www.德州仪器.com
universalserialbus(usb)产品
host/自-poweredandbus-poweredhubs
在
OC
EN
地
0.1
µ
F
2, 3
5
4
6, 7, 8
0.1
µ
F 120
µ
F
地
输出
TPS2041B
电源 供应
D+
D−
V
总线
Downstream
usb 端口
USB
控制
3.3 v 5 v
1
tps2041b,,tps2042b
tps2043b,tps2044b,tps2051b
tps2052b,tps2053b,tps2054b
SLVS514E–APRIL2004–REVISEDJANUARY2006
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
自-poweredandbus-poweredhubsdistributedataandpowertodownstreamfunctions.这
tps204xb/tps205xbcanprovide-powerdistributionsolutionstomanyoftheseclassesofdevices.
hostsandself-poweredhubshavealocalpowersupplythatpowerstheembeddedfunctionsandthe
downstreamports(看Figure30和Figure31).thispowersupplymustprovidefrom5.25vto4.75vtothe
boardsideofthedownstreamconnectionunderfull-loadandno-loadconditions.hostsandsphsarerequiredto
havecurrent-limitprotectionandmustreportovercurrentconditionstotheusbcontroller.typicalsphsare
desktoppcs,monitors,printers,andstand-alonehubs.
figure30.typicalone-portusbhost/自-poweredhub
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