Jɛɲɔgɔnya min bɛ kɛnɛma doni kondansɛriw ni kristalɛ doni cɛ

Elektɔriki sɛrɛkiliw la, kristalɛ-yɛrɛyɛrɛw ye wagati sɔrɔyɔrɔ dɔ ye min ka ca kosɛbɛ. Walasa ka kristalɛ-yɛrɛyɛrɛ daminɛ ka ɲɛ ani ka baara sabati, kɛnɛma doni-ta-minɛn minnu bɛ sɛrɛkili kɔnɔ, olu ka kan ka dilan ka ɲɛ ka kɛɲɛ n’a doni-ta-minɛn (CL) ye. Kondansɛriw ka bɛnbaliya bɛ se ka gɛlɛya lase jiginni ma, ka dɔ fara frequency deviation kan, ani hali sistɛmu basigibaliya.

Nin barokun in bɛna sɛgɛsɛgɛli caman kɛ kristalɛ jiginni doni seko kɔrɔ kan, jatebɔ fɛɛrɛ min bɛ kɛ kɛnɛma kondansɛriw la, ani jateminɛ nafamaw ciriw dilanni na.

Ⅰ. Kristali sɛgɛsɛgɛlikɛlan ka doni hakɛ (CL) ye mun ye?

A ka c’a la, kristalɛ dilannikɛlaw bɛ doni hakɛ tɔgɔlama (CL) jira kunnafonidilan kɔnɔ, i n’a fɔ 18pF, 20pF, 12pF, a ɲɔgɔnnaw O bɛ doni kapasitif jira, kristalɛ bɛ jateminɛ kɛ min kɔrɔ walasa k’a ka jiginni hakɛ tɔgɔlama sɔrɔ.

O kɔrɔ ye ko kristalɛ-yɛrɛyɛrɛ bɛ Se ka 'fɛrɛnkan tigitigi Bɔ dɔrɔn ni doni-ta-minɛn min bɛ Bɛn o ma, o bɛ Bɛn ni CL ye.

Ⅱ. Kɛnɛma doni kondansɛriw bɛ nɔ bila doni seko la cogo di?

Circuit oscillateur cristal typique bɛ nin cogo in na:

C1 ni C2 ye kɛnɛma kondansɛri fila ye minnu sirilen bɛ dugukolo la (a ka c’a la SMD kondansɛriw);

XTAL ka dakun fila bɛ tali kɛ kristalɛ jiginnikɛlan ka pinɛ fila la;

Tiɲɛ na, kristalɛ ka doni hakɛ CL min bɛ bɛn o ma, o bɛ latigɛ C1 ni C2 fɛ ka tugu ɲɔgɔn na, ka fara paraziti seko Cp kan min donna PCB ni pake fɛ.

Ⅲ. Jateminɛ kɛcogo: Kɛnɛma kondansɛri nafa bɛ dɔn cogo di ka da CL kan?

Formula min bɛ kɛ ka doni girinya hakɛ kelen (CL) ye, o ye nin ye:

Min:

C1, C2: Kɛnɛma kondansɛri minnu bɛ tali kɛ dugukolo la;

Cp : Paraziti ka capacitance min bɛ don PCB traces fɛ, pakew, a ɲɔgɔnnaw (a ka c’a la 2pF ka se 5pF ma, o bɛ se ka jateminɛ simulation walima expérience fɛ);

CL: Doni hakɛ tɔgɔlama min ɲɛfɔlen don kristalɛ oscillateur datasheet kɔnɔ.

【Misali min bɛ ɲɛfɔli kɛ】

A ka c’a la, kristalɛ ɲɛfɔli ye CL=18pF ye, ani PCB paraziti seko Cp ≈ 5pF. Walasa ka jatebɔ kɛ nafa bɛnnenw na C1 ni C2 kan:

Fɔlɔ, aw bɛ nafaw bila formula in nɔ na:

Ni an y’a miiri ko C1=C2=C, formula bɛ nɔgɔya ka kɛ:

O nɔ ye nin ye:

✅ O la, kɛnɛma kondansɛri minnu bɛ ladilikan di olu ye : C1=C2=.27pF ye (Nafa jɔnjɔn).

Ⅳ. Mun na kɛnɛma kondansɛri minnu tɛ bɛn ɲɔgɔn ma, olu bɛ gɛlɛyaw lase mɔgɔ ma?

Frequency deviation : Ni kɛnɛma kondansɛriw ka dɔgɔ kojugu walima ni u ka bon kojugu, kristalɛ bɛna bɔ a ka frequency nominal la, o bɛ kɛ sababu ye ka system clock filiw kɛ.

Daminɛ-gɛlɛya walima basigibaliya: Doni kojugu bɛ dɔ bɔ tɔnɔ sɔrɔli la, o bɛ se ka kɛ sababu ye ka kristalɛ dɛsɛ ka daminɛ walima ka frequency jitter sɔrɔ.

Dɔ farali fanga kan: Doni kɛcogo jugu bɛ na ni fanga caman ta ye kristalɛ oscillateur circuit kɔnɔ.

EMI caya : Yɛlɛma sabatibaliw bɛ se ka kɛ sababu ye ka frequences spurious (fɔkan nkalonmaw) lawuli, ka nɔ bila sistɛmu electromagnetic compatibility (EMC) la.

5. Bamako. Dilancogo ladilikanw ani Ɛntɛrinɛti walew

Aw ye kristalɛ oscillateur datasheet lajɛ ka ɲɛ

Aw bɛ CL nafa dɔn.

Kafoba ka topidiya min kofɔlen don, o faamuya.

Aw bɛ a lajɛ ni kɛnɛma kondansɛri hakɛ dɔ bɛ fɔ.

2. Aw ye board sigida yɛrɛ jateminɛ

Cp jateminɛ ni PCB simulation walima expérience ye.

Ni teliyaba-waatiw walima waati tigitigiw (misali la, kumaɲɔgɔnya siraw, MCU ka fɔkanba > 100MHz), jatebɔ walima kɔrɔbɔli tigitigi bɛ fɔ.

3. Aw bɛ baara kɛ ni kondansɛri simetrikiw ye

A ka c’a la, a bɛ fɔ ko C1=C2 ka frequency ni balance mankan cɛmancɛ kɛ.

Dilan asimɛtiri fana bɛ se ka kɛ ka ɲɛsin bɛnkan wajibiyalen kɛrɛnkɛrɛnnenw ma.

4. Baara kɛ ni SMD kondansɛri sɛrɛkili ye walasa ka debugging kɛ

Aw bɛ SMD kondansɛriw kɔlɔsi (misali la, 10pF, 15pF, 22pF, 27pF, a ɲɔgɔnnaw) walasa ka bɛnkan ɲuman sɔrɔ;

Aw bɛ bɔli sabatili ni frequency tiɲɛni lajɛ ni spectre analyseur walima oscilloscope ye.

6,Min bɛ deli ka kɛƝininkaliw

Kuncɛli

Kɛnɛma doni-ta-minɛnw dilanni kristalɛ-yɔrɔ-ko ye fɛn fitinin ye nka a nafa ka bon kosɛbɛ, min bɛ nɔ bila waatibolodacogo sabatili n’a tiɲɛni na k’a ɲɛsin a ma. Jatebla jɛɲɔgɔnya faamuyali CL ni C1/C2 cɛ, ani ka paramɛtiriw ladilan ka da PCB paraziti seko yɛrɛ kan, o ye fɛnba ye walasa ka jiginni dannamɔgɔ ni frequency tigitigi sɔrɔ.

Nizɛri teliya-sitɛmuw kɔnɔ, kumaɲɔgɔnya minɛnw, walima sigida minnu ka waati wajibiyalenw ka gɛlɛn kosɛbɛ, kristalɛ oscillateur ka doni hakɛ sugandili n’a bɛncogo ɲuman ye ɛntɛrinɛti baara ye min ka kan ka ta kosɛbɛ.

HCI (HCI) yelaboratuwari baarakɛlaw ka laboratuwari bɛ yen ani baarakɛminɛnw dilannikɛlaw ka kulu min ka baara kɛcogo bɛ san 20 ni kɔ bɔ, minnu bɛ baarakɛlaw ka bɛnkan ni sɛgɛsɛgɛli baara kɛ fu kiliyanw ye. Ni mago dɔw b’aw la o siratigɛ la, aw kana siga ka kuma an ka feerekɛlaw walima an ka fɛɛrɛbɔ baarakɛlaw fɛ.