Lan moo waral aparey reso yi di jëfandikoo 25MHz ak ay frequency yu bari?

Lan moo waral aparey reso yi di jëfandikoo 25MHz ak ay frequency yu bari?

Ci aparey reso yu melni kàrtu reso, commutateur, routeur, ak aparey Ethernet, tànneefu fréquence oscillateur kristal mingi aju ci fonction core aparey bi, li puce bi soxla, ak protocolu jokkoo bi. Jëfandikoo osilatëri kristal yu am fréquence 25MHz ak ay bariwaayam li ko gëna waral mooy sistemu fréquence bi dafa jege lool ak standard Ethernet yi, protokol jokkoo yi, ak architecture chip yi, loolu mooy tax ñu mëna yombal jëmmal, wàññi njëg yi, ak gëna mëna liggéey. Ay leeral yu leer ñu ngi ci suuf:

I. Lu tax nga tann 25MHz muy fréquence bu njëkk?

25MHz du valër buñ tànnee ci sa bopp. Dañu koy jëfandikoo bu bari ndax amna diggante bu mat te bari ak ay fréquence core yu bari ci jokkoog reso bi, loolu mooy yombal yokk wala xaaj fréquence yi.

1.1 méngoo ak li ñuy laaj ci fréquence Ethernet

Ethernet bu gaaw (100BASE-TX): Jëfandikoo montor bu 25MHz ngir joxe done.

Gigabit Ethernet (1000BASE{1}}T): Dafay jëfandikoo montor bu 125MHz, maanaam 25MHz × 5.

10GbE (10 Gigabit Ethernet) ak ci kaw: Doonte fréquence montor bi gëna mag (lu melni, 156.25MHz), mën nañu ko am suñu yokkee osilatëru kristal bu 25MHz jaaraleko ci PLL.

Loolu dafay wane ni 25MHz, muy fréquence clock bu njëkk bi, mën na jàppale ci anam wu direct wala indirect fréquence yiy doxal PHY/MAC ngir gaawaayu Ethernet bi gëna mag.

II. Xarala yu am solo ci samp gi

2.1 yomb bariwaayu frequency jaaraleko ci PLL

Puce reso yi (lu melni PHY, MAC, ak puce commutateur) dañuy faral di jëfandikoo sircuit PLL (Phase Locked Loop) ci biir ngir defar fréquence montor bi war . 25 MHz fréquence duggal bu yam la bu mëna defar fréquence gaawaay yu bari, lu melni:

MHz × 2=50MHz

MHz × 4=100MHz

MHz × 5=125MHz

MHz (ngir 10GbE)

Bi 25MHz nekkee fréquence bu yomb - ngir - xayma ay lim yu néew, dafay yombal jëmmal PLL, may tëjug bu gëna gaaw, ba noppi gëna dëgëral génne gi.

2.2 méngoo ak li ñuy laaj ci chip yi

Defarkatu puce reso yu bari (lu melni Broadcom, Realtek, Marvell, Intel, ak ñoom seen) dañuy jàppale bu baax dugal osilatëru kristal 25MHz ci li ñuy laaj ci seen puce PHY wala MAC, wala ñu joxe anam yu ñuy doxalee ngir dugal 25MHz.

III. Njariñu EMC, jëmmal sircuit, ak njëg

3.1 Kontrol EMI bu gëna baax ak njubte siñaal bu kawe

Buñu ko méngale ak osilatëri kristal yi am fréquence yu gëna kawe (lu melni, 50MHz, 100MHz, 125MHz, 150MHz, ak 200MHz), 25MHz dafa am njariñ yu bari ci wàllu jafe-jafe elektronik (EMI):

Frequency fundamental bu gëna ndaw dafay wàññi jafe-jafe armonic yi;

Routing PCB moo gëna yomba topp tegtali jëmmal EMI;

Wàññi liñuy laaj ci boîtier yi ak njubteg doole, yombal boole sistem bi.

3.2 Osilatëri kristal yu màgget, dëgër, te am njariñ

Osilatëru kristal 25MHz bokk nañu ci fréquence yiñ gëna jëfandikoo ci wàllu elektronik, ak njariñ yii:

Produit yu bari yu nekk ci biir etaser yi ak xeetu produit yu bari te wuute;

Njëg li yomb ci defar ak njëg yu yomb ci jënd;

Seen fournisseur bu mat te am diir bu gàtt ak kalite bu dëgër.

Loolu lu am solo la ci defarkati aparey reso yiy liggéey ci liggéey bu mag -.

IV. misaalu jëfandikoo ci jëmmal

Jël benn commutateur Ethernet Gigabit ci misaal:

Puce bi gëna mag biy doxal dafay laaj fréquence buy doxal bu 125MHz;

Ci jëmmal, mën nañu jëfandikoo ab osilatëru kristal bu 25MHz, ba noppi mën nañu yokk fréquence bi ba 125MHz jaaraleko ci PLL biñ tabax ci puce bi;

Ci jamano jooju, montor 25MHz mën nañu ko séddale ci yeneen modle (lu melni PHY, MAC, wala modle synchronisation montor) jaaraleko ci garabu montor;

Loolu mooy tax ñu am montor buñ boole muy benn, yombal architecture montor bi, ba noppi wàññi jafe-jafe sistem bi ak njëg yi.

Tënk

Sabab yi waral aparey reso yi di jëfandikoo 25MHz ak ay bariwaayam ni fréquence oscillateur kristal mën nañu ko tënk nii:

Osilatëru kristal Hangjing ñu ngi koy jëfandikoo bu bari ci aparey reso (kartu reso, kommutatër, routeur, Ethernet). Lu weesu produit usine yi, danuy joxe itam osilatëri kristal yu am tàngoor wu kawe (-55 degre) te mën nanu joxe ay osilatëri kristal ak ay pexe yu méngoo. Soo amee soxla bu jëm ci loolu, jokkool ak jaaykat yi wala ndawi xarala yi ci Hangjing.