Mumaseketi emagetsi, makristasi oscillator ndeimwe yeawa akajairika masosi masosi. Kuti uone kutanga kwakakodzera uye kushanda kwakadzikama kwekristaro oscillator, iyo yekunze inotakura capacitors munharaunda inofanirwa kugadzirwa nenzira kwayo zvinoenderana neyakatakura capacitance (CL). Zvisizvo capacitor kuenzanisa zvinogona kukonzera kuoma mu oscillation, kuwedzera frequency kutsauka, uye kunyangwe kusagadzikana kwehurongwa.
Ichi chinyorwa chichapa ongororo yakadzama yezvinoreva crystal oscillator load capacitance, iyo yekuverenga nzira yekunze capacitors, uye zvinobatika zvinotariswa mudunhu dhizaini.
Ⅰ. Chii chinonzi capacitance (CL) yekristaro oscillator?
Vagadziri veCrystal vanowanzo tsanangura kukosha kwezita rekuremerwa (CL) mudhetabheti, senge 18pF, 20pF, 12pF, zvichingodaro. Izvi zvinomiririra capacitive load pasi payo iyo crystal inokwenenzverwa kuti iwane maitikiro ayo ezita oscillation.
Mune mamwe mazwi, iyo crystal oscillator inogona kuburitsa chaiyo frequency chete kana yakaenzana mutoro capacitance yakaenzana neCL.
Ⅱ. Ko External Load Capacitors Inobata Sei Mutoro Wekutakura?
Yakajairika crystal oscillator wedunhu inotora inotevera fomu:
C1 uye C2 maviri ekunze capacitors akabatanidzwa pasi (kazhinji SMD capacitors);
Iwo maviri materminals eXTAL akabatana nemapini maviri ekristaro oscillator;
Mukuita, iyo yakaenzana mutoro capacitance CL yekristaro inotarirwa neC1 uye C2 mumutsara, yakasanganiswa neparasitic capacitance Cp yakaunzwa nePCB uye pasuru.
Ⅲ. Yekuverengera Formula: Maitiro ekuona iyo Yekunze Capacitor Kukosha Kwakavakirwa paCL?
Iyo formula yeyakaenzana mutoro capacitance (CL) ndeiyi inotevera:
Kupi:
C1, C2: External capacitors akabatanidzwa pasi;
Cp: Parasitic capacitance yakaunzwa nePCB traces, kurongedza, nezvimwewo (kazhinji 2pF kusvika 5pF, inogona kufungidzirwa kuburikidza nekuenzanisa kana ruzivo);
CL: Nominal load capacitance inotsanangurwa mucrystal oscillator dheteti.
【Muenzaniso Wokuenzanisira】
Fungidzira kuti kutsanangurwa kwekristaro ndeye CL=18pF, uye PCB parasitic capacitance Cp ≈ 5pF. Kuverenga kukosha kwakakodzera kweC1 neC2:
Kutanga, chinja maitiro mufomura:
Tichingotora C1=C2=C, fomula yacho inorerutsa ku:
Mhedzisiro yacho ndeiyi:
✅ Naizvozvo, anokurudzirwa ekunze capacitor ndeiyi: C1=C2 =27pF (Standard Value).
Ⅳ. Sei Mismatched External Capacitors Inokonzera Matambudziko?
Frequency deviation: Kana ekunze capacitor ari diki kana kuti akakurisa, kristaro inotsauka kubva pazita rayo frequency, zvichikonzera kukanganisa system wachi.
Kutanga{{0}kuoma kana kusagadzikana: Kunyanya kurodha kunoderedza kuwanda, izvo zvinogona kuita kuti kristaro itadze kutanga kana kusangana nefrequency jitter.
Kuwedzera mashandisirwo emagetsi: Kurodha zvisina kunaka kunotungamira kune yakakwira simba rekushandisa mukristaro oscillator wedunhu.
Yakawedzera EMI: Kusagadzikana oscillations kunogona kuburitsa spurious frequencies, inokanganisa system electromagnetic kuenderana (EMC).
Ⅴ. Dhizaini Kurudziro uye Maitiro eInjiniya
Nyatsoongorora iyo crystal oscillator dhatabheti
Sarudza kukosha kweCL.
Nzwisisa inokurudzirwa yedunhu topology.
Tarisa kana huwandu hwekunze capacitor values hunokurudzirwa.
2. Funga nezvemamiriro ebhodhi chaiwo
Kufungidzira Cp uchishandisa PCB simulation kana ruzivo.
Pamawachi akakwira-anomhanya kana kuti akanyatsojeka (semuenzaniso, masisitimu ekutaurirana, mainfrequency eMCU > 100MHz), maverengero chaiwo kana kuyedza anokurudzirwa.
3. Shandisa symmetrical capacitors
Zvinowanzo kurudzirwa kuti C1=C2 iise pakati pe frequency nebalance ruzha.
Asymmetrical dhizaini inogona zvakare kushandiswa kune yakakosha yekufananidza zvinodiwa.
4. Shandisa SMD capacitor array yekugadzirisa
Edza neSMD capacitors (semuenzaniso, 10pF, 15pF, 22pF, 27pF, nezvimwewo) kuti uwane yakakodzera;
Tarisa kugadzikana kwekubuda uye kurongeka kwema frequency uchishandisa spectrum analyzer kana oscilloscope.
6,CommonFAQ
|
Mibvunzo |
Mhinduro |
|
Kana CL=12pF, iyo yekunze capacitor inofanira kuva yakakosha sei? |
Kana Cp=5pF, ipapo C1=C2≈14pF |
|
Sei mamwe maMCU asingade ekunze capacitors? |
Mamwe masekete ekristaro oscillator akavaka{{0}mukutakura macapacitor (semu, STM32), saka hapana macapacitor ekunze anodiwa. |
|
Ko kusapindirana kwekunze capacitors kukuvadza crystal oscillator here? |
Kazhinji, havazopisa kana kukuvadza, asi vanogona kukonzera kutadza kwekutanga kana zvikanganiso zve frequency. |
Mhedziso
Dhizaini yekunze inotakura capacitors yekristaro oscillator idiki asi yakakosha tsanangudzo inobata zvakananga kugadzikana uye kurongeka kwewachi system. Kunzwisisa kukarukureta ukama pakati CL uye C1/C2, uye kugadzirisa parameters inobva chaiyo PCB parasitic capacitance, chinhu chinokosha pakuwana yakavimbika oscillation uye chaiyo frequency.
Mune-zvinomhanyisa masisitimu edhijitari, michina yekufambisa mashoko, kana masisitimu ane zvinodiwa newachi zvakanyanya, kusarudza nemazvo uye kuenzanisa kugona kwekristaro ibasa reinjiniya rinofanirwa kukosheswa.
HCIine rabhoritari yehunyanzvi uye timu yeanjiniya ekushandisa ane anopfuura makore makumi maviri echiitiko, ichipa emahara nyanzvi yekufananidza uye masevhisi ekuyedza kune vatengi. Kana iwe uine chero zvaunoda mune izvi, ndapota inzwa wakasununguka kuonana nevatengesi vedu kana vashandi vehunyanzvi.