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RegulatorProtection
R1
V
O
V
REF
1
R2
(2)
C1
(3 x 10
–7
) x (r1
r2)
(r1 x r2)
(3)
输出 voltAGE
程序编制 手册
输出
电压
R1 R2 C1
GNDNR
FB
在 输出
EN
V
在
V
输出
R1
C1
R2
0.01
µ
F
TPS79601
1
µ
F
1.8 v
3.6v
14.0 k
Ω
57.9 k
Ω
30.1 k
Ω
30.1 k
Ω
33 pf
15 pf
2.2
µ
F
tps79601,tps79618,tps79625
tps79628,tps79630,tps79633
SLVS351D–SEPTEMBER2002–REVISEDOCTOBER2004
Therecommendeddesignprocedureistochoose
r2=30.1k
Ω
tosetthedividercurrentat40µa,c1=
thetps796xxpmos-passtransistorhasabuilt-在
15pfforstability,andthencalculater1using
backdiodethatconductsreversecurrentwhenthe
equation2:
inputvoltagedropsbelowtheoutputvoltage(e.g.,
duringpowerdown).currentisconductedfromthe
outputtotheinputandisnotinternallylimited.如果
extendedreversevoltageoperationisanticipated,
externallimitingmightbeappropriate.
Inordertoimprovethestabilityoftheadjustable
TheTPS796xxfeaturesinternalcurrentlimitingand
版本,itissuggestedthatasmallcompensation
thermalprotection.duringnormaloperation,这
capacitorbeplacedbetweenoutandfb.这
tps796xxlimitsoutputcurrenttoapproximately2.8
approximatevalueofthiscapacitorcanbecalculated
一个.whencurrentlimitingengages,theoutputvoltage
asequation3:
scalesbacklinearlyuntiltheovercurrentcondition
ends.whilecurrentlimitingisdesignedtoprevent
grossdevicefailure,careshouldbetakennotto
exceedthepowerdissipationratingsofthepackage.
Thesuggestedvalueofthiscapacitorforseveral
ifthetemperatureofthedeviceexceedsapproxi-
resistorratiosisshowninthetablebelow(看
mately165
°
c,热的-protectioncircuitryshutsit
figure23).ifthiscapacitorisnotused(suchasina
向下.oncethedevicehascooleddowntobelow
统一体-gainconfiguration)thentheminimumrec-
approximately140
°
c,regulatoroperationresumes.
ommendedoutputcapacitoris2.2µfinsteadof1µf.
figure23.tps79601adjustableldoregulatorprogramming
10
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