www.德州仪器.com
APPLICATIONINFORMATION
TPS715A33
在 输出
V
在
V
输出
C1
0.1
µ
F
0.47
µ
F
地
ExternalCapacitorRequirements
PowerDissipationandJunctionTemperature
P
d(最大值)
T
J
最大值
T
一个
R
JA
(1)
P
D
V
在
V
输出
I
输出
(2)
RegulatorProtection
TPS715A01
TPS715A33
SBVS047A–MAY2004–REVISEDDECEMBER2004
TheTPS715AxxfamilyofLDOregulatorshasbeenoptimizedforultralowpowerapplicationssuchasthe
msp430microcontroller.itsultralowsupplycurrentmaximizesefficiencyatlightloads,anditshighinputvoltage
rangemakesitsuitableforsuppliessuchasunconditionedsolarpanels.
figure14.typicalapplicationcircuit(fixedvoltageversion)
althoughnotrequired,a0.047-µforlargerinputbypasscapacitor,connectedbetweeninandgndandlocated
closetothedevice,isrecommendedtoimprovetransientresponseandnoiserejectionofthepowersupplyasa
全部的.ahigher-valueinputcapacitormaybenecessaryiflarge,快-上升-timeloadtransientsareanticipatedand
ifthedeviceislocatedseveralinchesfromthepowersource.
TheTPS715AxxrequiresanoutputcapacitorconnectedbetweenOUTandGNDtostabilizetheinternalcontrol
循环.anycapacitor(includingceramicandtantalum)thatis
≥
0.47µfproperlystabilizesthisloop.
toensurereliableoperation,worst-casejunctiontemperatureshouldnotexceed150
°
c.thisrestrictionlimitsthe
powerdissipationtheregulatorcanhandleinanygivenapplication.toensurethejunctiontemperatureiswithin
acceptablelimits,calculatethemaximumallowabledissipation,p
d(最大值)
,andtheactualdissipation,p
D
,这个
mustbelessthanorequaltoP
d(最大值)
.
themaximum-电源-dissipationlimitisdeterminedusingequation1:
在哪里:
•
T
J
maxisthemaximumallowablejunctiontemperature.
•
R
θ
JA
isthethermalresistancejunction-至-ambientforthepackage(seethedissipationratingtable).
•
T
一个
istheambienttemperature.
theregulatordissipationiscalculatedusingequation2:
powerdissipationresultingfromquiescentcurrentisnegligible.
thetps715axxpmos-passtransistorhasabuilt-inbackdiodethatconductsreversecurrentwhentheinput
voltagedropsbelowtheoutputvoltage(forexample,duringpower-向下).currentisconductedfromtheoutput
totheinputandisnotinternallylimited.ifextendedreversevoltageoperationisanticipated,externallimiting
mightbeappropriate.
thetps715axxfeaturesinternalcurrentlimiting.duringnormaloperation,thetps715axxlimitsoutputcurrent
toapproximately500ma.whencurrentlimitingengages,theoutputvoltagescalesbacklinearlyuntilthe
overcurrentconditionends.takecarenottoexceedthepowerdissipationratingsofthepackage.
7
: 点此下载
