sata电源及信号接口定义Word格式文档下载.docx

sata电源及信号接口定义Word格式文档下载.docx

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SATA1.5Gb/sFirst-generationSerialATAinterfaces,alsoknownasSATA/150,runat1.5Gigahertz（GHz）.SerialATAuses8B/10Bencodingatthephysicallayer.Thisencodingschemehasanefficiencyof80%,resultinginanactualdatatransferrateof1.2Gigabitspersecond（Gb/s）,or150megabytespersecond（MB/s）.TherelativesimplicityofaseriallinkandtheuseofLVDSallowboththeuseoflongerdrivecablesandaneasiertransitionpathtohigherspeeds.

SATA3.0Gb/sSoonafterSATA'

sintroduction,enhancementsweremadetothestandard.A3Gb/ssignallingratewasaddedtothePHYlayer,offeringuptotwicethedatathroughput.ToensureseamlessbackwardcompatibilitybetweenolderSATAandthenewerfasterSATA/3Gbsdevices,thelatterdevicesarerequiredtosupporttheoriginal1.5Gb/srate.Inpractice,someolderSATAsystemsthatdonotsupportSATAspeednegotiationrequiretheperipheraldrive'

sspeedbemanuallyhardlimitedto150&

Acirc;

MB/swiththeuseofajumperfora300&

MB/sdrive.

LikeSATA1.5Gb/s,SATA3Gb/suses8B/10Bencodingresultinginanactualdatatransferrateof2.4Gb/s,or300MB/s.

The3.0&

Gb/sspecificationhasbeenverywidelyreferredtoas“SerialATAII”（“SATAII”）,contrarytothewishesoftheSerialATAstandardsorganizationthatauthoredit.TheofficialwebsitenotesthatSATAIIwasinfactthatorganization'

snameatthetime,theSATA3Gb/sspecificationbeingonlyoneofmanythattheformerSATAIIdefined,andsuggeststhat“SATA3Gb/s”beusedinstead.（TheSerialATAstandardsorganizationhassincechangednames,andisnow“TheSerialATAInternationalOrganization”,abbreviatedSATA-IO.）

SATA-IOplanstofurtherincreasethemaximumthroughputofSerialATAto600&

MB/saroundtheyear2007.

SATA3Gb/sissometimesalsoreferredtoasSATA/300orSATAII,continuingthelineofPATA/100,PATA/133andSATA/150.

SATA6.0Gb/sSATA-IOplanstomakea6.0Gb/sstandard.Althoughthetheoreticalthoroughputwouldbedoubled,conventionalharddiskscan'

tapproachsaturatingthisspeed.

SerialATAinnovationsSATAdropsthemaster/slavesharedbusofPATA,givingeachdeviceadedicatedcableanddedicatedbandwidth.WhilethisrequirestwicethenumberofhostcontrollerstosupportthesamenumberofSATAdevices,atthetimeofSATA'

sintroductionthiswasnolongerasignificantdrawback.AnothercontrollercouldbeaddedintoacontrollerASICatlittlecostbeyondtheadditionoftheextrasevensignallinesandprintedcircuitboard（PCB）spaceforthecableheader.

FeaturesallowedforbySATAbutnotbyPATAincludehot-swappingandnativecommandqueueing.

ToeasetheirtransitiontoSATA,manymanufacturershaveproduceddriveswhichusecontrollerslargelyidenticaltothoseontheirPATAdrivesandincludeabridgechiponthelogicboard.BridgeddriveshaveaSATAconnector,mayincludeeitherorbothkindsofpowerconnectors,andgenerallyperformidenticallytonativedrives.Theymay,however,lacksupportforsomeSATA-specificfeatures.Asof2004,allmajorharddrivemanufacturersproduceeitherbridgedornativeSATAdrives.

SATAdrivesmaybepluggedintoSerialAttachedSCSI（SAS）controllersandcommunicateonthesamephysicalcableasnativeSASdisks.SASdisks,however,maynotbepluggedintoaSATAcontroller.

CablesandConnectorsPhysically,theSATApoweranddatacablesarethemostnoticeablechangefromParallelATA.TheSATAstandarddefinesadatacableusingsevenconductorsand8&

mmwidewaferconnectorsoneachend.SATAcablescanbeupto1m（39in）long.PATAribboncables,incomparison,carryeither40-or80-conductorwiresandarelimitedto46cm（18in）inlength.ThereductioninconductorsmakesSATAconnectorsandcablesmuchnarrowerthanthoseofPATA,thusmakingthemmoreconvenienttoroutewithintightspacesandreducingobstructionstoaircooling.UnlikeearlyPATAconnectors,SATAconnectorsarekeyed—itisnotpossibletoinstallcableconnectorsupsidedownwithoutconsiderableforce.

TheSATAstandardalsospecifiesapowerconnectorsharplydifferingfromthefour-pinMolexconnectorusedbyPATAdrivesandmanyothercomputercomponents.Likethedatacable,itiswafer-based,butitswider15-pinshapeshouldpreventconfusionbetweenthetwo.Theseeminglylargenumberofpinsareusedtosupplythreedifferentvoltagesifnecessary—3.3&

V,5&

V,and12&

V.Eachvoltageissuppliedbythreepinsgangedtogether（and5pinsforground）.Thisisbecausethesmallpinscannotsupplysufficientcurrentforsomedevices,sotheyarecombined.Onepinfromeachofthethreevoltagesisalsousedforhotplugging.Thesamephysicalconnectionsareusedon3.5-in（90mm）and2.5-in（70mm）（notebook）harddisks.SomeSATAdrivesincludeinPATAstylefour-pinMolexconnectorforusewithpowersuppliesthatlacktheSATApowerconnector.Also,adaptorsareavailabletoconvertaPATAstylepowerconnectortoSATApowerconnector.

ExternalSATAeSATAwasstandardizedinmid-2004,withspecificallydefinedcables,connectors,andsignalrequirementsforexternalSATAdrives.eSATAischaracterizedby:

FullSATAspeedforexternaldisks（115MB/shavebeenmeasuredwithexternalRAIDenclosures）

∙NoprotocolconversionfromIDE/SATAtoUSB/Firewire,alldiskfeaturesareavailabletothehost

∙Cablelengthisrestrictedto2m,USBandFirewirespanlongerdistances.

∙Minimumandmaximumtransmitvoltagedecreasedto400mV-500mV

∙Minimumandmaximumreceivevoltagedecreasedto240mV-500mV

USBandFirewirerequireconversionofallcommunicationwiththeexternaldisk,soexternalUSB/FirewireenclosuresincludeanIDEorSATAbridgechipthattranslatesfromtheATAprotocoltoUSBorFirewire.DrivefeatureslikeS.M.A.R.T.cannotbeexploitedthatwayandtheachiveabletransferspeedwithUSB/Firewireisonlyabouthalfoftheentirebusdatarateofabout50MB/s.ThislimitedeffectivedatatransferratebecomesveryvisiblewhenusinganexternalRAIDarrayandalsowithfastsinglediskswhichmayyieldwellover70MB/sduringrealuse.

Currently,mostPCmotherboardsdonothaveaneSATAconnector.eSATAmaybeenabledthroughtheadditionofaneSATAhostbusadapter（HBA）orbracketconnectorfordesktopsystemsorwithaCardbusorExpressCardfornotebooks.

Note:

PriortothefinalspecificationforeSATA,therewereanumberofproductsdesignedforexternalconnectionsofSATAdrives.SomeoftheseusetheinternalSATAconnectororevenconnectorsdesignedforotherinterfacespecifications,suchasIEEE1394.TheseproductsarenoteSATAcompliant.

eSATAdoesnotprovidepower,whichmeansthatexternal2.5"

diskswhichwouldotherwisebepoweredovertheUSBorFirewirecableneedaseparatepowercablewhenconnectedovereSATA.

eSATAcomparedtootherbuses

eSATA

PATA

FireWire1394b

USB2.0

ActualSpeed

2.4>

Gib/s

1064Mib/s

786Mib/s

~375Mib/s

Max.cablelength

2meters

46centimetres

4.5meters16cablescanbe

daisychainedupto72meters

5meters

Powercablerequired?

Yes

No

DevicesperChannel

1（5withmultiplier）

3（3rddevicereadonly）

63

127

BackwardcompatibilityThebackwardcompatibilityofSATAharddiscsisvirtuallynon-existentinthesensethatSATAdriveswillnotworkwiththesameconnectorsthatIDE,SCSI,oranyotherformatofharddriveconnectto.Itis,however,possibletopurchaseconvertorsthatattachtotherearoftheSATAharddiscandwillallowittofunctionasanIDEdrive.ThiscanproveusefulinsituationswhereonewishestousetheirSATAdriveonoldermotherboardsthatmaynothaveSATAconnections,etc.

SATAvsSCSISCSIcurrentlyofferstransferrateshigherthanSATA,butisamorecomplexbususuallyresultinginhighercoststotheuser.SomedrivemanufacturersofferlongerwarrantiesforSCSIdevices,however,indicatingapossiblyhighermanufacturingqualitycontrolofSCSIdevicescomparedtoPATA/SATAdevices.

conn_sata.gif（10.79KB）

3030299030-SATA-15P-RA-core-power-connector-dwg.gif（14.14KB）

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