Xa kuthelekiswa ne-LDO, isekethe ye-DC-DC inzima kakhulu kwaye inengxolo, kwaye iimfuno zoyilo kunye noyilo ziphezulu. Umgangatho woyilo uchaphazela ngokuthe ngqo ukusebenza kwe-DC-DC, ngoko ke kubaluleke kakhulu ukuqonda i-layout ye-DC-DC
1. Uyilo olubi
● EMI, DC-DC SW pin iya kuba dv/dt ephezulu, xa kuthelekiswa idv/dt eliphezulu kuya kubangela uphazamiseko EMI kakhulu;
● Ingxolo ephantsi komhlaba, umgca ongaphantsi komhlaba awulungile, uya kuvelisa ingxolo enkulu yokutshintsha kwingcingo yomhlaba, kwaye ezi ngxolo ziya kuchaphazela ezinye iindawo zesekethe;
● Ukuhla kwamandla ombane kuveliswa kwi-wiring. Ukuba i-wiring inde kakhulu, ukuhla kombane kuya kuveliswa kwi-wiring, kwaye ukusebenza kakuhle kwe-DC-DC yonke kuya kuncitshiswa.
2. Imigaqo ngokubanzi
● Tshintsha isekethe enkulu yangoku ibemfutshane kangangoko;
● Umhlaba womqondiso kunye nomhlaba ophezulu-yangoku (umhlaba wamandla) zihanjiswa ngokwahlukeneyo kwaye ziqhagamshelwe kwindawo enye kwitshiphu GND.
①Indlela emfutshane yokutshintsha
I-LOOP1 ebomvu kumzobo ongezantsi yindlela ehamba ngayo yangoku xa umbhobho we-DC-DC ophezulu wecala uvuliwe kwaye umbhobho wecala eliphantsi ucinyiwe. I-LOOP2 eluhlaza yindlela yokuhamba yangoku xa umbhobho wecala eliphezulu uvaliwe kwaye umbhobho wecala eliphantsi uvuliwe;
Ukuze wenze iilophu ezimbini zibe zincinci kangangoko kwaye ungenise ukuphazamiseka okuncinci, le migaqo ilandelayo kufuneka ilandelwe:
●I-inductance kufutshane ne-SW pin kangangoko kunokwenzeka;
● I-Input capacitance ngokusondeleyo kwi-VIN pin ngokusemandleni;
● Umhlaba we-input and output capacitors kufuneka ube kufutshane ne-PGND pin.
●Sebenzisa indlela yokubeka ucingo lobhedu;
Kutheni unokwenza oko?
● Umgca omde kakhulu kunye nomgca omde kakhulu uya kwandisa i-impedance, kwaye umsinga omkhulu uya kuvelisa i-voltage ephezulu ye-ripple kule impedance enkulu;
● I-fine kakhulu kunye nocingo olude kakhulu luya kwandisa i-parasitic inductance, kunye nesandi sokutshintsha ukudibanisa kwi-inductance kuya kuchaphazela ukuzinza kwe-DC-DC kwaye kubangele iingxaki ze-EMI.
● I-parasitic capacitance kunye ne-impedance iya kwandisa ilahleko yokutshintsha kunye nelahleko ekucinyweni kunye nokuchaphazela ukusebenza kakuhle kwe-DC-DC.
②ukubekwa kwindawo enye
Indawo enye yokumisa ibhekisa kwindawo enye yokumisa phakathi komhlaba womqondiso kunye nomhlaba wamandla. Kuya kubakho ingxolo enkulu yokutshintsha kumhlaba wamandla, ngoko kuyafuneka ukuba unqande ukubangela uphazamiseko kwiimpawu ezincinci ezibuthathaka, ezifana ne-FB feedback pin.
● Umhlaba ophakamileyo wangoku: L, Cin, Cout, Cboot xhuma kwinethiwekhi yomhlaba wangoku ophezulu;
● Umhlaba wangoku ophantsi: I-Css, i-Rfb1, i-Rfb2 iqhagamshelwe ngokwahlukileyo kuthungelwano lomhlaba womqondiso;
Oku kulandelayo luyilo lwebhodi yophuhliso ye-TI. Ubomvu yindlela yangoku xa kuvulwa ityhubhu ephezulu, kwaye eluhlaza okwesibhakabhaka yindlela yangoku xa kuvulwa ityhubhu ephantsi. Olu luyilo lulandelayo lunolu ncedo lulandelayo:
● I-GND ye-input and output capacitors idityaniswe nobhedu. Xa ufaka iziqwenga, umhlaba wesibini kufuneka uhlanganiswe ngokusemandleni.
● Indlela yangoku ye-Dc-Dc-ton kunye ne-Toff imfutshane kakhulu;
● Umqondiso omncinci osekunene usisiseko sendawo enye, ekude nefuthe lesandi esikhulu sokutshintsha kwangoku ngakwesobunxele;
3. Imizekelo
Uyilo lwesekethe ye-DC-DC BUCK eqhelekileyo inikwe ngezantsi, kwaye la manqaku alandelayo anikwe kwi-SPEC:
● I-Input capacitors, ii-tubes ze-MOS eziphezulu, kunye ne-diode zenza iilophu zokutshintsha ezincinci kunye nezifutshane;
● I-Input capacitance ngokusondeleyo kangangoko kunokwenzeka kwi-Vin Pin pin;
● Qinisekisa ukuba lonke uqhagamshelo lwengxelo lufutshane kwaye luthe ngqo, kwanokuba izichasi zengxelo kunye nezinto eziyimbuyekezo zikufutshane netshiphu kangangoko kunokwenzeka;
●SW kude nemiqondiso ebuthathaka efana ne-FB;
● Xhuma i-VIN, i-SW, kwaye ngokukodwa i-GND ngokwahlukileyo kwindawo enkulu yobhedu ukupholisa i-chip kunye nokuphucula ukusebenza kwe-thermal kunye nokuthembeka kwexesha elide;
4. Shwankathela
uyilo lwesekethe DC-DC kubaluleke kakhulu, nto leyo echaphazela ngqo uzinzo ukusebenza kunye nokusebenza DC-DC. Ngokubanzi, i-SPEC ye-DC-DC chip iya kunika isikhokelo soyilo, esinokubhekiswa kuyo kuyilo.