COS321SR

COS321/COS358/COS324
www.cosine-ic.com 1Features
■Operateson2.1V~5.5VSupplies
■LowQuiescentCurrent:85μA
■GainBandwidthProduct:1.5MHz
■SlewRate:1V/µs
■Rail-to-RailOutput
■UnityGainStable
■NoPhaseReversal
■ExtendedTemperatureRanges
From-40°Cto+125°C
■SmallPackaging
COS321availableinSOT23-5/SOP8
COS358availableinSOP8/MSOP8
COS324availableinSOP14/TSSOP14
Applications
■PortableEquipment
■SensorConditioning
■AnalogActiveFilters
■MedicalEquipment
■AudioOutput
■WhiteGoods
■BatteryorSolarPoweredSystemsGeneralDescription
TheCOS321(single),COS358(dual)and
COS324(quad)aremicro-power,lowcost
amplifiersoperatedon2.1Vto5.5Vsupplies.
Despitetheirlowquiescentcurrent,the
COS358familyprovidesexcellentoverall
performanceandversatility.Theyhave
rail-to-railoutputvoltagerangewhichextends
towithin10mVofeachrail,providingthe
maximumoutputdynamicrangewithexcellent
overdriverecovery.
COS358familyisunitygainstableandhasa
gainbandwidthproductof1.5MHz(typical).
TheyprovidehighCMRRandPSRR
performanceandcanoperatefromasingle
supplyvoltageaslowas2.1V.Thesefeatures
maketheCOS358familywellsuitedfor
single-supply,battery-poweredapplications.
Theycanbeusedasplus-inreplacementsfor
manycommerciallyavailableop-ampsto
reducepowerandimproveoutputrangeand
performance.
Rev1.1
Copyright@2018CosineNanoelectronicsInc.Allrightsreserved
Theinformationprovidedhereisbelievedtobeaccurateandreliable.CosineNanoelectronicsassumes
noreliabilityforinaccuraciesandomissions.Specificationsdescribedandcontainedherearesubjected
tochangewithoutnoticeonthepurposeofimprovingthedesignandperformance.Allofthisinformation
describedhereinshouldnotbeimpliedorgrantedforanythirdparty.1.5MHz,LowCost
MicroPowerOperationalAmplifiers
COS321/COS358/COS324
www.cosine-ic.com 21.PinConfigurationandFunctions
COS321 COS321 COS358 COS324
PinFunctions
Name Description Note
+VsPositivepowersupplyAbypasscapacitorof0.1μFasclosetothepartas
possibleshouldbeplacedbetweenpowersupplypins
orbetweensupplypinsandground.
-VsNegativepowersupply
orgroundIfitisnotconnectedtoground,bypassitwitha
capacitorof0.1μFasclosetothepartaspossible.
-IN NegativeinputInvertinginputoftheamplifier.Voltagerangeofthis
pincangofrom-Vs-0.3Vto+Vs-1V.
+IN PositiveinputNon-invertinginputoftheamplifier.Thispinhasthe
samevoltagerangeas–IN.
OUTOutputTheoutputvoltagerangeextendstowithinmillivolts
ofeachsupplyrail.
NC Noconnection
2.PackageandOrderingInformation
ModelChannelOrderNumber Package PackageOptionMarking
Information
COS3211COS321TR SOT23-5TapeandReel,3000 C321
COS321SR SOP-8TapeandReel,3000COS321
COS3582COS358SR SOP-8 COS35 TapeandReel,4000 8
COS358MR MSOP-8 COS35 TapeandReel,3000 8
COS3244COS324SR SOP-14TapeandReel,3000COS324
COS324TR TSSOP-14 COS32 TapeandReel,4000 4
COS321/COS358/COS324
www.cosine-ic.com 33.ProductSpecification
3.1AbsoluteMaximumRatings(1)
Parameter Rating Units
PowerSupply:+Vsto-Vs 6.0 V
InputVoltage -Vs-0.5Vto+Vs+0.5V V
InputCurrent(2)10 mA
StorageTemperatureRange -65to150 °C
JunctionTemperature 150 °C
OperatingTemperatureRange -40to125 °C
ESDSusceptibility,HBM 2000 V
(1)Stressesexceedingtheabsolutemaximumratingsmaydamagethedevice.Thedevicemaynotfunctionorbeoperable
abovetherecommendedoperatingconditionsandstressingthepartstotheselevelsisnotrecommended.Inaddition,
extendedexposuretostressesabovetherecommendedoperatingconditionsmayaffectdevicereliability.Theabsolute
maximumratingsarestressratingsonly.
(2)Inputterminalsarediode-clampedtothepower-supplyrails.Inputsignalsthatcanswingmorethan0.5Vbeyondthe
supplyrailsshouldbecurrent-limitedto10mAorless.
3.2ThermalData
Parameter Rating Unit
PackageThermalResistance,RθJA
(Juntion-to-ambient)190(SOT23-5)
206(MSOP8)
155(SOP8)
105(TSSOP14)
82(SOP14)°C/W
3.3RecommendedOperatingConditions
Parameter Rating Unit
DCSupplyVoltage 2.1V~5.5V V
Inputcommon-modevoltagerange -Vs~+Vs V
Operatingambienttemperature -40to+85 °C
COS321/COS358/COS324
www.cosine-ic.com 43.4ElectricalCharacteristics
(+VS=+5V,-VS=0,VCM=VS/2,TA=+25°C,RL=10kΩtoVS/2,unlessotherwisenoted)
Parameter Symbol Conditions MinTypMaxUnit
InputCharacteristics
InputOffsetVoltage VOS 1.05.0mV
InputOffsetVoltageDrift ΔVOS/ΔT-40to125°C 5 μV/°C
InputBiasCurrent IB 2.5 pA
InputOffsetCurrent IOS 2.5 pA
Common-ModeVoltageRangeVCM VS=5.5V -0.1 4.5V
Common-ModeRejectionRatioCMRRVCM=0.1Vto4.5V 125 dB
Open-LoopVoltageGain AOLVO=0.2Vto4.5V 120 dB
OutputCharacteristics
OutputVoltageSwingfromRailRL=100kΩ 1 mV
RL=10kΩ 10 mV
RL=2kΩ 40 mV
Short-CircuitCurrentISR Sourcing 45 mA
ISK Sinking 50 mA
PowerSupply
OperatingVoltageRange 2.1 5.5V
PowerSupplyRejectionRatioPSRRVS=+1.8Vto+5.5V 80100 dB
QuiescentCurrent/AmplifierIQ 85 μA
DynamicPerformance
GainBandwidthProduct GBWPG=+1 1.5 MHz
SlewRate SR G=+1,2VOutputStep 1 V/μs
NoisePerformance
VoltageNoiseDensity en f=1kHz 28 nV/√Hz
COS321/COS358/COS324
www.cosine-ic.com 54.0ApplicationNotes
DrivingCapacitiveLoads
Drivinglargecapacitiveloadscancausestabilityproblemsforvoltagefeedbackopamps.Asthe
loadcapacitanceincreases,thefeedbackloop’sphasemargindecreases,andtheclosedloop
bandwidthisreduced.Thisproducesgainpeakinginthefrequencyresponse,withovershootand
ringinginthestepresponse.Aunitygainbuffer(G=+1)isthemostsensitivetocapacitiveloads,but
allgainsshowthesamegeneralbehavior.
Whendrivinglargecapacitiveloadswiththeseopamps(e.g.,>100pFwhenG=+1),asmallseries
resistorattheoutput(RISOinFigure1)improvesthefeedbackloop’sphasemargin(stability)by
makingtheoutputloadresistiveathigherfrequencies.Itdoesnot,however,improvethebandwidth.
ToselectRISO,checkthefrequencyresponsepeaking(orstepresponseovershoot)onthebench.If
theresponseisreasonable,youdonotneedRISO.Otherwise,startRISOat1kΩandmodifyitsvalue
untiltheresponseisreasonable.
Figure1.IndirectlyDrivingHeavyCapacitiveLoad
AnimprovementcircuitisshowninFigure2.ItprovidesDCaccuracyaswellasACstability.RF
providestheDCaccuracybyconnectingtheinvertingsignalwiththeoutput,CFandRISOserveto
counteractthelossofphasemarginbyfeedingthehighfrequencycomponentoftheoutputsignal
backtotheamplifier’sinvertinginput,therebypreservingphasemarginintheoverallfeedbackloop.
Figure2.IndirectlyDrivingHeavyCapacitiveLoadwithDCAccuracy
COS321/COS358/COS324
www.cosine-ic.com 6Fornon-invertingconfiguration,therearetwootherswaystoincreasethephasemargin:(a)by
increasingtheamplifier’sgainor(b)byplacingacapacitorinparallelwiththefeedbackresistorto
counteracttheparasiticcapacitanceassociatedwithinvertingnode,asshowninFigure3.
Figure3.AddingaFeedbackCapacitorintheNon-invertingConfiguration
Power-SupplyBypassingandLayout
TheCOS321/2/4operatesfromasingle+2.1Vto+5.5Vsupplyordual±1.05Vto±2.75Vsupplies.
Forsingle-supplyoperation,bypassthepowersupply+Vswitha0.1μFceramiccapacitorwhich
shouldbeplacedclosetothe+Vspin.Fordual-supplyoperation,boththe+Vsandthe-Vssupplies
shouldbebypassedtogroundwithseparate0.1μFceramiccapacitors.2.2μFtantalumcapacitorcan
beaddedforbetterperformance.
Thelengthofthecurrentpathisdirectlyproportionaltothemagnitudeofparasiticinductancesand
thusthehighfrequencyimpedanceofthepath.Highspeedcurrentsinaninductivegroundreturn
createanunwantedvoltagenoise.Broadgroundplaneareaswillreducetheparasiticinductance.
Thusagroundplanelayerisimportantforhighspeedcircuitdesign.
TypicalApplicationCircuits
DifferentialAmplifier
ThecircuitshowninFigure4performsthedifferentialfunction.Iftheresistorsratiosareequal(R4/
R3=R2/R1),thenVOUT=(VIP–VIN)×R2/R1+VREF.
COS321/COS358/COS324
www.cosine-ic.com 7
Figure4.DifferentialAmplifier
LowPassActiveFilter
Whenreceivinglow-levelsignals,limitingthebandwidthoftheincomingsignalsintothesystemis
oftenrequired.ThesimplestwaytoestablishthislimitedbandwidthistoplaceanRCfilteratthe
noninvertingterminaloftheamplifier.Ifevenmoreattenuationisneeded,amultiplepolefilteris
required.TheSallen-Keyfiltercanbeusedforthistask,asFigure5.Forbestresults,theamplifier
shouldhaveabandwidththatis8to10timesthefilterfrequencybandwidth.Failuretofollowthis
guidelinecanresultinreductionofphasemargin.Thelargevaluesoffeedbackresistorscancouple
withparasiticcapacitanceandcauseundesiredeffectssuchasringingoroscillationinhigh-speed
amplifiers.Keepresistorsvalueaslowaspossibleandconsistentwithoutputloadingconsideration.
Figure5.Two-PoleLow-PassSallen-KeyActiveFilter
COS321/COS358/COS324
www.cosine-ic.com 85.PackageInformation
5.1SOT23-5(PackageOutlineDimensions)
5.2SOP8(PackageOutlineDimensions)

COS321/COS358/COS324
www.cosine-ic.com 95.3MSOP8(PackageOutlineDimensions)
5.4SOP14(PackageOutlineDimensions)

COS321/COS358/COS324
www.cosine-ic.com 105.5TSSOP14(PackageOutlineDimensions)
6.RelatedParts
PartNumber Description
COS6042 24kHz,0.5μA,Nano-PowerOpAmps,1.4Vto5.5VSupply
COS8042 160MHz,5.5mA,HighSpeedOpAmps,3Vto12VSupply
COS2172 10MHz,1.2mA,RRIOOpAmps,4.5to40VSupply
COS2333 350kHz,18μA,PrecisionOpAmps,1.8to5.5VSupply,ZeroDrift,Vos<10μV COS8552 1.5MHz,55μA,PrecisionOpAmps,1.8to5.5VSupply,ZeroDrift,Vos<10μV COS2388 9MHz,570μA,PrecisionOpAmps,1.8to5.5VSupply,ZeroDrift,Vos<10μV COS2227 10MHz,1.3mA,PrecisionOpAmps,4.5to36VSupply,Vos<50μV COS2182 5MHz,580μA,RRIOPrecisionOpAmps,4.5to40VSupply,Vos<50μV COS620 1.5MHz,1.3mA,InstrumentationAmps,4.5to36VSupply,Vos<50μV COSINA333150kHz,65μA,InstrumentationAmps,1.8to5.5VSupply,Vos<25μV