AN051 Input Capacitor Selection MP2130
Tlhahisoleseding ya Sehlahiswa
Tataiso ea ho Khetha Capacitor ea Input bakeng sa MP2130
MP2130 ke sesebelisoa se fetolehang sa monolithic step-down switch-mode se tlang ka matla a kahare a MOSFET. E ka fana ka tlhahiso e tsoelang pele ea 3.5A hona joale ka mojaro o babatsehang le taolo ea mohala ho tloha ho 2.7V-to-6V input vol.tage. Sesebelisoa se na le tšobotsi e hahelletsoeng ka bonolo e thusang ho ramp nyolla tlhahiso voltage ka lebelo le laoloang la polao, ho thibela ho thunya ha ho qala. MP2130 e boetse e kenyelletsa nako ea ho emisa ha bonolo ea 1ms ha e holofalitsoe, e leng r.amps theolela setšupiso sa ka hare, ka tsela e tšoanang e ntša sephetho.
Kakaretso
Noutu ena ea ts'ebeliso e fana ka tataiso ea ho khetha capacitor e loketseng ea ho kenya MP2130. E hlalosa mohloli oa li-overshoots 'me e fana ka mokhoa oa ho khetha capacitor e loketseng ea ho kenya ho sireletsa IC ho tloha ho feta.tage tshenyo.
Why Overshoot Voltage etsahala
Overshoot voltage etsahala ka lebaka la ho tsoa ka tšohanyetso ha motlakase oa motlakase nakong ea nako e bonolo ea ho emisa. Ho thibela ho fetellatage senya, e kholo input capacitor ka monya overshoot voltage.
Ho Khetha Capacitor e Loketseng ea ho Kena
Ho etsa bonnete ba hore LS-FET ea hajoale ha e fete moeli o fosahetseng oa hajoale, sebelisa boleng ba karolelano ho bala motlakase oa motlakase. Haeba motlakase o mobe o le ka tlase ho moeli o fosahetseng oa hona joale, joale tlhahiso ea voltage e ka laoloa ho tloha ho boleng ba lebitso ho ea ho 0V ka nako e tsitsitseng ea ho emisa ha bonolo. Nakong ea ho emisa ha bonolo, lekanya boemo bo tlase ka ho fetisisa ba inductor bo fosahetseng u sebelisa equation e fanoeng bukaneng.
Litaelo tsa Tšebeliso ea Sehlahisoa: Tataiso ea Khetho ea Input Capacitor bakeng sa MP2130
Ho khetha capacitor e loketseng ea ho kenya MP2130:
- Bala bukana ka hloko ho utloisisa mohloli oa overshoot voltage le tlhoko ea ho kenya capacitor.
- Bala kakaretso ea boleng ba motlakase oa motlakase ho netefatsa hore LS-FET ha e fete moeli o fosahetseng oa hajoale.
- Hakanya boemo bo tlase ka ho fetesisa ba inductor nakong ea ho emisa ha bonolo u sebelisa equation e fanoeng bukaneng.
- Khetha capacitor e kenang e khonang ho monya overshoot voltage le ho kopana le bonyane ba boleng ba capacitance bo khothaletsoang bukeng ea tataiso.
- Kenya capacitor ea ho kenya ho latela litaelo tsa moetsi.
Ka ho latela mehato ena, o ka khetha capacitor e loketseng ea ho kenya MP2130 e sirelletsang IC ho overvolving.tage senya mme e netefatsa ts'ebetso e nepahetseng ea sesebelisoa.
TS'ELISO
Motso oa voltagE overshoot holim'a pini ea ho kenya nakong ea ho emisa ha bonolo le mokhoa oa ho khetha capacitor ea ho kenya li hlahisoa bukeng ena ea kopo. Tlas'a maemo a bobebe le a-output-capacitor e kholo, buck IC e sebetsa ka mokhoa o bonolo oa ho emisa 'me e ka sebetsa joalo ka potoloho e sa rateheng. Molaetsa ona oa ts'ebeliso o hlalosa mokhoa oa ho khetha capacitor e nepahetseng ho monya matla ho tsoa ho li-capacitor tse laoloang ho thibela ho fetella.tage. E boetse e na le thuso bakeng sa likarolo tse ling tsa Buck tse nang le mosebetsi o bonolo oa ho emisa.
Tataiso ea ho Khetha Capacitor ea Input bakeng sa MP2130
MP2130 ke sefetoleli sa monolithic step-down switch-mode se nang le matla a ka hare a MOSFET. E fihlella tlhahiso e tsoelang pele ea 3.5A ho tloha ho 2.7V-to-6V input vol.tage e nang le taolo e ntle haholo ea mojaro le mela. MP2130 e na le qalo e bonolo e hahiloeng ka har'a ramps up the output voltage ka lebelo le laoloang la polao, ho qoba ho thunya ho feta tekano qalong. Ha e holofetse, MP2130 ramps theosa referense ea ka hare ka tsela e tšoanang e ntša sephetho. Nako ea ho emisa hangata e ka ba 1ms.
Nakong ea ho emisa ha bonolo, MOSFET e ka hare e ka tlase e fetoha ho laola sekhahla sa ho bolaoa ha voltamo.tage e latelang sesupo sa ka hare. Tlas'a boemo ba boima bo bobebe le ba-output-capacitor e kholo, MOSFET e lehlakoreng le phahameng e batla e tima nakong ea ts'ebetso ea ho emisa ha bonolo. Matla a bolokiloeng ho capacitor ea tlhahiso a fetisetsa ho capacitor ea ho kenya ka inductor. The topology e fetohela ho boost converter e nang le MOSFET e lehlakoreng le holimo e sebetsang joalo ka parasitic diode, joalo ka ha ho bonts'itsoe ho Setšoantšo sa 1. The boost voltage etsa hore ho be le overshoot holim'a capacitor ea ho kenya; ka linako tse ling overshoot ena e feta absolute maximum voltage (VABS) ea pini ea ho kenya 'me e ka senya IC. Ho thibela sena, eketsa boleng ba capacitor ho monya matla ana ho latela tataiso ena ea khetho ea capacitor.
LIEKETSENG
Lisebelisoa tse ling tse khethehileng kapa lits'ebetso tsa tlhahlobo li hloka tlhahiso ea voltage ho oa ka sekhahla se laoloang ka nako e behiloeng e holofalitsoe: Karolo ena e bitsoa soft-stop. Hangata, ts'ebetso ena e baka molumo oa tlhahisotage ho oela hantle, ho tšoana le ho qala ha bonolo. Tlhokomelo e tlameha ho nkuoa maemong a bobebe le boemo bo boholo ba capacitor kaha ho ka ba le overshoot voltage holim'a pini ea ho kenya e bakoang ke ketsahalo ena. E le ho sireletsa IC hore e se ke ea senngoa ke overshoot ena, capacitor ea ho kenya e hloka ho eketseha ho monya overshoot ena.Tlhaloso ena ea kopo e hlalosa mohloli oa ho feta, 'me e fana ka mokhoa oa ho khetha capacitor e loketseng ea ho kenya.
KE HOBANE'NG PHAHAMENG MOLLOTAGE HLAHALA
Setšoantšo sa 1 se bontša phetoho ea topology nakong ea ho emisa ha bonolo. Nakong ea ho emisa ha bonolo, MOSFET (LS-FET) ea lehlakoreng le tlase e fetoha ho laola sekhahla sa sekhahla sa phallo.tage, e latelang sesupo sa ka hare. Tlas'a boima bo bobebe le boemo bo boholo ba capacitor e hlahisoang, MOSFET e lehlakoreng le phahameng e lula e le teng ka nako e khuts'oane feela ea nako ea ho emisa ha bonolo. Ha LS-FET e fetoha, hona joale inductor e qala ho phalla ho tloha ho capacitor ea tlhahiso ho ea ho SW pin. Li-capacitor tsa CO1 le CO2, inductor L, LS-FET, parasitic diode D1, le input capacitor CIN e fetoha potoloho e matlafatsang. Sena se ka etsa hore voltage holim'a pinana ea VIN ho phahama ka potlako le ho feta, joalokaha ho bontšitsoe setšoantšong sa 2. Ho sireletsa IC ho tloha overvololtage senya, sebelisa capacitor e kholo ea ho kenya letsoho ho monya overshoot.
HO KHETHA MOKHOA OA HO HLOKAHALA HO PELE
a. LS-FET ea Hona Joale e ke ke ea Feta Moeli o Mobe oa Hona Joale
Ho nolofatsa tlhahlobo, sebelisa boleng ba karolelano ho bala hona joale ho inductor. Haeba negative inductor current e le ka tlase ho moedi o mobe, ebe sephetho sa voltage e ka laoloa ho tloha ho boleng ba lebitso ho ea ho 0V ka nako e tsitsitseng ea ho emisa ha bonolo. U ka sheba Setšoantšo sa 2. Nakong ea ho emisa ha bonolo, lekanya hore na motlakase o tlase ka ho fetesisa o sebelisa equation e ka tlase:
Moo INeg e leng eona e mpe ka ho fetesisa ea hajoale,
- OC ke capacitor ea tlhahiso,
- OV ke matla a tlhahisotage,
- Stop ke nako e bonolo ea ho emisa.
Tlas'a boemo bona, matla ohle a bolokiloeng ho capacitor ea tlhahiso a fetisetsa ho capacitor ea ho kenya. Nahana ka tahlehelo ea conduction ho inductor, MOSFET ea lehlakore le tlase (LS-FET) le diode ea parasitic, hakanya katleho ea 80% ea phetisetso ea boost converter. Ka hona, matla a fetisitsoeng a ka baloa ka equation e ka tlase:
Moo WBoost e leng matla a fetisitsoeng.
Ho monya matla ana le ho sireletsa IC, tlhahiso ea hona joale ea voltage plus the overshoot voltage ke ke ea feta VABS ho phini ea ho kenya. Capacitor e nyane e hlokahalang e ka baloa ka tlase:
Moo CIN(Min) e leng bonyane ba ho kenya capacitor, 'me VABS ke boleng bo phahameng ka ho fetesisa ba phini ea ho kenya.
b. LS ea Hona Joale e Feta Moeli o Mobe oa Hona Joale
Ka linako tse ling matla a bolokiloeng ho capacitor ea tlhahiso a kholo haholo (ha tlhahiso ea voltage phahameng, kapa capacitance ea tlhahiso e kholo, kapa ka bobeli). IC ha e khone ho laola tlhahiso ea voltage sebelisa tšupiso ea kahare nakong ea ho emisa ha bonolo hobane moeli o fosahetseng oa hajoale o sirelletsang LS-FET o thibela ho tsamaisoa ha maemo a holimo hona joale. Boemong bona, tlhahiso ea voltage ha e theohele ho zero nakong ea ho emisa ha bonolo 'me motlakase oa motlakase o lekanyetsoa ke moeli o fosahetseng oa LS-FET, joalokaha ho bontšitsoe setšoantšong sa 3.
Capacitor e hlahisoang e tsoa moeling oa hajoale. Haeba capacitor e hlahisoang e feta CO (Max), motlakase oa inductor o lekanyelitsoe ho:
Moo CO(Max) e leng boleng ba moeli oo inductor e leng teng moeling o fosahetseng;
INeg_Lim ke moeli o fosahetseng oa hajoale oa LS-FET.
Setšoantšo sa 3 se boetse se bontša mokhoa oa ho fetisa o nolofalitsoeng haeba hona joale o fihla moeling o fosahetseng oa hona joale. Ka mokhoa ona, teba ea hona joale ea boleng bo lekanang le moeli o fosahetseng oa hona joale o ntša capacitor ea tlhahiso. Ha ho nahanoa ka tahlehelo ea conduction ho inductor, LS-FET, le diode ea parasitic, hakanya katleho ea 80% ea ho fetisa converter. Ebe matla a fetisitsoeng a ka baloa ka tlase:
Ho ka baloa bonyane capacitor ea ho kenya e hlokahalang hona joale:
EXAMPLE MORATSO
Se latelang ke exampcalculation ea input-capacitor e sebelisa mokhoa o qaqileng oa moralo o hlalositsoeng pele bakeng sa MP2130. MP2130 ke mofetoleli oa monolithic, oa ho theoha, oa switch-mode o nang le matla a ka hare a MOSFET. E fihlella tlhahiso e tsoelang pele ea 3.5A ho tloha ho 2.7V-to-6V input vol.tage. E na le taolo e ntle haholo ea mojaro le mola. Lipalo li ipapisitse le li-parameter tse latelang:
- VABS =6.5V
- INeg_Lim=2.5A
- tSStop=1ms
- VIN=4.5V
- VO=3.3V
- L=1µH
- CO=10µF + 470µF E-Cap.
Taba ea pele, CO_Max e baloa ho ipapisitsoe le Equation (4):
Ho sena mohlalaample, CO e nyane ho feta CO_Max 'me inductor ea hajoale e ke ke ea feta moeli o fosahetseng oa hajoale. Bala boleng ba ho kenya capacitor ka li-equations (2) le (3), kapa lipalo (5) le (6). Ka hona, bonyane bo hlokahalang ho kenya capacitor ke:
Ka hona, bonyane capacitor ea ho kenya e lokela ho ba kholo ho feta 190µF, 'me ka ho khetheha e sebelise 330µF capacitor bakeng sa ex ena.ample. Ka tlaase mona ke mothinya oa bonyane input capacitance vs. tlhahiso capacitance bakeng sa ex enaample.
TS'ELISO
Motso oa sesosa sa ho kenya voltagE overshoot nakong ea ho emisa ha bonolo le mokhoa oa ho khetha capacitor ea ho kenya li hlahisoa bukeng ena ea kopo. Tlas'a maemo a boima bo bobebe bo nang le capacitor e kholo ea tlhahiso, mokhoa o bonolo oa ho emisa o ka sebetsa joalo ka potoloho ea boost. Molaetsa ona oa ts'ebeliso o hlalosa mokhoa oa ho khetha boleng bo nepahetseng ba capacitor ho monya matla ho tsoa ho li-capacitor tse laoloang. Moqapi example le ts'ebetso e boetse e thusa baenjiniere ho theha litharollo tse bonolo tse ipapisitseng le boleng bo fapaneng ba capacitor ea tlhahiso.
TSEBISO: Lintlha tse tokomaneng ena li ka fetoha ntle le tsebiso. Basebelisi ba tlameha ho fana ka tiisetso le ho netefatsa hore litokelo tsa Letlotlo la Bohlale la motho oa boraro ha li hataketsoe ha ba kopanya lihlahisoa tsa MPS ts'ebetsong efe kapa efe. MPS e ke ke ea nka boikarabello bofe kapa bofe ba molao bakeng sa likopo life kapa life tse boletsoeng.
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