Govoreći o teškom problemu prekidačkog napajanja, 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: Električne performanse, trasa procesa, sigurnosni zahtjevi, uticaj EMC -a itd .; Među faktorima koje treba uzeti u obzir električna je najosnovnija, ali je EMC najteže razumjeti, a uska grla mnogih projekata leže u EMC -u. Sledi 22 uputstva za deljenje PCB ploče i EMC.

1, zrelo kolo može biti ležerno PCB dizajn EMI kolo

Uticaj navedenog kola na EMC se može zamisliti, ulazni filteri su ovdje; Lightning-proof pressure sensitivity; Otpor R102 za sprečavanje struje udara (s relejem za smanjenje gubitaka); Key error mode X capacitance and Y capacitance with inductor filtering; Postoje osigurači koji utječu na sigurnosnu ploču; Svaki od ovih uređaja je od vitalne važnosti, a funkciju i djelovanje svakog uređaja treba pažljivo cijeniti. 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. Krug i EMC: (najpoznatija glavna topologija preletača, pogledajte koji ključni dijelovi kola sadrže EMC mehanizam)

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. Ali promjenjiva električna struja proizvodi promjenjivo magnetsko polje, a promjenjivo magnetsko polje može proizvesti električno polje (u stvari, ovo je poznata Maxwellova jednadžba i koristim jednostavan jezik), a promjenjivo električno polje može proizvesti i magnetsko polje polje. Zato pazite da obratite pažnju na mjesta gdje postoje stanja uključivanja/isključivanja, to je jedan od izvora EMC -a, a ovo je jedan od izvora EMC -a. 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! Druge dvije petlje su upijajuće petlje i ispravljačke petlje, prvo razumite unaprijed, a zatim razgovarajte!

3. Povezanost između dizajna PCB -a i EMC -a

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. Dio konstrukcije, uzemljenje radijatora nije dobro će utjecati na uzemljenje oklopljene verzije;

4. Ako je osjetljivi dio preblizu izvoru smetnji, poput EMI kruga i razvodne cijevi, to će neizbježno dovesti do slabe EMC, pa je potrebno jasno područje izolacije.

5. Ožičenje RC apsorpcijske petlje.

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:

Kao što je prikazano u isprekidanom okviru na gornjoj slici, ožičenje pina kondenzatora X je uvučeno. Možete naučiti kako ožičenje igle kondenzatora učiniti vanjskim (pomoću ožičenja struje stiskanja). Na taj način učinak filtriranja X kondenzatora može postići najbolje stanje.

4. Priprema za dizajn PCB -a: (ako ste potpuno spremni, dizajn može biti stabilan korak po korak kako biste izbjegli prevrtanje dizajna i ponovno pokretanje)

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. Odabir rute procesa: odabir jednoslojne dvoslojne ploče ili višeslojna ploča, prema shematskom dijagramu i veličini ploče, cijeni i drugoj sveobuhvatnoj procjeni.

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. Rastojanje ulaznog jastučića osigurača veće je od 3.0 mm prema sigurnosnim propisima, a stvarna ploča je 3.5 mm (jednostavno rečeno, udaljenost puzanja osigurača je 3.5 mm prije i 3.0 mm poslije).

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. Sigurnosni propisi za prvu fazu zahtijevaju 6.4 mm (električni razmak), a udaljenost puzanja treba biti 7.6 mm. (Imajte na umu da se ovo odnosi na stvarni ulazni napon, potrebno je pogledati tabelu radi specifičnog proračuna, podaci su samo za referencu, ovisno o stvarnoj situaciji)

5. Cold ground and hot ground are clearly marked for the first stage; L, N oznaka, INPUT AC INPUT oznaka, oznaka upozorenja osigurača i tako dalje trebaju biti jasno označene;

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. U sigurnosnim propisima razumite izolacijske karakteristike bliskog mjesta sa PCB pločom, koje mjesto je osnovna izolacija, koje mjesto je ojačana izolacija, različita standardna udaljenost izolacije nije ista. Najbolje je provjeriti standarde i izračunati električnu udaljenost, udaljenost puzanja.

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. Veza između Y kapacitivnosti i struje curenja i kontaktne struje.

I tako dalje, detaljno će objasniti kako napustiti udaljenost, kako ispuniti sigurnosne zahtjeve.

6, PCB dizajn rasporeda napajanja

1. Prvo izmjerite veličinu PCB -a i broj komponenti kako bi se postigla dobra gustoća ili će gusta, rijetka biti ružna.

2. Modularizirajte krug, uzmite osnovne uređaje kao središte i prvo postavite ključne uređaje.

3. Uređaj je okomit ili vodoravan protiv pozicioniranja, jedan je lijep, drugi je prikladan plug-in rad, posebne okolnosti mogu uzeti u obzir nagib.

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

5. Smanjite područje petlje što je više moguće tokom izgleda. Četiri petlje će biti detaljno objašnjene kasnije.

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

Slijedi prva djevičanska PCB ploča koju sam nacrtao, prije mnogo godina, bilo je jako teško završiti, možda postoji mali problem u sredini, ali opći izgled vrijedi naučiti:

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. Ulazni i izlazni priključci su fiksni i ne mogu se pomicati. Ploča je pravokutna.

Ovdje je raspored odozdo prema gore, slijeva nadesno, a rasipanje topline ovisi o ljusci.

2. EMI krug je još uvijek jasnog smjera protoka, što je vrlo važno, inače nije lijepo i loše za EMC.

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. Gornji sloj velike snage općenito postaje negativan, a donji sloj pozitivan.

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. Cijenjenje primjera PCB -a

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. Razumijevanje četiri petlje dizajna PCB -a: (osnovni zahtjev rasporeda PCB -a je mala površina četiri petlje)

Osim toga, apsorpcijska petlja (RCD apsorpcija, RC apsorpcija MOS cijevi i RC apsorpcija ispravljačke cijevi) je također vrlo važna, što je ujedno i petlja koja stvara visokofrekventno zračenje. Ako imate pitanja o gornjoj brojci, slobodno ih raspravite. Ne bojimo se nikakvih pitanja.

9. Vruća tačka dizajna PCB -a (plutajuća tačka potencijala) i žica za uzemljenje:

Pitanja kojima je potrebna pažnja:

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. Petlja koju stvaraju žarišta je mala i ožičenje je kratko, a ožičenje nije što je moguće deblje, ali sve dok je struja dovoljna.

3. Kabel za uzemljenje mora biti uzemljen na jednom mjestu. Uzemljenje glavnog napajanja i signalno uzemljenje odvojeno, uzorak za uzorkovanje ide odvojeno.

4. Uzemljenje radijatora mora biti spojeno na glavno uzemljenje.