Capacitor Voltage Derating Guidelines yePCB Dhizaini

Nhanganyaya: Mutengo weKusatsanangurika

Mushure mekuongorora mazana ekutadza kwemagetsi emagetsi paHighleap Electronics, imwe pateni inobuda nguva dzose: isina kukwana capacitor voltage derating. Chinjanji che12V chinofambiswa ne16V-yakatemerwa MLCCs inoratidzika kuva inodhura kusvika kudzoka kumunda kwatanga mwedzi mitanhatu mushure mekutumirwa. Icho chikonzero chinoratidza sekuparara kwedielectric nguva isati yakwana, kukurumidza kuchembera, kana kurasikirwa kwese kwekushanda pasi pemamiriro ekushanda epasirese.

Kubvisa voltage ye capacitor zvinoreva kushandisa capacitor iri pasi pevoltage yayo yepamusoro. Iyi tsika inokanganisa zvakananga magadzirirwo matatu akakosha: kuvimbika kwenguva refu, kutonga kushushikana kwekupisa, uye kugona kushanda zvakanaka pasi peDC bias. Kune vagadziri vePCB, kubvisa voltage kwakakodzera hakusi kushandisa mainjiniya zvakanyanya asi chinhu chakakosha kune zvigadzirwa zvinofanirwa kurarama kupfuura nguva yewarandi.

Chii chinonzi Capacitor Voltage Derating?

Kubviswa kwevoltage ye capacitor kunoratidza mukana wekuchengetedza pakati pevoltage chaiyo yekushanda nevoltage yepamusoro yechikamu. Chiyero chekubviswa kwevoltage chinoratidza hukama uhwu seDR = V_operating / V_rated . Sisitimu ye12V inoshandisa capacitor ine 25V-rated inowana 48% derating, ichipa dziviriro yakakura kubva kumagetsi anochinja uye kukwegura.

Vagadziri vanotsanangura zviyero zvakanyanya pasi pemamiriro emurabhoritari akakodzera ane zvishoma zvinotarisirwa zvehupenyu, nepo zvikumbiro zvepasirese zvichiunza tembiricha yebhasikoro, voltage ripple, uye zviitiko zvekuvhiya izvo zvinokurumidza kukanganisa ma capacitor anoshanda pedyo nemagetsi.

Nei Capacitor Voltage Derating Isiri-Kukurukurirana

Dzivirira Dielectric Kuparara

Dielectric kuputsika kunomiririra njodzi uye kukundikana kusingadzoreki. Kana simba remunda wemagetsi richipfuura kugona kwe dielectric zvinhu, kupera kwemuviri kunoitika. Misiyano yekugadzira uye hurema hwemicroscopic inoderedza kuparara chaiko pazasi pezviyero zvakayerwa. Voltage derating inovimbisa kuti simba remunda wemagetsi rinoramba riri mukati memiganhu yakachengeteka kunyangwe nechikamu-kune-chikamu musiyano.

Kuvandudza Kuvimbika Kwenguva Yakareba uye Kuchembera

Capacitor lifespan inotevera exponential hukama nevoltage kusagadzikana uye tembiricha. Kushanda pa90% yemagetsi akayerwa kunogona kuderedza hupenyu hunotarisirwa ne50% zvichienzaniswa ne50% voltage stress. Nguva-inotsamira dielectric kuparara kunomhanyisa sezvo voltage inoswedera yakatemerwa miganhu, nekutadza kukwira kuri kuwedzera zvakanyanya. Yakakodzera capacitor voltage derating inopa 5-10x kuvandudzwa mukati menguva pakati pekutadza.

Bata Transient Overshoot uye Surge Zviitiko

Switched-mode magetsi emagetsi anogadzira voltage spikes panguva yekuchinja shanduko. Motokari inrush currents inogadzira njanji inotakura inodarika 150% yezita remagetsi. Izvi zviitiko zvenguva pfupi zvinowanzoitika mumasisitimu akaiswa asi hazviwanzo kuoneka panguva yekuyedzwa kwebhenji. Yakakwana voltage derating inopa inodiwa headroom kuti itore overshoot zviitiko pasina chikamu kushushikana kana kukuvara.

Deredza DC Bias Kurasikirwa muMLCC

Macapacitor eceramic ane layer yakawanda anowana kurasikirwa kwakanyanya kwe capacitance pasi pe DC bias voltage. Ma dielectric eClass II akadai seX5R neX7R anogona kurasikirwa ne60-80% ye nominal capacitance kana achishanda pedyo ne rated voltage. 10μF MLCC yakayerwa ye16V inogona kupa 2-3μF chete kana yaiswa 12V DC bias. Izvi zvinoita kuti capacitor voltage irambe yakakosha pakuchengetedza functional capacitance values.

Kuti uwane ongororo yakakwana yekugadzira, shandisa chinyorwa ichi pamwe chete neDFM review uye zvikamu zve circuit board pakutarisa zvinodiwa zve stackup, assembly, kana bvunzo.

Capacitor Voltage Derating Guidelines neType

MLCC Voltage Derating Zvinodiwa

1. X5R / X7R MLCCs - 50-70% inoderera
   Yakakomba DC bias mhedzisiro inotanga pamusoro ~ 50% yeyakayerwa voltage, ichidzikisa inoshanda capacitance zvinoshamisa. Kune 12V njanji, izvi zvinowanzoda kusarudza 25V kana 50V yakayerwa zvikamu kuchengetedza capacitance uye kuvimbika kwenguva refu.
2. C0G / NP0 MLCCs - ~ 20% kuderedza
   Aya ma dielectrics anoratidza kushoma DC bias kusiyanisa asi achiri kubatsirwa kubva kune yekuchengetedza muganho kudzivirira kuparara uye kuve nechokwadi chekushanda kwakagadzikana pasi petembiricha uye kushushikana kwemagetsi.

Tantalum Capacitor Derating

1. Standard tantalum capacitors - 50% derating (zvishoma)
   Tantalum's isingadzokeri yekutadza modhi inogona kukonzeresa kutiza nekupisa kana kubatika kana wanyanya kushushikana. Iyo 50% yekuzvidza mutemo inokurudzirwa pasi rose kune zvekutengesa zvemagetsi.
2. Mauto / aerospace application - 60-70% inoderera
   Zvikamu zvinovimbika zvakanyanya zvinoteera nhungamiro dzakasimba (kushanda pa30-40% yemagetsi akayerwa) kubvisa njodzi yekutadza kunotyisa.

Aluminium Electrolytic Voltage Derating

1. General derating nhungamiro - 20-30%
   Voltage stress inomhanyisa kubuda kwe electrolyte, iyo inotowedzera zvakapetwa patembiricha ye10°C yega yega. Kuderedza kushanda kwemagetsi kunodzikisira kupisa kwemukati uye zvine chinangwa kuwedzera capacitor hupenyu hwese.

Firimu uye High-Voltage Capacitor Derating

1. Firimu capacitors - 10-20% kuderedza
   Firimu dielectrics inopa yakanakisa kugadzikana kwemagetsi uye kuzvipodza hunhu, saka chete mwenje derating inodiwa pasi pemamiriro akajairwa.
2. High-voltage capacitors (> 1kV) - 30-50% kuderedza
   Makuru anodzikira madhiri anodiwa kuti udzivise kutangwa kwechikamu, uko kuburitswa kwecorona kunokonzeresa kukurumidza kushatisa dielectric.

Maitiro ekuverenga Capacitor Voltage Derating muChaiyo PCB Dhizaini

Iyo derating ratio formula inopa nzwisiso yekukurumidza mukukwana kwedhizaini: DR = V_operating / V_rated. Kune njanji ye12V inoshandisa 16V-yakatemerwa X7R MLCC, DR = 12/16 = 75%, iyo inopfuura nhungamiro inokurudzirwa uye inotsanangura maitiro ekutadza akajairika mumagadzirirwo akaderedzwa mutengo.

Funga nezvemuenzaniso unoshanda: chikamu chekutonga simba chakatsanangura ma capacitor e10μF X7R akaongororwa e16V pa 12V rail. Chiyero chekurasa simba che75% chakatyora gwara re50-70%, uye DC bias curves yakaratidza kuti capacitance chaiyo yakaderera kusvika pa3μF pa12V, zvichiita kuti 70% functional shouldfall isashande. Kuchinja kune zvikamu zve25V-rated kwakawana 48% voltage derating ukuwo 8-9μF capacitance inoshanda.

Capacitor Voltage Derating Under Special Conditions

DC Bias Effect paMLCC Capacitance

DC bias ndiyo inonyanya kukosha uye inowanzo fungirwa chinhu muMLCC inoshoreka. Sezvo dhetabheti capacitance inotsanangurwa pa 0V, chaiyo-yenyika kukosha inodonha zvakanyanya sezvo yakashandiswa voltage inowedzera. X7R capacitors inogona kurasikirwa ne40-60% yekugona kwavo pa50% yemagetsi akayerwa, uye anosvika 60-80% pa75%. Kuchengeta magetsi ekushanda ari pasi pehafu yehuwandu hwakayerwa kazhinji kunochengetedza 60-80% yezita rekugona uye kunovimbisa hunhu hwakagadzikana pane tembiricha uye mitoro mamiriro.

High Temperature uye Voltage Derating

Tembiricha inokwidziridza kushushikana kwevoltage uye inomhanyisa kuderedzwa kwe dielectric. Sezvo mamiriro ekushanda anofamba kupfuura 85 ° C, dielectric inova nyore nyore kuparara kunoenderana nenguva, ichida kusimba kuderera. Gwaro rinoshanda nderokudzikisa reshiyo inotenderwa yekudzikisira ne5–10 muzana yemapoinzi pa10°C yega yega pamusoro pe85°C. Masisitimu ari pamusoro pe105°C anofanirwa kushandisa 60–70% derating kunyangwe mhando dzemacapacitor dzinowanzobvumira kushandiswa kwepamusoro.

Ripple Yazvino uye Surge Dziviriro

Ripple yazvino inowedzera kushushikana kwekushisa kuburikidza neESR-inoenderana neI²R kudziyisa, kazhinji inosimudza tembiricha yemukati ne20–30°C. Uku kusimuka kwemafuta kunoderedza yakachengeteka yekushanda voltage uye inoita kuti kuwedzeredza kunosungirwa kuchengetedza kuvimbika kwenguva refu. Masekete ane mitoro inorema inorema-senge vatyairi vemota, DC-link capacitor, uye inopisa-plug-inotarisana-inotarisana neakakosha inrush uye zviitiko zvekuvhiya, uko kusanganisa 40-50% voltage derating nekudzvinyirira kwakakodzera kunopa dziviriro yakasimba.

Mamiriro eIndasitiri yeCapacitor Voltage Derating

Multiple international standards inopa yakajeka-voltage-derating kurudziro iyo mainjiniya anogona kutaura panguva yekusarudza capacitor uye PCB dhizaini.

• MIL-HDBK-338B - Inotsanangura nheyo dzekudzikira mitemo: 60% yeyakayerwa voltage kune yakakwirira-yakavimbika masisitimu, 80% yemagetsi ekutengesa.
• NASA Technical Standards - Inoda 50% derating yeceramic capacitors uye 40% ye tantalum mune spaceflight hardware kuti ive nechokwadi chekuvimbika kwakakosha.
• IPC-9592B - Inopa kutungamira kwemagetsi ekutengesa, ichikurudzira yakanyanya voltage kushushikana kwe70-80% kune yakajairwa-kuvimbika maapplication.

Aya mazinga eindasitiri anopindirana pane akafanana derating ratios kunyangwe achishandira zvikamu zvakasiyana, zvichiratidza kubvumirana kwakakura kweinjiniya pahukama pakati pekushushikana kwevoltage uye kuvimbika kwenguva refu.

Inoshanda PCB Dhizaini Kurudziro

Kuita chaiyo capacitor voltage derating kunoda akati wandei maitiro akakosha:

• Bvunza DC bias curves usati wapedzisa sarudzo dzeMLCC -Nominal capacitance values ​​inova isina zvazvinoreva kuKirasi II dielectrics pasina kunzwisisa kushanda kwemagetsi maratidziro.
• Taura 50V-yakatemerwa MLCCs ye12V njanji seyakajairwa tsika - Izvi zvinovimbisa 1μF capacitor inoburitsa padyo ne1μF pasi pemamiriro ekusarura.
• Shandisa tiered derating mazano zvichienderana nekukosha kwedunhu -Chengetedzo-yakakosha njanji njanji inobvumidza 40-50% kudzikisira nepo isiri-yakakosha bypass application inogona kugamuchira 60-70% kuderera.
• Gwaro rinodzikira reshiyo zvakajeka muBOM uye madhirowa egungano - Taura "10μF 25V (derating ye12V njanji)" pane kungo "10μF 16V" kudzivirira zvinotsiva panguva yekushomeka kwechikamu.

Kuenderana kwekushandisa kwemaitiro aya kunovimbisa kuti ma capacitors anoita sekutsanangurwa kwaakaitwa mumamiriro ekushanda chaiwo, kuderedza kutadza kwemunda uye kuvandudza kuvimbika kwese kwehurongwa.

mhedziso

Mune yangu PCB dhizaini dhizaini kuHighleap Electronics, imwe pateni inowirirana: yakakodzera voltage derating ndiyo inoita kuti zvigadzirwa zvakavimbika mumunda. Iyo 50V MLCC pane njanji ye12V haina kunyanya dhizaini-ndizvo zvinongodiwa neDC bias curve kuti capacitor iunze kukosha kwayo kwekushanda.

Iyo yakakosha poindi yakatwasuka: iyo DC bias curve inonyanya kukosha kupfuura yezita capacitance. A "10 µF" MLCC inodonha kusvika ku3 µF pasi pekurerekera haizotsigire simba rakagadzikana, zvisinei kuti dhetabheti inoti kudii.

Madhizaini anobudirira anotevera mitemo mishoma yakaratidza: 50–70% kuderera kweMLCCs, 50% yetantalum, uye 20-30% yealuminium electrolytics, ine mamwe margin ekupisa kwakanyanya, ripple, uye mavhisi mamiriro. Isa izvi nguva dzose, uye ma capacitor achaita zvinofanotaura muhupenyu hwese chigadzirwa.