0
登录后你可以
  • 下载海量资料
  • 学习在线课程
  • 观看技术视频
  • 写文章/发帖/加入社区
创作中心
发布
  • 发文章

  • 发资料

  • 发帖

  • 提问

  • 发视频

创作活动
INA821IDRGT

INA821IDRGT

  • 厂商:

    BURR-BROWN(德州仪器)

  • 封装:

    WFDFN8_EP

  • 描述:

    仪表 放大器 1 电路 8-SON(3x3)

  • 数据手册
  • 价格&库存
INA821IDRGT 数据手册
Order Now Product Folder Support & Community Tools & Software Technical Documents INA821 SBOS893D – AUGUST 2018 – REVISED JUNE 2020 INA821 35-µV Offset, 7-nV/√Hz Noise, Low-Power, Precision Instrumentation Amplifier 1 Features 3 Description • • The INA821 is a high-precision instrumentation amplifier that offers low power consumption and operates over a wide single-supply or dual-supply range. A single external resistor sets any gain from 1 to 10,000. The device has high precision as a result of super-beta input transistors, which provide low input offset voltage, offset voltage drift, input bias current, and input voltage and current noise. Additional circuitry protects the inputs against overvoltage up to ±40 V. Low offset voltage: 10 µV (typ), 35 µV (max) Gain drift: 5 ppm/°C (G = 1), 35 ppm/°C (G > 1) (max) Noise: 7 nV/√Hz Bandwidth: 4.7 MHz (G = 1), 290 kHz (G = 100) Stable with 1-nF capacitive loads Inputs protected up to ±40 V Common-mode rejection: 112 dB, G = 10 (min) Power supply rejection: 110 dB, G = 1 (min) Supply current: 650 µA (max) Supply range: – Single-supply: 4.5 V to 36 V – Dual-supply: ±2.25 V to ±18 V Specified temperature range: –40°C to +125°C Packages: 8-pin SOIC, VSSOP, and WSON 1 • • • • • • • • • • The INA821 is optimized to provide a high commonmode rejection ratio. At G = 1, the common-mode rejection ratio exceeds 92 dB across the full input common-mode range. The device is designed for lowvoltage operation from a 4.5-V single supply, and dual supplies up to ±18 V. The INA821 is available in 8-pin SOIC, VSSOP, and WSON packages, and is specified over the –40°C to +125°C temperature range. 2 Applications Analog input module Flow transmitter Battery test LCD test Electrocardiogram (ECG) Surgical equipment Process analytics (pH, gas, concentration, force and humidity) INA821 Simplified Internal Schematic -IN INA821 RG RG BODY SIZE (NOM) SOIC (8) 4.90 mm × 3.91 mm VSSOP (8) 3.00 mm × 3.00 mm WSON (8) 3.00 mm x 3.00 mm 30 10 k + 10 k 25 24.7 k ± 24.7 k + OUT ± OverVoltage Protection PACKAGE (1) For all available packages, see the package option addendum at the end of the data sheet. ± RG +IN PART NUMBER Typical Distribution of Input Stage Offset Voltage Drift +VS OverVoltage Protection Device Information(1) REF + 10 k 10 k Amplifiers (%) • • • • • • • 20 15 10 5 -VS G 1 49.4 k: RG VO G V IN V IN VREF 0 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 Input Stage Offset Voltage Drift (PV/qC) 0.4 D002 1 An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications, intellectual property matters and other important disclaimers. PRODUCTION DATA. INA821 SBOS893D – AUGUST 2018 – REVISED JUNE 2020 www.ti.com Table of Contents 1 2 3 4 5 6 7 Features .................................................................. Applications ........................................................... Description ............................................................. Revision History..................................................... Device Comparison Table..................................... Pin Configuration and Functions ......................... Specifications......................................................... 7.1 7.2 7.3 7.4 7.5 7.6 7.7 8 1 1 1 2 3 4 5 Absolute Maximum Ratings ...................................... 5 ESD Ratings ............................................................ 5 Recommended Operating Conditions....................... 5 Thermal Information .................................................. 5 Electrical Characteristics........................................... 6 Typical Characteristics: Table of Graphs .................. 8 Typical Characteristics ............................................ 10 Detailed Description ............................................ 19 8.1 Overview ................................................................. 19 8.2 Functional Block Diagram ....................................... 19 8.3 Feature Description................................................. 20 8.4 Device Functional Modes........................................ 26 9 Application and Implementation ........................ 26 9.1 Application Information............................................ 26 9.2 Typical Application .................................................. 29 9.3 Other Application Examples.................................... 31 10 Power Supply Recommendations ..................... 32 11 Layout................................................................... 32 11.1 Layout Guidelines ................................................. 32 11.2 Layout Example .................................................... 33 12 Device and Documentation Support ................. 34 12.1 12.2 12.3 12.4 12.5 12.6 12.7 Device Support .................................................... Documentation Support ........................................ Receiving Notification of Documentation Updates Support Resources ............................................... Trademarks ........................................................... Electrostatic Discharge Caution ............................ Glossary ................................................................ 34 34 34 34 34 34 34 13 Mechanical, Packaging, and Orderable Information ........................................................... 34 4 Revision History NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Changes from Revision C (July 2019) to Revision D • Page Added DRG (WSON) package and associated content to data sheet .................................................................................. 1 Changes from Revision B (May 2019) to Revision C Page • Changed DGK (VSSOP) package from advanced information (preview) to production data (active) ................................... 1 • Changed Figure 9, Typical Distribution of Input Offset Current, to show correct image ...................................................... 11 • Changed Figure 27, Typical Distribution of Gain Error, G = 1, to show improved data....................................................... 14 Changes from Revision A (December 2018) to Revision B Page • Added 8-pin DGK (VSSOP) advanced information package and associated content to data sheet ..................................... 1 • Changed Applications bullets ................................................................................................................................................. 1 Changes from Original (August 2018) to Revision A • 2 Page First release of production-data data sheet ........................................................................................................................... 1 Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 INA821 www.ti.com SBOS893D – AUGUST 2018 – REVISED JUNE 2020 5 Device Comparison Table DEVICE DESCRIPTION GAIN EQUATION RG PINS AT PIN G = 1 + 49.4 kΩ / RG 2, 3 INA821 35-µV Offset, 0.4 µV/°C VOS Drift, 7-nV/√Hz Noise, HighBandwidth, Precision Instrumentation Amplifier INA819 35-µV Offset, 0.4 µV/°C VOS Drift, 8-nV/√Hz Noise, Low-Power, Precision Instrumentation Amplifier G = 1 + 50 kΩ / RG 2, 3 INA818 35-µV Offset, 0.4 µV/°C VOS Drift, 8-nV/√Hz Noise, Low-Power, Precision Instrumentation Amplifier G = 1 + 50 kΩ / RG 1, 8 INA828 50-µV Offset, 0.5 µV/°C VOS Drift, 7-nV/√Hz Noise, Low-Power, Precision Instrumentation Amplifier G = 1 + 50 kΩ / RG 1, 8 INA333 25-µV VOS, 0.1 µV/°C VOS Drift, 1.8-V to 5-V, RRO, 50-µA IQ, Chopper-Stabilized INA G = 1 + 100 kΩ / RG 1, 8 PGA280 20-mV to ±10-V Programmable Gain IA With 3-V or 5-V Differential Output; Analog Supply up to ±18 V Digital programmable N/A INA159 G = 0.2 V Differential Amplifier for ±10-V to 3-V and 5-V Conversion G = 0.2 V/V N/A PGA112 Precision Programmable Gain Op Amp With SPI Digital programmable N/A Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 3 INA821 SBOS893D – AUGUST 2018 – REVISED JUNE 2020 www.ti.com 6 Pin Configuration and Functions D and DGK Packages 8-Pin SOIC and 8-Pin VSSOP Top View DRG Package 8-Pin WSON Top View ±IN 1 8 +VS RG 2 7 OUT RG 3 6 REF +IN 4 5 ±VS ±IN 1 RG 2 RG 3 +IN 4 Thermal Pad 8 +VS 7 OUT 6 REF 5 ±VS Not to scale Not to scale Pin Functions PIN NAME NO. –IN 1 +IN OUT I/O DESCRIPTION I Negative (inverting) input 4 O Positive (noninverting) input 7 — Output RG 2, 3 I REF 6 — Reference input. This pin must be driven by a low impedance source. –VS 5 — Negative supply +VS 8 — Positive supply Thermal pad — — Thermal pad internally connected to –VS. Connect externally to –VS or leave floating. 4 Gain setting pin. Place a gain resistor between pin 2 and pin 3. Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 INA821 www.ti.com SBOS893D – AUGUST 2018 – REVISED JUNE 2020 7 Specifications 7.1 Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted) (1) MIN MAX –20 20 Voltage –40 40 REF pin –20 20 (–Vs) – 0.5 (+Vs) + 0.5 Supply voltage Signal input pins Signal output pins Output short-circuit (2) –50 Junction Temperature, TJ V V 150 175 Storage Temperature, Tstg (2) V Continuous Operating Temperature, TA (1) UNIT –65 °C 150 Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. Short-circuit to VS / 2. 7.2 ESD Ratings VALUE V(ESD) (1) (2) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1) ±1500 Charged-device model (CDM), per JEDEC specification JESD22-C101 (2) ±750 UNIT V JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process. 7.3 Recommended Operating Conditions over operating free-air temperature range (unless otherwise noted) Single-supply Supply voltage, VS Dual-supply Specified temperature, TA Specified temperature MIN MAX 4.5 36 ±2.25 ±18 –40 125 UNIT V °C 7.4 Thermal Information INA821 THERMAL METRIC (1) D (SOIC) DGK (VSSOP) DRG (WSON) 8 PINS 8 PINS 8 PINS UNIT RθJA Junction-to-ambient thermal resistance 119.6 215.4 55.6 °C/W RθJC(top) Junction-to-case (top) thermal resistance 66.3 66.3 57.9 °C/W RθJB Junction-to-board thermal resistance 61.9 97.8 28.6 °C/W ψJT Junction-to-top characterization parameter 20.5 10.5 1.8 °C/W ψJB Junction-to-board characterization parameter 61.4 96.1 28.6 °C/W RθJC(bot) Junction-to-case (bottom) thermal resistance N/A N/A 12.1 °C/W (1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report. Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 5 INA821 SBOS893D – AUGUST 2018 – REVISED JUNE 2020 www.ti.com 7.5 Electrical Characteristics at TA = 25°C, VS = ±15 V, RL = 10 kΩ, VREF = 0 V, and G = 1 (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX INA821ID, INA821DRG 10 35 INA821IDGK 10 40 UNIT INPUT Input stage offset voltage (1) (2) VOSI TA = –40°C to +125°C INA821ID, INA821DRG (3) INA821IDGK 80 vs temperature, TA = –40°C to +125°C VOSO Output stage offset voltage (1) (2) µV 75 0.1 0.4 INA821ID, INA821DGK 50 350 INA821DRG 50 400 TA = –40°C to +125°C (3) µV/°C µV 850 vs temperature, TA = –40°C to +125°C 5 G = 1, RTI 110 120 G = 10, RTI 114 130 G = 100, RTI 130 135 G = 1000, RTI 136 µV/°C PSRR Power-supply rejection ratio zid Differential impedance 100 || 1 GΩ || pF zic Common-mode impedance 100 || 7 GΩ || pF RFI filter, –3-dB frequency 45 Operating input range (4) VCM Input overvoltage range CMRR Common-mode rejection ratio 140 (V–) + 2 VS = ±2.25 V to ±18 V, TA = –40°C to +125°C dB MHz (V+) – 2 See Figure 51 to Figure 54 TA = –40°C to +125°C (3) ±40 At DC to 60 Hz, RTI, VCM = (V–) + 2 V to (V+) – 2 V, G=1 92 105 At DC to 60 Hz, RTI, VCM = (V–) + 2 V to (V+) – 2 V, G = 10 112 125 At DC to 60 Hz, RTI, VCM = (V–) + 2 V to (V+) – 2 V, G = 100 132 145 At DC to 60 Hz, RTI, VCM = (V–) + 2 V to (V+) – 2 V, G = 1000 140 150 V V dB BIAS CURRENT IB Input bias current IOS Input offset current VCM = VS / 2 0.15 TA = –40°C to +125°C 0.5 2 VCM = VS / 2 0.15 TA = –40°C to +125°C 0.5 2 nA nA NOISE VOLTAGE eNI Input stage voltage noise (5) f = 1 kHz, G = 100, RS = 0 Ω eNO Output stage voltage noise (5) f = 1 kHz, RS = 0 Ω In Noise current 7 fB = 0.1 Hz to 10 Hz, G = 100, RS = 0 Ω nV/√Hz 0.14 µVPP 65 nV/√Hz fB = 0.1 Hz to 10 Hz, RS = 0 Ω 2.5 µVPP f = 1 kHz 130 fA/√Hz fB = 0.1 Hz to 10 Hz, G = 100 4.7 pAPP GAIN G Gain equation 1 + (49.4 kΩ / RG) Range of gain (1) (2) (3) (4) (5) 6 1 V/V 10000 V/V Total offset, referred-to-input (RTI): VOS = (VOSI) + (VOSO / G). Offset drifts are uncorrelated. Input-referred offset drift is calculated using: ΔVOS(RTI) = √[ΔVOSI2 + (ΔVOSO / G)2]. Specified by characterization. Input voltage range of the Instrumentation Amplifier input stage. The input range depends on the common-mode voltage, differential voltage, gain, and reference voltage. See Typical Characteristic curves Figure 51 through Figure 54 for more information. Total RTI voltage noise is equal to: eN(RTI) = √[eNI2 + (eNO / G)2]. Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 INA821 www.ti.com SBOS893D – AUGUST 2018 – REVISED JUNE 2020 Electrical Characteristics (continued) at TA = 25°C, VS = ±15 V, RL = 10 kΩ, VREF = 0 V, and G = 1 (unless otherwise noted) PARAMETER GE Gain error Gain vs temperature (6) TYP MAX G = 1, VO = ±10 V TEST CONDITIONS MIN ±0.005% ±0.025% G = 10, VO = ±10 V ±0.025% ±0.15% G = 100, VO = ±10 V ±0.025% ±0.15% G = 1000, VO = ±10 V ±0.05% G = 1, TA = –40°C to +125°C ±5 G > 1, TA = –40°C to +125°C ±35 G = 1 to 10, VO = –10 V to 10 V, RL = 10 kΩ Gain nonlinearity 1 G = 100, VO = –10 V to 10 V, RL = 10 kΩ UNIT ppm/°C 10 15 G = 1000, VO = –10 V to 10 V, RL = 10 kΩ 10 G = 1 to 100, VO = –10 V to 10 V, RL = 2 kΩ 30 ppm OUTPUT (V–) + 0.15 Voltage swing (V+) – 0.15 Load capacitance stability V 1000 pF ZO Closed-loop output impedance f = 10 kHz 1.3 Ω ISC Short-circuit current Continuous to VS / 2 ±20 mA G=1 4.7 MHz G = 10 970 G = 100 290 G = 1000 30 G = 1, VO = ±10 V 2.0 FREQUENCY RESPONSE BW SR Bandwidth, –3 dB Slew rate 0.01%, G = 1 to 100, VSTEP = 10 V tS Settling time kHz V/µs 6 0.01%, G = 1000, VSTEP = 10 V 40 0.001%, G = 1 to 100, VSTEP = 10 V 10 0.001%, G = 1000, VSTEP = 10 V 50 µs REFERENCE INPUT RIN Input impedance 10 Voltage range (V–) kΩ (V+) Gain to output 1 Reference gain error V V/V 0.01% POWER SUPPLY VS Power-supply voltage IQ Quiescent current (6) Single-supply Dual-supply 4.5 36 ±2.25 ±18 VIN = 0 V 600 vs temperature, TA = –40°C to +125°C 650 870 V µA The values specified for G > 1 do not include the effects of the external gain-setting resistor, RG. Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 7 INA821 SBOS893D – AUGUST 2018 – REVISED JUNE 2020 www.ti.com 7.6 Typical Characteristics: Table of Graphs at TA = 25°C, VS = ±15 V, RL = 10 kΩ, VREF = 0 V, and G = 1 (unless otherwise noted) Table 1. Table of Graphs DESCRIPTION FIGURE Typical Distribution of Input Stage Offset Voltage Figure 1 Typical Distribution of Input Stage Offset Voltage Drift Figure 2 Typical Distribution of Output Stage Offset Voltage Figure 3 Typical Distribution of Output Stage Offset Voltage Drift Figure 4 Input Stage Offset Voltage vs Temperature Figure 5 Output Stage Offset Voltage vs Temperature Figure 6 Typical Distribution of Input Bias Current, TA = 25°C Figure 7 Typical Distribution of Input Bias Current, TA = 90°C Figure 8 Typical Distribution of Input Offset Current Figure 9 Input Bias Current vs Temperature Figure 10 Input Offset Current vs Temperature Figure 11 Typical CMRR Distribution, G = 1 Figure 12 Typical CMRR Distribution, G = 10 Figure 13 CMRR vs Temperature, G = 1 Figure 14 CMRR vs Temperature, G = 10 Figure 15 Input Current vs Input Overvoltage Figure 16 CMRR vs Frequency (RTI) Figure 17 CMRR vs Frequency (RTI, 1-kΩ source imbalance) Figure 18 Positive PSRR vs Frequency (RTI) Figure 19 Negative PSRR vs Frequency (RTI) Figure 20 Gain vs Frequency Figure 21 Voltage Noise Spectral Density vs Frequency (RTI) Figure 22 Current Noise Spectral Density vs Frequency (RTI) Figure 23 0.1-Hz to 10-Hz RTI Voltage Noise, G = 1 Figure 24 0.1-Hz to 10-Hz RTI Voltage Noise, G = 1000 Figure 25 0.1-Hz to 10-Hz RTI Current Noise Figure 26 Typical Distribution of Gain Error, G = 1 Figure 27 Typical Distribution of Gain Error, G = 10 Figure 28 Input Bias Current vs Common-Mode Voltage Figure 29 Gain Error vs Temperature, G = 1 Figure 30 Gain Error vs Temperature, G = 10 Figure 31 Supply Current vs Temperature Figure 32 Gain Nonlinearity, G = 1 Figure 33 Gain Nonlinearity, G = 10 Figure 34 Offset Voltage vs Negative Common-Mode Voltage Figure 35 Offset Voltage vs Positive Common-Mode Voltage Figure 36 Positive Output Voltage Swing vs Output Current Figure 37 Negative Output Voltage Swing vs Output Current Figure 38 Short-Circuit Current vs Temperature Figure 39 Large-Signal Frequency Response Figure 40 THD+N vs Frequency Figure 41 Overshoot vs Capacitive Loads Figure 42 Small-Signal Response, G = 1 Figure 43 Small-Signal Response, G = 10 Figure 44 Small-Signal Response, G = 100 Figure 45 8 Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 INA821 www.ti.com SBOS893D – AUGUST 2018 – REVISED JUNE 2020 Typical Characteristics: Table of Graphs (continued) Table 1. Table of Graphs (continued) DESCRIPTION FIGURE Small-Signal Response, G = 1000 Figure 46 Large-Signal Step Response Figure 47 Closed-Loop Output Impedance Figure 48 Differential-Mode EMI Rejection Ratio Figure 49 Common-Mode EMI Rejection Ratio Figure 50 Input Common-Mode Voltage vs Output Voltage, G = 1, VS = 5 V Figure 51 Input Common-Mode Voltage vs Output Voltage, G = 100, VS = 5 V Figure 52 Input Common-Mode Voltage vs Output Voltage, VS = ±5 V Figure 53 Input Common-Mode Voltage vs Output Voltage, VS = ±15 V Figure 54 Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 9 INA821 SBOS893D – AUGUST 2018 – REVISED JUNE 2020 www.ti.com 7.7 Typical Characteristics at TA = 25°C, VS = ±15 V, RL = 10 kΩ, VREF = 0 V, and G = 1 (unless otherwise noted) 15 30 10 Amplifiers (%) Amplifiers (%) 25 5 20 15 10 5 0 -30 -25 -20 -15 -10 -5 0 5 10 15 Input Stage Offset Voltage (PV) N = 2667 Mean = 3.1 µV 20 25 0 -0.4 30 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 Input Stage Offset Voltage Drift (PV/qC) D001 Std. Dev. = 8.1 µV N = 81 Mean = -0.03 µV/°C Figure 1. Typical Distribution of Input Stage Offset Voltage 0.4 D002 Std. Dev. = 0.09 µV/°C Figure 2. Typical Distribution of Input Stage Offset Voltage Drift 15 16 14 Amplifiers (%) Amplifiers (%) 12 10 5 10 8 6 4 2 0 -200 -100 0 100 Input Stage Offset Voltage (PV) N = 2667 Mean = 7.7 µV 0 -5 200 -4 -3 D003 Std. Dev. = 50.7 µV N = 81 Mean = –1.09 µV/°C 100 500 75 400 50 25 0 -25 -50 -100 -50 Mean +3V -3V -25 0 25 50 75 Temperature (qC) 100 5 D004 Std. Dev. = 0.94 µV/°C 125 150 300 200 100 0 -100 -200 -300 -400 -500 -50 D005 81 units Mean +3V -3V -25 0 25 50 75 Temperature (qC) 100 125 150 D006 81 units Figure 5. Input Stage Offset Voltage vs Temperature 10 4 Figure 4. Typical Distribution of Output Stage Offset Voltage Drift Input-Referred Offset Voltage (PV) Input-Referred Offset Voltage (PV) Figure 3. Typical Distribution of Output Stage Offset Voltage -75 -2 -1 0 1 2 3 Output Offset Voltage Drift (PV/qC) Figure 6. Output Stage Offset Voltage vs Temperature Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 INA821 www.ti.com SBOS893D – AUGUST 2018 – REVISED JUNE 2020 Typical Characteristics (continued) 20 20 15 15 Amplifiers (%) Amplifiers (%) at TA = 25°C, VS = ±15 V, RL = 10 kΩ, VREF = 0 V, and G = 1 (unless otherwise noted) 10 5 10 5 0 -300 -200 N = 292 TA = 25°C -100 0 100 Input Bias Current (pA) Mean = 45 pA 200 0 -200 300 -150 -100 D007 Std. Dev. = 62 pA N = 292 TA = 90°C Figure 7. Typical Distribution of Input Bias Current, TA = 25°C -50 0 50 100 Input Bias Current (pA) Mean = 34 pA 150 D008 Std. Dev. = 52 pA Figure 8. Typical Distribution of Input Bias Current, TA = 90°C 25 1 Avg 3V 3V 0.8 20 0.6 Input Bias Current (nA) Amplifiers (%) 200 15 10 5 0.4 0.2 0 -0.2 -0.4 -0.6 -0.8 0 -300 -200 N = 94 -100 0 100 Input Offset Current (pA) Mean = –38.82 pA 200 -1 -50 300 -30 D050 N = 294 Std. Dev. = 47.24 pA Figure 9. Typical Distribution of Input Offset Current -10 10 30 50 70 90 Temperature (qC) 110 130 150 D009 G=1 Figure 10. Input Bias Current vs Temperature 25 0.5 20 0.3 0.2 Amplifiers (%) Input Offset Current (nA) 0.4 0.1 0 -0.1 15 10 -0.2 -0.3 5 Avg 3V 3V -0.4 -0.5 -50 -30 N = 294 -10 10 30 50 70 90 Temperature (qC) 110 130 150 0 -20 -16 D010 G=1 N = 294 G=1 Figure 11. Input Offset Current vs Temperature -12 -8 -4 0 4 8 12 Common-Mode Rejection Ratio (PV/V) Mean = 4.87 µV/V 16 20 D011 Std. Dev. = 4.14 µV/V Figure 12. Typical CMRR Distribution, G = 1 Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 11 INA821 SBOS893D – AUGUST 2018 – REVISED JUNE 2020 www.ti.com Typical Characteristics (continued) at TA = 25°C, VS = ±15 V, RL = 10 kΩ, VREF = 0 V, and G = 1 (unless otherwise noted) 150 Common-Mode Rejection Ratio (dB) 30 20 15 10 5 0 -2 -1.5 N = 294 G = 10 -1 -0.5 0 0.5 1 1.5 Common-Mode Rejection Ratio (PV/V) Mean = 0.51 µV/V 125 100 Unit 1 Unit 2 Unit 3 Unit 4 Unit 5 75 50 -50 2 -25 N=5 Std. Dev. = 0.42 µV/V Figure 13. Typical CMRR Distribution, G = 10 Input Current (mA) Common-Mode Rejection Ratio (dB) 150 125 75 -50 Unit 1 Unit 2 Unit 3 Unit 4 Unit 5 -25 0 25 50 75 Temperature (qC) N=5 100 125 150 16 6 12 4 8 2 4 0 0 -2 -4 -4 -8 -6 -12 -8 Input Current -16 Output Voltage -20 20 30 40 50 -40 -30 -20 -10 0 10 Input Voltage (V) D015 VS = ±18 V G = 10 Figure 16. Input Current vs Input Overvoltage 140 Common-Mode Rejection Ratio (dB) Common-Mode Rejection Ratio (dB) D013 20 120 100 80 60 G=1 G = 10 G = 100 G = 1000 100 1k 10k 100k Frequency (Hz) 1M 10M 120 100 80 60 40 20 0 10 D016 Figure 17. CMRR vs Frequency (RTI) 12 150 G=1 D014 140 0 10 125 8 Figure 15. CMRR vs Temperature, G = 10 20 100 10 -10 -50 160 40 25 50 75 Temperature (qC) Figure 14. CMRR vs Temperature, G = 1 175 100 0 D012 Output Voltage (V) Amplifiers (%) 25 Submit Documentation Feedback G=1 G = 10 G = 100 G = 1000 100 1k 10k Frequency (Hz) 100k 1M D017 Figure 18. CMRR vs Frequency (RTI, 1-kΩ source imbalance) Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 INA821 www.ti.com SBOS893D – AUGUST 2018 – REVISED JUNE 2020 Typical Characteristics (continued) 160 160 140 140 120 120 Negative Power Supply Rejection Ratio (dB) Positive Power Supply Rejection Ratio (dB) at TA = 25°C, VS = ±15 V, RL = 10 kΩ, VREF = 0 V, and G = 1 (unless otherwise noted) 100 80 60 40 20 G=1 G = 10 G = 100 G = 1000 0 -20 100 80 60 40 20 G=1 G = 10 G = 100 G = 1000 0 -20 -40 -40 1 10 100 1k Frequency (Hz) 10k 100k 1 10 100 1k Frequency (Hz) D018 Figure 19. Positive PSRR vs Frequency (RTI) G=1 G = 10 G = 100 G = 1000 Voltage Noise Spectral Density (nV/—Hz) Gain (dB) 40 20 0 -60 10 D019 1000 60 -40 100k Figure 20. Negative PSRR vs Frequency (RTI) 80 -20 10k G=1 G = 10 G = 100 G = 1000 100 1k 10k 100k Frequency (Hz) 1M 100 10 100m 10M D020 Figure 21. Gain vs Frequency 1 10 100 1k Frequency (Hz) 10k 100k D021 Figure 22. Voltage Noise Spectral Density vs Frequency (RTI) Noise (0.5 PV/div) Current Noise Spectral Density (fA/—Hz) 1k 100 10 100m 1 10 100 Frequency (Hz) 1k Time (1 s/div) 10k D023 D022 Figure 23. Current Noise Spectral Density vs Frequency (RTI) G=1 Figure 24. 0.1-Hz to 10-Hz RTI Voltage Noise, G = 1 Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 13 INA821 SBOS893D – AUGUST 2018 – REVISED JUNE 2020 www.ti.com Typical Characteristics (continued) Noise (20 nV/div) Noise (0.5 pA/div) at TA = 25°C, VS = ±15 V, RL = 10 kΩ, VREF = 0 V, and G = 1 (unless otherwise noted) Time (1 s/div) Time (1 s/div) D024 D025 G=1 G = 1000 Figure 25. 0.1-Hz to 10-Hz RTI Voltage Noise, G = 1000 Figure 26. 0.1-Hz to 10-Hz RTI Current Noise 30 20 18 16 14 20 Amplifiers (%) Amplifiers (%) 25 15 10 12 10 8 6 4 5 2 0 -250 -200 -150 -100 N = 5412 G=1 -50 0 50 100 Gain Error (ppm) Mean = 30 ppm 150 200 0 -900 250 Std. Dev. = 55 ppm N = 293 G = 10 Figure 27. Typical Distribution of Gain Error, G = 1 Mean = 152 ppm 900 D027 Std. Dev. = 291 ppm 100 45qC 25qC 125qC 80 Gain Error (ppm) Input Bias Current (nA) -300 0 300 600 Input Stage Offset Voltage (PV) Figure 28. Typical Distribution of Gain Error, G = 10 0.5 0.3 -600 D026 0.1 -0.1 60 40 20 0 -0.3 -20 -0.5 -15 -12 -9 -6 -3 0 3 6 Common-Mode Voltage (V) 9 12 15 -40 -50 VS = ±15 V -10 10 Average of 294 units Figure 29. Input Bias Current vs Common-Mode Voltage 14 -30 D028 Submit Documentation Feedback 30 50 70 90 Temperature (qC) 110 130 150 D029 G=1 Figure 30. Gain Error vs Temperature, G = 1 Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 INA821 www.ti.com SBOS893D – AUGUST 2018 – REVISED JUNE 2020 Typical Characteristics (continued) at TA = 25°C, VS = ±15 V, RL = 10 kΩ, VREF = 0 V, and G = 1 (unless otherwise noted) 1500 0.9 1250 0.84 1000 0.78 0.72 500 250 IQ (mA) Gain Error (ppm) 750 0 -250 -500 0.66 0.6 0.54 0.48 -750 0.42 -1000 -1500 -50 -25 0 25 50 75 Temperature (qC) Average of 294 units 100 125 0.3 -50 150 0.4 Nonlinearity (ppm) Nonlinearity (ppm) 0.6 0.2 0 -0.2 -0.4 -0.6 -0.8 -4 -2 0 2 Output Voltage (V) 4 6 8 10 10 8 6 4 2 0 -2 -4 -6 -8 -10 -12 -14 -16 -10 -8 -6 D032 G=1 30 50 70 Temperature (qC) 90 110 130 150 D031 -4 -2 0 2 Output Voltage (V) 4 6 8 10 D033 G = 10 Figure 33. Gain Nonlinearity, G = 1 Figure 34. Gain Nonlinearity, G = 10 150 175 40qC 25qC 85qC 125qC 150 125 125 100 100 Offset Voltage (PV) Offset Voltage (PV) 10 Figure 32. Supply Current vs Temperature 0.8 -6 -10 G = 10 Figure 31. Gain Error vs Temperature, G = 10 -8 -30 D030 1 -1 -10 VS = r 15 V VS = r 2.25 V 0.36 -1250 75 50 25 0 40qC 25qC 85qC 125qC 75 50 25 0 -25 -25 -50 -75 -15 -14.6 -14.2 -13.8 -13.4 -13 -12.6 Input Common-Mode Voltage (V) -50 12 -12.2 D034 Figure 35. Offset Voltage vs Negative Common-Mode Voltage 12.4 12.8 13.2 13.6 14 14.4 Input Common-Mode Voltage (V) 14.8 D035 Figure 36. Offset Voltage vs Positive Common-Mode Voltage Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 15 INA821 SBOS893D – AUGUST 2018 – REVISED JUNE 2020 www.ti.com Typical Characteristics (continued) 15 -14 14.9 -14.1 14.8 -14.2 14.7 -14.3 Output Voltage (V) Output Voltage (V) at TA = 25°C, VS = ±15 V, RL = 10 kΩ, VREF = 0 V, and G = 1 (unless otherwise noted) 14.6 14.5 14.4 14.3 ± qC 25qC 85qC 125qC 14.2 14.1 -14.4 -14.5 -14.6 -14.7 -14.8 -14.9 14 -15 0 2 4 6 8 10 Output Current (mA) 12 14 16 0 18 20 16 Output Amplitude (Vp) 20 30 10 0 -10 -20 -30 -40 6 8 10 Output Current (mA) 12 14 16 D037 Vs = r15 V Vs = r5 V 14 12 10 8 6 4 ISC, Source ISC, Sink -50 -60 -50 -30 -10 10 30 50 70 90 Temperature (qC) 110 130 2 0 100 150 0.01 -80 100 1k Frequency (Hz) 10k -100 100k 10M D039 Positive Overshoot Negative Overshoot 45 40 35 Overshoot (%) -60 1M Figure 40. Large-Signal Frequency Response Total Harmonic Distortion + Noise (dB) G=1 G = 10 G = 100 10k 100k Frequency (Hz) 50 -40 0.1 1k D038 Figure 39. Short-Circuit Current vs Temperature 1 Total Harmonic Distortion + Noise (%) 4 Figure 38. Negative Output Voltage Swing vs Output Current 40 0.001 10 2 D036 Figure 37. Positive Output Voltage Swing vs Output Current Short-Circuit Current (mA) ± qC 25qC 85qC 125qC 30 25 20 15 10 5 0 1 D040 10 100 Capacitive Load (pF) 1000 D041 500-kHz measurement bandwidth 1-VRMS output voltage 100-kΩ load Figure 41. THD+N vs Frequency 16 Figure 42. Overshoot vs Capacitive Loads Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 INA821 www.ti.com SBOS893D – AUGUST 2018 – REVISED JUNE 2020 Typical Characteristics (continued) 75 75 50 50 Output Amplitude (mV) Output Amplitude (mV) at TA = 25°C, VS = ±15 V, RL = 10 kΩ, VREF = 0 V, and G = 1 (unless otherwise noted) 25 0 -25 -50 -75 -5 25 0 -25 -50 -2.5 0 G=1 2.5 5 7.5 Time (µs) 10 12.5 -75 -5 15 -2.5 RL = 10 kΩ CL = 100 pF G = 10 50 50 25 0 -25 -50 G = 100 2.5 5 7.5 Time (µs) 10 12.5 15 D043 RL = 10 kΩ CL = 100 pF Figure 44. Small-Signal Response 75 Output Amplitude (mV) Output Amplitude (mV) Figure 43. Small-Signal Response 75 -75 -5 0 D042 25 0 -25 -50 -2.5 0 2.5 5 7.5 Time (µs) 10 RL = 10 kΩ 12.5 -75 -25 15 0 D044 CL = 100 pF G = 1000 Figure 45. Small-Signal Response 25 Time (µs) 50 75 D045 RL = 10 kΩ CL = 100 pF Figure 46. Small-Signal Response Output Input Amplitude (2 V/div) Output Impedence (:) 100 10 1 0.1 1 Time (10 µs/div) D046 Figure 47. Large-Signal Step Response 10 100 1k 10k Frequency (Hz) 100k 1M 10M D047 Figure 48. Closed-Loop Output Impedance Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 17 INA821 SBOS893D – AUGUST 2018 – REVISED JUNE 2020 www.ti.com Typical Characteristics (continued) 120 140 100 120 100 80 EMIRR (dB) EMIRR (dB) at TA = 25°C, VS = ±15 V, RL = 10 kΩ, VREF = 0 V, and G = 1 (unless otherwise noted) 60 40 80 60 40 20 20 0 10M 100M 1G Frequency (Hz) 0 10M 10G Figure 49. Differential-Mode EMI Rejection Ratio VREF = 0 V VREF = 2.5 V 4 3 2 1 VREF = 0 V VREF = 2.5 V 4 3 2 1 0 0 1 2 3 4 5 Output Voltage (V) VS = 5 V 0 6 1 2 3 4 5 6 Output Voltage (V) C006 G=1 VS = 5 V Figure 51. Input Common-Mode Voltage vs Output Voltage C006 G = 100 Figure 52. Input Common-Mode Voltage vs Output Voltage 15 5 Common-Mode Voltage (V) 4 Common-Mode Voltage (V) D049 Figure 50. Common-Mode EMI Rejection Ratio 0 3 2 1 0 -1 -2 -3 G=1 -4 G = 100 -5 ±6 ±4 VS = ±5 V 10 5 0 -5 -10 -15 G=1 G = 100 -20 ±2 0 Output Voltage (V) 2 4 6 ±20 ±10 0 Output Voltage (V) C006 VREF = 0 V VS = ±15 V Figure 53. Input Common-Mode Voltage vs Output Voltage 18 10G 5 Common-Mode Voltage (V) Common-Mode Voltage (V) 5 100M 1G Frequency (Hz) D048 10 20 C006 VREF = 0 V Figure 54. Input Common-Mode Voltage vs Output Voltage Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 INA821 www.ti.com SBOS893D – AUGUST 2018 – REVISED JUNE 2020 8 Detailed Description 8.1 Overview The INA821 is a monolithic precision instrumentation amplifier that incorporates a current-feedback input stage and a four-resistor difference amplifier output stage. The functional block diagram in the next section shows how the differential input voltage is buffered by Q1 and Q2 and is forced across RG, which causes a signal current to flow through RG, R1, and R2. The output difference amplifier, A3, removes the common-mode component of the input signal and refers the output signal to the REF pin. The VBE and voltage drop across R1 and R2 produces output voltages on A1 and A2 that are approximately 0.8 V lower than the input voltages. Each input is protected by two field-effect transistors (FETs) that provide a low series resistance under normal signal conditions, and preserve excellent noise performance. When excessive voltage is applied, these transistors limit input current to approximately 8 mA. 8.2 Functional Block Diagram +VS VB RB IB Cancellation RB IB Cancellation -VS +VS 40 k ± ± + ± + 40 k A1 A2 A3 OUT + 40 k REF 40 k +VS +VS -VS +VS Q1 -IN Overvoltage Protection SuperNPN +VS R1 25 k +VS RG -VS Q2 +IN Overvoltage Protection R2 25 k RG (External) -VS SuperNPN -VS RG -VS Copyright © 2017, Texas Instruments Incorporated Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 19 INA821 SBOS893D – AUGUST 2018 – REVISED JUNE 2020 www.ti.com 8.3 Feature Description 8.3.1 Setting the Gain Figure 55 shows that the gain of the INA821 is set by a single external resistor (RG) connected between the RG pins (pins 1 and 8). V+ +VS Overvoltage Protection -IN 1 49.4 k: RG 10 k ± RG G 10 k + RG 24.7 k ± 24.7 k + OUT VO RG G V IN V IN VREF ± Overvoltage Protection +IN + 10 k 10 k REF -VS Copyright © 2017, Texas Instruments Incorporated V- Figure 55. Simplified Diagram of the INA821 With Gain and Output Equations The value of RG is selected according to: 49.4 k: G 1 RG (1) Table 2 lists several commonly used gains and resistor values. The 49.4-kΩ term in Equation 1 is a result of the sum of the two internal 24.7-kΩ feedback resistors. These on-chip resistors are laser-trimmed to accurate absolute values. The accuracy and temperature coefficients of these resistors are included in the gain accuracy and drift specifications of the INA821. As shown in Figure 55 and explained in more details in the Layout section, make sure to connect low-ESR, 0.1-µF ceramic bypass capacitors between each supply pin and ground, that are placed as close to the device as possible. Table 2. Commonly-Used Gains and Resistor Values 20 DESIRED GAIN RG (Ω) NEAREST 1% RG (Ω) 1 NC NC 2 49.4 k 49.9 k 5 12.35 k 12.4 k 10 5.489 k 5.49 k 20 2.600 k 2.61 k 50 1.008 k 1k 100 499 499 200 248 249 500 99 100 1000 49.4 49.9 Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 INA821 www.ti.com SBOS893D – AUGUST 2018 – REVISED JUNE 2020 8.3.1.1 Gain Drift The stability and temperature drift of the external gain setting resistor (RG) also affects gain. The contribution of RG to gain accuracy and drift is determined from Equation 1. The best gain drift of 5 ppm/℃ (maximum) is achieved when the INA821 uses G = 1 without RG connected. In this case, gain drift is limited by the slight mismatch of the temperature coefficient of the integrated 10-kΩ resistors in the differential amplifier (A3). At gains greater than 1, gain drift increases as a result of the individual drift of the 24.7-kΩ resistors in the feedback of A1 and A2 relative to the drift of the external gain resistor (RG.) The low temperature coefficient of the internal feedback resistors significantly improves the overall temperature stability of applications using gains greater than 1 V/V over alternate options. Low resistor values required for high gain make wiring resistance an important consideration. Sockets add to the wiring resistance and contribute additional gain error (such as a possible unstable gain error) at gains of approximately 100 or greater. To maintain stability, avoid parasitic capacitance of more than a few picofarads at RG connections. Careful matching of any parasitics on the RG pins maintains optimal CMRR over frequency; see Figure 17. 8.3.2 EMI Rejection Texas Instruments developed a method to accurately measure the immunity of an amplifier over a broad frequency spectrum extending from 10 MHz to 6 GHz. This method uses an EMI rejection ratio (EMIRR) to quantify the ability of the INA821 to reject EMI. The offset resulting from an input EMI signal is calculated using Equation 2: 'VOS § VRF _ PEAK 2 ¨ ¨ 100 mVP © · ¸ ˜ 10 ¸ ¹ § EMIRR (dB) · ¨ ¸ 20 © ¹ where • VRF_PEAK is the peak amplitude of the input EMI signal. (2) Figure 56 and Figure 57 show the INA821 EMIRR graph for differential and common-mode EMI rejection across this frequency range. Table 3 lists the EMIRR values for the INA821 at frequencies commonly encountered in real-world applications. Applications listed in Table 3 are centered on or operated near the particular frequency shown. Depending on the end-system requirements, additional EMI filters may be required near the signal inputs of the system. Incorporating known good practices, such as using short traces, low-pass filters, and damping resistors combined with parallel and shielded signal routing, may be required. 140 120 120 100 EMIRR (dB) EMIRR (dB) 100 80 60 60 40 40 20 20 0 10M 80 100M 1G Frequency (Hz) 10G 0 10M D049 Figure 56. Common-Mode EMIRR Testing 100M 1G Frequency (Hz) 10G Figure 57. Differential-Mode EMIRR Testing Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 D048 21 INA821 SBOS893D – AUGUST 2018 – REVISED JUNE 2020 www.ti.com Table 3. INA821 EMIRR for Frequencies of Interest FREQUENCY APPLICATION OR ALLOCATION DIFFERENTIAL EMIRR COMMON-MODE EMIRR 400 MHz Mobile radio, mobile satellite, space operation, weather, radar, ultrahigh-frequency (UHF) applications 60 dB 88 dB 900 MHz Global system for mobile communications (GSM) applications, radio communication, navigation, GPS (up to 1.6 GHz), GSM, aeronautical mobile, UHF applications 58 dB 60 dB 1.8 GHz GSM applications, mobile personal communications, broadband, satellite, L-band (1 GHz to 2 GHz) 66 dB 89 dB ® 2.4 GHz 802.11b, 802.11g, 802.11n, Bluetooth , mobile personal communications, industrial, scientific and medical (ISM) radio band, amateur radio and satellite, S-band (2 GHz to 4 GHz) 73 dB 98 dB 3.6 GHz Radiolocation, aero communication and navigation, satellite, mobile, S-band 99 dB 111 dB 802.11a, 802.11n, aero communication and navigation, mobile communication, space and satellite operation, C-band (4 GHz to 8 GHz) 83 dB 91 dB 5 GHz 8.3.3 Input Common-Mode Range The linear input voltage range of the INA821 input circuitry extends within 2 V of power supplies and maintains excellent common-mode rejection throughout this range. The common-mode range for the most common operating conditions are shown in Figure 58 to Figure 61. The common-mode range for other operating conditions is best calculated using the Common-Mode Input Range Calculator for Instrumentation Amplifiers. 5 VREF = 0 V VREF = 2.5 V Common-Mode Voltage (V) Common-Mode Voltage (V) 5 4 3 2 1 0 1 2 3 4 5 Output Voltage (V) VS = 5 V 3 2 1 0 6 1 2 3 4 5 6 Output Voltage (V) C006 G=1 VS = 5 V Figure 58. Input Common-Mode Voltage vs Output Voltage C006 G = 100 Figure 59. Input Common-Mode Voltage vs Output Voltage 15 5 Common-Mode Voltage (V) 4 Common-Mode Voltage (V) VREF = 2.5 V 4 0 0 3 2 1 0 -1 -2 -3 G=1 -4 G = 100 -5 ±6 ±4 VS = ±5 V 10 5 0 -5 -10 -15 G=1 G = 100 -20 ±2 0 Output Voltage (V) 2 4 6 ±20 VREF = 0 V ±10 0 Output Voltage (V) C006 VS = ±15 V Figure 60. Input Common-Mode Voltage vs Output Voltage 22 VREF = 0 V 10 20 C006 VREF = 0 V Figure 61. Input Common-Mode Voltage vs Output Voltage Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 INA821 www.ti.com SBOS893D – AUGUST 2018 – REVISED JUNE 2020 8.3.4 Input Protection The inputs of the INA821 device are individually protected for voltages up to ±40 V. For example, a condition of –40 V on one input and +40 V on the other input does not cause damage. Internal circuitry on each input provides low series impedance under normal signal conditions. If the input is overloaded, the protection circuitry limits the input current to a value of approximately 8 mA. +V ZD1 +VS IN + Input Voltage Source Overvoltage Protection Input Transistor ± -VS ZD2 -V Figure 62. Input Current Path During an Overvoltage Condition 10 20 8 16 6 12 4 8 2 4 0 0 -2 -4 -4 -8 -6 -12 -8 Input Current -16 Output Voltage -20 20 30 40 50 -10 -50 -40 -30 -20 -10 0 10 Input Voltage (V) Output Voltage (V) Input Current (mA) During an input overvoltage condition, current flows through the input protection diodes into the power supplies, as shown in Figure 62. If the power supplies are unable to sink current, then Zener diode clamps (ZD1 and ZD2 in Figure 62) must be placed on the power supplies to provide a current pathway to ground. Figure 63 shows the input current for input voltages from –40 V to +40 V when the INA821 is powered by ±15-V supplies. D015 Figure 63. Input Current vs Input Overvoltage Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 23 INA821 SBOS893D – AUGUST 2018 – REVISED JUNE 2020 www.ti.com 8.3.5 Operating Voltage The INA821 operates over a power-supply range of 4.5 V to 36 V (±2.25 V to ±18 V). CAUTION Supply voltages higher than 40 V (±20 V) can permanently damage the device. Parameters that vary over supply voltage or temperature are shown in the Typical Characteristics section of this data sheet. 8.3.6 Error Sources Most modern signal-conditioning systems calibrate errors at room temperature. However, calibration of errors that result from a change in temperature is normally difficult and costly. Therefore, minimize these errors by choosing high-precision components, such as the INA821, that have improved specifications in critical areas that impact the precision of the overall system. Figure 64 shows an example application. +15 V RG VDIFF = VOUT / G 5.49 k INA VCM = 10 V RS± 0.99 k VOUT = 1 V ±VS RG REF RS+ 1k +VS C2 C1 ±15 V Figure 64. Example Application With G = 10 V/V and a 1-V Output Voltage Resistor-adjustable devices (such as the INA821) show the lowest gain error in G = 1 because of the inherently well-matched drift of the internal resistors of the differential amplifier. At gains greater than 1 (for instance, G = 10 V/V or G = 100 V/V), the gain error becomes a significant error source because of the contribution of the resistor drift of the 24.7-kΩ feedback resistors in conjunction with the external gain resistor. Except for very high gain applications, the gain drift is by far the largest error contributor compared to other drift errors, such as offset drift. The INA821 offers excellent gain error over temperature for both G > 1 and G = 1 (no external gain resistor). Table 5 summarizes the major error sources in common INA applications and compares the three cases of G = 1 (no external resistor) and G = 10 (5.49-kΩ external resistor) and G = 100 (499-Ω external resistor). All calculations are assuming an output voltage of VOUT = 1 V. Thus, the input signal VDIFF (given by VDIFF= VOUT/G) exhibits smaller and smaller amplitudes with increasing gain G. In this example, VDIFF = 1 mV at G = 1000. All calculations refer the error to the input for easy comparison and system evaluation. As Table 5 shows, errors generated by the input stage (such as input offset voltage) are more dominant at higher gain, while the effects of output stage are suppressed because they are divided by the gain when referring them back to the input. the gain error and gain drift error are much more significant for gains greater than 1 because of the contribution of the resistor drift of the 24.7-kΩ feedback resistors in conjunction with the external gain resistor. In most applications, static errors (absolute accuracy errors) can readily be removed during calibration in production, while the drift errors are the key factors limiting overall system performance. 24 Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 INA821 www.ti.com SBOS893D – AUGUST 2018 – REVISED JUNE 2020 Table 4. System Specifications for Error Calculation QUANTITY VALUE UNIT VOUT 1 V VCM 10 V VS 1 V RS+ 1000 Ω RS– 999 Ω RG tolerance 0.01 % RG drift 10 ppm/°C Temperature range upper limit 105 °C Table 5. Error Calculation INA821 VALUES ERROR SOURCE ERROR CALCULATION SPECIFICATION UNIT G=1 ERROR (ppm) G = 100 ERROR (ppm) G = 1000 ERROR (ppm) ABSOLUTE ACCURACY AT 25°C Input offset voltage VOSI / VDIFF 35 µV 35 350 3500 Output offset voltage VOSO / (G × VDIFF) 300 µV 350 350 350 Input offset current IOS × maximum (RS+, RS–) / VDIFF 0.5 nA 1 5 50 dB 251 251 251 CMRR (min) VCM / (10CMRR/20 × VDIFF) 92 (G = 1), 112 (G = 10), 132 (G = 100) PSRR (min) (VCC – VS)/ (10PSRR/20 × VDIFF) 110 (G = 1), 114 (G = 10), 130 (G = 100) dB 3 20 32 Gain error from INA (max) GE(%) × 104 0.02 (G = 1), 0.15 (G = 10, 100) % 200 1500 1500 Gain error from external resistor RG (max) GE(%) × 104 0.01 % 100 100 100 Total absolute accuracy error (ppm) at 25°C, worst case sum of all errors — — 940 2576 5738 Total absolute accuracy error (ppm) at 25°C, average rms sum of all errors — — 487 1603 3834 5 (G = 1), 35 (G = 10, 100) ppm/°C 400 2800 2800 DRIFT TO 105°C Gain drift from INA (max) GTC × (TA – 25) Gain drift from external resistor RG (max) GTC × (TA – 25) 10 ppm/°C 800 800 800 Input offset voltage drift (max) (VOSI_TC / VDIFF) × (TA – 25) 0.4 µV/°C 32 320 3200 Output offset voltage drift [VOSO_TC / ( G × VDIFF)] × (TA – 25) 5 µV/°C 400 400 400 Offset current drift IOS_TC × maximum (RS+, RS–) × (TA – 25) / VDIFF 20 pA/°C 2 16 160 Total drift error to 105°C (ppm), worst case sum of all errors — — 1634 4336 7360 Total drift error to 105°C (ppm), typical rms sum of all errors — — 980 2957 4348 10 (G = 1, 10), 15 (G = 100) ppm of FS 10 10 15 eNI = 7, eNO = 65 µVPP 1335 886 3566 0.13 pA/√Hz 0.4 2 11 RESOLUTION Gain nonlinearity Voltage noise (at 1 kHz) BW ´ (eNI2 + eNO G 2 6 ´ VDIFF Current noise (at 1kHz) IN × maximum (RS+, RS–) × √BW / VDIFF Total resolution error (ppm), worst case sum of all errors — — 1345 896 3581 Total resolution error (ppm), typical rms sum of all errors — — 1335 886 3566 Total error (ppm), worst case sum of all errors — — 3919 7808 16724 Total error (ppm), typical rms sum of all errors — — 1726 3478 6806 TOTAL ERROR Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 25 INA821 SBOS893D – AUGUST 2018 – REVISED JUNE 2020 www.ti.com 8.4 Device Functional Modes The INA821 has a single functional mode and is operational when the power supply voltage is greater than 4.5 V (±2.25 V). The maximum power-supply voltage for the INA821 is 36 V (±18 V). 9 Application and Implementation NOTE Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality. 9.1 Application Information 9.1.1 Reference Pin The output voltage of the INA821 is developed with respect to the voltage on the reference pin (REF.) Often in dual-supply operation, REF (pin 6) connects to the low-impedance system ground. In single-supply operation, offsetting the output signal to a precise midsupply level is useful (for example, 2.5 V in a 5-V supply environment). To accomplish this level shift, a voltage source must be connected to the REF pin to level-shift the output so that the INA821 drives a single-supply analog-to-digital converter (ADC). The voltage source applied to the reference pin must have a low output impedance. As shown in Figure 65, any resistance at the reference pin ( RREF in Figure 65) is in series with one of the internal 10-kΩ resistors. V+ +VS -IN OverVoltage Protection 10 k ± RG RG RG +IN 10 k + 24.7 k ± 24.7 k + OUT ± OverVoltage Protection REF + 10 k 10 k RREF -VS V- Figure 65. Parasitic Resistance Shown at the Reference Pin 26 Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 INA821 www.ti.com SBOS893D – AUGUST 2018 – REVISED JUNE 2020 Application Information (continued) The parasitic resistance at the reference pin (RREF) creates an imbalance in the four resistors of the internal difference amplifier that results in a degraded common-mode rejection ratio (CMRR). Figure 66 shows the degradation in CMRR of the INA821 as a result of the increased resistance at the reference pin. For the best performance, keep the source impedance to the REF pin (RREF) less than 5 Ω. Common-Mode Rejection Ratio (dB) 120 100 80 60 0Ω 5Ω 40 10 Ω 20 15 Ω 20 Ω 0 10 100 1k 10k Frequency (Hz) Figure 66. The Effect of Increasing Resistance at the Reference Pin Voltage reference devices are an excellent option for providing a low-impedance voltage source for the reference pin. However, if a resistor voltage divider generates a reference voltage, buffer the divider by an op amp, as shown in Figure 67, to avoid CMRR degradation. ±IN OUT ±VS INA821 RG REF RG RG 5V OPA191 5V 100 k + +IN +VS 5V 1 F 100 k ± Copyright © 2017, Texas Instruments Incorporated Figure 67. Use an Op Amp to Buffer Reference Voltages Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 27 INA821 SBOS893D – AUGUST 2018 – REVISED JUNE 2020 www.ti.com Application Information (continued) 9.1.2 Input Bias Current Return Path The input impedance of the INA821 is extremely high (approximately 100 GΩ.) However, a path must be provided for the input bias current of both inputs. This input bias current is typically 150 pA. High input impedance means that this input bias current changes little with varying input voltage. For proper operation, Input circuitry must provide a path for this input bias current. Figure 68 shows various provisions for an input bias current path. Without a bias current path, the inputs float to a potential that exceeds the common-mode range of the INA821 and the input amplifiers saturate. If the differential source resistance is low, the bias current return path connects to one input (as shown in the thermocouple example in Figure 68). With a higher source impedance, using two equal resistors provides a balanced input with possible advantages of a lower input offset voltage as a result of bias current and better high-frequency common-mode rejection. Microphone, Hydrophone, and So Forth TI Device 47 kW 47 kW Thermocouple TI Device 10 kW TI Device Center tap provides bias current return. Copyright © 2017, Texas Instruments Incorporated Figure 68. Providing an Input Common-Mode Current Path 28 Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 INA821 www.ti.com SBOS893D – AUGUST 2018 – REVISED JUNE 2020 9.2 Typical Application Figure 69 shows a three-pin programmable-logic controller (PLC) design for the INA821. This PLC reference design accepts inputs of ±10 V or ±20 mA. The output is a single-ended voltage of 2.5 V ±2.3 V (or 200 mV to 4.8 V). Typically, PLCs have these input and output ranges. ±10 V REF5025 R1 = 100 NŸ 1 F VOUT VIN GND NR 15 V 1 F 1 F 15 V R2 = 4.17 NŸ ±20 mA -IN +VS RG REF R3 = RG = 10.4 NŸ 20 Ÿ INA821 RG +IN OUT VOUT 2.5 V ± 2.3 V -VS -15 V Copyright © 2017, Texas Instruments Incorporated Figure 69. PLC Input (±10 V, 4 mA to 20 mA) 9.2.1 Design Requirements For this application, the design requirements are as follows: • 4-mA to 20-mA input with less than 20-Ω burden • ±20-mA input with less than 20-Ω burden • ±10-V input with impedance of approximately 100 kΩ • Maximum 4-mA to 20-mA or ±20 mA burden voltage equal to ±0.4 V • Output range within 0 V to 5 V 9.2.2 Detailed Design Procedure There are two modes of operation for the circuit shown in Figure 69: current input and voltage input. This design requires R1 >> R2 >> R3. Given this relationship, Equation 3 calculates the current input mode transfer function. VOUT-I = VD ´ G + VREF = -(IIN ´ R3) ´ G + VREF where • • • • G represents the gain of the instrumentation amplifier. VD represents the differential voltage at the INA821 inputs. VREF is the voltage at the INA821 REF pin. IIN is the input current. (3) Equation 4 shows the transfer function for the voltage input mode. R2 VOUT-V = VD ´ G + VREF = - VIN ´ ´ G + VREF R 1 + R2 where • VIN is the input voltage (4) Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 29 INA821 SBOS893D – AUGUST 2018 – REVISED JUNE 2020 www.ti.com Typical Application (continued) R1 sets the input impedance of the voltage input mode. The minimum typical input impedance is 100 kΩ. The R1 value is 100 kΩ because increasing the R1 value also increases noise. The value of R3 must be extremely small compared to R1 and R2. The value of R3 is 20 Ω because that resistance value is smaller than R1 and yields an input voltage of ±400 mV when operating in current mode (±20 mA). Use Equation 5 to calculate R2 if VD = ±400 mV, VIN = ±10 V, and R1 = 100 kΩ. R2 R ´ VD VD = VIN ´ ® R2 = 1 = 4.167 kW R 1 + R2 VIN - VD (5) The value obtained from Equation 5 is not a standard 0.1% value, so 4.17 kΩ is selected. R1 and R2 use 0.1% tolerance resistors to minimize error. Use Equation 6 to calculate the gain of the instrumentation amplifier. V - VREF 4.8 V - 2.5 V V = 5.75 V G = OUT = VD 400 mV (6) Equation 7 calculates the gain-setting resistor value using the INA821 gain equation (Equation 1). 49.4 k: 49.4 k: RG 10.4 k: G 1 5.75 1 (7) Use a standard 0.1% resistor value of 10.5 kΩ for this design. 9.2.3 Application Curves Figure 70 and Figure 71 show typical characteristic curves for the circuit in Figure 69. C001 5 5 4 Output Voltage (V) Output Voltage (V) 4 3 2 1 2 1 0 -10 -5 0 5 10 Input Voltage (V) 0 -20 -10 0 Input Current (mA) Figure 70. PLC Output Voltage vs Input Voltage 30 3 10 20 C001 Figure 71. PLC Output Voltage vs Input Current Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 INA821 www.ti.com SBOS893D – AUGUST 2018 – REVISED JUNE 2020 9.3 Other Application Examples 9.3.1 Resistance Temperature Detector Interface Figure 72 illustrates a 3-wire interface circuit for resistance temperature detectors (RTDs). The circuit incorporates analog linearization and has an output voltage range from 0 V to 5 V. The linearization technique employed is described in Analog linearization of resistance temperature detectors analog application journal. Series and parallel combinations of standard 1% resistor values are used to achieve less than 0.02°C of error over a 200°C temperature span. 15 V NR 1 F VIN GND -IN RG INA821 801 RG +IN Pt100 RTD 100 REF 100 k 100 +VS 4.99 k VOUT 0 V at 0°C 5 V at 200°C 25 mV/°C OUT -VS 4.99 k VOUT 1 F 1 F REF5050 -15 V 105 k 1.18 k Copyright © 2017, Texas Instruments Incorporated 5 0.018 4.5 0.016 4 0.014 3.5 0.012 Error (ƒC) Output Voltage (V) Figure 72. A 3-Wire Interface for RTDs With Analog Linearization 3 2.5 2 0.01 0.008 0.006 1.5 1 0.004 0.5 0.002 0 0 0 50 100 150 200 0 Temperature (°C) 50 100 150 Temperature (°C) Figure 73. Transfer Function of 3-Wire RTD Interface 200 C001 Figure 74. Temperature Error Over Full Temperature Range Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 31 INA821 SBOS893D – AUGUST 2018 – REVISED JUNE 2020 www.ti.com 10 Power Supply Recommendations The nominal performance of the INA821 is specified with a supply voltage of ±15 V and midsupply reference voltage. The device also operates using power supplies from ±2.25 V (4.5 V) to ±18 V (36 V) and non-midsupply reference voltages with excellent performance. Parameters that can vary significantly with operating voltage and reference voltage are shown in the Typical Characteristics section. 11 Layout 11.1 Layout Guidelines Attention to good layout practices is always recommended. For best operational performance of the device, use good PCB layout practices, including: • Make sure that both input paths are well-matched for source impedance and capacitance to avoid converting common-mode signals into differential signals. Even slight mismatch in parasitic capacitance at the gain setting pins can degrade CMRR over frequency. For example, in applications that implement gain switching using switches or PhotoMOS® relays to change the value of RG, select the component so that the switch capacitance is as small as possible and most importantly so that capacitance mismatch between the RG pins is minimized. • Noise propagates into analog circuitry through the power pins of the circuit as a whole and of the device. Bypass capacitors reduce the coupled noise by providing low-impedance power sources local to the analog circuitry. – Connect low-ESR, 0.1-µF ceramic bypass capacitors between each supply pin and ground, placed as close to the device as possible. A single bypass capacitor from V+ to ground is applicable for singlesupply applications. • To reduce parasitic coupling, run the input traces as far away from the supply or output traces as possible. If these traces cannot be kept separate, crossing the sensitive trace perpendicular is much better than in parallel with the noisy trace. • Place the external components as close to the device as possible. As shown in Figure 75, keep RG close to the pins to minimize parasitic capacitance. • Keep the traces as short as possible. • Connect exposed thermal pad to negative supply –V. 32 Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 INA821 www.ti.com SBOS893D – AUGUST 2018 – REVISED JUNE 2020 11.2 Layout Example +V C2 RG INA821 RG -IN OUT ±VS R3 REF +IN +VS R2 R1 C1 -V +V Use ground pours for shielding the input signal pairs Place bypass capacitors as close to IC as possible GND C2 R1 ±IN 1 ±IN +VS 8 2 RG OUT 7 3 RG REF 6 4 +IN -VS 5 OUT R3 +IN Low-impedance connection for reference terminal R2 GND C1 REF -V Copyright © 2017, Texas Instruments Incorporated Figure 75. Example Schematic and Associated PCB Layout Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 33 INA821 SBOS893D – AUGUST 2018 – REVISED JUNE 2020 www.ti.com 12 Device and Documentation Support 12.1 Device Support 12.1.1 Development Support • SPICE-based analog simulation program — TINA-TI software folder • Common-Mode Input Range Calculator for Instrumentation Amplifiers 12.2 Documentation Support 12.2.1 Related Documentation For related documentation see the following: • Texas Instruments, Comprehensive Error Calculation for Instrumentation Amplifiers application note • Texas Instruments, REF50xx Low-Noise, Very Low Drift, Precision Voltage Reference data sheet • Texas Instruments, OPAx191 36-V, Low Power, Precision, CMOS, Rail-to-Rail Input/Output, Low Offset Voltage, Low Input Bias Current Op Amp data sheet 12.3 Receiving Notification of Documentation Updates To receive notification of documentation updates, navigate to the device product folder on ti.com. In the upper right corner, click on Alert me to register and receive a weekly digest of any product information that has changed. For change details, review the revision history included in any revised document. 12.4 Support Resources TI E2E™ support forums are an engineer's go-to source for fast, verified answers and design help — straight from the experts. Search existing answers or ask your own question to get the quick design help you need. Linked content is provided "AS IS" by the respective contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of Use. 12.5 Trademarks E2E is a trademark of Texas Instruments. Bluetooth is a registered trademark of Bluetooth SIG, Inc. PhotoMOS is a registered trademark of Panasonic Electric Works Europe AG. All other trademarks are the property of their respective owners. 12.6 Electrostatic Discharge Caution This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications. 12.7 Glossary SLYZ022 — TI Glossary. This glossary lists and explains terms, acronyms, and definitions. 13 Mechanical, Packaging, and Orderable Information The following pages include mechanical, packaging, and orderable information. This information is the most current data available for the designated devices. This data is subject to change without notice and revision of this document. For browser-based versions of this data sheet, refer to the left-hand navigation. 34 Submit Documentation Feedback Copyright © 2018–2020, Texas Instruments Incorporated Product Folder Links: INA821 PACKAGE OPTION ADDENDUM www.ti.com 18-Apr-2023 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan (2) Lead finish/ Ball material MSL Peak Temp Op Temp (°C) Device Marking (3) Samples (4/5) (6) INA821ID ACTIVE SOIC D 8 75 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 125 INA821 Samples INA821IDGKR ACTIVE VSSOP DGK 8 2500 RoHS & Green NIPDAUAG | SN Level-2-260C-1 YEAR -40 to 125 1X4Q Samples INA821IDGKT ACTIVE VSSOP DGK 8 250 RoHS & Green NIPDAUAG | SN Level-2-260C-1 YEAR -40 to 125 1X4Q Samples INA821IDR ACTIVE SOIC D 8 2500 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 125 INA821 Samples INA821IDRGR ACTIVE SON DRG 8 3000 RoHS & Green NIPDAU Level-1-260C-UNLIM -40 to 125 INA821 Samples INA821IDRGT ACTIVE SON DRG 8 250 RoHS & Green NIPDAU Level-1-260C-UNLIM -40 to 125 INA821 Samples (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
INA821IDRGT 价格&库存

很抱歉,暂时无法提供与“INA821IDRGT”相匹配的价格&库存,您可以联系我们找货

免费人工找货