www.德州仪器.com
在
OC1
EN1
OC2
EN2
地
0.1
µ
F
2
8
3
5
4
7
33
µ
F
33
µ
F
地
1
OUT1
TPS2062
电源 供应
D+
D−
V
总线
地
D+
D−
V
总线
Downstream
usb 端口
USB
控制
3.3 v
5 v
33
µ
F
地
OUT2
D+
D−
V
总线
33
µ
F
地
D+
D−
V
总线
6
0.1
µ
F
0.1
µ
F
0.1
µ
F
0.1
µ
F
低-powerbus-poweredandhigh-powerbus-poweredfunctions
tps2061,tps2062,tps2063
tps2065,tps2066,tps2067
SLVS490B–DECEMBER2003–REVISEDDECEMBER2004
applicationinformation(持续)
figure27.typicalfour-portusbhost/自-poweredhub
bphsobtainallpowerfromupstreamportsandoftencontainanembeddedfunction.thehubsarerequiredto
powerupwithlessthanoneunitload.thebphusuallyhasoneembeddedfunction,andpowerisalways
availabletothecontrollerofthehub.iftheembeddedfunctionandhubrequiremorethan100maonpowerup,
thepowertotheembeddedfunctionmayneedtobekeptoffuntilenumerationiscompleted.thiscanbe
accomplishedbyremovingpowerorbyshuttingofftheclocktotheembeddedfunction.powerswitchingthe
embeddedfunctionisnotnecessaryiftheaggregatepowerdrawforthefunctionandcontrollerislessthanone
unitload.thetotalcurrentdrawnbythebus-powereddeviceisthesumofthecurrenttothecontroller,这
embeddedfunction,andthedownstreamports,anditislimitedto500mafromanupstreamport.
bothlow-powerandhigh-powerbus-poweredfunctionsobtainallpowerfromupstreamports;低-电源
functionsalwaysdrawlessthan100ma;高-powerfunctionsmustdrawlessthan100maatpowerupandcan
drawupto500maafterenumeration.iftheloadofthefunctionismorethantheparallelcombinationof44
Ω
and10µfatpowerup,thedevicemustimplementinrushcurrentlimiting(seefigure28).withtps206x,这
internalfunctionscoulddrawmorethan500ma,whichfitstheneedsofsomeapplicationssuchasmotordriving
电路.
19
: 点此下载
