Amplifier and Data Converter Selection Guide (Rev. B

More documents

Recommendations

Info

52 ADCs by Architecture➔Delta-Sigma (∆Σ) ADCsDelta-sigma converters are capable of veryhigh resolution, and are ideal for convertingsignals over a very wide range of frequenciesfrom DC to several megahertz. In a deltasigmaADC, the input signal is oversampled bya modulator, then filtered and decimated by adigital filter producing a high-resolution datastream at a lower sampling rate.The delta-sigma architecture approachallows resolution to be traded for speed andboth to be traded for power. This nearlycontinuous relationship between data rate,resolution and power consumption makesdelta-sigma converters extraordinarily flexible.In many delta-sigma converters, thisrelationship is programmable, allowing asingle device to handle multiplemeasurement requirements.Because delta-sigma converters oversampletheir inputs, they can perform mostanti-aliasing filtering in the digital domain.Modern VLSI design techniques havebrought the cost of complex digital filters farbelow the cost of their analog equivalents.Formerly unusual functions, such assimultaneous 50Hz and 60Hz notch filtering,are now built into many delta-sigma ADCs.Typical high-resolution applications fordelta-sigma ADCs include audio, industrialprocess control, analytical and testinstrumentation and medical instrumentation.Recent innovations in ADC architectureshave led to a new class of ADC architecturewhich uses both the pipeline and theoversampling principle.These, very high-speedconverters push the data rates into the MSPSrange, while maintaining resolutions of16-bits and higher.These speeds enable ahost of new wide bandwidth signal processingapplications such as communications andmedical imaging.Most delta-sigma ADCs have inherentlydifferential inputs. They measure the actualdifference between two voltages, instead ofthe difference between one voltage andground. The differential input structure of adelta-sigma makes it ideal for measuringdifferential sources such as bridge sensorsand thermocouples. Frequently, no inputamplifiers are required for theseapplications.Delta-sigma converters work differently thanSAR converters. A SAR takes a "snapshot" ofan input voltage and analyzes it to determinethe corresponding digital code. A delta-sigmameasures the input signal for a certainperiod of time and outputs a digital codecorresponding to the signal's average overthat time. It is important to remember theway delta-sigma converters operate,particularly for designs incorporatingmultiplexing and synchronization.It is very easy to synchronize delta-sigmaconverters together, so that they sample atthe same time but it's more difficult tosynchronize a delta-sigma converter to anexternal event. Delta-sigma converters arehighly resistant to system clock jitter. Theaction of oversampling effectively averagesthe jitter, reducing its impact on noise.AnalogInputDifferentialAmplifierDACModulatorIntegratorMany delta-sigma converters include inputbuffers and programmable gain amplifiers(PGA). An input buffer increases the inputimpedance to allow direct connection to highsource impedance signals. A PGA increasesthe converter’s resolution when measuringsmall signals. Bridge sensors are an exampleof a signal source that can take advantage ofthe PGA within the converter.Every ADC requires a reference, and forhigh-resolution converters, low-noise,low-drift references are critical. Mostdelta-sigma converters have differentialreference inputs.The following pages provide a broad rangeof delta-sigma ADCs available fromTI for a wide range of applications.To help facilitate the selection process,an interactive online data converterparametric search engine is available atdataconverter.ti.com with links to alldata converter specifications.ComparatorDigitalFilterDelta-sigma ADCs consist of a delta-sigma modulator followed by a digitaldecimation filter. The modulator incorporates a comparator and integrator in afeedback loop with a DAC. The loop is synchronized by a clock.DigitalOutputAmplifier and Data Converter Selection Guide Texas Instruments 3Q 2007
Complete Analog Front End for Bridge SensorsADS1230, ADS1232, ADS1234ADCs by ArchitectureDelta-Sigma (∆Σ) ADCs53➔Get samples, datasheets and evaluation modules at: www.ti.com/sc/device/PARTnumber (Replace PARTnumber with ADS1230, ADS1232 or ADS1234)Key Features• Very low noise:• 17nV RMS at 10SPS (PGA = 128)• 44nV RMS at 80SPS (PGA = 128)• 19.2-bit noise-free resolution at Gain = 64• Excellent 50 and 60Hz rejection (at 10SPS)• 1-channel differential input: ADS1230• 2-channel differential input: ADS1232• 4-channel differential input: ADS1234• Built-in temperature sensor• Simple 2-wire serial digital interface• Supply range: 2.7V to 5.25V• Packaging:• TSSOP-16 (ADS1230)• TSSOP-24 (ADS1232)• TSSOP-28 (ADS1234)Applications• Weigh scales• Strain gauges• Pressure sensors• Industrial process controlThe ADS1230, ADS1232 and ADS1234 are precision 20-bit and 24-bit, respectively, delta-sigmaADCs with an onboard very low noise programmable gain amplifier and internal oscillator. ThePGA supports user-selectable gains of 1, 2, 64 and 128. The ADC features 23.5-bits effectiveresolution, is comprised of a 3rd-order modulator and 4th-order digital filter and supports 10SPSor 80SPS data rates. All functions are controlled by dedicated I/O pins for easy operation.AINP1AINN1AINP2AINN2AINP3AINN3ADS1234Only AINP4AINN4AVDDInputMUXA1/TEMP [1] A0Gain = 1, 2, 64, 128PGAAGNDNOTE: (1) A1 for ADS1234, TEMP for ADS1232.CAPADS1232ADS1234REFP REFN DVDD24-Bit∆Σ ADCInternal OscillatorExternal OscillatorCAP CLKIN/XTAL1 XTAL2 DGNDADS1232 functional block diagram. Reference design available, see page 114.GAIN[1:0]PDWNDRDY/DOUTSCLKSPEED16-Channel, Fast Cycling, 24-Bit, Low-Noise ADCADS1258Get samples, datasheets and evaluation modules at: www.ti.com/sc/device/ADS1258Key Features• 24-bits, no missing codes• Fixed-channel or automatic-channel scan• Data rate: 125kSPS fixed-channel;23.7kSPS auto-scan of 16-channels• Low noise: 2.8µV RMS at 1.8kSPS• Integral nonlinearity: 0.0003%• Offset drift: 0.02µV/°C• Gain drift: 0.4ppm/°C• Power dissipation: 42mW• Standby, sleep and power-down modes• Supply range: +5V (unipolar);±2.5V (bipolar)• Packaging: QFN-48Applications• Medical, avionics and process control• Machine and system monitoring• Fast scan multi-channel instrumentation• Industrial systems• Test and measurement systemsThe ADS1258 is a 16-channel (multiplexed), delta-sigma ADC that provides single-cycle settleddata at a channel scan rate from 1.8kSPS to 23.7kSPS. A flexible input multiplexer acceptscombinations of eight differential or 16 single-ended inputs with a full-scale differential rangeof 5V, or true bipolar range of ±2.5V, when operating with a 5V reference. Internal systemmonitor registers provide supply voltage, temperature, reference voltage, gain and offset data.ANALOG INPUTS1…16AINCOMAVDDInternalMonitoring16:1AnalogInputMUXAVSSMUXOUTADS1258 functional block diagram.ADCINVREF∆ΣModulatorEXTCLKIN/OUTDVDDADS1258DigitalFilterOscillatorGPIO[7:0]GPIOSPIInterfaceControlDGNDCSDRDYSCLKDINDOUTSTARTRESETPWDNTexas Instruments 3Q 2007Amplifier and Data Converter Selection Guide
Page 6 and 7: 6 Amplifiers➔Texas Instruments (T
Page 8 and 9: 8Amplifiers➔Precision Operational
Page 10 and 11: 10 Amplifiers➔Precision Operation
Page 12 and 13: 12➔AmplifiersPrecision Operationa
Page 14 and 15: 14AmplifiersPrecision Operational A
Page 16 and 17: 16Amplifiers➔High-Speed Amplifier
Page 18 and 19: 18➔AmplifiersHigh-Speed Amplifier
Page 20 and 21: 20 Amplifiers➔Video AmplifiersVid
Page 22 and 23: 22Amplifiers➔Video AmplifiersVide
Page 24 and 25: 24➔AmplifiersComparatorsLow-Power
Page 26 and 27: 26 Amplifiers➔Difference Amplifie
Page 28 and 29: 28 Amplifiers➔Analog Current Shun
Page 30 and 31: 30 Amplifiers➔Instrumentation Amp
Page 32 and 33: 32➔AmplifiersSingle-Supply Instru
Page 34 and 35: 34 Amplifiers➔Programmable Gain A
Page 36 and 37: 36➔AmplifiersVoltage-Controlled G
Page 38 and 39: 38➔AmplifiersAudio AmplifiersPure
Page 40 and 41: 40Amplifiers➔Audio Power Amplifie
Page 42 and 43: 42 Amplifiers➔Power Amplifiers an
Page 44 and 45: 44 Amplifiers➔Pulse Width Modulat
Page 46 and 47: 46➔AmplifiersSensor Conditioners
Page 48 and 49: 48 Amplifiers➔Integrating Amplifi
Page 50 and 51: 50 Amplifiers➔Amplifiers for Driv
Page 54 and 55: 54➔ADCs by ArchitectureDelta-Sigm
Page 56 and 57: 56 ADCs by Architecture➔Wide Band
Page 58 and 59: 58 ADCs by Architecture➔SAR ADCsS
Page 60 and 61: 60ADCs by Architecture➔SAR ADCs18
Page 62 and 63: 62➔ADCs by ArchitectureSuccessive
Page 64 and 65: 64 ADCs by Architecture➔Pipeline
Page 66 and 67: 66➔ADCs by ArchitecturePipeline A
Page 68 and 69: 68➔ADCs by ArchitecturePipeline A
Page 70 and 71: 70➔DACs by ArchitectureHigh-Accur
Page 72 and 73: 72DACs by Architecture➔High-Accur
Page 74 and 75: 74DACs by Architecture➔High-Accur
Page 76 and 77: 76DACs by Architecture➔Current St
Page 78 and 79: 78➔Analog Monitoring and ControlA
Page 80 and 81: 80 Analog Monitoring and Control➔
Page 82 and 83: 82Voltage References➔ Voltage Ref
Page 84 and 85: 84➔Temperature SensorsTemperature
Page 86 and 87: 86Quick Reference Selection TableAD
Page 94 and 95: 94Quick Reference Selection TableDA
Page 96 and 97: 96Quick Reference Selection TableDA
Page 98 and 99: 98Quick Reference Audio Selection T
Page 100 and 101: 100Quick Reference Audio Selection
Page 102 and 103:
102➔Design and Evaluation ToolsFi
Page 104 and 105:
104➔Design and Evaluation ToolsSi
Page 106 and 107:
106➔Design and Evaluation ToolsEv
Page 108 and 109:
108➔Design and Evaluation ToolsDa
Page 110 and 111:
110➔Design and Evaluation ToolsDa
Page 112 and 113:
112➔Design and Evaluation ToolsAm
Page 114 and 115:
114➔Design and Evaluation ToolsAp
Page 116 and 117:
116Device Index➔DevicePageDAC7643
Page 118 and 119:
118Device Index➔DevicePageTLV2544
Page 120 and 121:
Texas Instruments Incorporated14950
show all

Amplifier and Data Converter Selection Guide (Rev. B

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?