E thehiloe ho PCB Moralo oa phepelo ea motlakase, pampiri ena e hlahisa mekhoa e metle ka ho fetisisa ea sebopeho sa PCB, mehlala le mekhoa ea ho ntlafatsa ts’ebetso ea mochini oa motlakase o bonolo oa switcher.

Ha o rera moralo oa phepelo ea motlakase, ho nahaneloa pele ke sebaka sa lupu sa ‘mele sa likonopo tse peli tse ntseng li chencha. Although these loop regions are largely invisible in the power module, it is important to understand the respective current paths of the two loops because they extend beyond the module. Ho loop 1 e bonts’itsoeng ho Setšoantšo sa 1, hona joale ho ithaopela ho kenya letsoho ho feta capacitor (Cin1) ho fetela ho MOSFET ho ea ho inductor le ho tsoa ha capacitor (CO1) ka nako e tsoelang pele ea ho tsamaisa MOSFET, mme qetellong e khutlela ho input kgaoleditse capacitor.

Schematic diagram of loop in the power module www.elecfans.com

Setšoantšo sa 1 Setšoantšo sa sekema sa loop mojuleng oa matla

Loop 2 is formed during the turn-off time of the internal high-end MOSFEts and the turn-on time of the low-end MOSFEts. Matla a bolokiloeng ho inductor ea ka hare a phalla ka har’a phetho ea ho feta capacitor le li-MOSFEts tse tlase pele a khutlela GND (bona Setšoantšo sa 1). Sebaka seo likhahla tse peli li sa tsamaellaneng (ho kenyeletsoa moeli o pakeng tsa likonopo) ke sebaka se nang le DI / DT e phahameng hona joale. The input bypass capacitor (Cin1) e bapala karolo ea bohlokoa ho fepeleng maqhubu a phahameng ho mofetoleli le ho khutlisetsa maqhubu a phahameng hona joale tseleng ea ona ea mohloli.

Sehlahisoa sa bypass capacitor (Co1) ha se na AC ea hajoale, empa se sebetsa joalo ka sefahla sa maqhubu a phahameng sa ho chencha lerata. Bakeng sa mabaka a kaholimo, li-capacitor tsa ho kenya le ho hlahisa li lokela ho beoa haufi ka hohle kamoo ho ka khonehang ho lithapo tsa bona tsa VIN le VOUT mojulung ona. Joalo ka ha ho bonts’itsoe ho Setšoantšo sa 2, khaello e hlahisoang ke likhokelo tsena e ka fokotsoa ka ho etsa hore wiring lipakeng tsa li-capacitor tse fetang le lipini tsa bona tsa VIN le VOUT li be khuts’oane ka bophara kamoo ho ka khonehang.

Setšoantšo sa 2 SIMPLE SWITCHER loop

Nyenyefatsa inductance ka moralo PCB o na le melemo e ‘meli e meholo. Taba ea mantlha, ntlafatsa ts’ebetso ea likarolo ka ho khothaletsa phetiso ea matla lipakeng tsa Cin1 le CO1. Sena se tiisa hore module eo e na le hf e ntle e fetang, e fokotsa litlhoro tsa motlakase tse matlafatsang ka lebaka la boemo bo phahameng ba DI / DT. E boetse e fokotsa lerata la sesebelisoa le khatello ea motlakase ho netefatsa ts’ebetso e tloaelehileng. Taba ea bobeli, fokotsa EMI.

Li-capacitor tse hokahaneng le likhahla tse fokolang tsa likokoana-hloko li bonts’a litšobotsi tse tlase tsa impedance ho maqhubu a phahameng, ka hona ho fokotsa mahlaseli a kotsi. Ceramic capacitors (X7R kapa X5R) kapa li-capacitor tse ling tse tlase tsa ESR lia khothaletsoa. Lisebelisoa tse ling tsa ho kenya letsoho li ka sebetsa ha feela li-capacitor tse ling li beoa pela GND le VIN e fela. The Power module of the SIMPLE SWITCHER is uniquely designed to have low radiation and conducted EMI. However, follow the PCB layout guidelines described in this article to achieve higher performance.

Moralo oa potoloho oa hajoale oa potoloho hangata oa hlokomolohuoa, empa o bapala karolo ea bohlokoa ho ntlafatseng moralo oa phepelo ea motlakase. In addition, ground wires to Cin1 and CO1 should be shortened and widened as much as possible, and bare pads should be directly connected, which is especially important for input capacitor (Cin1) ground connections with large AC currents.

Lithakhisa tse theotsoeng (ho kenyeletsoa liphahlo tse se nang letho), li-capacitor tsa tlhahiso le tlhahiso, li-capacitor tse bonolo, le lihanyetsi tsa maikutlo mojuleng kaofela li lokela ho hokahanngoa le lera la PCB. Lera lena le ka sebelisoa e le tsela ea ho khutla e nang le ts’ebetso e tlase haholo ea hajoale ebile e le sesebelisoa sa ho chesa mocheso se tšohloang ka tlase.

FEIE. 3 Moralo oa moralo oa module le PCB joalo ka impedance ea mocheso

Resistor resistor e lokela ho beoa haufi ka hohle kamoo ho ka khonehang ho pini ea FB (maikutlo) mojuleng ona. To minimize the potential noise extraction value at this high impedance node, it is critical to keep the line between the FB pin and the feedback resistor’s middle tap as short as possible. Available compensation components or feedforward capacitors should be placed as close to the upper feedback resistor as possible. Bakeng sa mohlala, bona setšoantšo sa moralo oa PCB tafoleng ea data ea module.

For AN example layout of LMZ14203, see the application guide document AN-2024 provided at www.naTIonal.com.

Litlhahiso tsa Moralo oa Phokotso ea Mocheso

Sebopeho sa li-module, ha se ntse se fana ka melemo ea motlakase, se na le tšusumetso e mpe ho moralo oa ho chesa mocheso, moo matla a lekanang a qhaloang ho tsoa libakeng tse nyane. To address this problem, a single large bare pad is designed on the back of the Power module package of the SIMPLE SWITCHER and is electrically grounded. Pad e thusa ho fana ka tšitiso e tlase haholo ea mocheso ho tsoa ho li-MOSFEts tsa kahare, tseo hangata li hlahisang mocheso o mongata, ho PCB.

The impedance ea mocheso (θJC) ho tloha mateanong a semiconductor ho isa sephuthelong se kantle sa lisebelisoa tsena ke 1.9 ℃ / W. Le ha ho fihlella boleng ba θJC bo etelletseng pele indastering ho nepahetse, boleng bo tlase ba θJC ha bo utloahale ha phallo ea motlakase (θCA) ea sephutheloana se kantle moeeng e le kholo haholo! Haeba ho se na tsela ea mocheso oa mocheso o tlase oa mocheso o fanoang moeeng o haufi, mocheso o tla bokellana holim’a sethala se se nang letho mme o ke ke oa qhalana. Joale ke eng e khethollang θCA? Khanyetso ea mocheso ho tloha mohahong o senang letho e laoloa ka botlalo ke moralo oa PCB le sink e amanang le eona ea mocheso.

Joale ho sheba ka potlako mokhoa oa ho rala PCB e bonolo ntle le mapheoana, setšoantšo sa 3 se bonts’a module le PCB joalo ka impedance ea mocheso. Hobane khatello ea mocheso lipakeng tsa mateano le bokaholimo ba sephutheloana sa kantle e batla e le holimo ha e bapisoa le tšitiso ea mocheso ho tloha mateanong ho ea pitseng e se nang letho, re ka iphapanyetsa tsela ea ho chesa mocheso ea θJA nakong ea khakanyo ea pele ea khanyetso ea mocheso ho tloha mateanong moea o potileng (θJT).

Mohato oa pele oa moralo oa ho chesa mocheso ke ho tseba hore na matla a tla qhaloa ke a makae. Matla a sebelisoang ke module (PD) a ka baloa habonolo ho sebelisoa graph e sebetsang hantle (η) e phatlalalitsoeng tafoleng ea data.

Ka mor’a moo re sebelisa litšitiso tsa mocheso o phahameng ka ho fetesisa mohahong, TAmbient, le mocheso o lekantsoeng oa mateano, TJuncTIon (125 ° C), ho tseba hore na mocheso oa mocheso o hlokahalang bakeng sa li-module tse pakiloeng ho PCB.

Kamora nako, re sebelisitse khakanyo e nolofalitsoeng ea phetisetso ea mocheso o phahameng o fetisang holim’a PCB (e nang le mapheoana a koporo a 1-ounce a sa senyehang le masoba a mangata a siling mochesong kaholimo le tlase) ho tseba sebaka sa poleiti se hlokahalang bakeng sa ho chesa mocheso.

Khakanyo e hlokahalang ea PCB ha e nahane ka karolo e bapaloang ke masoba a mocheso a futhumatsang a fetisang mocheso ho tloha siling e kaholimo ea tšepe (sephutheloana se hokahane le PCB) ho ea lera le ka tlase la tšepe. Lera le ka tlase le sebetsa e le karolo ea bobeli ea bokaholimo eo ka eona convection e ka fetisang mocheso ho tloha poleiting. Ho lokela hore ho sebelisoe likoti tse pholileng tse 8 ho isa ho tse 10 bakeng sa ho lekanyetsa sebaka sa boto hore se sebetse. Khanyetso ea mocheso oa teba ea mocheso e hakantsoe ke equation e latelang.

Khakanyo ena e sebetsa ho lesoba le tloaelehileng la bophara ba limithara tse 12 le bophara ba 0.5 oz ea koporo. Masoba a mangata a ho teba ka mocheso ha ho khoneha a lokela ho raloa sebakeng sohle se ka tlasa sethala se se nang letho, ‘me masoba ana a teba mocheso a lokela ho theha sehlopha se nang le sebaka sa 1 ho isa ho 1.5mm.

bofello

Module oa motlakase oa SIMPLE SWITCHER e fana ka mokhoa o mong ho meralo e rarahaneng ea phepelo ea motlakase le meralo e tloaelehileng ea PCB e amanang le li-converter tsa DC / DC. Ha liphephetso tsa peakanyo li tlositsoe, mosebetsi o mong oa boenjineri o ntse o hloka ho etsoa ho ntlafatsa ts’ebetso ea mojule ka mokhoa o motle oa ho feta le mocheso oa mocheso.