Chifukwa Chiyani Zida Zamtaneti Zimagwiritsa Ntchito 25MHz ndi Kuchuluka Kwake Monga Ma frequency?

Chifukwa Chiyani Zida Zamtaneti Zimagwiritsa Ntchito 25MHz ndi Kuchuluka Kwake Monga Ma frequency?

Pazida zama netiweki monga makhadi a netiweki, ma switch, ma routers, ndi zida za Efaneti, kusankha kwa ma frequency a crystal oscillator kumatsimikiziridwa ndi magwiridwe antchito a chipangizocho, zofunikira za chip, ndi miyezo yolumikizirana. Kugwiritsiridwa ntchito kwa ma crystal oscillator okhala ndi mafupipafupi a 25MHz ndi kuchulukitsa kwake makamaka chifukwa cha kayendedwe kafupipafupi kachitidwe kameneka ndi mfundo za Efaneti, ndondomeko zoyankhulirana, ndi zomangamanga za chip, zomwe zimathandiza kupanga kosavuta, kuchepetsa ndalama, ndi ntchito yabwino. Kufotokozera mwatsatanetsatane kwaperekedwa pansipa:

I. Chifukwa Chiyani Musankhe 25MHz Monga Mafupipafupi Oyambira?

25MHz si mtengo wosankhidwa mwachisawawa. Amagwiritsidwa ntchito kwambiri chifukwa ali ndi ubale wophatikizika wokhala ndi ma frequency angapo oyambira kulumikizana ndi netiweki, kumathandizira kuchulutsa pafupipafupi kapena kugawa.

1.1 Imakwaniritsa Zofunikira za Ethernet Standard Frequency

Fast Ethernet (100BASE-TX): Imagwiritsa ntchito wotchi ya 25MHz ngati nthawi yotumizira deta.

Gigabit Ethernet (1000BASE-T): Imagwiritsa ntchito wotchi ya 125MHz, yomwe ndi 25MHz × 5.

10GbE (10 Gigabit Efaneti) ndi pamwamba: Ngakhale mawotchi akuluakulu afupipafupi ndi apamwamba (mwachitsanzo, 156.25MHz), amatha kutengedwa mwa kuchulukitsa 25MHz crystal oscillator kudzera pa PLL.

Izi zikuwonetsa kuti 25MHz, monga ma frequency wotchi yoyambira, imatha kuthandizira mwachindunji kapena mosalunjika ma frequency ogwiritsira ntchito a PHY/MAC pa liwiro la Efaneti wamba.

II. Technical Implementation Convenience

2.1 Kuchulukitsitsa kosavuta kudzera pa PLL

Ma tchipisi a netiweki (monga PHY, MAC, ndi ma switch chips) nthawi zambiri amagwiritsa ntchito masiwiti a PLL (Phase Locked Loop) mkati kuti apange ma frequency ofunikira ogwirira ntchito. 25MHz ndi mafupipafupi olowera omwe amatha kutulutsa{1}}liwiro lachangu, monga:

25MHz × 2=50MHz

25MHz × 4=100MHz

25MHz × 5=125MHz

25MHz × 6.25=156.25MHz (ya 10GbE)

Popeza 25MHz ndi mafupipafupi osavuta-ku{2}}kuwerengera machulukitsi ochepa, imathandizira kamangidwe ka PLL, imathandizira kutseka mwachangu, ndikuwonetsetsa kutulutsa kokhazikika.

2.2 Yogwirizana ndi Zofunikira za Mainstream Chip

Ambiri opanga ma chip zida za netiweki (monga Broadcom, Realtek, Marvell, Intel, etc.) amathandizira momveka bwino kulowetsa kwa 25MHz crystal oscillator pazofunikira za wotchi ya tchipisi ta PHY kapena MAC, kapena amapereka mitundu yogwiritsira ntchito 25MHz.

III. Ubwino mu EMC, Circuit Design, ndi Mtengo

3.1 Kuwongolera Kwabwino kwa EMI ndi Kukhulupirika Kwapamwamba Kwambiri

Poyerekeza ndi ma crystal oscillator okhala ndi ma frequency apamwamba (mwachitsanzo, 50MHz, 100MHz, 125MHz, 150MHz, ndi 200MHz), 25MHz imapereka maubwino ofunikira potengera Electromagnetic Interference (EMI):

Kuchepa kwafupipafupi kofunikira kumabweretsa kusokoneza kochepa kwa harmonic;

Mayendedwe a PCB ndiosavuta kutsatira EMI kapangidwe kake;

Zofunikira zochepa zotsekera ndi kukhulupirika kwa mphamvu, kuwongolera kusakanikirana kwadongosolo.

3.2 Okhwima, Okhazikika, komanso Otsika mtengo-Ma Crystal Oscillator Ogwira Ntchito

25MHz crystal oscillators ndi ena mwa ma frequency omwe amagwiritsidwa ntchito kwambiri pamakampani amagetsi, ndi zabwino izi:

Zochulukira--zogulitsa mashelufu ndi mitundu yosiyanasiyana;

Mitengo yotsika yopangira zinthu komanso mitengo yotsika mtengo yogula;

Makina okhwima okhwima okhala ndi nthawi yayitali yotsogola komanso mtundu wokhazikika.

Izi ndizokopa kwambiri opanga zida zama netiweki omwe amapanga-zambiri.

IV. Chitsanzo Chogwiritsira Ntchito Mumapangidwe Othandiza

Kutenga chosinthira cha Gigabit Ethernet mwachitsanzo:

Chip chachikulu chowongolera chimafuna mafupipafupi ogwiritsira ntchito 125MHz;

M'mapangidwe, 25MHz crystal oscillator ingagwiritsidwe ntchito, ndipo mafupipafupi akhoza kuchulukitsidwa kufika 125MHz pogwiritsa ntchito chip chopangidwa-mu PLL;

Panthawiyi, wotchi ya 25MHz ikhoza kugawidwa ku ma modules ena (monga PHY, MAC, kapena mawotchi ogwirizanitsa ma modules) kupyolera mumtengo wa wotchi;

Izi zimakwaniritsa gwero logwirizana la wotchi, zimathandizira kamangidwe ka mawotchi, komanso zimachepetsa zovuta zamakina ndi ndalama.

Chidule

Zifukwa zomwe zida zamagetsi zimagwiritsira ntchito 25MHz ndikuchulukitsa kwake ngati mafunde a crystal oscillator zitha kufotokozedwa mwachidule motere:

Hangjing Crystal Oscillators amagwiritsidwa ntchito kwambiri pazida zamaukonde (makadi ochezera, ma switch, ma routers, Efaneti). Kuonjezera pa zinthu zamakampani-timaperekanso zinthu zambiri-zotentha kwambiri{3}}zotsika kwambiri (-55~+125 digiri) ndipo titha kupereka ma crystal oscillator ndi njira zofananira. Ngati muli ndi zofunikira, chonde khalani omasuka kulumikizana ndi ogulitsa a Hangjing kapena akatswiri.