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PCB Cov Lus Qhia Rau DDR4 Thiab Kev Txhim Kho Kev Txhim Kho Rau PCBs

Apr 20, 2022

Raws li cov toj roob hauv pes ntawm kev siv tshuab computer txuas ntxiv hloov zuj zus thiab hloov pauv, cov qauv tshiab tau tshwm sim thiab cov cuab yeej cuab yeej cuab tam yuav tsum tau hloov kho kom haum. Cov nqe lus no tseem siv tau rau kev hloov pauv hauv cov qauv ntawm DDR3 rau DDR4.

Cov kev nce qib hauv random nkag tau txais kev nco tau kuj tau txhim kho kev ua tau zoo tag nrho. Yog li ntawd, txhawm rau ua kom zoo dua ntawm RAM tshiab, PCB tsim yuav tsum tau hloov pauv, ib yam li lawv tau ua thaum tus qauv USB hloov pauv los ntawm USB 2.0 rau USB 3.0. Cov kev hloov pauv no tsis tu ncua thiab tsim nyog raws li kev lag luam xav tau rau kev ua haujlwm ntau dua, kev ua tau zoo dua, thiab cov yam ntxwv siab dua ntxiv mus rau kev lag luam.

Txawm hais tias cov neeg feem coob yuav tsis pom lossis pom cov kev hloov pauv vaj tse uas xav tau rau PCB tsim, qhov no tsis txo qis qhov tseem ceeb ntawm cov kev hloov pauv tseem ceeb no.

1. Yuav tsum hloov PCB Layout dab tsi los siv DDR4?

Muab ob npaug rau Cov Ntaub Ntawv Tus Nqi 4 (DDR4), luv luv, los ntawm ob hom qauv sib txawv. Ib hom qauv yog qhov me me dual inline nco module (260 pins), lossis So-DIMM, uas yog siv hauv cov khoom siv nqa tau xws li laptops. Lwm hom module yog dual in-line nco module (288 pins), lossis DIMM luv luv, siv hauv cov khoom siv xws li desktops thiab servers.

Yog li, tau kawg, thawj qhov kev hloov pauv hauv architecture yog vim muaj pes tsawg tus pins. Cov iteration yav dhau los (DDR3) ntawm DIMMs siv 240 tus pins, thaum So-DIMMs muaj 204 tus pins. Cov lus hais saum toj no DDR4 DIMMs siv 288 tus pins. Nrog ntau tus pins lossis kev sib cuag, DDR4 muaj peev xwm DIMM loj dua, cov ntaub ntawv zoo dua qub, rub tawm nrawm dua, thiab ua kom muaj zog dua.

ddr ram chip

Nrog rau qhov kev txhim kho kev ua tau zoo tag nrho los ntawm kev tsim qauv nkhaus (hauv qab) uas tso cai rau kev sib txuas zoo dua, muaj kev nyab xeeb dua thiab txhim kho kev ruaj ntseg thiab lub zog thaum lub sijhawm teeb tsa. Tsis tas li ntawd, kev ntsuam xyuas lub rooj ntev zaum tau ua pov thawj tias DDR4 ua rau 50 feem pua ​​​​kev ua tau zoo nce mus txog 3,200 MTs (megabits ib thib ob hloov pauv).

Thiab, cov kev ua tau zoo no tau ua tiav nrog kev siv hluav taws xob txo qis: txhua DIMM rub tsuas yog 1.2 volts, tsis yog 1.5 txog 1.35 volts xav tau los ntawm cov qauv dhau los. Tag nrho cov kev hloov pauv no txhais tau hais tias cov neeg tsim qauv PCB yuav tsum rov ntsuas lawv txoj hauv kev tsim los siv DDR4.

2. PCB DDR4 Cov Lus Qhia Tsim

Yog tias peb xav tau cov khoom siv hluav taws xob lossis cov khoom siv los ua haujlwm ntawm qib siab, peb xav tau cov qauv PCB meej uas suav nrog kev siv DDR4. Qhov no yog to taub zoo. Ntxiv nrog rau qhov xav tau kev tsim qauv raug, nws kuj yuav tsum ua raws li niaj hnub nco.

Cov neeg tsim qauv PCB tseem yuav tsum xav txog ntau yam ntawm lwm yam, xws li kev faib chaw thiab kev sib txuas tseem ceeb. Kuj tseem muaj qhov xav tau los tswj cov theem pib tsim, raws li rau kev ua tiav, kev tsim qauv yuav tsum ua kom tau raws li cov txheej txheem txuas thiab cov qauv tsim.

Yuav kom tswj tau cov ntaub ntawv zoo, PCBs yuav tsum ua raws li cov cabling thiab cov kev coj ua zoo tshaj plaws (PCBs), vim tias tsis ua li ntawd tuaj yeem ua rau muaj ntau yam teeb meem, suav nrog kev cuam tshuam thiab hluav taws xob emissions. Cov neeg tsim qauv PCB tseem yuav tsum tau siv cov txheej txheem tsim nyog kom ua tiav cov kiv cua loj-tawm thiab cov npoo siab kom tswj tau qis BER thiab cov ntaub ntawv ntau ntawm 1.6 txog 3.2 Gbps. Ib zaug ntxiv, tsis muaj cov txheej txheem tsim qauv tsim nyog, peb cov PCBs yuav ntsib teeb meem kev ncaj ncees thiab ua rau muaj kev sib tham thiab ua rau (ntau dhau) jitter.

3. DDR4 Cabling Guidelines and Length and Spacing rules

Kev ua tiav txoj hauv kev zoo tshaj plaws hauv PCB tsim yuav tsum tau muab tso rau ntawm DIMM connectors thiab siv cov cim xeeb chips. Feem ntau, DDR4 SDRAM xav kom luv luv cabling thiab qhov sib nrug kom ua tiav lub sij hawm ncov thiab pom cov teeb liab kev ncaj ncees. Cov neeg tsim qauv PCB tseem yuav tsum sib pauv tus pins hauv pawg teeb liab cuam tshuam. Tsis tas li ntawd, cov teeb liab thaiv ntawm qhov khoob, teeb liab txheej thaiv nyob ib sab, thiab kev siv dav hlau sib cais yuav tsum zam thaum siv.

Tsis tas li ntawd, yog tias ua tau, peb yuav tsum tau xa cov cim xeeb interface ntawm cov txheej txheem hluav taws xob lossis cov av tsim nyog (GND). Tsis tas li ntawd, koj tuaj yeem pab txo lossis tshem tawm qhov sib txawv ntawm qhov sib txawv los ntawm kev routing DQ (cov ntaub ntawv tawm tswv yim / tso zis), DQS (cov ntaub ntawv xaiv), thiab DM (cov ntaub ntawv npog) cov cim hauv tib lub byte channel pawg ntawm tib txheej. Lub moos teeb liab muaj kev nthuav tawm ntev dua li DQS cov cim, yog li lub moos teeb tsa kev sib dhos ntev feem ntau yuav tsum tau ntev dua li qhov ntev tshaj plaws DQS kev sib raug zoo hauv ob kab inline nco module.

Thaum kawg, peb yuav tsum nco ntsoov tias txhua pawg pawg thawj coj sib txawv thiab yog li qhov yuav tsum tau sib nrug. Yog li ntawd, ib qho kev daws teeb meem (xws li Cadence Clarity™ 3D Solver) yuav tsum tau siv los tsim kev sib tham hauv qab no -50dB ntawm cov cim tseem ceeb. Nco tseg: Tsis muaj qhov yuav tsum tau ntev ntawm lub moos mus rau DQS, tab sis muaj qhov yuav tsum tau ntev ntawm lub moos mus rau cov lus txib / tswj / chaw nyob. Qhov ntev yuav tsum tau nyob ntawm Dk (dielectric tas li) ntawm cov khoom thiab cov load ntawm txhua SDRAM. 4.

4. DDR4 Layer Allocation thiab Data Channel Reference

DQS, DQ, thiab DM tes hauj lwm tuaj yeem raug xa mus rau cov txheej txheem sab hauv stripline hauv pawg. Hloov chaw, chaw nyob / hais kom ua / tswj thiab moos yuav tsum tau taug kev ntawm cov khaubncaws sab nraud povtseg ze rau SDRAM kom txo qis tshaj qhov sib txuas.

Chaw nyob / hais kom ua / tswj SDRAM vias yuav tsum muaj vias txuas nrog hauv av (shaded vias) ntxiv ntawm txhua SDRAM kom txo cov vias coupling.

Tsis tas li ntawd, qhov chaw nyob thiab tswj kev siv hluav taws xob txheej lossis hauv av nyob ntawm tus maub los. Nco ntsoov tias DIMMs muaj chaw nyob thiab tswj cov txheej txheem siv hluav taws xob, thaum nyob rau hauv BGAs (pob daim phiaj arrays) tsis tshua muaj chaw nyob thiab tswj cov ntaub ntawv siv hluav taws xob.

ddr4(1)

DDR4, zoo li cov qauv tiam dhau los (DDR3), yuav tsum muaj kev tsim qauv tshiab hauv nws qhov kev siv. Obviously, cov qauv tsim tau hloov pauv kom haum rau qhov kev ua tau zoo dua qub, uas yog qhov cuam tshuam ntawm kev tsim kho tshiab. Txawm li cas los xij, ua raws li cov qauv tsim thiab cov txheej txheem topology tuaj yeem ua kom muaj txiaj ntsig zoo los ntawm kev ua kom zoo dua ntawm tus qauv tshiab niaj hnub no.

Txawm hais tias koj tab tom siv ib daim ntawv ntawm DDR nco lossis ua haujlwm ntawm tus qauv tsim nrog tshwj xeeb xav tau cov teeb liab, Cadence's suite ntawm cov qauv tsim thiab tshuaj ntsuam xyuas tuaj yeem pab koj. tsim sai dua li qhov koj xav tau "ob npaug ntawm cov ntaub ntawv tus nqi".

ND2+N8+IN12

Zhejiang NeoDen Technology Co., LTD., nrhiav tau nyob rau hauv 2010, yog ib lub chaw tsim khoom tshwj xeeb hauv SMT xaiv thiab qhov chaw tshuab,reflow qhov cub, stencil tshuab luam ntawv,SMT ntau lawm kabthiab lwm yam khoom SMT. Peb muaj peb tus kheej R & D pab pawg thiab tus kheej lub Hoobkas, ua kom zoo dua ntawm peb tus kheej kev paub txog R&D, kev cob qhia zoo, tau txais lub koob npe nrov los ntawm cov neeg siv khoom thoob ntiaj teb.

Hauv kaum xyoo no, peb tus kheej tsim NeoDen4, NeoDen IN6, NeoDen K1830, NeoDen FP2636 thiab lwm yam khoom siv SMT, uas muag zoo thoob plaws ntiaj teb. Txog tam sim no, peb tau muag ntau dua 10, 000pcs tshuab thiab xa tawm mus rau ntau dua 130 lub teb chaws thoob ntiaj teb, tsim kom muaj lub koob npe nrov hauv kev ua lag luam. Hauv peb lub ntiaj teb Ecosystem, peb koom tes nrog peb tus khub zoo tshaj plaws kom xa cov kev pab cuam muag khoom ntau dua, kev ua haujlwm siab thiab kev txhawb nqa zoo.

Ntxiv: No.18, Tianzihu Avenue, Tianzihu Town, Anji County, Huzhou City, Zhejiang Province, Suav teb

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