear of the fuse is consistent.

6. Verhouding tussen Y kapasitansie en lekstroom en kontakstroom.

En so meer, sal dit in detail verduidelik hoe om die afstand te verlaat, hoe om veiligheidsvereistes te doen.

6, PCB -ontwerp van die uitleg van die kragtoevoer

1. Meet eers die grootte van die PCB en die aantal komponente, sodat ‘n goeie digtheid of ‘n digte, yl lelik sal wees.

2. Moduleer die kring, neem die kerntoestelle as die middelpunt en plaas die sleuteltoestelle eerste.

3. Die toestel is vertikaal of horisontaal anti-posisioneer, die een is pragtig, die ander is gerieflik om in te skakel, spesiale omstandighede kan die kanteling oorweeg.

4. Take cabling into consideration and arrange the layout in the most reasonable position for subsequent cabling.

5. Verminder die lusgebied soveel as moontlik tydens die uitleg. Die vier lusse sal later in detail verduidelik word.

Do the above points, of course, flexible use, more reasonable layout will be born soon.

Die volgende is die eerste maag -PCB wat ek geteken het, baie jare gelede, dit was baie moeilik om af te handel; daar kan ‘n klein probleem in die middel wees, maar die algemene uitleg is die moeite werd om te leer:

In this figure, the power density is still relatively high. The control part of LLC, the auxiliary source part and the BUCK circuit driver (high-power multi-channel output) part are on the small board, which is not taken out. Let’s take a look at the layout characteristics of the main power:

1. In- en uitsetterminale is vas en kan nie verskuif word nie. Die bord is reghoekig.

Hier is die uitleg van onder na bo, van links na regs, en die hitte -afvoer is afhanklik van die dop.

2.EMI -stroombaan is nog steeds ‘n duidelike vloeirigting, wat baie belangrik is, anders is dit nie mooi en sleg vir EMC nie.

3. The position of large capacitor should consider PFC loop and LLC main power loop as far as possible;

4. The current of the side side is relatively large. In order to run the current and dissipate the heat of the rectifier tube, this layout is adopted. Die boonste laag van hoë krag gaan oor die algemeen negatief, en die onderste laag word positief.

Each board has its own characteristics, of course, also has its own difficulties, how to reasonably solve the key, we can understand the layout of reasonable selection of meaning?

7. Waardering van PCB -voorbeelde

I think it is a good place to do it. Of course, there will always be defects, which can also be pointed out. It is not easy for a single panel to be so compact, so you can use this board to learn and discuss! Behind will also be for this board to explain learning, we first enjoy.

8. Understanding of the four loops of PCB design :(the basic requirement of PCB layout is the small area of the four loops)

In addition, the absorption loop (RCD absorption, RC absorption of MOS tube and RC absorption of rectifier tube) is also very important, which is also the loop that generates high frequency radiation. If you have any questions about the above figure, you are welcome to discuss them. We are not afraid of any questions.

9. PCB ontwerp hot spot (drywende potensiële punt) en gronddraad:

Sake wat aandag benodig:

1. Pay special attention to hot spots (high-frequency switching points), which are high-frequency radiation points. Cable layout has a great impact on EMC.

2. Die lus wat deur hot spots gevorm word, is klein en die bedrading is kort, en die bedrading is nie so dik as moontlik nie, maar solank die stroom voldoende is.

3. Die aardkabel moet op ‘n enkele punt geaard word. Die hoofkrag en die seingrond word apart geskei, die monsterneming word afsonderlik gedoen.

4. Die grond van die verkoeler moet aan die hoofkraggrond gekoppel word.