Bisa ga PCB layout na samar da wutar lantarki, wannan takarda tana gabatar da mafi kyawun hanyar shimfidar PCB, misalai da dabaru don haɓaka aikin madaidaicin madaidaicin ƙarfin wutar lantarki.

Lokacin tsara tsarin samar da wutar lantarki, abin da za a fara la’akari da shi shine madaidaicin madaidaicin madaidaicin madaukai biyu na canzawa. 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. A cikin madauki 1 da aka nuna a cikin Hoto 1, halin yanzu mai sarrafa kansa mai wucewa (Cin1) yana wucewa ta MOSFET zuwa inductor na ciki da fitarwa mai wucewa (CO1) yayin ci gaba da gudanar da MOSFET mai ƙarewa, kuma a ƙarshe ya dawo Input kewaye kewaye capacitor.

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

Hoto 1 Tsarin zane na madauki a cikin madaidaicin wutar lantarki

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. Ƙarfin da aka adana a cikin inductor na cikin gida yana gudana ta hanyar fitarwa mai wucewa ta hanyar fitarwa da ƙarancin MOSFEts kafin komawa GND (duba hoto 1). The region where two loops do not overlap each other (including the boundary between loops) is the region with high DI/DT current. Input bypass capacitor (Cin1) yana taka muhimmiyar rawa wajen samar da madaidaicin madaidaicin madaidaici ga mai canzawa da dawo da madaidaicin mitar zuwa hanyar sa.

Fitarwa mai wucewa (Co1) baya ɗaukar nauyin AC da yawa, amma yana aiki azaman matattara mai yawa don sauya amo. Don dalilan da ke sama, yakamata a sanya masu shigar da fitarwa da fitarwa kamar yadda zai yiwu ga nunin VIN da VOUT ɗin su akan ƙirar. Kamar yadda aka nuna a cikin Hoto na 2, za a iya rage shigarwar da waɗannan haɗin ke haifar ta hanyar sanya wayoyi tsakanin masu wucewa masu wucewa da na su VIN da VOUT fil ɗin su a takaice da faɗi.

Hoto 2 madauki mai sauyawa

Rage shigarwar cikin tsarin PCB yana da fa’idodi guda biyu. Na farko, haɓaka aikin ɓangaren ta hanyar haɓaka canja wurin makamashi tsakanin Cin1 da CO1. Wannan yana tabbatar da cewa module ɗin yana da madaidaicin hf, yana rage kololuwar ƙarfin wutar lantarki saboda babban DI/DT na yanzu. Hakanan yana rage amo na na’urar da matsi na ƙarfin lantarki don tabbatar da aiki na yau da kullun. Na biyu, rage girman EMI.

Capacitors da aka haɗa da ƙarancin parasitic inductance suna nuna ƙarancin halayen rashin ƙarfi zuwa madaidaiciyar mitoci, don haka rage sarrafa radiation. Ana ba da shawarar masu ƙarfin yumɓu (X7R ko X5R) ko wasu ƙananan ƙarancin ƙarfin ESR. Ƙarin masu ƙarfin shigarwa na iya shiga cikin wasa idan an sanya ƙarin masu haɓakawa kusa da ƙarshen GND da VIN. 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.

Sau da yawa ana yin sakaci akan tsarin hanyar da’irar, amma tana taka muhimmiyar rawa wajen haɓaka ƙirar samar da wutar lantarki. 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.

Filin ƙasa (gami da gammaye marasa ƙarfi), shigarwar da fitarwa masu ƙarfin wuta, masu farawa masu taushi, da masu tsayayyar amsawa a cikin ƙirar duk yakamata a haɗa su da madauki madaidaiciya akan PCB. Za’a iya amfani da wannan madaidaicin madaidaicin azaman hanyar dawowa tare da ƙarancin ƙarancin haɓaka na yanzu kuma azaman na’urar watsa zafi da aka tattauna a ƙasa.

FIG. 3 Tsarin zane na module da PCB azaman impedance na zafi

Hakanan yakamata a sanya mai tsayayyar amsawa kusa da FB (feedback) fil na module. 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. For an example, see the PCB layout diagram in the relevant module data table.

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

Shawarwarin Zane Mai Yaɗuwa

Ƙaƙƙarfan shimfidar kayayyaki, yayin samar da fa’idodin lantarki, yana da mummunan tasiri akan ƙirar ɓarnawar zafi, inda aka raba madaidaicin iko daga ƙananan Wurare. 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. Kushin yana taimakawa don samar da ƙarancin ƙarancin zafi daga MOSFEts na ciki, wanda yawanci ke haifar da mafi yawan zafi, zuwa PCB.

Rashin ƙarancin zafi (θJC) daga mahaɗin semiconductor zuwa fakitin waje na waɗannan na’urori shine 1.9 ℃/W. Yayin cimma ƙimar θJC da ke jagorantar masana’antu yana da kyau, ƙaramin θJC ba shi da ma’ana lokacin da ƙarancin zafi (θCA) na kunshin waje zuwa iska yayi yawa! Idan ba a ba da hanyar watsawar zafi mai ƙarancin zafi ba ga iskar da ke kewaye, zafin zai taru a kan kushin da ba shi da ƙarfi kuma ba za a iya watsa shi ba. Don haka menene ke ƙayyade θCA? The thermal resistance from bare pad to air is completely controlled by the PCB design and associated heat sink.

Yanzu don saurin duba yadda ake ƙera PCB mai sauƙi ba tare da ƙege ba, adadi na 3 yana kwatanta module ɗin da PCB azaman ƙarancin zafi. Saboda ƙarancin ƙarancin zafi tsakanin mahaɗa da saman fakitin waje yana da girman gaske idan aka kwatanta da ƙarancin zafi daga mahada zuwa kushin da babu ruwansa, za mu iya yin watsi da hanyar heatJA ta ɓarkewar zafi yayin ƙimar farko na juriya na zafi daga mahada zuwa iska mai kewaye (θJT).

Mataki na farko a cikin ƙirar ƙirar zafi shine don tantance adadin ƙarfin da za a watsa. Ana iya ƙididdige ikon da ke amfani da tsarin (PD) cikin sauƙi ta yin amfani da jadawali mai inganci (η) da aka buga a teburin bayanai.

Sannan muna amfani da ƙuntataccen zazzabi na matsakaicin zafin jiki a cikin ƙira, TAmbient, da ma’aunin zafin mahaɗin, TJuncTIon (125 ° C), don ƙayyade juriya na zafin da ake buƙata don samfuran kunshin akan PCB.

A ƙarshe, mun yi amfani da daidaitaccen kimantawa na matsakaicin matsakaicin canja wurin zafi akan farfajiyar PCB (tare da ƙusoshin jan ƙarfe 1-ounce da ramuka masu dumbin yawa a saman bene da ƙasa) don tantance yankin farantin da ake buƙata don watsawar zafi.

Kimantawa yankin PCB da ake buƙata baya la’akari da rawar da ramukan watsa zafi ke watsawa wanda ke canza zafi daga saman ƙarfe (kunshin yana haɗe da PCB) zuwa ƙaramin ƙarfe na ƙasa. Layer na ƙasa yana aiki azaman matakin farfajiya na biyu ta inda convection zai iya canja wurin zafi daga farantin. Aƙalla 8 zuwa 10 ramukan sanyaya ya kamata a yi amfani da su don kimanta yankin yankin don zama mai inganci. Ana kimanta juriya na zafi na matsewar zafi ta lissafin da ke biye.

Wannan kimantawa ya shafi rami na yau da kullun na mil mil 12 tare da bangon jan ƙarfe 0.5 oz. Kamar yadda yakamata a tsara ramukan zafi da yawa a duk yankin da ke ƙasa da kushin mayafi, kuma waɗannan ramukan ramin zafi yakamata su samar da tsararru tare da tazarar 1 zuwa 1.5mm.

ƙarshe

Ƙarfin wutar lantarki na SIMPLE SWITCHER yana ba da madaidaicin ƙirar ƙirar wutar lantarki mai rikitarwa da shimfidar PCB na yau da kullun waɗanda ke da alaƙa da masu canza DC/DC. Yayin da aka kawar da ƙalubalen shimfidawa, har yanzu ana buƙatar yin wasu ayyukan aikin injiniya don haɓaka aikin ƙirar tare da kewaya mai kyau da ƙirar watsa zafi.