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DYNAMICVOLTAGEPOSITIONING
SOFTSTART
LOWDROPOUTOPERATION100%DUTYCYCLE
Vin
最小值
Vout
最大值
Iout
最大值
r
ds
(在)
最大值
R
L
Iout
最大值
= 最大 输出 电流 加 inductor 波纹 电流
r
ds
(在)
最大值
= 最大 p-频道 转变 r
ds
(在)
R
L
= 直流 阻抗 的 这 inductor
Vout
最大值
= 名义上的 输出 电压 加 最大 输出 电压 容忍
使能
UNDERVOLTAGELOCKOUT
tps62200,tps62201
tps62202,tps62203,tps62207
tps62204,tps62205,tps62208
SLVS417D–MARCH2002–REVISEDMAY2004
detaileddescription(持续)
asdescribedinthepowersavemodeoperationsectionsandasdetailedinfigure2,theoutputvoltageis
typically0.8%abovethenominaloutputvoltageatlightloadcurrents,asthedeviceisinpowersavemode.这个
givesadditionalheadroomforthevoltagedropduringaloadtransientfromlightloadtofullload.duringaload
transientfromfullloadtolightload,thevoltageovershootisalsominimizedduetoactiveregulationturningon
然后-channelrectifierswitch.
thetps6220xhasaninternalsoftstartcircuitthatlimitstheinrushcurrentduringstart-向上.thisprevents
possiblevoltagedropsoftheinputvoltageincaseabatteryorahighimpedancepowersourceisconnectedto
theinputofthetps6220x.
thesoftstartisimplementedasadigitalcircuitincreasingtheswitchcurrentinstepsoftypically60ma,120ma,
240maandthenthetypicalswitchcurrentlimitof480ma.thereforethestart-uptimemainlydependsonthe
outputcapacitorandloadcurrent.typicalstart-uptimewith10µfoutputcapacitorand200maloadcurrentis
800µs.
thetps6220xoffersalowinputtooutputvoltagedifference,whilestillmaintainingoperationwiththe100%duty
cyclemode.inthismode,thep-channelswitchisconstantlyturnedon.thisisparticularlyusefulinbattery
poweredapplicationstoachievelongestoperationtimebytakingfulladvantageofthewholebatteryvoltage
范围.theminimuminputvoltagetomaintainregulation,dependingontheloadcurrentandoutputvoltage,能
becalculatedas
pullingtheenablelowforcesthepartintoshutdown,withashutdownquiescentcurrentoftypically0.1µa.inthis
模式,thep-channelswitchandn-channelrectifierareturnedoff,theinternalresistorfeedbackdivideris
disconnected,andthewholedeviceisinshutdownmode.ifanoutputvoltage,whichcouldbeanexternal
voltagesourceorsupercap,ispresentduringshutdown,thereverseleakagecurrentisspecifiedunderelectrical
特性.forproperoperationtheenablepinmustbeterminatedandmustnotbeleftfloating.
pullingtheenablehighstartsupthetps6220xwiththesoftstartaspreviouslydescribed.
theundervoltagelockoutcircuitpreventsthedevicefrommisoperationatlowinputvoltages.itpreventsthe
converterfromturningontheswitchorrectifiermosfetunderundefinedconditions.
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