Amplifier and Data Converter Selection Guide (Rev. B

More documents

Recommendations

Info

30 Amplifiers➔Instrumentation AmplifiersThe instrumentation amplifier (IA) is a highinput impedance, closed-loop, fixed- oradjustable-gain block that allows for theamplification of low-level signals in thepresence of common-mode errors and noise.TI offers many types of instrumentationamplifiers including single-supply, low-power,high-speed and low-noise devices. Theseinstrumentation amplifiers are available ineither the traditional three-op-amp or in thecost-effective two-op-amp topology.V INR G 25kΩA 3V INOver-VoltageProtectionOver-VoltageProtectionA 1A 260kΩ60kΩ60kΩ60kΩ50kΩG = 1 +R GThe three-op-amp topology is the benchmark for instrumentation amplifier performance.V ORefThree-Op-Amp VersionThe three-op-amp topology is the benchmarkfor instrumentation amplifier performance.These devices provide a wide gain range(down to G = 1) and generally offer the highestperformance. Symmetrical inverting andnon-inverting gain paths provide bettercommon-mode rejection at high frequencies.Some types use current-feedback-type inputop amps which maintain excellent bandwidthin high gain.Two-Op-Amp VersionThe two-op-amp topology can provide widercommon-mode voltage range, especially inlow-voltage, single-supply applications. Theirsimpler internal circuitry allows lower cost,lower quiescent current and smaller packagesizes. This topology, however, does not lenditself to gains less than four (INA125) or five(all others).RefVINV IN100kΩ25kΩV O = (V IN – V IN ) • G + V REFR G25kΩA 1A 2SingleSupplyV+100kΩTwo-op-amp topology provides widercommon-mode range in low-voltage,single-supply applications.V ODualSupplyV–Design ConsiderationsSupply voltage—TI has developed a series oflow-voltage, single-supply, rail-to-railinstrumentation amps suitable for a widevariety of applications requiring maximumdynamic signal range.Gain requirement—for high-gain applicationsconsider a low total noise device, becausedrift, input bias current and voltage offset allcontribute to error.Common-mode voltage range—the voltageinput range over which the amplifier canoperate and the differential pair behaves as alinear amplifier for differential signals.Input bias current—can be an importantfactor in many applications, especially thosesensing a low current or where the sensorimpedance is very high. The INA116 requiresonly 3fA typical of input bias current.Offset voltage and drift—IAs aregenerally used in high-gain applications,where any amp errors are amplified by thecircuit gain. These errors can become significantunless V OS and drift performance areconsidered in the device selection. Bipolarinput stage INAs generally have smaller errorcontribution from offset and drift in lowsource impedance applications.Current-feedback vs. voltage-feedback inputstage—appropriate for designers needinghigher bandwidth or a more consistent 3dBrolloff frequency over various gain settings.The INA128 and INA129 provide asignificantly higher 3dB rolloff frequency thanvoltage-feedback input stage instrumentationamps and have a 3dB rolloff at essentially thesame frequency in both G = 1 and G = 10configurations.Technical InformationIAs output the difference accurately betweenthe input signals providing Common-ModeRejection (CMR). It is the key parameter andmain purpose for using this type of device.CMR measures the device’s ability to rejectsignals that are common to both inputs.IAs are often used to amplify the differentialoutput of a bridge sensor, amplifying the tinybridge output signals while rejecting thelarge common-mode voltage. They provideexcellent accuracy and performance, yetrequire minimal quiescent current. Gain isusually set with a single external resistor.In some applications unwanted common-modesignals may be less conspicuous. Real-worldground interconnections are not perfect.What may, at first, seem to be a viablesingle-ended amplifier application canbecome an accumulation of errors. Errorvoltages caused by currents flowing inground loops sum with the desired inputsignal and are amplified by a single-endedinput amp. Even very low impedance groundscan have induced voltages from straymagnetic fields. As accuracy requirementsincrease, it becomes more difficult to designaccurate circuits with a single-ended inputamplifier. The differential input instrumentationamplifier is the answer.Amplifier and Data Converter Selection Guide Texas Instruments 3Q 2007
Single-Supply, RRIO, Low-Offset, Low-Drift Instrumentation AmplifiersINA326, INA327 (Shutdown Version)AmplifiersInstrumentation Amplifiers31➔Get samples, datasheets and app reports at: www.ti.com/sc/device/INA326 and www.ti.com/sc/device/INA327Key Features• Low offset: 100µV (max)• Low offset drift: 0.4µV/°C (max)• Excellent long-term stability• Very-low 1/f noise• True rail-to-rail I/O• Input common-mode range:• 20mV below negative rail• 100mV above positive rail• Wide output swing: within 10mV of rails• Single supply range: +2.7V to +5.5V• Temp range: –40°C to +85°C• Packaging: MSOP-8, MSOP-10Applications• Low-level transducer amplifier forbridges, load cells, thermocouples• Wide dynamic range sensormeasurements• High-resolution test systems• Weigh scales• Multi-channel data acquisition systems• Medical instrumentationThe INA326 uses a new, unique internal circuit topology that provides true rail-to-rail input. Unlikeother instrumentation amplifiers, it can linearly process inputs to 20mV below the negative powersupply rail, and 100mV above the positive power supply rail. Conventional instrumentation amplifierinput topologies cannot deliver such wide dynamic performance.In most instrumentation amplifiers, the ability to reject common-mode signals is derived through acombination of input amplifier CMR and accurately matched resistor ratios. The INA326 converts theinput voltage to a current, allowing the input amplifiers to accurately match and reject common-modeinput voltage and power supply variation without the use of resistors.V IN–Current MonitorI R1Current MonitorI R1 R 1I R1 Current MonitorV IN+A1A22I R1Current MonitorV+ V–0.1µFIR12I R1V 02I R12I R12I R1A3INA326INA326 functional block diagram.R 2 C 2IA COMMON2MHz Bandwidth, Rail-to-Rail Output, Single-Supply Instrumentation AmplifiersINA332, INA2332Get samples, datasheets, and app reports at: www.ti.com/sc/device/INA332 and www.ti.com/sc/device/INA2332Key Features• High gain accuracy: G = 5, 0.07%, 2ppm/°C• High CMRR: 73dB DC, 50dB at 45kHz• Low bias current: 0.5pA• Bandwidth: 2MHz• Slew rate: 5V/µs• Rail-to-rail output swing: (V+) –0.02V• Low quiescent current: 490µA max/ch• Packaging: MSOP-8 (single),TSSOP-14 (dual)The INA332 and INA2332 are rail-to-rail output, low-power, Gain = 5, CMOS instrumentationamplifiers that operate on 2.7V to 5.5V supplies. They offer excellent speed/power ratio with2MHz bandwidth and 490µA/channel supply current. Available shutdown/enable function addsadditional power savings by reducing current to 0.01µA.V REF40kΩG = 5 + (5R 2 /R 1 )10kΩR 140kΩR GR 2Applications• Industrial sensors:• Bridge, RTD, thermocouple, position• Physiological amplifiers: ECG, EEG, EMG• Field utility meters• PCMCIA cards• Test equipment• Automotive instrumentation–10kΩ–A 1 –A 3V IN –+A 2++V IN +INA332 functional block diagram.V+ V–ShutdownINA332V OUTTexas 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 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 52 and 53: 52 ADCs by Architecture➔Delta-Sig
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 88 and 89:
Page 90 and 91:
Page 92 and 93:
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

Create successful ePaper yourself

Delete template?

Save as template?