电荷泵

1

LTC1682/LTC1682-3.3/LTC1682-5

DoublerChargePumpswith

LowNoiLinearRegulator

sLowOutputNoi:60µV

RMS

(100kHzBW)

sAdjustableorFixedBoostedOutput

sAdjustableOutputVoltageRange:2.5Vto5.5V

sFixedOutputVoltages:3.3V,5V

sWideInputVoltageRange:1.8Vto4.4V

sUsSmallCeramicCapacitors

sNoInductorsRequired

sOutputCurrentupto50mA

s550kHzSwitchingFrequency

sLowOperatingCurrent:150µA

sLowShutdownCurrent:1µA

sInternalThermalShutdownandCurrentLimiting

sAvailablein8-PinMSOPandSOPackages

TheLTC®1682/LTC1682-3.3/LTC1682-5aredoublercharge

pumpswithaninternallownoi,lowdropout(LDO)linear

artsaredesignedtoprovidealownoi

boostedsupplyvoltageforpoweringnoinsitivedevices

suchashighfrequencyVCOsinwirelessapplications.

Aninternaldoublerchargepumpconvertsa1.8Vto4.4V

inputtoaboostedoutput,whiletheinternalLDOregulator

convertstheboostedvoltagetoalownoiregulatedoutput.

TheadjustableversionallowstheurtotV

OUT

viaexternal

ulatoriscapableofsupply-

wnreducesthe

supplycurrentto<5µA,removestheloadfromV

IN

by

disablingtheregulatoranddischargesV

OUT

toground

througha100Ωswitch.

TheLTC1682LDOregulatorisstablewithonly2µFonthe

eramiccapacitorscanbeud,reducingPC

boardarea.

TheLTC1682/LTC1682-3.3/LTC1682-5areshort-circuitand

tsareavailablein8-pin

MSOPandSOpackages.

,LTCandLTareregisteredtrademarksofLinearTechnologyCorporation.

Open-LoopClo-InPhaNoi

CENTER=902MHzRESBW=1kHz

SPAN=100kHzVBW=30Hz

SWP=10cREF=0dBm1682TA02

4.2VVCOPowerSupply,V

IN

=2.5Vto4.4V

sVCOPowerSuppliesinCellularPhones

s2-WayPagers

sWirelessPCMCIACards

sPortableMedicalInstruments

sLowPowerDataAcquisition

sRemoteTransmitters

AMPLITUDE

10dB/DIV

FEATURES

DESCRIPTIO

U

APPLICATIOS

U

TYPICALAPPLICATIO

U

36k

SHUTDOWN

15k

100k

4.7µF

0.22µF

V

IN

2.5VTO

4.4V

4.7µF

4.2V

1

2

3

4

8

7

6

5

V

OUT

SHDN

FB

GND

CPO

C

+

V

IN

C

–

1682TA01

LTC1682

VCO

MURATA

MQE001-902

1µF

4.7µF

1000pF

1k

B

M

P

C

1000pF

1000pF

4.7µF

V

C

f

OUT

902MHz

2

LTC1682/LTC1682-3.3/LTC1682-5

Theqdenotesspecificationsthatapplyoverthefulloperatingtemperature

range,otherwispecificationsareT

A

=25°=V

IN

=3V;C1=0.22µF;C2,C3,C4=4.7µF,unlessotherwinoted.

(Note1)

V

IN

toGround..............................................–0.3Vto5V

V

OUT

Voltage................................................–0.3Vto6V

CPOtoGround........................................................10V

SHDN,FILT/FBVoltageto

Ground.....................................–0.3Vto(V

IN

+0.3V)

V

OUT

Short-CircuitDuration............................Indefinite

I

OUT

......................................................................90mA

OperatingTemperatureRange

Commercial............................................0°Cto70°C

ExtendedCommercial(Note2)...........–40°Cto85°C

Industrial...........................................–40°Cto85°C

StorageTemperatureRange.................–65°Cto150°C

LeadTemperature(Soldering,10c)..................300°C

MaximumJunctionTemperature..........................125°C

ORDERPART

NUMBER

ORDERPART

NUMBER

LTC1682CMS8

LTC1682CMS8-3.3

LTC1682CMS8-5

LTC1682IMS8

LTC1682IMS8-3.3

LTC1682IMS8-5

LTC1682CS8

LTC1682CS8-3.3

LTC1682CS8-5

LTC1682IS8

LTC1682IS8-3.3

LTC1682IS8-5

MS8PARTMARKING

LTER

LTGT

LTGV

LTHM

LTGU

LTGW

ConsultfactoryforMilitarygradeparts.

S8PARTMARKING

PARAMETERCONDITIONSMINTYPMAXUNITS

V

IN

OperatingVoltageLTC1682q1.84.4V

LTC1682-3.3q24.4V

LTC1682-5q2.74.4V

I

VIN

ShutdownCurrentSHDN=0Vq15µA

I

VIN

OperatingCurrentI

OUT

=0mA,BurstModeTMOperation

0°Cto70°Cq150250µA

–40°Cto85°Cq150300µA

FBInputCurrentLTC1682,FB=1.235Vq–5050nA

FBVoltageLTC1682q1.2101.2351.260V

RegulatedOutputVoltageLTC1682-3.3,I

OUT

=1mAq3.233.303.37V

LTC1682-5,I

OUT

=1mAq4.95.05.1V

V

OUT

TemperatureCoefficient±50ppm

ChargePumpOscillatorFrequencyI

OUT

>200µA,V

IN

=1.8Vto4.4Vq480550620kHz

BurstModeisatrademarkofLinearTechnologyCorporation.

T

JMAX

=125°C,θ

JA

=120°C/W

T

JMAX

=125°C,θ

JA

=140°C/W

1682I

1682I33

1682I5

1682

168233

16825

ABSOLUTEMAXIMUMRATINGS

W

WW

U

1

2

3

4

V

OUT

SHDN

FILT/FB*

GND

8

7

6

5

CPO

C

+

V

IN

C

–

TOPVIEW

MS8PACKAGE

8-LEADPLASTICMSOP

*PIN3=FILTFORLTC1682-3.3/LTC1682-5

=FBFORLTC1682

TOPVIEW

S8PACKAGE

8-LEADPLASTICSO

1

2

3

4

8

7

6

5

V

OUT

SHDN

FILT/FB*

GND

CPO

C

+

V

IN

C

–

*PIN3=FILTFORLTC1682-3.3/LTC1682-5

=FBFORLTC1682

PACKAGE/ORDERINFORMATION

UUW

ELECTRICALCHARACTERISTICS

3

LTC1682/LTC1682-3.3/LTC1682-5

PARAMETERCONDITIONSMINTYPMAXUNITS

CPO(ChargePumpOutput)V

IN

=1.8V,I

OUT

=10mAq1830Ω

OutputResistanceV

IN

=3V,I

OUT

=10mAq1320Ω

V

IN

=4.4V,I

OUT

=10mAq1117Ω

V

OUT

DropoutVoltage(Note3)LTC1682,I

OUT

=10mA,V

OUT

=2.57V(Note5)q100160mV

LTC1682/LTC1682-3.3,I

OUT

=10mA,V

OUT

=3.3Vq75120mV

LTC1682/LTC1682-5,I

OUT

=10mA,V

OUT

=5Vq5090mV

V

OUT

EnableTimeI

OUT

=10mA2ms

V

OUT

OutputNoiVoltageLTC1682I

OUT

=10mA,10Hz≤f≤100kHz,V

OUT

=5V88µV

RMS

I

OUT

=10mA,10Hz≤f≤2.5MHz,V

OUT

=5V800µV

P-P

LTC1682-3.3I

OUT

=10mA,10Hz≤f≤100kHz,C

FILT

=1nF58µV

RMS

I

OUT

=10mA,10Hz≤f≤2.5MHz,C

FILT

=1nF500µV

P-P

LTC1682-5I

OUT

=10mA,10Hz≤f≤100kHz,C

FILT

=1nF64µV

RMS

I

OUT

=10mA,10Hz≤f≤2.5MHz,C

FILT

=1nF600µV

P-P

V

OUT

LineRegulationV

IN

=3Vto4V,I

OUT

=0mA(Note6)q520mV

V

OUT

LoadRegulationI

OUT

=1mAto10mAq310mV

I

OUT

=1mAto50mA(Note4)10mV

V

OUT

ShutdownResistanceSHDN=0V,ResistanceMeasuredtoGround,V

IN

=1.8Vq150350Ω

SHDN=0V,ResistanceMeasuredtoGround,V

IN

=4.4Vq50150Ω

SHDNInputThresholdV

IN

=1.8Vto4.4Vq0.411.6V

SHDNInputCurrentSHDN=V

IN

q–11µA

SHDN=0Vq–11µA

Note1:AbsoluteMaximumRatingsarethovaluesbeyondwhichthelife

ofadevicemaybeimpaired.

Note2:TheLTC1682Cisguaranteedtomeetspecifiedperformancefrom

0°Cto70°Candisdesigned,characterizedandexpectedtomeetthe

extendedtemperaturelimits,butisnottestedat–40°Cand85°

LTC1682Iisguaranteedtomeettheextendedtemperaturelimits.

Note3:Dropoutvoltageistheminimuminput/outputvoltagerequiredto

outtheoutput

voltagewillbeequalto:V

CPO

–V

DROPOUT

(eFigure4).

Note4:Operatingconditionsarelimitedbymaximumjunction

ulatedoutputspecificationwillnotapplyforall

operatingatmaximuminputvoltage,theoutputcurrentrangemaybe

eratingatmaximumoutputcurrent,theinputvoltage

rangemaybelimited.

Note5:LimitedbytheLDOdisableswitchpointof1.45V

IN

.

Note6:dbackcurrentis25µA.

Theqdenotesspecificationsthatapplyoverthefulloperatingtemperature

range,otherwispecificationsareT

A

=25°=V

IN

=3V;C1=0.22µF;C2,C3,C4=4.7µF,unlessotherwinoted.

ELECTRICALCHARACTERISTICS

4

LTC1682/LTC1682-3.3/LTC1682-5

OscillatorFrequencyvs

Temperature

OperatingCurrentvsV

IN

(NoLoad)

V

OUT

TransientRespon

V

OUT

200µV/DIV

100µs/DIV1682G04

C

CPO

=C

OUT

=4.7µFV

OUT

=5V

I

OUT

=10mAT

A

=25°C

V

IN

=3VC

FILT

=1nF

LTC1682-5OutputNoi

(BW=10Hzto2.5MHz)

ShutdowntoEnableTiming

MinandMaxV

CPO

vsV

IN

CPOOutputResistancevsV

IN

EnabletoShutdownTiming

TYPICALPERFORACECHARACTERISTICS

UW

V

IN

(V)

1.5

R

C

P

O

(

Ω)

35

30

25

20

15

10

5

2.0

2.53.03.5

1682G01

4.04.5

T

A

=25°C

C1=0.22µF

I

OUT

=10mA

V

IN

(V)

1.5

V

C

P

O

(

V

)

9

8

7

6

5

4

3

2.0

2.53.03.5

1682G02

4.04.5

V

CPO

=2(V

IN

)

(A)

(A)THEMAXIMUMGENERATEDNOLOAD

CPOVOLTAGE

(B)THEMINIMUMALLOWABLECPOVOLTAGE,

ATFULLLOAD,TOENSURETHATTHELDO

ISNOTDISABLED

(B)

V

CPO

=1.45(V

IN

)

T

A

=25°C

TIME(µs)

050

∆

V

O

U

T

(

m

V

)

I

O

U

T

(

m

A

)

100200150

250

300

1682G02

10

5

0

–5

–10

15

10

5

0

T

A

=25°C

V

IN

=3V

V

OUT

=4V

C

OUT

=10µF

200µs/DIV

S

H

D

N

(

V

)

V

O

U

T

(

V

)

2

0

4

3

2

1

0

1682G05

T

A

=25°C

V

IN

=3V

V

OUT

=4V

I

OUT

=10mA

C

CPO

=C

OUT

=10µF

1ms/DIV

S

H

D

N

(

V

)

V

O

U

T

(

V

)

2

0

4

3

2

1

0

1682G06

NOLOAD

T

A

=25°C

V

IN

=3V

V

OUT

=4V

C

OUT

=10µF

TEMPERATURE(°C)

–50

565

560

555

550

545

540

535

530

2575

1682G07

–250

50100125

O

S

CI

L

L

A

T

I

O

N

F

R

E

Q

U

E

N

C

Y

(

k

H

z

)

V

IN

=3V

V

IN

(V)

O

P

E

R

A

T

I

N

G

C

U

R

R

E

N

T

(

µ

A

)

220

200

180

160

140

120

100

80

60

1682G08

1.5

2.0

2.53.03.54.04.5

T

A

=25°C

LTC1682-3.3

LTC1682-5

LTC1682

5

LTC1682/LTC1682-3.3/LTC1682-5

V

OUT

(Pin1):LowNoiRegulatedOutputVoltage.V

OUT

shouldbebypasdwitha≥2µFlowESRcapacitoras

OUT

rangeis2.5Vto5.5V.

SHDN(Pin2):lowontheSHDN

highenables

inuouslyenablethepartconnectSHDNto

V

IN

.Whenthepartisinshutdown,V

OUT

willbeconnected

togroundviaa100ΩswitchandCPOwillbehigh

impedancedisconnectedfromV

IN

.

FB(Pin3)(LTC1682):Thevoltageonthispiniscompared

totheinternalreferencevoltage(1.235V)bytheerror

rnal

resistordividerisrequiredbetweenV

OUT

andFBtoadjust

theoutputvoltage.

FILT(Pin3)(LTC1682-3.3/LTC1682-5):Thispinisud

llya1nF

capacitorisconnectedfromFILTtoground.

GND(Pin4):SystemGround.

C–(Pin5):FlyingCapacitorNegativeInput.

V

IN

(Pin6):InputVoltage,1.8Vto4.4V.V

IN

shouldbe

bypasdwitha≥2µFlowESRcapacitorasclotothe

umcapaci-

tancevalueof0.1µFisrequired.

C+(Pin7):FlyingCapacitorPositiveInput.

CPO(Pin8):UnregulatedChargePumpOutputVoltage.

Approximately1.95(V

IN

)witha≥2µF

imumV

OUT

enabletimeis

required,theCPOcapacitorshouldbe2×theV

OUT

capacitor.

PINFUNCTIONS

UUU

TEMPERATURE(°C)

–50

V

O

U

T

V

O

L

T

A

G

E

(

V

)

5.030

5.020

5.010

5.000

4.990

3.340

3.330

3.320

3.310

3.300

3.290

1.238

1.240

1.236

1.234

1682G09

–25

25

50125

0

75

100

LTC1682

LTC1682-3.3

LTC1682-5

V

IN

=3V

I

OUT

=10mA

V

OUT

VoltagevsTemperature

TYPICALPERFORACECHARACTERISTICS

UW

OUTPUTCURRENT(mA)

0

V

O

U

T

V

O

L

T

A

G

E

(

V

)

4.994

4.993

3.300

4.997

4.996

4.995

5.000

4.999

4.998

1525404550

1682G10

3.299

3.298

3.297

3.296

3.295

3.294

510

20

3035

V

IN

=3.3V

T

A

=25°C

LTC1682-5

LTC1682-3.3

V

OUT

VoltagevsOutputCurrent

6

LTC1682/LTC1682-3.3/LTC1682-5

1682BlockDiagram

BLOCKDIAGRASM

W

–

+

–

+

+

–

CHARGEPUMP

AND

SLEWCONTROL

550kHz

OSCILLATOR

POWER-

ON

RESET

SD

REGEN

ENB

REGEN

FB

CLK1

REGB

SHDN

C1

0.22µF

C

+

V

IN

V

IN

V

REF

=1.235V

C

–

275k

C3

4.7µF

38k

328k

1:100

1µA/2µA

SD

LDO

100Ω

ENB

GND

CPO

V

OUT

1682F01

C2

4.7µF

R1

R2

C4

4.7µF

8

57

6

2

34

1

7

LTC1682/LTC1682-3.3/LTC1682-5

–

+

–

+

–

+

CHARGEPUMP

AND

SLEWCONTROL

550kHz

OSCILLATOR

POWER-

ON

RESET

SD

FILT

REGEN

ENB

REGEN

CLK1

REGB

SHDN

C1

0.22µF

C

+

V

IN

V

IN

200k

RB

200k

RA

120k/65.5k

V

REF

=1.235V

C

–

275k

C3

4.7µF

1nF

38k

328k

1:100

1µA/2µA

SD

100Ω

ENB

GND

CPO

V

OUT

1682F02

C2

4.7µF

C4

4.7µF

8

57

6

2

3

4

1

LDO

1682-3.3/LTC1682-5BlockDiagram

BLOCKDIAGRASM

W

8

LTC1682/LTC1682-3.3/LTC1682-5

Operation

TheLTC1682usaswitched-capacitorchargepumpto

generateaCPOvoltageofapproximately2(V

IN

).CPO

powersaninternallowdropoutlinearregulatorthatsup-

pliesaregulatedoutputatV

OUT

.Internalcomparatorsare

udtonCPOandV

IN

voltagesforpower-upcondi-

putcurrentisndtodeterminethe

edinternalbandgap

isudasthevoltagereferenceandatrimmedinternal

oscillatorisudtocontrolthechargepumpswitches.

Thechargepumpisadoublerconfigurationthatusone

abled,a2-pha

nonoverlappingclockcontrolsthechargepumpswitches.

Atstart-up,theLDOisdisabledandtheloadisremoved

Oreaches1.75(V

IN

)theLDOis

allsbelow1.45(V

IN

)theLDOwillbe

lly,thechargepumprunsopenloopwith

sgreaterthan

1.95(V

IN

)andI

OUT

islessthan100µA,thechargepump

willoperateinBurstModeoperationforincreadeffi-

tMode

operation,theclockisdisabledwhenCPOreaches1.95(V

IN

)

switchingfrequencyisprecilycontrolledtoensurethat

thefrequencyisabove455kHzandattheoptimumrateto

tchedgeratesare

ectiveoutput

resistanceatCPOisdependentonthevoltageatV

IN

,CPO

Rcapacitorof≥2µF

shouldbeudatCPOforminimumnoi.

TheLDOisudtofiltertherippleonCPOandtotan

outputvoltageindependentofCPO.V

OUT

istbyan

requiresa

capacitoronV

OUT

forstabilityandimprovedloadtransient

Rcapacitorof≥2µFshouldbeud.

OutputVoltageSelection

TheLTC1682-3.3/LTC1682-5versionshaveinternal

LTC1682outputvoltageistusinganexternalresistor

divider(eFigure3).Theoutputvoltageisdetermined

usingthefollowingformula:

V

OUT

=1.235V(1+R1/R2)

Theoutputvoltagerangeis2.5Vto5.5V.

MaximumV

OUT

andI

OUT

Calculations

Themaximumavailableoutputvoltageandcurrentcanbe

calculatedbadontheopencircuitCPOvoltage,the

dropoutvoltageoftheLDOandtheeffectiveoutput

ncircuitCPO

voltageisapproximately2(V

IN

)(eFigure4).

nganAuxiliaryRegulatorfromCPO

APPLICATIONSINFORMATION

WUU

U

R1

56k

R2

18k

C1

0.22µF

C4

4.7µF

1682F03

V

IN

3.6V

C3

4.7µF

5.1V

V

RIPPLE

=800µV

P-P

1

2

3

4

8

7

6

5

V

OUT

SHDN

FB

GND

CPO

C

+

V

IN

C

–

LTC1682

C2

4.7µF

IN

3.3V

OUT

GND

C5

EXTERNALLDO

V

OUT

=1.235V(1+R1/R2)

+

–2V

IN

R

CPO

C

CPO

V

CPO

V

OUT

I

LOAD

1682F04

R

DROPOUT

V

DROPOUT

+

–

lentCircuit

9

LTC1682/LTC1682-3.3/LTC1682-5

Thefollowingformulacanbeudtofindthemaximum

outputvoltagethatmaybeprogrammedforagiven

minimuminputvoltageandoutputcurrentload:

V

OUT(MAX)

=(2)(V

IN(MIN)

)–(I

OUT

)(R

CPO

)–V

DROPOUT

withtheconditionthat(I

OUT

)(R

CPO

)<0.55V

IN

.

Example:

V

IN(MIN)

=3V

I

OUT

=10mA

R

CPO(MAX)

=20Ω

MaxunloadedCPOvoltage=6V

LoadedCPOvoltage=6V–(10mA)(20Ω)=5.8V

V

DROPOUT(MAX)

=0.08V

V

OUT(MAX)

=(6V)–(0.2V)–(0.08V)=5.72V

V

OUT

<5.5Vand(I

OUT

)(R

CPO

)<0.55V

IN

,0.2V<1.65V.

Forminimumnoiapplications,theLDOmustbekeptout

ofdropouttopreventCPOnoifromcouplingintoV

OUT

.

ExternalCPOLoading

TheCPOoutputcandriveanexternalload(anLDO,for

example).Thecurrentrequiredbythisadditionalloadwill

reducetheavailablecurrentfromV

OUT

.Iftheexternalload

requires5mA,thenthemaximumavailablecurrentatV

OUT

willbereducedby5mA.

Short-CircuitandThermalProtection

V

OUT

alcir-

unctiontempera-

tureexceeds150°C,ive

powerdissipationduetoheavyloadswillalsocauthe

parttoshutdownwhenthejunctiontemperatureexceeds

150°twillbecomeenabledwhenthejunction

temperaturedropsbelow140°aultcondition

remainsinplace,thepartwillcyclebetweentheshutdown

andenabledstates.

CapacitorSelection

ForbestperformanceitisrecommendedthatlowESR

capacitorsbeudforC2,C3andC4inFigure1to

reducenoiandripple.C2mustbe≥2µFandC3must

beequaltoorgreaterthanC2.C4isdependentonthe

rgepumpdemandslarge

APPLICATIOSIFORATIO

WUU

U

instantaneouscurrentswhichmayinducerippleonto

acommonvoltagerail.C4shouldbe≥2µFandaspike

reducingresistorof2.2Ωmayberequiredbetween

V

IN

andthesupply.

AlowESRceramiccapacitorisrecommendedforthe

flyingcapacitorC1withavalueof0.22µoador

highV

IN

asmallercapacitorcouldbeudtoreduceripple

onCPOwhichwouldreflectaslowerrippleonV

OUT

.

Ifaminimumenabletimeisrequired,theCPOoutputfilter

capacitorshouldbeatleast2×theV

OUT

filtercapacitor.

WhentheLDOisfirstenabled,theCPOcapacitorwill

dumpalargeamountofchargeintotheV

OUT

thedropintheCPOvoltagefallsbelow1.45(V

IN

),theLDO

willbedisabledandtheCPOvoltagewillhavetochargeup

to1.75(V

IN

)ultingcycling

extendstheenabletime.

A1nFfiltercapacitorfortheLTC1682-3.3/LTC1682-5

shouldbeconnectedbetweentheFILTpinandgroundfor

optimumnoiperformance.

OutputRipple

TheoutputnoiandrippleonCPOincludesaspike

componentfromthechargepumpswitchesandadroop

componentwhichisdependentontheloadcurrentandthe

rgepumphasbeencarefullydesigned

tominimizethespikecomponent;however,lowESR

capacitorsareesntialtoreducetheremainingspike

energyeffectontheCPOvoltage.C3shouldbeincread

forhighloadcurrentstominimizethedroopcomponent.

RipplecomponentsonCPOaregreatlyreducedatV

OUT

by

theLDO;however,C2shouldalsobealowESRcapacitor

toimprovefilteringoftheCPOnoi.

Shutdown

WhenSHDNpinispulledlow(<0.4V),thepartwillbein

shutdown,thesupplycurrentwillbe<5µAandV

OUT

will

beconnectedtogroundthrougha100Ω-

tion,CPOwillbehighimpedanceanddisconnectedfrom

V

IN

.

Ifshutdownisnotrequired,connectSHDNtoV

IN

which

willcontinuouslyenablethepart.

10

LTC1682/LTC1682-3.3/LTC1682-5

APPLICATIONSINFORMATION

WUU

U

GeneralLayoutConsiderations

Duetothehighswitchingfrequencyandhightransient

currentsproducedbythedevice,carefulboardlayoutisa

boardlayoutusingagroundplaneandshort

connectionstoallcapacitorswillimprovenoiperfor-

manceandensureproperregulation(Figure5).

TheFILTpinontheLTC1682-3.3/LTC1682-5isahigh

ecurrentsatthispinmustbe

minimized.

MeasuringOutputNoi

MeasuringtheLTC1682lownoilevelsrequirescare.

Figure6showsatesttupfortakingthemeasurement.

Goodconnectionandsignalhandlingtechniqueshould

yieldabout500µV

P-P

measurementinvolvesACcouplingtheLTC1682output

intothetesttup’sinputandterminatingthisconnection

with50Ω.Coaxialconnectionsmustbemaintainedto

prervemeasurementintegrity.

Power-OnRet

Uponinitialpower-up,apower-onretcircuitensures

thattheinternalfunctionsarecorrectlyinitializedwhen

IN

reachesapproximately1V,the

power-onretcircuitwillenablethepartaslongasthe

SHDNpinisheldhigh.

ThermalConsiderations

Thepowerhandlingcapabilityofthedevicewillbelimited

bythemaximumratedjunctiontemperature(125°C).The

devicepowerdissipationP

D

=I

OUT

(2V

IN

–V

OUT

)+

V

IN

(4mA).Thedevicedissipatesthemajorityofitsheat

throughitspins,especiallyGND(Pin4).Thermalresis-

tancetoambientcanbeoptimizedbyconnectingGNDto

alargecopperregiononthePCB,whichrvesasaheat

ationswhichoperatetheLTC1682nearmaxi-

mumpowerlevelsshouldmaximizethecopperareaatall

pinxceptC+,C–andFILT/FBandensurethatthereis

someairflowovertheparttocarryawayexcessheat.

1

2

3

4

LTC1682-3.3/5

8

7

6

5

C1

V

OUT

V

IN

1682F05

C3

C2

GND

SHDN

C4

C

FILT

LTC1682

DEMO

BOARD

OSCILLOSCOPE

BANDWIDTH

FILTER

CONNECTBNCAND

R

LOAD

GROUNDTOTHE

OUTPUTCAPACITOR

GROUNDTERMINALE5

PLACECOUPLING

CAPACITORINSHIELDED

BOXWITHCOAXIAL

CONNECTOR

COUPLING

CAPACITOR

BNCCABLES

ORCOUPLERS

BATTERYOR

LOWNOISEDC

POWERSUPPLY

V

OUT

R

LOAD

R*

R*

*50ΩTERMINATIONS

HP-11048COR

EQUIVALENT

R*

NOTE:KEEPBNCCONNECTIONS

ASSHORTASPOSSIBLE

PLACEBANDWIDTHFILTER

COMPONENTSINSHIELDEDBOX

WITHCOAXIALCONNECTORS

PREAMPLIFIER

1822

INPUT

1682F06

–

+

20dB

1682NoiMeasurementTestSetup

Figure5

11

LTC1682/LTC1682-3.3/LTC1682-5

Dimensionsininches(millimeters)EDESCRIPTION

U

MS8Package

8-LeadPlasticMSOP

(LTCDWG#05-08-1660)

TYPICALAPPLICATION

U

C1

0.22µF

C

FILT

1nF

1682TA03

V

IN

3.3V

C2

4.7µF

3.3V

1

2

SHUTDOWN

3

4

8

7

6

5

V

OUT

SHDN

FILT

GND

CPO

C

+

V

IN

C

–

LTC1682-3.3

C3

4.7µF

C4

4.7µF

V

RIPPLE

=500µV

P-P

3.3VtoLowNoi3.3VConverter

S8Package

8-LeadPlasticSmallOutline(Narrow0.150)

(LTCDWG#05-08-1610)

MSOP(MS8)1197

*DIMENSIONDOESNOTINCLUDEMOLDFLASH,ASH,

PROTRUSIONSORGATEBURRSSHALLNOTEXCEED0.006"(0.152mm)PERSIDE

**DIMENSIONDOESNOTINCLUDEINTERLEADFLASHORPROTRUSIONS.

INTERLEADFLASHORPROTRUSIONSSHALLNOTEXCEED0.006"(0.152mm)PERSIDE

0.021

±0.006

(0.53±0.015)

0

°–6°TYP

SEATING

PLANE

0.007

(0.18)

0.040

±0.006

(1.02±0.15)

0.012

(0.30)

REF

0.006±0.004

(0.15±0.102)

0.034±0.004

(0.86±0.102)

0.0256

(0.65)

TYP

12

3

4

0.192±0.004

(4.88±0.10)

8

7

6

5

0.118±0.004*

(3.00±0.102)

0.118±0.004**

(3.00±0.102)

1

2

3

4

0.150–0.157**

(3.810–3.988)

8

7

6

5

0.189–0.197*

(4.801–5.004)

0.228–0.244

(5.791–6.197)

0.016–0.050

0.406–1.270

0.010–0.020

(0.254–0.508)

×45°

0°–8°TYP

0.008–0.010

(0.203–0.254)

SO80996

0.053–0.069

(1.346–1.752)

0.014–0.019

(0.355–0.483)

0.004–0.010

(0.101–0.254)

0.050

(1.270)

TYP

ASH

SHALLNOTEXCEED0.006"(0.152mm)PERSIDE

EAD

FLASHSHALLNOTEXCEED0.010"(0.254mm)PERSIDE

*

**

12

LTC1682/LTC1682-3.3/LTC1682-5

128235fs,sn128235LT/TP07994K•PRINTEDINUSA

©LINEARTECHNOLOGYCORPORATION1999

LinearTechnologyCorporation

1630McCarthyBlvd.,Milpitas,CA95035-7417

(408)432-1900qFAX:(408)

RELATEDPARTS

PARTNUMBERDESCRIPTIONCOMMENTS

LTC1340LowNoi,Voltage-BoostedVaractorDriverGenerates5VVaractorDrivefrom3VSupply

LTC1517-XMicropower,RegulatedChargePumpDoublerinSOT-23I

CC

=6µA;ShortCircuit/ThermalProtected

LT1521300mALowDropoutRegulatorMicropower;GoodTransientRespon

LTC1522Micropower,Regulated5VChargePumpUltralowPower:TypicalOperatingI

CC

=6µA

LT1761Series100mALowNoiLDORegulatorinSOT-23I

CC

=20µA;20µV

RMS

OutputNoi

TYPICALAPPLICATION

U

WideInputRangeVCOSupply(V

IN

>4.4V)

SHUTDOWN

C1

0.22µF

C4

4.7µF

3V

(REQUIREDFOR

START-UP)

Q1

FMMT3904

1682ta04

V

IN

3VTO6V

C3

4.7µF

5V

LOWNOISE

1

2

3

4

8

7

6

5

V

OUT

SHDN

FILT

GND

CPO

C

+

V

IN

C

–

R1

470Ω

LTC1682-5

C2

4.7µF

C

FILT

1nF

D1

1N4148

VCO