Chiwerengero cha opanga digito ndi akatswiri opanga ma board a digito mu gawo laumisiri chikuchulukirachulukira, zomwe zikuwonetsa momwe msika ukuyendera. Ngakhale kutsindika kwa mapangidwe a digito kwabweretsa chitukuko chachikulu muzinthu zamagetsi, kudakalipo, ndipo nthawi zonse padzakhala madera ozungulira omwe amalumikizana ndi analogi kapena malo enieni. Njira zopangira ma waya m'magawo a analogi ndi digito zili ndi zofanana, koma mukafuna kupeza zotsatira zabwino, chifukwa cha njira zawo zopangira ma waya osiyanasiyana, mawonekedwe osavuta opangira ma waya sakhalanso njira yabwino kwambiri.

Nkhaniyi ikufotokoza za kufanana ndi kusiyana kwakukulu pakati pa waya wa analogi ndi digito potengera ma bypass capacitor, magetsi, mapangidwe apansi, zolakwika zamagetsi, ndi kusokoneza kwamagetsi (EMI) chifukwa cha waya wa PCB.

Chiwerengero cha opanga digito ndi akatswiri opanga ma board a digito mu gawo laumisiri chikuchulukirachulukira, zomwe zikuwonetsa momwe msika ukuyendera. Ngakhale kutsindika kwa mapangidwe a digito kwabweretsa chitukuko chachikulu muzinthu zamagetsi, kudakalipo, ndipo nthawi zonse padzakhala madera ozungulira omwe amalumikizana ndi analogi kapena malo enieni. Njira zopangira ma waya m'magawo a analogi ndi digito zili ndi zofanana, koma mukafuna kupeza zotsatira zabwino, chifukwa cha njira zawo zopangira ma waya osiyanasiyana, mawonekedwe osavuta opangira ma waya sakhalanso njira yabwino kwambiri.

Nkhaniyi ikufotokoza za kufanana ndi kusiyana kwakukulu pakati pa waya wa analogi ndi digito potengera ma bypass capacitor, magetsi, mapangidwe apansi, zolakwika zamagetsi, ndi kusokoneza kwamagetsi (EMI) chifukwa cha waya wa PCB.

Kuwonjezera bypass kapena decoupling capacitors pa bolodi dera ndi malo capacitors awa pa bolodi ndi nzeru kwa digito ndi analogi mapangidwe. Koma chochititsa chidwi, zifukwa zake ndi zosiyana.

Pakupanga ma waya a analogi, ma bypass capacitor nthawi zambiri amagwiritsidwa ntchito kudutsa ma siginecha apamwamba kwambiri pamagetsi. Ngati ma bypass capacitor sanawonjezedwe, ma siginecha apamwamba kwambiriwa amatha kulowa tchipisi ta analogi tcheru kudzera pamapini amagetsi. Nthawi zambiri, kuchuluka kwa ma siginecha apamwambawa kumaposa kuthekera kwa zida za analogi kupondereza ma siginecha apamwamba kwambiri. Ngati bypass capacitor sichigwiritsidwa ntchito pamayendedwe a analogi, phokoso limatha kuyambitsidwa munjira yazizindikiro, ndipo muzovuta kwambiri, zitha kuyambitsa kugwedezeka.

Pakupanga kwa analogi ndi digito PCB, bypass kapena decoupling capacitors (0.1uF) akuyenera kuyikidwa pafupi ndi chipangizocho. The magetsi decoupling capacitor (10uF) ayenera kuikidwa pa khomo lamagetsi khomo la bolodi dera. Nthawi zonse, zikhomo za capacitors izi ziyenera kukhala zazifupi.

Pa bolodi la dera mu Chithunzi 2, njira zosiyanasiyana zimagwiritsidwa ntchito poyendetsa magetsi ndi mawaya apansi. Chifukwa cha mgwirizano wosayenerawu, zida zamagetsi ndi mabwalo omwe ali pa bolodi loyang'anira dera amatha kusokonezedwa ndi ma electromagnetic.

Mu gulu limodzi la Chithunzi 3, mphamvu ndi mawaya apansi ku zigawo zomwe zili pa bolodi la dera zili pafupi. Chiŵerengero chofananira cha mzere wamagetsi ndi mzere wapansi mu bolodi la dera ili ndi loyenera monga momwe tawonetsera pa Chithunzi 2. Kuthekera kwa zipangizo zamagetsi ndi mabwalo mu bolodi loyang'anira dera lomwe likukhudzidwa ndi electromagnetic interference (EMI) limachepetsedwa ndi 679 / 12.8 nthawi kapena pafupifupi nthawi 54.
　　
Pazida zamagetsi monga olamulira ndi mapurosesa, ma capacitor ophatikizika amafunikiranso, koma pazifukwa zosiyanasiyana. Ntchito imodzi ya ma capacitor awa ndikuchita ngati banki "yaing'ono".

M'mabwalo a digito, kuchuluka kwamagetsi kumafunika nthawi zambiri kuti musinthe zipata. Popeza kusinthana kwa mafunde osakhalitsa kumapangidwa pa chip panthawi yosintha ndikuyenda kudzera mu bolodi la dera, ndizopindulitsa kukhala ndi ndalama zowonjezera "zopuma". Ngati palibe ndalama zokwanira posinthira, mphamvu yamagetsi idzasintha kwambiri. Kusintha kwamagetsi ochulukirapo kupangitsa kuti siginecha ya digito ilowe m'malo osadziwika bwino, ndipo kungayambitse makina aboma mu chipangizo cha digito kugwira ntchito molakwika.

Kusintha kwapano komwe kumadutsa mumayendedwe a board board kumapangitsa kuti ma voliyumu asinthe, ndipo mawonekedwe a board board amakhala ndi parasitic inductance. Njira yotsatirayi ingagwiritsidwe ntchito kuwerengera kusintha kwa magetsi: V = LdI/dt. Pakati pawo: V = kusintha kwamagetsi, L = mayendedwe a board board trace inductance, dI = kusintha kwapano kudzera mumayendedwe, dt = nthawi yosintha.
　　
Chifukwa chake, pazifukwa zambiri, ndikwabwino kugwiritsa ntchito bypass (kapena decoupling) capacitors pamagetsi kapena pazikhomo zamagetsi zamagetsi zamagetsi.

Chingwe chamagetsi ndi waya pansi ziyenera kuyendetsedwa pamodzi

Malo a chingwe chamagetsi ndi waya wapansi amalumikizana bwino kuti achepetse kuthekera kwa kusokonezedwa kwa ma elekitiroma. Ngati chingwe chamagetsi ndi pansi sizikugwirizana bwino, kuzungulira kwadongosolo kudzapangidwa ndipo phokoso likhoza kupangidwa.

Chitsanzo cha mapangidwe a PCB pomwe chingwe chamagetsi ndi mzere wapansi sizikugwirizana bwino chikuwonetsedwa mu Chithunzi 2. Pa bolodi lozungulira ili, malo ozungulira opangidwa ndi 697cm². Pogwiritsa ntchito njira yomwe yasonyezedwa mu Chithunzi 3, kuthekera kwa phokoso lamagetsi pa kapena kuchoka pa bolodi loyendetsa magetsi mu loop likhoza kuchepetsedwa kwambiri.

Kusiyana pakati pa njira zama waya za analogi ndi digito

▍Ndege yapansi panthaka ndi vuto

Chidziwitso choyambirira cha wiring board board chimagwira ntchito pa ma analogi ndi ma digito. Lamulo lofunika kwambiri ndilo kugwiritsa ntchito ndege yapansi yosasokonezeka. Kuganiza bwino kumeneku kumachepetsa mphamvu ya dI/dt (kusintha kwanthawi ndi nthawi) m'mabwalo a digito, zomwe zimasintha kuthekera kwapansi ndikupangitsa phokoso kulowa mabwalo a analogi.

Njira zopangira ma waya za digito ndi analogi ndizofanana, kupatula kumodzi. Kwa mabwalo a analogi, palinso mfundo ina yoti muzindikire, ndiko kuti, sungani mizere ya digito ndi malupu mu ndege yapansi kutali ndi maulendo a analogi momwe mungathere. Izi zikhoza kutheka mwa kulumikiza ndege yapansi ya analogi ku kugwirizana kwapansi kwa dongosolo padera, kapena kuika dera la analogi kumapeto kwa bolodi la dera, lomwe ndilo mapeto a mzere. Izi zachitika kuti kusokoneza kwakunja panjira ya chizindikiro kukhala kochepa.

Palibe chifukwa chochitira izi kwa mabwalo a digito, omwe amatha kulekerera phokoso lambiri pamtunda wapansi popanda mavuto.

Chithunzi 4 (kumanzere) chimasiyanitsa kusintha kwa digito kuchokera kudera la analogi ndikulekanitsa magawo a digito ndi analogi a dera. (Kumanja) Kuthamanga kwafupipafupi ndi kutsika kwafupipafupi kuyenera kupatulidwa momwe zingathere, ndipo zigawo zikuluzikulu zafupipafupi ziyenera kukhala pafupi ndi zolumikizira bolodi.

Chithunzi 5 Kamangidwe ziwiri pafupi kwambiri pa PCB, n'zosavuta kupanga parasitic capacitance. Chifukwa cha kukhalapo kwa mphamvu yamtunduwu, kusintha kwachangu kwamagetsi pamayendedwe amodzi kumatha kupanga chizindikiro chapano panjira ina.

Chithunzi 6 Ngati simukusamala za kuyika kwa zotsatizana, zotsata mu PCB zitha kutulutsa mzere wa inductance ndi mutual inductance. Izi parasitic inductance ndi zovulaza kwambiri pakugwira ntchito kwa mabwalo kuphatikiza mabwalo osinthira digito.

▍Malo agawo

Monga tafotokozera pamwambapa, pamapangidwe aliwonse a PCB, gawo la phokoso la dera ndi gawo la "chete" (gawo lopanda phokoso) liyenera kupatulidwa. Nthawi zambiri, mabwalo a digito amakhala "olemera" m'phokoso ndipo samamva phokoso (chifukwa mabwalo a digito ali ndi kulekerera kwaphokoso kokulirapo); M'malo mwake, kulolerana kwa phokoso lamagetsi kwa ma analogi ndi kochepa kwambiri.

Mwa awiriwa, mabwalo a analogi ndi omwe amamva phokoso lakusintha. Mu mawaya a makina osakanikirana, mabwalo awiriwa ayenera kupatulidwa, monga momwe tawonetsera pa Chithunzi 4.
　　
▍Zigawo za Parasitic zopangidwa ndi mapangidwe a PCB

Zinthu ziwiri zoyambira za parasitic zomwe zingayambitse mavuto zimapangika mosavuta pamapangidwe a PCB: parasitic capacitance ndi parasitic inductance.

Popanga bolodi lozungulira, kuyika zizindikiro ziwiri pafupi ndi mzake kumapanga mphamvu ya parasitic. Mungathe kuchita izi: Pazigawo ziwiri zosiyana, ikani kalozera kamodzi pamwamba pa mzere wina; kapena pagawo lomwelo, ikani kalozera kamodzi pafupi ndi katsambo kena, monga momwe chithunzi 5 chikusonyezera.
　　
M'masanjidwe awiriwa, kusintha kwamagetsi pakapita nthawi (dV/dt) panjira imodzi kungayambitsenso kutsata kwina. Ngati njira inayo ndi yopingasa kwambiri, yomwe imapangidwa ndi gawo lamagetsi imasinthidwa kukhala voteji.
　　
Kuthamanga kwamagetsi othamanga nthawi zambiri kumachitika kumbali ya digito ya kapangidwe ka ma analogi. Ngati ma track omwe ali ndi ma voltage transients othamanga ali pafupi ndi ma analogi apamwamba kwambiri, cholakwika ichi chidzakhudza kwambiri kulondola kwa dera la analogi. M'malo awa, mabwalo a analogi ali ndi zovuta ziwiri: kulekerera kwawo phokoso kumakhala kochepa kwambiri kusiyana ndi maulendo a digito; ndipo mawonekedwe apamwamba a impedance amapezeka kwambiri.
　　
Kugwiritsa ntchito imodzi mwa njira ziwiri zotsatirazi kungachepetse chodabwitsa ichi. Njira yomwe imagwiritsidwa ntchito kwambiri ndikusintha kukula pakati pa ziwonetsero molingana ndi capacitance equation. Kukula kothandiza kwambiri kusintha ndi mtunda pakati pa ziwonetsero ziwirizo. Tiyenera kuzindikira kuti kusintha d kuli mu denominator ya capacitance equation. Pamene d ikuwonjezeka, mphamvu ya capacitive idzachepa. Kusintha kwina komwe kungasinthidwe ndi kutalika kwa njira ziwirizo. Pachifukwa ichi, kutalika kwa L kumachepa, ndipo mphamvu ya capacitive pakati pa zizindikiro ziwirizi idzachepanso.
　　
Njira ina ndiyo kuyala waya pansi pakati pa njira ziwirizi. Waya wapansi ndi wocheperako, ndipo kuwonjezera njira ina ngati iyi kufooketsa gawo lamagetsi losokoneza, monga momwe tawonetsera pa Chithunzi 5.
　　
Mfundo ya parasitic inductance mu bolodi yozungulira ndi yofanana ndi ya parasitic capacitance. Ndikonso kuyala mipata iwiri. Pazigawo ziwiri zosiyana, ikani kalozera kamodzi pamwamba pa mzere wina; kapena pagawo lomwelo, ikani kalozera kamodzi pafupi ndi mzake, monga momwe chithunzi 6 chikusonyezera.

M'makonzedwe awiriwa a mawaya, kusintha kwamakono (dI / dt) kwa kufufuza ndi nthawi, chifukwa cha inductance ya ndondomekoyi, idzapanga magetsi pamtunda womwewo; ndipo chifukwa cha kukhalapo kwa mutual inductance, idzakhala Mphamvu yofananira imapangidwa mwanjira ina. Ngati kusintha kwamagetsi pamayendedwe oyamba ndikokwanira, kusokoneza kungachepetse kulolerana kwamagetsi pagawo la digito ndikuyambitsa zolakwika. Chodabwitsa ichi sichimangochitika m'mabwalo a digito, koma chodabwitsachi chimakhala chofala kwambiri m'mabwalo a digito chifukwa cha mafunde akuluakulu osinthasintha nthawi yomweyo m'mabwalo a digito.
　　
Kuti muchotse phokoso lomwe lingakhalepo kuchokera kuzinthu zosokoneza ma elekitiroma, ndi bwino kulekanitsa mizere "yabata" ya analogi ku madoko aphokoso a I/O. Kuti muyese kupeza mphamvu yochepetsera mphamvu ndi maukonde apansi, kutsekemera kwa mawaya a digito kuyenera kuchepetsedwa, ndipo kugwirizanitsa kwa mabwalo a analogi kuyenera kuchepetsedwa.
　　
03

Mapeto

Magawo a digito ndi analogi akatsimikiziridwa, kuwongolera mosamala ndikofunikira pa PCB yopambana. Njira yopangira ma wiring nthawi zambiri imayambitsidwa kwa aliyense ngati lamulo, chifukwa ndizovuta kuyesa kupambana kwakukulu kwa mankhwalawa mu malo a labotale. Choncho, ngakhale kufanana kwa njira zopangira ma waya za digito ndi analogi, kusiyana kwa njira zawo zamawaya kuyenera kuzindikirika ndikutengedwa mozama.