Compatible, 12-Bit, ADC and Temp Sensor w/Int Ref

36 Pages·2013·1.15 MB·English

ADS1018
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Ultra-Small, Low-Power, SPI™-Compatible, 12-Bit,
Analog-to-Digital Converter and Temperature Sensor with Internal Reference
CheckforSamples:ADS1018
FEATURES DESCRIPTION
1
• Ultra-SmallQFNPackage: The ADS1018 is a precision analog-to-digital
23 converter (ADC) with 12 bits of resolution offered in
2mm×1,5mm × 0,4mm
an ultra-small, leadless QFN-10 package or an
• WideSupplyRange:2.0Vto5.5V
MSOP-10 package. The ADS1018 is designed with
• LowCurrentConsumption: precision, power, and ease of implementation in
– ContinuousMode:Only150 μA mind. The ADS1018 features an integrated voltage
reference and oscillator. Data are transferred via a
– Single-ShotMode:AutoPower-Down
SPI-compatible serial interface. The ADS1018
• ProgrammableDataRate: operates from a single power supply ranging from
128SPS to3300SPS 2.0Vto5.5V.
• Single-CycleSettling The ADS1018 can perform conversions at rates up to
• InternalTemperatureSensor: 3300 samples per second (SPS). A programmable
1°C(max)Error gain amplifier (PGA) is integrated in the ADS1018
that offersinput rangesfromaslowas±256mVup to
• InternalLow-DriftVoltageReference
the supply rails, allowing both large and small signals
• InternalOscillator to be measured with high resolution. The ADS1018
• InternalPGA alsofeaturesaninput multiplexer(MUX)thatprovides
two differential or four single-ended inputs. The
• FourSingle-Endedor TwoDifferentialInputs
ADS1018 can also function as a high-accuracy
temperature sensor. This temperature sensor can be
APPLICATIONS
used for system-level temperature monitoring or cold-
• TemperatureMeasurement junctioncompensationfor thermocouples.
• PortableInstrumentation The ADS1018 operates either in continuous
• ConsumerGoods conversion mode or single-shot mode that
automatically powers down after a conversion and
• BatteryMonitoring
greatly reduces current consumption during idle
• FactoryAutomationandProcessControls periods. The ADS1018 is specified from –40°C to
+125°C.
VDD
0.1mF
VDD GND GND
1 MW 500W 0.1mF AIN0 VDD Device
1mF Voltage
AIN1 Reference
500W 0.1mF
1 MW
SCLK
GND GND MUX PGA 12-BitDS SPI CS
ADC Interface DOUT/DRDY
VDD GND DIN
1 MW 500W 0.1mF AIN2
1mF HighAccuracy
AIN3 Oscillator Temp Sensor
500W 0.1mF GND
1 MW
GND GND
GND
1
Pleasebeawarethatanimportantnoticeconcerningavailability,standardwarranty,anduseincriticalapplicationsof
TexasInstrumentssemiconductorproductsanddisclaimerstheretoappearsattheendofthisdatasheet.
SPIisatrademarkofMotorola.
2
Allothertrademarksarethepropertyoftheirrespectiveowners.
3
PRODUCTIONDATAinformationiscurrentasofpublicationdate. Copyright©2012–2013,TexasInstrumentsIncorporated
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarilyincludetestingofallparameters.
ADS1018
SBAS526B–NOVEMBER2012–REVISEDOCTOBER2013 www.ti.com
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with
appropriateprecautions.Failuretoobserveproperhandlingandinstallationprocedurescancausedamage.
ESDdamagecanrangefromsubtleperformancedegradationtocompletedevicefailure.Precisionintegratedcircuitsmaybemore
susceptibletodamagebecauseverysmallparametricchangescouldcausethedevicenottomeetitspublishedspecifications.
ORDERING INFORMATION
For the most current package and ordering information, see the Package Option Addendum at the end of this
document,orvisitthedeviceproductfolderatwww.ti.com.
ABSOLUTE MAXIMUM RATINGS(1)
VALUE UNIT
VDDtoGND –0.3to+5.5 V
100,momentary mA
Analoginputcurrent
10,continuous mA
AnaloginputvoltagetoGND –0.3toVDD+0.3 V
DIN,DOUT/DRDY,SCLK,andCSvoltagetoGND –0.3to+5.5 V
Operatingtemperaturerange –40to+125 °C
Maximumjunctiontemperature +150 °C
Storagetemperaturerange –60to+150 °C
Humanbodymodel(HBM)
±4000 V
Electrostaticdischarge JEDECstandard22,testmethodA114-C.01,allpins
(ESD)ratings Chargeddevicemodel(CDM)
±1000 V
JEDECstandard22,testmethodC101,allpins
(1) StressesabovethoselistedunderAbsoluteMaximumRatingsmaycausepermanentdamagetothedevice.Exposuretoabsolute
maximumconditionsforextendedperiodsmayaffectdevicereliability.
PRODUCTFAMILY
MAXIMUM INPUTCHANNELS PACKAGE
RESOLUTION SAMPLERATE [Differential DESIGNATOR
DEVICE (Bits) (SPS) (Single-Ended)] PGA INTERFACE SPECIALFEATURES MSOP,QFN
ADS1118 16 860 2(4) Yes SPI Temperaturesensor BBEI,SDQ
ADS1018 12 3300 2(4) Yes SPI Temperaturesensor BTNQ,SDZ
ADS1115 16 860 2(4) Yes I2C Comparator BOGI,N4J
ADS1114 16 860 1(1) Yes I2C Comparator BRNI,N5J
ADS1113 16 860 1(1) No I2C None BROI,N6J
ADS1015 12 3300 2(4) Yes I2C Comparator BRPI,N7J
ADS1014 12 3300 1(1) Yes I2C Comparator BRQI,N8J
ADS1013 12 3300 1(1) No I2C None BRMI,N9J
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ELECTRICAL CHARACTERISTICS
MaximumandminimumspecificationsapplyfromT =–40°Cto+125°C,unlessotherwisenoted.
A
TypicalvaluesareatT =+25°C.AllspecificationsareatVDD=3.3Vandfull-scale(FS)=±2.048V,unlessotherwise
A
noted.
PARAMETER TESTCONDITIONS MIN TYP MAX UNIT
ANALOGINPUT
Full-scaleinputvoltagerange VIN=(AINP)–(AINN) SeeTable2 V
Analoginputvoltage AINPorAINNtoGND GND VDD V
ZID Differentialinputimpedance SeeTable1
FS=±6.144V(1) 8 MΩ
FS=±4.096V(1),±2.048V 6 MΩ
ZIC Common-modeinputimpedance
FS=±1.024V 3 MΩ
FS=±0.512V,±0.256V 100 MΩ
SYSTEMPERFORMANCE
Resolution Nomissingcodes 12 Bits
DR Datarate 128,250,490,920,1600,2400,3300 SPS
Dataratevariation Alldatarates –10% 10%
Outputnoise SeeTypicalCharacteristics
INL Integralnonlinearity DR=128SPS,FS=±2.048V(2) 0.5 LSB
FS=±2.048V,differentialinputs 0 ±0.5 LSB
EO Offseterror
FS=±2.048V,single-endedinputs ±0.25 LSB
Offsetdrift FS=±2.048V 0.002 LSB/°C
EG Gainerror(3) FS=±2.048VatTA=+25°C 0.05% 0.25%
FS=±0.256V 7 ppm/°C
Gaindrift(3)(4) FS=±2.048V 5 40 ppm/°C
FS=±6.144V(1) 5 ppm/°C
PGAgainmatch(3) MatchbetweenanytwoPGAgains 0.02% 0.1%
Gainmatch Matchbetweenanytwoinputs 0.05% 0.1%
Offsetmatch Matchbetweenanytwoinputs 0.25 LSB
TEMPERATURESENSOR
Temperaturesensorrange –40 +125 °C
Temperaturesensorresolution 0.125 °C/LSB
TA=0°Cto+70°C 0.25 ±1 °C
Temperaturesensoraccuracy TA=–40°Cto+125°C 0.5 ±2 °C
vssupply 0.125 ±1 °C/V
DIGITALINPUT/OUTPUT
VIH Logicinputlevel,high 0.7VDD VDD V
VIL Logicinputlevel,low GND 0.2VDD V
VOH Logicoutputlevel,high IOH=1mA 0.8VDD V
VOL Logicoutputlevel,low IOL=1mA GND 0.2VDD V
IH Inputleakage,high VIH=5.5V ±10 μA
IL Inputleakage,low VIL=GND ±10 μA
(1) Thisparameterexpressesthefull-scalerangeoftheADCscaling.InnoeventshouldmorethanVDD+0.3Vor5.5V(whicheveris
smaller)beappliedtothisdevice.
(2) Best-fitINL;covers99%offull-scale.
(3) IncludesallerrorsfromtheonboardPGAandreference.
(4) Notproductiontested;ensuredbycharacterization.
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ELECTRICAL CHARACTERISTICS (continued)
MaximumandminimumspecificationsapplyfromT =–40°Cto+125°C,unlessotherwisenoted.
A
TypicalvaluesareatT =+25°C.AllspecificationsareatVDD=3.3Vandfull-scale(FS)=±2.048V,unlessotherwise
A
noted.
PARAMETER TESTCONDITIONS MIN TYP MAX UNIT
POWER-SUPPLYREQUIREMENTS
Power-supplyvoltage 2 5.5 V
Power-downcurrentatTA=+25°C 0.5 2 μA
Power-downcurrentuptoTA=+125°C 5 μA
ICC Supplycurrent
OperatingcurrentatTA=+25°C 150 200 μA
OperatingcurrentuptoTA=+125°C 300 μA
VDD=5.0V 0.9 mW
PD Powerdissipation VDD=3.3V 0.5 mW
VDD=2.0V 0.3 mW
TEMPERATURE
Tstg Storagetemperature –60 +150 °C
Specifiedtemperature –40 +125 °C
THERMAL INFORMATION
ADS1018
THERMALMETRIC(1) MSOP(DGS) QFN(RUG) UNITS
10PINS 10PINS
θ Junction-to-ambientthermalresistance 186.8 245.2
JA
θ Junction-to-case(top)thermalresistance 51.5 69.3
JCtop
θ Junction-to-boardthermalresistance 108.4 172.0
JB
°C/W
ψ Junction-to-topcharacterizationparameter 2.7 8.2
JT
ψ Junction-to-boardcharacterizationparameter 106.5 170.8
JB
θ Junction-to-case(bottom)thermalresistance n/a n/a
JCbot
(1) Formoreinformationabouttraditionalandnewthermalmetrics,seetheICPackageThermalMetricsapplicationreport,SPRA953.
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PARAMETER MEASUREMENT INFORMATION
SPI TIMING CHARACTERISTICS
t
CS CSH
tCSSC tSCLK tSPWH tSCCS
SCLK
tDIST tDIHD tSPWL tSCSC
DIN
t
t t DOHD t
CSDOD DOPD CSDOZ
Hi-Z Hi-Z
DOUT
Figure1. SerialInterfaceTiming
TIMINGREQUIREMENTS:SERIALINTERFACETIMING(1)
PARAMETER MIN MAX UNIT
t CSlowtofirstSCLK:setuptime(2) 100 ns
CSSC
t SCLKperiod 250 ns
SCLK
t SCLKpulsewidth:high 100 ns
SPWH
100 ns
t SCLKpulsewidth:low(3)
SPWL
28 ms
t ValidDINtoSCLKfallingedge:setuptime 50 ns
DIST
t ValidDINtoSCLKfallingedge:holdtime 50 ns
DIHD
t SCLKrisingedgetovalidnewDOUT:propagationdelay(4) 50 ns
DOPD
t SCLKrisingedgetoDOUTinvalid:holdtime 0 ns
DOHD
t CSlowtoDOUTdriven:propagationdelay 100 ns
CSDOD
t CShightoDOUTHi-Z:propagationdelay 100 ns
CSDOZ
t CShighpulse 200 ns
CSH
t FinalSCLKfallingedgetoCShigh 100 ns
SCCS
(1) AtT =–40°Cto+125°CandVDD=2.0Vto5.5V,unlessotherwisenoted.
A
(2) CScanbetiedlow.
(3) HoldingSCLKlowlongerthan28msresetstheSPIinterface.
(4) DOUTload=20pF||100kΩtoGND.
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PIN CONFIGURATIONS
RUGPACKAGE
QFN-10 DGSPACKAGE
(TopView) MSOP-10
(TopView)
DIN
10
SCLK 1 10 DIN
SCLK 1 9 DOUT/DRDY
CS 2 9 DOUT/DRDY
CS 2 8 VDD
GND 3 8 VDD
GND 3 7 AIN3
AIN0 4 7 AIN3
AIN0 4 6 AIN2
AIN1 5 6 AIN2
5
AIN1
PINDESCRIPTIONS
PINNAME PINNO. FUNCTION DESCRIPTION
AIN0 4 Analoginput Differentialchannel1:positiveinputorsingle-endedchannel1input
AIN1 5 Analoginput Differentialchannel1:negativeinputorsingle-endedchannel2input
AIN2 6 Analoginput Differentialchannel2:positiveinputorsingle-endedchannel3input
AIN3 7 Analoginput Differentialchannel2:negativeinputorsingle-endedchannel4input
CS 2 Digitalinput Chipselect;activelow
DIN 10 Digitalinput Serialdatainput
DOUT/DRDY 9 Digitaloutput Serialdataoutcombinedwithdataready;activelow
GND 3 Analog Ground
SCLK 1 Digitalinput Serialclockinput
VDD 8 Analog Powersupply:2.0Vto5.5V
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TYPICAL CHARACTERISTICS
AtT =+25°CandVDD=3.3V,unlessotherwisenoted.
A
300 5
4.5
250
A) 4
A) VDD= 5 V m
Current (m 210500 n Current ( 32..553 VDD= 2 V
g VDD= 3.3 V w
eratin 100 VDD= 2 V er-Do 1.52 VDD= 3.3 V
p w
O o
P 1
50
0.5
VDD= 5 V
0 0
-40 -20 0 20 40 60 80 100 120 140 -40 -20 0 20 40 60 80 100 120 140
Temperature (°C) Temperature (°C)
Figure2.OPERATINGCURRENTvsTEMPERATURE Figure3.POWER-DOWNCURRENTvsTEMPERATURE
150 60
FS =±4.096 V(1) FS =±1.024 V
100 50
FS =±2.048 V FS =±0.512 V
VDD= 5 V
50
40
V)m 0 VDD = 2 V V)m
e ( e ( 30
ag -50 ag VDD= 4 V
et Volt -100 et Volt 2100 VDD= 3 V
Offs -150 Offs
0
-200 VDD= 2 V
VDD = 5 V
-250 -10
-300 -20
-40 -20 0 20 40 60 80 100 120 140 -40 -20 0 20 40 60 80 100 120 140
Temperature (°C) Temperature (°C)
Figure4.SINGLE-ENDEDOFFSETVOLTAGE Figure5.DIFFERENTIALOFFSETVOLTAGE
vsTEMPERATURE (1) vsTEMPERATURE
0.05 4
FS =±0.256 V DR = 3300 SPS
0.04 3 FS =±2.048 V
14k Samples
0.03
FS =±0.512 V s) 2
or (%) 00..0021 e (LSB 1
ain Err 0 ±4F.S0 9=6± V1(.10),2 a4n Vd,±±62..104448 VV(,1) ut Cod -01
G -0.01 utp
-0.02 O -2
-0.03 -3
-0.04 -4
-40 -20 0 20 40 60 80 100 120 140 0 2000 4000 6000 8000 10000 12000 14000
Temperature (°C) Reading Number
Figure6.GAINERRORvsTEMPERATURE Figure7.NOISEPLOT
(1) Thisparameterexpressesthefull-scalerangeoftheADCscaling.InnoeventshouldmorethanVDD+0.3Vbeappliedtothisdevice.
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TYPICAL CHARACTERISTICS (continued)
AtT =+25°CandVDD=3.3V,unlessotherwisenoted.
A
1
Average Temperature Error
0.8 Average “ 3 sigma
Average “ 6 sigma
0.6
C)
ƒor ( 0.4
Err 0.2
e 0
ur
erat -0.2
p
m -0.4
e
T
-0.6
-0.8
-1
-40 -20 0 20 40 60 80 100 120
Temperature (ƒC) C001
Figure8.TEMPERATURESENSORERROR
vsAMBIENTTEMPERATURE
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OVERVIEW
The ADS1018 is a very small, low-power, 12-bit, delta-sigma (ΔΣ) analog-to-digital converter (ADC). The
ADS1018 is extremely easy to configure and design into a wide variety of applications, and allows precise
measurements to be obtained with very little effort. Both experienced and novice users of data converters find
designingwiththeADS1018tobeintuitiveandproblem-free.
The ADS1018 consists of a ΔΣ ADC core with adjustable gain, internal voltage reference, clock oscillator, and
SPI interface. This device is also a highly linear and accurate temperature sensor. All of these features are
intended to reduce required external circuitry and improve performance. Figure 9 shows the ADS1018 functional
blockdiagram.
The ADS1018 ADC core measures a differential signal (V ) that is the difference of AIN and AIN . A
IN P N
multiplexer (MUX) is available on the ADS1018. The converter core consists of a differential, switched-capacitor
ΔΣ modulator followed by a digital filter. This architecture results in very strong attenuation in any common-mode
signals. Input signals are compared to the internal voltage reference. The digital filter receives a high-speed
bitstreamfromthemodulatorandoutputsacodeproportionaltotheinput voltage.
The ADS1018 has two available conversion modes: single-shot mode and continuous conversion mode. In
single-shot mode, the ADC performs one conversion of the input signal upon request and stores the value in an
internal result register. The device then enters a power-down state. This mode is intended to provide significant
power savings in systems that only require periodic conversions or when there are long idle periods between
conversions. In continuous conversion mode, the ADC automatically begins a conversion of the input signal as
soonasthepreviousconversioniscomplete.Therateofcontinuousconversionisequaltotheprogrammed data
rate.Datacanbereadatanytimeandalwaysreflectthemost recentlycompletedconversion.
VDD
Device
Voltage
MUX Reference
Gain = 2/3,1, CS
AIN0 2, 4, 8, or 16
SCLK
AIN1 PGA 12-BitDS SPI DIN
ADC Interface
DOUT/DRDY
AIN2
Temperature
Oscillator
AIN3 Sensor
GND
Figure9. ADS1018FunctionalBlockDiagram
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MULTIPLEXER
The ADS1018 contains an input multiplexer, as shown in Figure 10. Either four single-ended or two differential
signals can be measured. Additionally, AIN0, AIN1, and AIN2 may be measured differentially to AIN3. The
multiplexer is configured by three bits (MUX[2:0], bits 14-12) in the Config register. When single-ended signals
aremeasured,thenegativeinputoftheADCisinternallyconnectedtoGNDbyaswitchwithinthemultiplexer.
VDD Device
AIN0
VDD
GND
AIN
P
AIN1 AIN
N
VDD
GND
AIN2
VDD
GND
AIN3
GND
GND
Figure10. ADS1018MUX
When measuring single-ended inputs, note that the negative range of the output codes is not used. These codes
areintendedformeasuringnegativedifferentialsignals,suchas(AIN –AIN )< 0.Electrostaticdischarge(ESD)
P N
diodes to VDD and GND protect the ADS1018 inputs. To prevent the ESD diodes from turning on, the absolute
voltageonanyinputmuststaywithintherangegiveninEquation1:
GND–0.3V<AINx<VDD+0.3V (1)
If the voltages on the input pins can possibly violate these conditions, external Schottky clamp diodes and series
resistors may be required to limit the input current to safe values (see the Absolute Maximum Ratings table).
Although the analog inputs can support signals marginally above supply, under no circumstances should any
analogordigitalinputoroutputbedriventogreaterthan5.5Vwithrespect totheGNDpin.
Also, overdriving one unused input on the ADS1018 may affect conversions currently taking place on other input
pins.If overdrivingunusedinputsispossible,TIrecommendsclampingthesignalwithexternalSchottky diodes.
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