Ib, Industrial EMC Test Standards thiab Core Requirements
Kev ntsuam xyuas EMC ntawm cov khoom siv hauv kev lag luam yuav tsum ua raws li peb -theem system ntawm International Electrotechnical Commission (IEC), European Standards (EN), thiab Suav National Standards (GB). Cov khoom kuaj tseem ceeb muaj xws li:
Radiated emission (RE): Qhov ntsuas zaus npog 30MHz mus rau 1GHz, thiab cov cuab yeej yuav tsum tau txais cov khoom siv hluav taws xob siv hluav taws xob tsawg dua lossis sib npaug li 40dB μ V / m (10m nrug) los ntawm tus kav hlau txais xov hauv lub anechoic chamber. Lub moos teeb liab thiab nws cov kev sib haum xeeb ntawm qhov tawg code LCD yog qhov chaw hluav taws xob tseem ceeb, thiab yog tias tsis ua kom zoo rau hauv kev tsim, lawv yuav ua rau siab tshaj tus qauv.
Kev cuam tshuam kev cuam tshuam (CE): Qhov ntsuas zaus yog nyob nruab nrab ntawm 150kHz thiab 30MHz, thiab qhov cuam tshuam hluav taws xob ntawm cov kab hluav taws xob yog ntsuas los ntawm kab impedance stabilization network (LISN). Yog tias lub zog hluav taws xob ntawm lub LCD txuas tsis tau txais kev tsim qauv lim, siab - lub suab nrov zaus yuav raug xa mus rau daim phiaj hluav taws xob los ntawm txoj kab hluav taws xob, cuam tshuam rau lwm yam khoom siv.
Electrostatic Discharge (ESD): Raws li IEC 61000-4-2 tus qauv, siv ± 8kV tiv tauj tawm thiab ± 15kV cua tawm mus rau cov khoom siv casing thiab interface. Yog hais tias lub kov vaj huam sib luag los yog interface ntawm lub LCD disconnected tsis muaj kev tiv thaiv, ESD tej zaum yuav ua rau cov zaub txawv txav los yog Circuit Court puas.
Surge Immunity (SURGE): Simulate xob laim tawm tsam lossis kev hloov pauv tam sim no los ntsuas cov cuab yeej muaj peev xwm tiv taus qhov hluav taws xob hluav taws xob. Nyob rau hauv ib puag ncig kev lag luam, qhov tawg code LCD yuav tsum tiv taus qhov cuam tshuam ntawm qhov tsawg kawg yog ± 2kV.
2, Kev soj ntsuam ntawm EMC cuam tshuam qhov chaw hauv LCD nrog Broken Code
Qhov teeb meem EMC ntawm tawg code LCD feem ntau yog los ntawm cov hauv qab no:
Lub moos teeb liab harmonics: Lub voj voog tsav tsheb ntawm qhov tawg code LCD feem ntau siv lub siab - moos zaus (xws li 15MHz), uas ua rau ntau qhov sib haum xeeb (xws li 150MHz thiab 300MHz) tom qab Fourier series nthuav dav. Yog hais tias lub moos teeb liab tsis tau lim los yog tiv thaiv, harmonics yuav tawg mus rau hauv qhov chaw los ntawm PCB thaiv los yog connectors, ua rau RE tshaj tus qauv.
Lub hwj chim mov suab nrov: Yog hais tias lub hwj chim module ntawm lub disconnected LCD tsis siv ib tug π - hom lim los yog hom inductor, lub siab - zaus suab nrov ntawm lub switching fais fab mov (xws li 100kHz mus rau 1MHz) tej zaum yuav ua rau lub hwj chim daim phiaj los ntawm lub hwj chim kab, ua rau muaj teeb meem CE.
Interface coupling: Yog hais tias lub teeb liab interface ntawm lub LCD disconnected (xws li SPI, I2C) tsis siv optoelectronic los yog sib nqus sib cais, sab nraud cuam tshuam yuav ob peb mus rau tus neeg tsav tsheb Circuit Court los ntawm cov teeb liab kab, ua rau txawv txav zaub.
PCB layout defects: Yog hais tias siab - cov kab teeb liab ceev (xws li cov kab moos) tsis txawv txav, lossis cov hauv av digital thiab cov av analog tsis raug cais los ntawm cov hlaws sib nqus, nws yuav ua rau hauv av cuam tshuam thiab txo ESD kev tiv thaiv.
3, EMC tiv thaiv technology system rau LCD nrog tawg code
Hauv kev teb rau cov kev cuam tshuam tau hais los saum no, ib qho kev tiv thaiv rau LCD nrog cov lej tawg yuav tsum tau tsim los ntawm peb yam: xaiv cov khoom siv, kev tsim qauv, thiab kev ua kom zoo ntawm Circuit Court.
1. Cov khoom siv thiab kev ua kom zoo dua qub
Cov txheej txheem txheej: Txau ITO txheej txheej rau ntawm qhov chaw ntawm lub vijtsam kom tswj tau qhov chaw tiv thaiv nyob rau hauv thaj tsam ntawm 10 ⁶ -10 ⁹ Ω / sq, uas tuaj yeem tawm hluav taws xob zoo li qub thiab txhim kho ESD kev tiv thaiv rau ± 8kV.
Shielding npog tsim: Ntxiv tooj liab ntawv thaiv npog rau hauv cov chaw tseem ceeb ntawm PCB, xws li tsav tsheb ICs thiab moos circuits, thiab txuas lawv mus rau hauv av los ntawm vias kom txo tau nyob ze - teb coupling. Ib qho kev lag luam siab transmitter txo cov hluav taws xob siv ntawm 300MHz zaus taw tes los ntawm 15dB los ntawm qhov tsim no.
Cable shielding: Cov teeb liab thiab lub hwj chim kab siv twisted khub shielded nyob ntawm tej, nrog rau lub shielding txheej txiav 360℃rau lub connector vaj tse kom txo tau hom hluav taws xob. Ib qho kev lag luam servo tsav tau txo kev cuam tshuam los ntawm 10dB los ntawm kev txhim kho no.
2. Circuit Court optimization tsim
Fais fab filtering: Ntxiv ib π - hom lim rau lub hwj chim input davhlau ya nyob twg, nrog inductance qhov tseem ceeb xws li 100 μ H mus rau 1mH thiab capacitance qhov tseem ceeb xws li 0.1 μ F mus rau 10 μ F, kom suppress sib txawv thiab hom suab nrov. Ib qho kev lag luam sensor txo qhov cuam tshuam qhov hluav taws xob ntawm lub hwj huam mov kawg kom qis dua tus nqi txwv los ntawm kev tsim qauv no.
Cov teeb liab lim: Ntxiv RC qis- dhau lim mus rau lub teeb liab analog tawm tswv yim, nrog rau kev txiav tawm zaus teem rau 1.5 npaug ntawm lub teeb liab bandwidth, kom txo tau siab - suab nrov zaus. Ib yam khoom siv kho mob siv cov cuab yeej no los txo cov teeb liab kab hluav taws xob los ntawm 8dB.
Clock teeb liab ua: Txuas lub sij hawm nce ntug ntawm lub moos teeb liab thiab txo nws qhov siab - zaus harmonic amplitude; Los yog txo lub moos zaus (xws li los ntawm 15MHz mus rau 8MHz) thiab txav cov ntsiab lus sib haum xeeb sab nraum qhov ntsuas zaus. Ib lub vaj huam sib luag ib leeg txo cov nqi hluav taws xob 150MHz mus rau 1/20 los ntawm kev tsim cov zaus txo.
3. Grounding thiab layout optimization
Ib qho taw qhia hauv av: Hauv qis- zaus circuits (<1MHz), a star shaped grounding structure is used, where the digital ground and analog ground are connected at a single point through magnetic beads to avoid ground potential differences. A certain industrial controller has reduced ground bounce noise to 2mV through this design.
Multilayer PCB tsim: Hauv plaub txheej PCB, cov txheej txheem ywj pheej thiab cov txheej txheem hluav taws xob tau teeb tsa, thiab kev sib txuas sib txuas tau ua tiav los ntawm vias los txo cov electromagnetic coupling. Ib yam khoom siv tsheb thauj mus los txo cov hluav taws xob emission los ntawm 12dB los ntawm qhov kev teeb tsa no.
Kev rho tawm qhov kev xav tau yooj yim: faib cov txheej txheem ntawm analog circuits, digital circuits, thiab lub zog hluav taws xob rau hauv ib cheeb tsam, thiab teeb cov kab sib cais ntawm cov cheeb tsam kom txo cov teeb liab cuam tshuam. Ib lub ntsuas ntse ntse tau txo qhov ESD tsis ua haujlwm los ntawm 90% los ntawm kev tsim qauv no.
4, Kev Tshawb Fawb Kev Lag Luam thiab Kev Tshawb Fawb Txog Kev Lag Luam
Case 1: Rectification ntawm ntau dhau hluav taws xob emissions los ntawm industrial siab transmitters
Ib qho kev lag luam siab transmitter tshaj tus qauv los ntawm 10dB ntawm 300MHz zaus taw tes, thiab tau kho los ntawm cov kev ntsuas hauv qab no:
Ntxiv cov ntaub thaiv npog ntawm PCB los npog ADC thiab MCU modules, ua kom muaj kev tiv thaiv kev tiv thaiv los ntawm 15dB;
Hloov cov kab hluav taws xob thiab cov teeb liab mus rau cov kab sib tw twisted shielded xov hlau. Tom qab grounding lub shielding txheej, cov hluav taws xob siv zog txo los ntawm 8dB;
Optimize PCB thaiv, ua kom luv luv siab -frequency teeb liab kab ntev, thiab txo qhov sib txawv hom hluav taws xob los ntawm 5dB.
Thaum kawg, cov cuab yeej dhau IEC 61000-4-3 hluav taws xob emission test.
Case 2: Rectification ntawm tsis txaus ESD kev tiv thaiv ntawm industrial sensors
Ib qho kev lag luam sensor tau ntsib kev ua haujlwm tsis zoo thaum lub sijhawm ± 8kV tiv tauj kev kuaj xyuas. Cov kev kho kom raug muaj xws li:
Ntxiv cov khoom siv roj hmab rau ntawm cov seams ntawm lub plhaub kom ua kom muaj kev tiv thaiv zoo rau 50dB;
Ntxiv ib lub TVS diode array ntawm lub teeb liab input davhlau ya nyob twg nrog ib tug clamp voltage tsawg dua los yog sib npaug zos rau 6V kom zoo tiv thaiv downstream Circuit Court;
Optimize PCB thaiv, nce qib hauv av tooj liab ntawv, thiab txo ESD zog txuas.
Thaum kawg, lub cuab yeej dhau IEC 61000-4-2 ESD xeem.
