Peb feem ntau piv cov siv lead ua oscillator rau lub plawv ntawm lub digital Circuit Court, vim hais tias tag nrho cov kev ua hauj lwm ntawm lub digital circuit yog inseparable ntawm lub moos teeb liab, thiab siv lead ua oscillator ncaj qha tswj tag nrho cov system. Yog tias siv lead ua oscillator tsis ua haujlwm, tag nrho cov kab ke yuav ua rau tuag tes tuag taw, yog li cov siv lead ua oscillator yog qhov yuav tsum tau ua ua ntej rau digital circuit pib ua haujlwm.
Crystal oscillator, raws li peb feem ntau hais, yog quartz siv lead ua oscillator thiab quartz siv lead ua resonator. Lawv yog ob qho tib si ua los ntawm cov nyhuv piezoelectric ntawm quartz siv lead ua. Kev siv lub tshuab hluav taws xob rau ob lub electrodes ntawm lub quartz siv lead ua ua rau lub tshuab deformation ntawm cov siv lead ua, qhov kev siv tshuab siab rau ob sab ua rau hluav taws xob tshwm sim hauv cov siv lead ua. Thiab ob qho tib si ntawm cov phenomena no yog thim rov qab. Siv cov cuab yeej no, alternating voltages yog siv rau ob sab ntawm cov siv lead ua thiab cov wafer vibrates mechanically, nrog rau tsim alternating hluav taws xob teb. Hom kev vibration thiab hluav taws xob no feem ntau me me, tab sis ntawm qee zaus, qhov amplitude yuav nce ntxiv, uas yog piezoelectric resonance, zoo ib yam li LC voj resonance peb nquag pom.
Raws li lub plawv ntawm digital circuit, crystal oscillator ua lub luag haujlwm li cas hauv cov khoom ntse? Lub tsev ntse xws li cua txias, curtains, kev ruaj ntseg, saib xyuas thiab lwm yam khoom, txhua tus xav tau wireless kis tau tus mob module, lawv los ntawm Bluetooth, WIFI los yog ZIGBEEE raws tu qauv, module ntawm ib kawg mus rau lwm yam kawg, los yog ncaj qha los ntawm lub xov tooj ntawm tes tswj, thiab lub wireless module yog lub hauv paus tseem ceeb, cuam tshuam rau kev ruaj ntseg ntawm tag nrho cov system, yog li xaiv lub kaw lus siv cov siv lead ua oscillator. Txiav txim siab qhov ua tiav lossis tsis ua tiav ntawm cov circuits digital.
Vim qhov tseem ceeb ntawm crystal oscillator hauv digital circuit, peb yuav tsum tau ceev faj thaum siv thiab tsim:
1. Muaj cov quartz siv lead ua nyob rau hauv cov siv lead ua oscillator, uas yooj yim ua rau quartz siv lead ua tawg thiab puas thaum nws raug cuam tshuam los yog poob los ntawm sab nraud, thiab tom qab ntawd cov siv lead ua oscillator tsis tuaj yeem vibrated. Yog li ntawd, kev txhim kho txhim khu kev qha ntawm cov siv lead ua oscillator yuav tsum tau txiav txim siab hauv kev tsim ntawm Circuit Court, thiab nws txoj hauj lwm yuav tsum tsis txhob nyob ze ntawm lub phaj ntug thiab cov khoom siv plhaub kom deb li deb tau.
2. Ua tib zoo saib xyuas qhov kub thiab txias thaum vuam los ntawm tes lossis tshuab. Crystal kev co yog rhiab rau qhov kub thiab txias, vuam kub yuav tsum tsis txhob siab dhau, thiab lub sij hawm cua sov yuav tsum luv li sai tau.
Tsim nyog siv lead ua oscillator layout tuaj yeem cuam tshuam cov kab hluav taws xob cuam tshuam.
1. Cov lus piav qhia txog teeb meem
Cov khoom lag luam yog lub koob yees duab teb, uas muaj tsib ntu hauv: core control board, sensor board, camera, SD memory card thiab roj teeb. Lub plhaub yog lub plhaub yas, thiab lub rooj tsav xwm me me tsuas muaj ob qhov cuam tshuam: DC5V sab nraud fais fab interface thiab USB interface rau cov ntaub ntawv xa mus. Tom qab kuaj hluav taws xob, nws pom tau hais tias muaj txog 33MHz teeb meem suab nrov cuam tshuam.
Cov ntaub ntawv xeem thawj yog raws li nram no:
2. Tshawb xyuas qhov teeb meem
Cov khoom no lub plhaub yas plhaub, cov khoom siv uas tsis yog-shielding, tag nrho cov kev sim tsuas yog lub hwj chim qaum thiab USB cable tawm ntawm lub plhaub, puas yog qhov cuam tshuam zaus taw tes yog tawg los ntawm lub hwj chim qaum thiab USB cable? Yog li ntawd, cov kauj ruam hauv qab no raug coj mus kuaj:
(1) Ntxiv cov nplhaib sib nqus tsuas yog nyob rau ntawm lub zog qaum, cov txiaj ntsig kev xeem: kev txhim kho tsis pom tseeb;
(2) Tsuas yog ntxiv cov nplhaib sib nqus ntawm USB cable, cov txiaj ntsig kev xeem: qhov kev txhim kho tseem tsis pom tseeb;
(3) Ntxiv cov nplhaib sib nqus rau ob qho tib si USB cable thiab lub zog qaum, cov txiaj ntsig kev xeem: qhov kev txhim kho yog pom tseeb, tag nrho cov zaus ntawm kev cuam tshuam tau txo qis.
Nws tuaj yeem pom los ntawm cov saum toj no tias cov ntsiab lus cuam tshuam zaus raug coj tawm los ntawm ob lub interfaces, uas tsis yog qhov teeb meem ntawm lub zog interface lossis USB interface, tab sis cov ntsiab lus cuam tshuam sab hauv txuas nrog rau ob lub interfaces. Shielding tsuas yog ib qho interface tsis tuaj yeem daws qhov teeb meem.
Los ntawm kev ntsuas nyob ze, nws pom tias 32.768KHz siv lead ua oscillator los ntawm cov tub ntxhais tswj lub rooj tsavxwm tsim cov hluav taws xob muaj zog, uas ua rau cov cables nyob ib puag ncig thiab GND txuas 32.768KHz harmonic suab nrov, uas yog tom qab txuas thiab tawg los ntawm kev sib txuas USB cable thiab zog kab. Cov teeb meem crystal oscillator yog tshwm sim los ntawm ob qho teeb meem hauv qab no:
(1) Cov siv lead ua vibration yog ze ze rau ntawm ntug ntawm lub phaj, uas yooj yim ua rau lub suab nrov crystal vibration.
(2) Nws muaj cov kab teeb liab nyob rau hauv cov siv lead ua oscillator, uas yog ib qho yooj yim ua rau lub suab nrov ntawm cov teeb liab kab sib txuas siv lead ua oscillator.
(3) Cov khoom lim tau muab tso rau hauv qab siv lead ua oscillator, thiab lub lim capacitor thiab kev sib txuam tsis sib xws tsis tau teem caij raws li cov teeb liab taw qhia, uas ua rau cov nyhuv lim dej lim dej tsis zoo.
3, kev daws
Raws li kev txheeb xyuas, cov kev ntsuas hauv qab no tau txais:
(1) Lub lim capacitance thiab txuam tsis kam ntawm cov siv lead ua ze rau CPU nti yog qhov zoo dua tso tawm ntawm ntug ntawm lub rooj tsavxwm;
(2) Nco ntsoov tsis txhob nteg hauv av hauv qhov chaw tso khoom siv lead ua thiab qhov projection hauv qab no;
(3) Lub lim capacitance thiab kev sib txuam ua haujlwm ntawm cov siv lead ua yog npaj raws li lub teeb liab kev taw qhia, thiab muab tso rau zoo zoo thiab compact nyob ze ntawm lub Crystal;
(4) Cov siv lead ua tau muab tso rau ze ntawm lub nti, thiab cov kab ntawm ob yog luv thiab ncaj li sai tau.
4. Cov lus xaus
Niaj hnub no ntau lub tshuab siv lead ua oscillator moos zaus yog siab, cuam tshuam kev sib raug zoo zog muaj zog; Kev cuam tshuam harmonics tsis yog tsuas yog kis tau los ntawm cov tswv yim thiab cov kab tawm, tab sis kuj radiated los ntawm qhov chaw. Yog tias qhov kev teeb tsa tsis tsim nyog, nws yog ib qho yooj yim uas yuav ua rau muaj teeb meem hluav taws xob muaj zog, thiab nws nyuaj rau kev daws los ntawm lwm txoj kev. Yog li ntawd, nws yog ib qho tseem ceeb heev rau kev teeb tsa ntawm crystal oscillator thiab CLK teeb liab kab hauv PCB board layout.
Nco tseg ntawm PCB tsim ntawm crystal oscillator
(1) Lub coupling capacitor yuav tsum nyob ze rau lub hwj huam mov tus pin ntawm crystal oscillator li sai tau. Txoj hauj lwm yuav tsum tau muab tso rau hauv kev txiav txim: raws li lub hwj huam mov inflow kev taw qhia, lub capacitor nrog lub peev xwm tsawg tshaj plaws yuav tsum tau muab tso rau hauv kev txiav txim los ntawm qhov loj tshaj mus rau qhov tsawg tshaj plaws.
(2) Lub plhaub ntawm cov siv lead ua oscillator yuav tsum yog hauv av, uas tuaj yeem tawg cov siv lead ua oscillator tawm sab nraud, thiab tseem tuaj yeem tiv thaiv kev cuam tshuam ntawm cov teeb liab sab nraud ntawm cov siv lead ua oscillator.
(3) Tsis txhob xaim nyob rau hauv lub siv lead ua oscillator kom paub meej tias hauv pem teb yog tag nrho. Nyob rau tib lub sijhawm, tsis txhob xaim hauv 300mil ntawm cov siv lead ua oscillator, txhawm rau tiv thaiv cov siv lead ua oscillator los ntawm kev cuam tshuam nrog kev ua haujlwm ntawm lwm cov xov hlau, cov khoom siv thiab cov txheej txheem.
(4) Cov kab ntawm lub moos teeb liab yuav tsum luv li sai tau, cov kab yuav tsum dav dua, thiab qhov sib npaug yuav tsum pom nyob rau hauv qhov ntev ntawm cov xaim thiab deb ntawm cov cua sov.
(5) Cov siv lead ua oscillator yuav tsum tsis txhob muab tso rau ntawm ntug ntawm lub rooj tsavxwm PCB, tshwj xeeb tshaj yog nyob rau hauv kev tsim ntawm daim npav board.
