www.德州仪器.com
在
OC1
OC2
2
8
3
5
4
7
0.1
µ
F 10
µ
F
内部的
函数
OUT1
电源 供应
3.3 v
EN1
6
0.1
µ
F 10
µ
F
OUT2
内部的
函数
0.1
µ
F
10
µ
F
USB
控制
地
V
总线
D−
D+
EN2
地
1
TPS2042B
usbpower-distributionrequirements
tps2041b,,tps2042b
tps2043b,tps2044b,tps2051b
tps2052b,tps2053b,tps2054b
SLVS514E–APRIL2004–REVISEDJANUARY2006
applicationinformation(持续)
figure32.高-powerbus-poweredfunction(例子,tps2042b)
usbcanbeimplementedinseveralways,和,regardlessofthetypeofusbdevicebeingdeveloped,一些
电源-distributionfeaturesmustbeimplemented.
•
hosts/自-poweredhubsmust:
–current-limitdownstreamports
–ReportovercurrentconditionsonUSBV
总线
•
总线-poweredhubsmust:
–enable/disablepowertodownstreamports
–powerupat<100ma
–limitinrushcurrent(<44
Ω
and10µf)
•
functionsmust:
–Limitinrushcurrents
–powerupat<100ma
thefeaturesetofthetps204xb/tps205xballowsthemtomeeteachoftheserequirements.theintegrated
电流-limitingandovercurrentreportingisrequiredbyhostsandself-poweredhubs.thelogic-levelenableand
controlledrisetimesmeettheneedofbothinputandoutputportsonbus-poweredhubs,aswellastheinput
portsforbus-poweredfunctions(看Figure33通过Figure36).
22