www.德州仪器.com
universalserialbus(usb)产品
host/自-poweredandbus-poweredhubs
tps2061,tps2062,tps2063
tps2065,tps2066,tps2067
SLVS490B–DECEMBER2003–REVISEDDECEMBER2004
applicationinformation(持续)
theuniversalserialbus(usb)interfaceisa12-mb/s,or1.5-mb/s,multiplexedserialbusdesignedfor
低-至-mediumbandwidthpcperipherals(e.g.,keyboards,printers,scanners,andmice).thefour-wireusb
interfaceisconceivedfordynamicattach-detach(hotplug-unplug)ofperipherals.twolinesareprovidedfor
differentialdata,andtwolinesareprovidedfor5-vpowerdistribution.
usbdataisa3.3-vlevelsignal,butpowerisdistributedat5vtoallowforvoltagedropsincaseswherepower
isdistributedthroughmorethanonehubacrosslongcables.eachfunctionmustprovideitsownregulated3.3v
fromthe5-vinputoritsowninternalpowersupply.
theusbspecificationdefinesthefollowingfiveclassesofdevices,eachdifferentiatedbypower-消耗量
(所需的)东西:
•
hosts/自-poweredhubs(sph)
•
总线-poweredhubs(bph)
•
低-电源,总线-poweredfunctions
•
高-电源,总线-poweredfunctions
•
自-poweredfunctions
sphsandbphsdistributedataandpowertodownstreamfunctions.thetps206xhashighercurrentcapability
thanrequiredbyoneusbport;所以,itcanbeusedonthehostsideandsuppliespowertomultipledownstream
portsorfunctions.
hostsandsphshavealocalpowersupplythatpowerstheembeddedfunctionsandthedownstreamports(看
figure27).thispowersupplymustprovidefrom5.25vto4.75vtotheboardsideofthedownstream
connectionunderfull-loadandno-loadconditions.hostsandsphsarerequiredtohavecurrent-limitprotection
andmustreportovercurrentconditionstotheusbcontroller.typicalsphsaredesktoppcs,monitors,printers,
andstand-alonehubs.
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