Order Now Product Folder Support & Community Tools & Software Technical Documents OPA189, OPA2189, OPA4189 SBOS830 – JUNE 2017 1 Features 3 Description • The OPAx189 (OPA189, OPA2189, and OPA4189) series of high-precision operational amplifiers are ultra-low noise, fast-settling, zero-drift devices that provide rail-to-rail output operation and feature a unique MUX-friendly architecture. These features and excellent ac performance, combined with only 0.4 µV of offset and 0.0035 µV/°C of drift over temperature, makes the OPAx189 well-suited for precision instrumentation, signal measurement, and active filtering applications. Moreover, the MUX-friendly input architecture prevents inrush current when applying large differential voltages which improves settling performance in multi-channel systems, all while providing robust ESD protection during shipment, handling, and assembly. All versions are specified from –40°C to +125°C. Ultra-High Precision: – Ultra-Low Offset Voltage: 0.4 μV – Zero-Drift: 0.0035 μV/°C Excellent DC Precision: – CMRR: 168 dB – Open-Loop Gain: 170 dB Low Noise: – VN at 1 kHz: 5.8 nV/√Hz – 0.1-Hz to 10-Hz Noise: 110 nVPP Excellent Dynamic Performance: – Gain Bandwidth: 14 MHz – Slew Rate: 20 V/µs – Fast Settling: 10-V, 0.01% in 1.5 µs Robust Design: – MUX-Friendly Inputs – RFI/EMI Filtered Inputs Wide Supply Range: 4.5 V to 36 V Quiescent Current: 1.7 mA (Maximum) Rail-to-Rail Output Input Includes Negative Rail 1 • • • • • • • • Device Information(1) PART NUMBER OPA189 OPA2189 OPA4189 2 Applications • • • • • PACKAGE BODY SIZE (NOM) SOIC (8) 4.90 mm × 3.90 mm SOT-23 (5) 2.90 mm × 1.60 mm VSSOP (8) 3.00 mm × 3.00 mm SOIC (8) 4.90 mm × 3.90 mm VSSOP (8) 3.00 mm × 3.00 mm SOIC (14) 8.65 mm × 3.90 mm TSSOP (14) 5.00 mm × 4.40 mm (1) For all available packages, see the package option addendum at the end of the data sheet. Precision Multi-Chanel Systems Bridge Amplifier Strain Gauges Temperature Measurement Resistance Temperature Detectors OPAx189 Preserves R-C Settling Performance in a Switched or Multiplexed Application OPAx189 MUX-Friendly Input Settles Quickly and Maintains High Input Impedance When Switched Analog Inputs OPAx189 MUX-friendly Inputs Prevents Loading of Source OPAx189 Bridge Sensor Thermocouple + Robust MUX-Friendly Inputs without Anti-Parallel Diodes Voltage OPAx189 4:2 HV MUX + OPAx189 Competitor HV Amp Current Sensing LED Photo Detector Optical Sensor Classical High-Voltage Op Amp Anti-Parallel Diodes Loads Source High-Voltage Multiplexed Input High-Voltage Level Translation Input Time Copyright © 2017, Texas Instruments Incorporated C003 Copyright © 2017, Texas Instruments Incorporated 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. ADVANCE INFORMATION for pre-production products; subject to change without notice. ADVANCE INFORMATION OPAx189, Precision, 36-V, 14-MHz, MUX-Friendly Low-Noise, Rail-to-Rail Output, Zero-Drift Operational Amplifiers OPA189, OPA2189, OPA4189 SBOS830 – JUNE 2017 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 7.8 8 8.6 Device Functional Modes........................................ 19 1 1 1 2 3 4 7 9 9.1 Application Information............................................ 20 9.2 Typical Applications ................................................ 20 10 System Examples................................................ 27 10.1 24-Bit, Delta-Sigma, Differential Load Cell or Strain Gauge Sensor Signal Conditioning.......................... 27 11 Power Supply Recommendations ..................... 28 12 Layout................................................................... 29 Absolute Maximum Ratings ...................................... 7 ESD Ratings.............................................................. 7 Recommended Operating Conditions....................... 7 Thermal Information: OPA189 .................................. 8 Thermal Information: OPA2189 ................................ 8 Thermal Information: OPA4189 ................................ 8 Electrical Characteristics........................................... 9 Typical Characteristics ............................................ 11 12.1 Layout Guidelines ................................................. 29 12.2 Layout Example .................................................... 29 13 Device and Documentation Support ................. 30 ADVANCE INFORMATION 13.1 13.2 13.3 13.4 13.5 13.6 13.7 13.8 Detailed Description ............................................ 12 8.1 8.2 8.3 8.4 8.5 Overview ................................................................. Functional Block Diagram ....................................... Feature Description................................................. Noise Performance ................................................. Basic Noise Calculations ........................................ Application and Implementation ........................ 20 12 12 13 18 18 Device Support...................................................... Documentation Support ........................................ Related Links ........................................................ Receiving Notification of Documentation Updates Community Resources.......................................... Trademarks ........................................................... Electrostatic Discharge Caution ............................ Glossary ................................................................ 30 30 30 31 31 31 31 31 14 Mechanical, Packaging, and Orderable Information ........................................................... 31 4 Revision History 2 DATE REVISION NOTES June 2017 * Initial release. Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 OPA189, OPA2189, OPA4189 www.ti.com SBOS830 – JUNE 2017 5 Device Comparison Table FEATURES PRODUCT OPA188 5-µV, 0.05-µV/°C, 7-nV/√Hz, 10-MHz, True Rail-to-Rail Input/Output, 5.5-V, Zero-Drift CMOS OPA388 10-µV, 0.05-µV/°C, 25-µA, Rail-to-Rail Input/Output, 5.5-V, Zero-Drift CMOS OPA333 25-µV, 0.8-µV/°C, 140-µA, 2.5-MHz, Rail-to-Rail Input/Output, 36-V, e-Trim CMOS OPA191 120-µV, 10-MHz, 5.1-nV/√Hz, 36-V JFET Input Industrial Op Amp OPA140 2.2-nV/√Hz, 150-µV, 18-MHz, 36-V Bipolar Op Amp in SOT-23 package OPA209 ADVANCE INFORMATION 25-µV, 0.085-µV/°C, 8.8-nV/√Hz, Rail-to-Rail Output, 36-V, Zero-Drift CMOS Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 3 OPA189, OPA2189, OPA4189 SBOS830 – JUNE 2017 www.ti.com 6 Pin Configuration and Functions OPA189 D and DGK Packages 8-Pin SOIC, 8-Pin VSSOP Top View ±IN 2 +IN 3 V± 4 8 NC ± 7 V+ + 6 OUT 5 NC OUT 1 V± 2 +IN 3 5 V+ 4 ±IN ± 1 + NC OPA189 DBV Package 5-Pin SOT-23 Top View Not to scale Not to scale NC - No internal connection. Pin Functions: OPA189 ADVANCE INFORMATION PIN OPA189 NAME I/O DESCRIPTION D (SOIC) DGK (VSSOP) DBV (SOT-23) –IN 2 4 I Inverting input +IN 3 3 I Noninverting input NC 1, 5, 8 — — No internal connection (can be left floating) OUT 6 1 O Output V– 4 2 — Negative (lowest) power supply V+ 7 5 — Positive (highest) power supply 4 Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 OPA189, OPA2189, OPA4189 www.ti.com SBOS830 – JUNE 2017 OPA2189 D and DGK Packages 8-Pin SOIC, 8-Pin VSSOP Top View OUT A 1 8 V+ ±IN A 2 7 OUT B +IN A 3 6 ±IN B V± 4 5 +IN B Not to scale Pin Functions: OPA2189 I/O DESCRIPTION NO. –IN A 2 I Inverting input channel A +IN A 3 I Noninverting input channel A –IN B 6 I Inverting input channel B +IN B 5 I Noninverting input channel B OUT A 1 O Output channel A OUT B 7 O Output channel B V– 4 — Negative supply V+ 8 — Positive supply ADVANCE INFORMATION PIN NAME Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 5 OPA189, OPA2189, OPA4189 SBOS830 – JUNE 2017 www.ti.com OPA4189 D and PW Packages 14-Pin SOIC, 14-Pin TSSOP Top View OUT A 1 14 OUT D ±IN A 2 13 ±IN D +IN A 3 12 +IN D V+ 4 11 V± +IN B 5 10 +IN C ±IN B 6 9 ±IN C OUT B 7 8 OUT C Not to scale ADVANCE INFORMATION NC - No internal connection. Pin Functions: OPA4189 PIN I/O DESCRIPTION NAME NO. –IN A 2 I Inverting input channel A +IN A 3 I Noninverting input channel A –IN B 6 I Inverting input channel B +IN B 5 I Noninverting input channel B –IN C 9 I Inverting input channel C +IN C 10 I Noninverting input channel C –IN D 13 I Inverting input channel D +IN D 12 I Noninverting input channel D OUT A 1 O Output channel A OUT B 7 O Output channel B OUT C 8 O Output channel C OUT D 14 O Output channel D V– 11 — Negative supply V+ 4 — Positive supply NC — — No internal connection (can be left floating) 6 Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 OPA189, OPA2189, OPA4189 www.ti.com SBOS830 – JUNE 2017 7 Specifications 7.1 Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted) (1) MIN Signal input pins VS = (V+) – (V–) Dual-supply Common-mode Voltage ±20 (V–) – 0.5 (V+) – (V–) + 0.2 Current ±10 Operating, TA (2) Continuous Continuous –55 150 Junction, TJ mA 150 Storage, Tstg (1) V (V+) + 0.5 Differential Output short circuit (2) Temperature UNIT 40 –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 ground, one amplifier per package. 7.2 ESD Ratings VALUE V(ESD) (1) (2) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1) ±4000 Charged-device model (CDM), per JEDEC specification JESD22-C101 (2) ±1000 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) MIN Supply voltage, VS = (V+) – (V–) Single-supply Dual-supply Specified temperature NOM MAX 4.5 36 ±2.25 ±18 –40 125 UNIT Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 V °C 7 ADVANCE INFORMATION Supply voltage MAX Single-supply OPA189, OPA2189, OPA4189 SBOS830 – JUNE 2017 www.ti.com 7.4 Thermal Information: OPA189 OPA189 THERMAL METRIC (1) D (SOIC) DGK (VSSOP) DBV (SOT) 8 PINS 8 PINS 5 PINS UNIT RθJA Junction-to-ambient thermal resistance 136 143 205 °C/W RθJC(top) Junction-to-case (top) thermal resistance 74 47 200 °C/W RθJB Junction-to-board thermal resistance 62 64 113 °C/W ΨJT Junction-to-top characterization parameter 19.7 5.3 38.2 °C/W ΨJB Junction-to-board characterization parameter 54.8 62.8 104.9 °C/W RθJC(bot) Junction-to-case (bottom) thermal resistance N/A N/A N/A °C/W (1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report. 7.5 Thermal Information: OPA2189 OPA2189 THERMAL METRIC (1) D (SOIC) DGK (VSSOP) 8 PINS 8 PINS UNIT ADVANCE INFORMATION RθJA Junction-to-ambient thermal resistance 136 143 °C/W RθJC(top) Junction-to-case (top) thermal resistance 74 47 °C/W RθJB Junction-to-board thermal resistance 62 64 °C/W ΨJT Junction-to-top characterization parameter 19.7 5.3 °C/W ΨJB Junction-to-board characterization parameter 54.8 62.8 °C/W RθJC(bot) Junction-to-case (bottom) thermal resistance N/A N/A °C/W (1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report. 7.6 Thermal Information: OPA4189 OPA4189 THERMAL METRIC (1) D (SOIC) PW (TSSOP) 14 PINS 14 PINS UNIT RθJA Junction-to-ambient thermal resistance 86 93 °C/W RθJC(top) Junction-to-case (top) thermal resistance 46 28 °C/W RθJB Junction-to-board thermal resistance 41 34 °C/W ΨJT Junction-to-top characterization parameter 11.3 1.9 °C/W ΨJB Junction-to-board characterization parameter 40.7 33.1 °C/W RθJC(bot) Junction-to-case (bottom) thermal resistance N/A N/A °C/W (1) 8 For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report. Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 OPA189, OPA2189, OPA4189 www.ti.com SBOS830 – JUNE 2017 7.7 Electrical Characteristics at TA = 25°C, VCM = VOUT = VS / 2, and RLOAD = 10 kΩ connected to VS / 2 (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX ±0.4 ±2.5 UNIT OFFSET VOLTAGE VOS Input offset voltage dVOS/dT Input offset voltage drift TA = –40°C to 125°C ±0.0035 ±0.02 µV/°C PSRR Power-supply rejection ratio TA = –40°C to 125°C ±0.005 ±0.05 µV/V ±70 ±300 TA = –40°C to 125°C µV ±4.5 INPUT BIAS CURRENT IB Input bias current TA = –20°C to 85°C RIN = 100 kΩ IOS Input offset current ±400 TA = –40°C to 125°C ±600 ±140 pA ±600 TA = –20°C to 85°C ±800 TA = –40°C to 125°C ±1200 NOISE Input voltage noise eN Input voltage noise density IN Input current noise density 17 f = 0.1 Hz to 10 Hz nVRMS 0.11 f = 10 Hz 5.8 f = 100 Hz 5.8 f = 1 kHz 5.8 f = 10 kHz 5.8 f = 1 kHz 165 ADVANCE INFORMATION EN µVPP nV/√Hz fA/rtHz INPUT VOLTAGE VCM Common-mode voltage range (V–) – 0.1 (V–) – 0.1 V ≤ VCM ≤ (V+) – 2.5 V CMRR Common-mode rejection ratio (V–) – 0.1 V ≤ VCM ≤ (V+) – 2.5 V TA = –40°C to 125°C (V+) – 2.5 VS = ±2.25 V 120 140 VS = ±18 V 146 168 VS = ±18 V 144 156 VS = ±2.25 V 116 130 V dB INPUT IMPEDANCE zid Differential input impedance zic Common-mode input impedance 100 || 2 MΩ || pF 60 || 4 TΩ || pF OPEN-LOOP GAIN AOL Open-loop voltage gain VS = ±18 V, (V–) + 0.3 V < VO < (V+) – 0.3 V, RLOAD = 10 kΩ 150 170 VS = ±18 V, (V–) + 0.3 V < VO < (V+) – 0.3 V, RLOAD = 10 kΩ TA = –40°C to 125°C 130 160 VS = ±18 V, (V–) + 0.6 V < VO < (V+) – 0.6 V, RLOAD = 2 kΩ 150 170 VS = ±18 V, (V–) + 0.6 V < VO < (V+) – 0.6 V, RLOAD = 2 kΩ TA = –40°C to 125°C 130 160 Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 dB 9 OPA189, OPA2189, OPA4189 SBOS830 – JUNE 2017 www.ti.com Electrical Characteristics (continued) at TA = 25°C, VCM = VOUT = VS / 2, and RLOAD = 10 kΩ connected to VS / 2 (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT FREQUENCY RESPONSE GBW Gain-bandwith Product AV = 1000 UGB Unity-gain Bandwith AV = 1 SR Slew rate G = 1, 10-V step THD+N Total harmonic distortion + noise G = 1, f = 1 kHz, VO = 3.5 VRMS tS Settling time tOR Overload recovery time 14 MHz 9 20 V/µs 0.0001% To 0.1% VS = ±18 V, G = 1, 10-V step 0.5 To 0.01% VS = ±18 V, G = 1, 10-V step 1.5 µs VIN × G = VS 400 ns OUTPUT No load Positive rail ADVANCE INFORMATION VO Voltage output swing from rail 5 15 RLOAD = 10 kΩ 20 110 RLOAD = 2 kΩ 80 500 No load Negative rail 5 15 RLOAD = 10 kΩ 20 110 RLOAD = 2 kΩ 80 500 20 110 TA = –40°C to 125°C, both rails, RLOAD = 10 kΩ ISC Short-circuit current CLOAD Capacitive load drive ZO Open-loop output impedance f = 1 MHz, IO = 0 A mV ±65 mA 100 Ω POWER SUPPLY VS = ±2.25 V (VS = 4.5 V) IQ Quiescent current per amplifier VS = ±18 V (VS = 36 V) IO = 0 A 1.3 1.7 TA = –40°C to 125°C IO = 0 A 1.3 1.8 IO = 0 A 1.3 1.7 TA = –40°C to 125°C IO = 0 A 1.3 1.8 mA TEMPERATURE TA Specified range VS Specified supply voltage range 10 –40 125 °C 4.5 (±2.25) 36 (±18) V Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 OPA189, OPA2189, OPA4189 www.ti.com SBOS830 – JUNE 2017 7.8 Typical Characteristics Table 1. Typical Characteristic Graphs DESCRIPTION FIGURE Offset Voltage Production Distribution Figure 1 Offset Voltage Drift Distribution Figure 2 at VS = ±18 V, VCM = VS / 2, RLOAD = 10 kΩ connected to VS / 2, and CL = 100 pF (unless otherwise noted) 45 14 40 12 35 Amplifiers (%) Amplifiers (%) 10 8 6 4 30 25 20 15 C001 µ = 46.67 nV σ = 374.5 nV VOS (maximum) = ±2.5 µV N = 2554 Figure 1. Offset Voltage Production Distribution Input Offset Voltage Drift (µV/ƒC) 0.02 0.015 0.01 0.005 0 -0.005 -0.01 -0.015 Input Offset Voltage (µV) 0 -0.02 3 2.5 2 1.5 1 0.5 0 -0.5 -1 -1.5 -2 -2.5 5 -3 0 ADVANCE INFORMATION 10 2 C002 µ = 3.79 nV/°C σ = 2.11 nV/°C N = 96 dVOS / dT (maximum) = ±0.02 µV/°C Figure 2. Offset Voltage Drift Distribution Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 11 OPA189, OPA2189, OPA4189 SBOS830 – JUNE 2017 www.ti.com 8 Detailed Description 8.1 Overview The OPAx189 operational amplifier combines precision offset and drift with excellent overall performance, making the device well-suited for many precision applications. The precision offset drift of only 0.0035 µV/°C provides stability over the entire temperature range. In addition, this device offers excellent linear performance with high CMRR, PSRR, and AOL. As with all amplifiers, applications with noisy or high-impedance power supplies require decoupling capacitors close to the device pins. In most cases, 0.1-µF capacitors are adequate. See Layout Guidelines for details and layout example. The OPAx189 is part of a family of zero-drift, MUX-friendly, rail-to-rail output operational amplifiers. These devices operate from 4.5 V to 36 V, are unity-gain stable, and are suitable for a wide range of general-purpose and precision applications. The zero-drift architecture provides ultra-low input offset voltage and near-zero input offset voltage drift over temperature and time. This choice of architecture also offers outstanding ac performance, such as ultra-low broadband noise, zero flicker noise, and outstanding distortion performance when operating below the chopper frequency. 8.2 Functional Block Diagram ADVANCE INFORMATION Figure 3 shows a representation of the proprietary OPAx189 architecture. Slew Boost Circuitry CLK CLK CCOMP +IN 36-V Differential Front End OUT ±IN GM1 GM2 GM3 CCOMP Ripple Reduction Technology Copyright © 2017, Texas Instruments Incorporated Figure 3. Functional Block Diagram 12 Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 OPA189, OPA2189, OPA4189 www.ti.com SBOS830 – JUNE 2017 8.3 Feature Description The OPA189, OPA2189, and OPA4189 series of op amps can be used with single or dual supplies from an operating range of VS = 4.5 V (±2.25 V) up to VS = 36 V (±18 V). These devices do not require symmetrical supplies; they only require a minimum supply voltage of 4.5 V (±2.25 V). For VS less than ±2.5 V, the common-mode input range does not include midsupply. Supply voltages higher than 40 V can permanently damage the device; see the Absolute Maximum Ratings table for details. Key parameters are given over the specified temperature range, TA = –40°C to +125°C, in Electrical Characteristics. Key parameters that vary over the supply voltage, temperature range, or frequency are shown in Typical Characteristics. The OPAx189 is unity-gain stable and free from unexpected output phase reversal. This device uses a proprietary, periodic autocalibration technique to provide low input offset voltage and very low input offset voltage drift over time and temperature. For lowest offset voltage and precision performance, optimize circuit layout and mechanical conditions. Avoid temperature gradients that create thermoelectric (Seebeck) effects in the thermocouple junctions formed from connecting dissimilar conductors. Cancel these thermally-generated potentials by ensuring they are equal on both input pins. Other layout and design considerations include: • Use low thermoelectric-coefficient conditions (avoid dissimilar metals). • Thermally isolate components from power supplies or other heat sources. Follow these guidelines to reduce the likelihood of junctions being at different temperatures, which may cause thermoelectric voltages of 0.1 µV/°C or higher, depending on the materials used. See Layout Guidelines for details and layout example. 8.3.1 Operating Characteristics The OPAx189 is specified for operation from 4.5 V to 36 V (±2.25 V to ±18 V). Many specifications apply from –40°C to +125°C. Parameters that can exhibit significant variance with regard to operating voltage or temperature are presented in the Typical Characteristics section. 8.3.2 Phase-Reversal Protection The OPAx189 has an internal phase-reversal protection. Many op amps exhibit a phase reversal when the input is driven beyond the linear common-mode range. This condition is most often encountered in noninverting circuits when the input is driven beyond the specified common-mode voltage range, causing the output to reverse into the opposite rail. The OPAx189 input prevents phase reversal with excessive common-mode voltage. Instead, the output limits into the appropriate rail. This performance is shown in Figure 4. Output Voltage (5 V/div) VIN VOUT Time (45 ms/div) C017 Figure 4. No Phase Reversal Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 13 ADVANCE INFORMATION • Shield operational amplifier and input circuitry from air currents, such as cooling fans. OPA189, OPA2189, OPA4189 SBOS830 – JUNE 2017 www.ti.com Feature Description (continued) 8.3.3 Input Bias Current Clock Feedthrough Zero-drift amplifiers such as the OPAx189 use switching on the inputs to correct for the intrinsic offset and drift of the amplifier. Charge injection from the integrated switches on the inputs can introduce short transients in the input bias current of the amplifier. The extremely short duration of these pulses prevents the pulses from amplifying, however the pulses may be coupled to the output of the amplifier through the feedback network. The most effective method to prevent transients in the input bias current from producing additional noise at the amplifier output is to use a low-pass filter such as an RC network. 8.3.4 EMI Rejection ADVANCE INFORMATION The OPAx189 uses integrated electromagnetic interference (EMI) filtering to reduce the effects of EMI interference from sources such as wireless communications and densely-populated boards with a mix of analog signal chain and digital components. EMI immunity can be improved with circuit design techniques; the OPAx189 benefits from these design improvements. Texas Instruments has developed the ability to accurately measure and quantify the immunity of an operational amplifier over a broad frequency spectrum extending from 10 MHz to 6 GHz. Figure 5 shows the results of this testing on the OPAx189. Table 2 lists the EMIRR IN+ values for the OPAx189 at particular frequencies commonly encountered in real-world applications. Applications listed in Table 2 may be centered on or operated near the particular frequency shown. Detailed information can also be found in EMI Rejection Ratio of Operational Amplifiers (SBOA128), available for download from www.ti.com. The electromagnetic interference (EMI) rejection ratio, or EMIRR, describes the EMI immunity of operational amplifiers. An adverse effect that is common to many op amps is a change in the offset voltage as a result of RF signal rectification. An op amp that is more efficient at rejecting this change in offset as a result of EMI has a higher EMIRR and is quantified by a decibel value. Measuring EMIRR can be performed in many ways, but this section provides the EMIRR IN+, which specifically describes the EMIRR performance when the RF signal is applied to the noninverting input pin of the op amp. In general, only the noninverting input is tested for EMIRR for the following three reasons: • Op amp input pins are known to be the most sensitive to EMI, and typically rectify RF signals better than the supply or output pins. • The noninverting and inverting op amp inputs have symmetrical physical layouts and exhibit nearly matching EMIRR performance • EMIRR is more simple to measure on noninverting pins than on other pins because the noninverting input terminal can be isolated on a PCB. This isolation allows the RF signal to be applied directly to the noninverting input terminal with no complex interactions from other components or connecting PCB traces. High-frequency signals conducted or radiated to any pin of the operational amplifier may result in adverse effects, as the amplifier would not have sufficient loop gain to correct for signals with spectral content outside the bandwidth. Conducted or radiated EMI on inputs, power supply, or output may result in unexpected DC offsets, transient voltages, or other unknown behavior. Take care to properly shield and isolate sensitive analog nodes from noisy radio signals and digital clocks and interfaces. The EMIRR IN+ of the OPAx189 is plotted versus frequency as shown in Figure 5. If available, any dual and quad op amp device versions have nearly similar EMIRR IN+ performance. The OPAx189 unity-gain bandwidth is 14 MHz. EMIRR performance below this frequency denotes interfering signals that fall within the op amp bandwidth. 14 Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 OPA189, OPA2189, OPA4189 www.ti.com SBOS830 – JUNE 2017 Feature Description (continued) 120 EMIRR IN+ (dB) 100 80 60 40 20 0 10M 100M 1G 10G Frequency (Hz) C005 Table 2. OPAx189 EMIRR IN+ for Frequencies of Interest FREQUENCY APPLICATION AND ALLOCATION EMIRR IN+ 400 MHz Mobile radio, mobile satellite, space operation, weather, radar, ultra-high frequency (UHF) applications 48.4 dB 900 MHz Global system for mobile communications (GSM) applications, radio communication, navigation, GPS (to 1.6 GHz), GSM, aeronautical mobile, UHF applications 52.8 dB 1.8 GHz GSM applications, mobile personal communications, broadband, satellite, L-band (1 GHz to 2 GHz) 69.1 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, Sband (2 GHz to 4 GHz) 88.9 dB 3.6 GHz Radiolocation, aero communication and navigation, satellite, mobile, S-band 82.5 dB 802.11a, 802.11n, aero communication and navigation, mobile communication, space and satellite operation, C-band (4 GHz to 8 GHz) 95.5 dB 5 GHz 8.3.5 EMIRR +IN Test Configuration Figure 6 shows the circuit configuration for testing the EMIRR IN+. An RF source is connected to the op amp noninverting input terminal using a transmission line. The op amp is configured in a unity-gain buffer topology with the output connected to a low-pass filter (LPF) and a digital multimeter (DMM). A large impedance mismatch at the op amp input causes a voltage reflection; however, this effect is characterized and accounted for when determining the EMIRR IN+. The multimeter samples and measures the resulting DC offset voltage. The LPF isolates the multimeter from residual RF signals that may interfere with multimeter accuracy. Ambient temperature: 25Û& +VS ± 50 Low-Pass Filter + RF source DC Bias: 0 V Modulation: None (CW) Frequency Sweep: 201 pt. Log -VS Not shown: 0.1 µF and 10 µF supply decoupling Sample / Averaging Digital Multimeter Figure 6. EMIRR +IN Test Configuration Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 15 ADVANCE INFORMATION Figure 5. EMIRR Testing OPA189, OPA2189, OPA4189 SBOS830 – JUNE 2017 www.ti.com 8.3.6 Electrical Overstress Designers often ask questions about the capability of an operational amplifier to withstand electrical overstress. These questions tend to focus on the device inputs, but may involve the supply voltage pins or even the output pin. Each of these different pin functions have electrical stress limits determined by the voltage breakdown characteristics of the particular semiconductor fabrication process and specific circuits connected to the pin. Additionally, internal electrostatic discharge (ESD) protection is built into these circuits to protect from accidental ESD events both before and during product assembly. Having a good understanding of this basic ESD circuitry and the relevance to an electrical overstress event is helpful. See Figure 7 for an illustration of the ESD circuits contained in the OPAx189 (indicated by the dashed line area). The ESD protection circuitry involves several current-steering diodes connected from the input and output pins and routed back to the internal power-supply lines, where the diodes meet at an absorption device internal to the operational amplifier. This protection circuitry is intended to remain inactive during normal circuit operation. An ESD event produces a short-duration, high-voltage pulse that is transformed into a short-duration, highcurrent pulse while discharging through a semiconductor device. The ESD protection circuits are designed to provide a current path around the operational amplifier core to prevent damage. The energy absorbed by the protection circuitry is then dissipated as heat. ADVANCE INFORMATION When an ESD voltage develops across two or more amplifier device pins, current flows through one or more steering diodes. Depending on the path that the current takes, the absorption device may activate. The absorption device has a trigger or threshold voltage that is above the normal operating voltage of the OPAx189 but below the device breakdown voltage level. When this threshold is exceeded, the absorption device quickly activates and clamps the voltage across the supply rails to a safe level. When the operational amplifier connects into a circuit (as shown in Figure 7), the ESD protection components are intended to remain inactive and do not become involved in the application circuit operation. However, circumstances may arise where an applied voltage exceeds the operating voltage range of a given pin. Should this condition occur, there is a risk that some internal ESD protection circuits may be biased on, and conduct current. Any such current flow occurs through steering-diode paths and rarely involves the absorption device. Figure 7 shows a specific example where the input voltage( VIN) exceeds the positive supply voltage (+VS) by 500 mV or more. Much of what happens in the circuit depends on the supply characteristics. If +VS can sink the current, one of the upper input steering diodes conducts and directs current to +VS. Excessively high current levels can flow with increasingly higher VIN. As a result, the data sheet specifications recommend that applications limit the input current to 10 mA. If the supply is not capable of sinking the current, VIN may begin sourcing current to the operational amplifier, and then take over as the source of positive supply voltage. The danger in this case is that the voltage can rise to levels that exceed the operational amplifier absolute maximum ratings. Another common question involves what happens to the amplifier if an input signal is applied to the input while the power supplies +VS or –VS are at 0 V. Again, this question depends on the supply characteristic while at 0 V, or at a level below the input signal amplitude. If the supplies appear as high impedance, then the operational amplifier supply current may be supplied by the input source through the current-steering diodes. This state is not a normal bias condition; the amplifier most likely does not operate normally. If the supplies are low impedance, then the current through the steering diodes can become quite high. The current level depends on the ability of the input source to deliver current, and any resistance in the input path. If there is any uncertainty about the ability of the supply to absorb this current, external zener diodes must be added to the supply pins, as shown in Figure 7. The zener voltage must be selected such that the diode does not turn on during normal operation. However, the zener voltage must be low enough so that the zener diode conducts if the supply pin begins to rise above the safe operating supply voltage level. 16 Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 OPA189, OPA2189, OPA4189 www.ti.com SBOS830 – JUNE 2017 (2) TVS RF +VS +V RI ESD CurrentSteering Diodes -In (3) RS +In Op Amp Core Edge-Triggered ESD Absorption Circuit ID RL (1) -V -VS (2) TVS (1) VIN = +VS + 500 mV. (2) TVS: +VS(max) > VTVSBR (min) > +VS. (3) Suggested value is approximately 5 kΩ. Figure 7. Equivalent Internal ESD Circuitry Relative to a Typical Circuit Application 8.3.7 MUX-Friendly Inputs The OPAx189 features a proprietary input stage design that allows an input differential voltage to be applied while maintaining high input impedance. Typically, high-voltage CMOS or bipolar-junction input amplifiers feature anti-parallel diodes that protect input transistors from large VGS voltages that may exceed the semiconductor process maximum and permanently damage the device. Large VGS voltages can be forced when applying a large input step, switching between channels, or attempting to use the amplifier as a comparator. OPAx189 solves these problems with a switched-input technique which prevents large input bias currents when large differential voltages are applied. This solves many issues seen in switched or multiplexed applications, where large disruptions to RC filtering networks are caused by fast switching between large potentials. OPAx189 offers outstanding settling performance due to these design innovations and built-in slew rate boost and wide bandwidth. The OPAx189 can also be used as a comparator. Differential and common-mode Absolute Maximum Ratings still apply relative to the power supplies. Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 17 ADVANCE INFORMATION VIN Out OPA189, OPA2189, OPA4189 SBOS830 – JUNE 2017 www.ti.com 8.4 Noise Performance Figure 8 shows the total circuit noise for varying source impedances with the operational amplifier in a unity-gain configuration (with no feedback resistor network and therefore no additional noise contributions). The OPAx189 and OPA211 are shown with total circuit noise calculated. The op amp itself contributes both a voltage noise component and a current noise component. The voltage noise is commonly modeled as a time-varying component of the offset voltage. The current noise is modeled as the time-varying component of the input bias current and reacts with the source resistance to create a voltage component of noise. Therefore, the lowest noise op amp for a given application depends on the source impedance. For low source impedance, current noise is negligible, and voltage noise generally dominates. The OPA189, OPA2189, and OPA4189 family has both low voltage noise and low current noise because of the CMOS input of the op amp. As a result, the current noise contribution of the OPAx189 series is negligible for any practical source impedance, which makes this device the better choice for applications with high source impedance. For more details on calculating noise, see Basic Noise Calculations. Voltage Noise Spectral Density, EO (V/Hz1/2) ADVANCE INFORMATION The equation in Figure 8 shows the calculation of the total circuit noise, with these parameters: • en = voltage noise • In = current noise • RS = source impedance • k = Boltzmann's constant = 1.38 × 10–23 J/K • T = temperature in degrees Kelvin (K) 10µ OPA211 1µ 100n OPAx189 10n 1n RS = 3.6 kŸ Resistor Noise 0.1n 1 10 100 1k 10k 100k 1M 10M Source Resistance, RS (Ÿ) Copyright © 2017, Texas Instruments Incorporated C003 RS = 3.6 kΩ is indicated in Figure 8. This is the source impedance above which OPAx189 is a lower noise option than the OPA211. Figure 8. Noise Performance of the OPAx189 and OPA211 in Unity-Gain Buffer Configuration 8.5 Basic Noise Calculations Low-noise circuit design requires careful analysis of all noise sources. External noise sources can dominate in many cases; consider the effect of source resistance on overall op amp noise performance. Total noise of the circuit is the root-sum-square combination of all noise components. The resistive portion of the source impedance produces thermal noise proportional to the square root of the resistance. This function is plotted in Figure 8. The source impedance is usually fixed; consequently, select the op amp and the feedback resistors to minimize the respective contributions to the total noise. Figure 9 illustrates both noninverting (A) and inverting (B) op amp circuit configurations with gain. In circuit configurations with gain, the feedback network resistors also contribute noise. In general, the current noise of the op amp reacts with the feedback resistors to create additional noise components. However, the extremely low current noise of the OPAx189 means that the current noise contribution can be neglected. The feedback resistor values can generally be chosen to make these noise sources negligible. Low impedance feedback resistors load the output of the amplifier. The equations for total noise are shown for both configurations. 18 Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 OPA189, OPA2189, OPA4189 www.ti.com SBOS830 – JUNE 2017 Basic Noise Calculations (continued) (A) Noise in Noninverting Gain Configuration R2 GND ± EO + RS + ± VS Source GND '1 = l1 + :2; A5 = ¥4 „ G$ „ 6(-) „ 45 d :3; A41 æ42 = ¨4 „ G$ „ 6(-) „ d 8 41 „ 42 h d h 41 + 42 ¾*V Thermal noise of R1 || R2 :4; G$ = 1.38065 „ 10F23 Boltzmann Constant :5; , h - 6(-) = 237.15 + 6(°%) (B) Noise in Inverting Gain Configuration R1 RS R2 h >-? Thermal noise of RS Temperature in kelvins :45 + 41 ; „ 42 42 2 p „ ¨:A0 ;2 + kA41 +45 æ42 o + FE0 „ H IG 45 + 41 45 + 41 + 42 :6; '1 = l1 + + :7; :45 + 41 ; „ 42 8 I d A41 +45 æ42 = ¨4 „ G$ „ 6(-) „ H h 45 + 41 + 42 ¾*V Thermal noise of (R1 + RS) || R2 GND :8; G$ = 1.38065 „ 10F23 :9; 6(-) = 237.15 + 6(°%) ± + ± d 8 ¾*V > 84/5 ? Noise at the output is given as EO, where EO VS 42 41 „ 42 2 2 p „ ¨:A5 ;2 + :A0 ;2 + kA41 æ42 o + :E0 „ 45 ;2 + lE0 „ d hp 41 41 + 42 :1; Source GND ADVANCE INFORMATION R1 Noise at the output is given as EO, where d , h - 2 > 84/5 ? Boltzmann Constant >-? Temperature in kelvins Copyright © 2017, Texas Instruments Incorporated (1) eN is the voltage noise of the amplifier. For the OPAx189 series of operational amplifiers, eN = 5.8 nV / √Hz at 1 kHz. (2) iN is the current noise of the amplifier. For the OPAx189 series of operational amplifiers, iN = 165 fA / √Hz at 1 kHz. (3) For additional resources on noise calculations visit TI's Precision Labs Series. Figure 9. Noise Calculation in Gain Configurations 8.6 Device Functional Modes The OPAx189 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 OPAx189 is 36 V (±18 V). Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 19 OPA189, OPA2189, OPA4189 SBOS830 – JUNE 2017 www.ti.com 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 The OPAx189 operational amplifier combines precision offset and drift with excellent overall performance, making the series ideal for many precision applications. The precision offset drift of only 0.0035 µV/°C provides stability over the entire temperature range. In addition, the device pairs excellent CMRR, PSRR, and AOL dc performance with outstanding low-noise operation. As with all amplifiers, applications with noisy or highimpedance power supplies require decoupling capacitors close to the device pins. In most cases, 0.1-µF capacitors are adequate. The following application examples highlight only a few of the circuits where the OPAx189 can be used. ADVANCE INFORMATION 9.2 Typical Applications 9.2.1 High-Side Voltage-to-Current (V-I) Converter The circuit shown in Figure 10 is a high-side voltage-to-current (V-I) converter. The converter translates an input voltage of 0 V to 2 V into an output current of 0 mA to 100 mA. Figure 11 shows the measured transfer function for this circuit. The low offset voltage and offset drift of the OPAx189 facilitates excellent dc accuracy for the circuit. V+ RS2 470 RS3 4.7 IRS2 IRS3 R4 10 k VRS2 VRS3 C7 2200 pF R5 330 Q2 + R3 200 + Q1 C6 1000 pF VIN + R2 10 ± VRS1 RS1 2k IRS1 VLOAD RLOAD ILOAD Copyright © 2016, Texas Instruments Incorporated Figure 10. High-Side Voltage-to-Current (V-I) Converter 20 Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 OPA189, OPA2189, OPA4189 www.ti.com SBOS830 – JUNE 2017 Typical Applications (continued) 9.2.1.1 Design Requirements The design requirements are: • Supply voltage: 5 V dc • Input: 0 V to 2 V dc • Output: 0 mA to 100 mA dc 9.2.1.2 Detailed Design Procedure For a successful design, pay close attention to the dc characteristics of the operational amplifier chosen for the application. To meet the performance goals, this application benefits from an operational amplifier with low offset voltage, low temperature drift, and rail-to-rail output. The OPAx189 CMOS operational amplifier is a highprecision, ultra-low offset, ultra-low drift amplifier, optimized for low-voltage, single-supply operation, with an output swing to within 15 mV of the positive rail. The OPAx189 family uses chopping techniques to provide low initial offset voltage and near-zero drift over time and temperature. Low offset voltage and low drift reduce the offset error in the system, making this family appropriate for precise dc control. The rail-to-rail output stage of the OPAx189 makes sure that the output swing of the operational amplifier is able to fully control the gate of the MOSFET devices within the supply rails. A detailed error analysis, design procedure, and additional measured results are given in reference design TIPD102, which is a step-by-step process to design a High-Side Voltage-to-Current (V-I) Converter. For step-by-step design procedure, circuit schematics, bill of materials, PCB files, simulation results, and test results, refer to TI Precision Design TIPD102, High-Side Voltage-to-Current (V-I) Converter (SLAU502). 9.2.1.3 Application Curves Figure 11 shows the measured transfer function for the high-side voltage-to-current converter shown in Figure 10 . 0.1 Load Output Current (A) 0.075 0.05 0.025 0 0 0.5 1 Input Voltage (V) 1.5 2 D001 Figure 11. Measured Transfer Function for High-Side V-I Converter Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 21 ADVANCE INFORMATION The V-I transfer function of the circuit is based on the relationship between the input voltage, VIN, and the three current sensing resistors: RS1, RS2, and RS3. The relationship between VIN and RS1 determines the current that flows through the first stage of the design. The current gain from the first stage to the second stage is based on the relationship between RS2 and RS3. OPA189, OPA2189, OPA4189 SBOS830 – JUNE 2017 www.ti.com 9.2.2 25-kHz Low-pass Filter R4 2.94 k C5 1 nF R1 590 R3 499 Input C2 39 nF ± Output + OPAx189 Copyright © 2017, Texas Instruments Incorporated Figure 12. 25-kHz Low-pass Filter 9.2.2.1 Design Requirements Low-pass filters are commonly employed in signal processing applications to reduce noise and prevent aliasing. The OPAx189 devices are ideally suited to construct high-speed, high-precision active filters. Figure 12 shows a second-order, low-pass filter commonly encountered in signal processing applications. ADVANCE INFORMATION Use the following parameters for this design example: • Gain = 5 V/V (inverting gain) • Low-pass cutoff frequency = 25 kHz • Second-order Chebyshev filter response with 3-dB gain peaking in the passband 9.2.2.2 Detailed Design Procedure The infinite-gain multiple-feedback circuit for a low-pass network function is shown in Figure 12. Use Equation 1 to calculate the voltage transfer function. 1 R1R3C2C5 Output s 2 Input s s C2 1 R1 1 R3 1 R4 1 R3R4C2C5 (1) This circuit produces a signal inversion. For this circuit, the gain at DC and the low-pass cutoff frequency are calculated by Equation 2: R4 Gain R1 fC 1 2S 1 R3R 4 C2C5 (2) ® Software tools are readily available to simplify filter design. WEBENCH Filter Designer is a simple, powerful, and easy-to-use active filter design program. The WEBENCH® Filter Designer lets the user create optimized filter designs using a selection of TI operational amplifiers and passive components from TI's vendor partners. Available as a web based tool from the WEBENCH Design Center, WEBENCH Filter Designer allows board-level designers to create, optimize, and simulate complete multistage active filter solutions within minutes. 22 Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 OPA189, OPA2189, OPA4189 www.ti.com SBOS830 – JUNE 2017 9.2.2.3 Application Curve 20 Gain (db) 0 -20 -40 -60 100 1k 10k Frequency (Hz) 100k 1M Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 ADVANCE INFORMATION Figure 13. OPAx189 Second-Order, 25-kHz, Chebyshev, Low-Pass Filter 23 OPA189, OPA2189, OPA4189 SBOS830 – JUNE 2017 www.ti.com 9.2.3 Discrete INA + Attenuation for ADC With 3.3-V Supply NOTE The TINA-TI files shown in the following sections require that either the TINA software (from DesignSoft™) or TINA-TI software be installed. Download the free TINA-TI software from the TINA-TI folder. Figure 14 shows an example of how the OPAx189 is used as a high-voltage, high-impedance front-end for a precision, discrete instrumentation amplifier with attenuation. The INA159 provides the attenuation that allows this circuit to simply interface with 3.3-V or 5-V analog-to-digital converters (ADCs). Click the following link download the TINA-TI file: Discrete INA. 15 V VOUTP OPAx189 5V VDIFF / 2 - 15 V RP 10 NŸ Ref 1 ADVANCE INFORMATION VCM 10V Ref 2 RG 500 Ÿ + VOUT(1) INA159 Sense 15 V ±VDIFF / 2 OPAx189 RN 10 NŸ VOUTN 15 V Copyright © 2017, Texas Instruments Incorporated (1) VOUT = VDIFF × (41 / 5) + (Ref 1) / 2. Figure 14. Discrete INA + Attenuation for ADC With 3.3-V Supply 9.2.4 Bridge Amplifier Figure 15 shows the basic configuration for a bridge amplifier. Click the following link to download the TINA-TI file: Bridge Amplifier Circuit. VEX R1 R R R R +5V VOUT VREF Copyright © 2017, Texas Instruments Incorporated Figure 15. Bridge Amplifier 9.2.5 Low-Side Current Monitor Figure 16 shows the OPAx189 configured in a low-side current-sensing application. The load current (ILOAD) creates a voltage drop across the shunt resistor (RSHUNT). This voltage is amplified by the OPAx189, with a gain of 201. The load current is set from 0 A to 500 mA, which corresponds to an output voltage range from 0 V to 10 V. The output range can be adjusted by changing the shunt resistor or gain of the configuration. Click the following link to download the TINA-TI file: Current-Sensing Circuit. 24 Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 OPA189, OPA2189, OPA4189 www.ti.com SBOS830 – JUNE 2017 VSYSTEM Load 15 V + VOUT = ILOAD * RSHUNT(1 + RF / RIN) OPAx189 RSHUNT 100 m VOUT / ILOAD= 1 V / 49.75 mA ± RIN RF 100 20 k CF Copyright © 2017, Texas Instruments Incorporated 150 pF Figure 16. Low-Side Current Monitor 9.2.6 Programmable Power Supply Figure 17 shows the OPAx189 configured as a precision programmable power supply using the 16-bit, voltage output DAC8581 and the OPA548 high-current amplifier. This application amplifies the digital-to-analog converter (DAC) voltage by a value of five, and handles a large variety of capacitive and current loads. The OPAx189 in the front-end provides precision and low drift across a wide range of inputs and conditions. Click the following link to download the TINA-TI file: Programmable Power-Supply Circuit. C1 500 nF R1 10 k R4 40 k R2 1k GND C2 500 nF +30V +15V ± OPAx189 + DAC8581 ± R3 10 k OPA548 + VOUT Output = ± 25V ±30V ±15V Input = ± 5V Copyright © 2017, Texas Instruments Incorporated Figure 17. Programmable Power Supply Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 25 ADVANCE INFORMATION ILOAD VOUT OPA189, OPA2189, OPA4189 SBOS830 – JUNE 2017 www.ti.com 9.2.7 RTD Amplifier With Linearization See Analog Linearization Of Resistance Temperature Detectors (SLYT442) for an in-depth analysis of Figure 18. Click the following link to download the TINA-TI file: RTD Amplifier with Linearization. 15 V (5 V) Out REF5050 In 1 µF 1 µF R2 49.1 kŸ R3 60.4 kŸ R1 4.99 kŸ OPAx189 V OUT 0°C = 0 V 200°C = 5 V R5 (1) 105.8 kŸ RTD Pt100 ADVANCE INFORMATION R4 1 kŸ Copyright © 2017, Texas Instruments Incorporated (1) R5 provides positive-varying excitation to linearize output. Figure 18. RTD Amplifier With Linearization 26 Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 OPA189, OPA2189, OPA4189 www.ti.com SBOS830 – JUNE 2017 10 System Examples 10.1 24-Bit, Delta-Sigma, Differential Load Cell or Strain Gauge Sensor Signal Conditioning OPAx189 is used in a 24-bit, differential load cell or strain gauge sensor signal conditioning system alongside the ADS1225. A pair of OPAx189 amplifiers are configured in a two-amp instrumentation amplifier (IA) configuration and are band-limited to reduce noise and allow heavy capacitive drive. The load cell is powered by an excitation voltage (denoted VEX) of 5-V and provides a differential voltage proportional to force applied. The differential voltage can be quite small and both outputs are biased to VEX / 2. G=1+ C4 0.1 nF 2 ® RF RG C5 0.1 µF C6 0.1 nF GND GND + GND GND OPAx189 VREFN ± RTRACE VREFP C1 10 µF RF 10 k +OUT +SENSE DVDD R1 1k -SENSE +5V AINP1 GND DVDD SCLK DRDY / DOUT RG 50 C2 1 µF CF 1 µF + +3V START CF 1 µF ± +5V RTRACE +15V VEX AVDD ADS1225 R2 1k Load Cell MSP430xxx or other host AINN1 ±OUT MODE +3V BUFEN RF 10 k GND TEMPEN C3 10 µF +15V ± GND GND GND OPAx189 + GND Copyright © 2017, Texas Instruments Incorporated Figure 19. 24-Bit, Differential Load Cell or Strain Gauge Sensor Signal Conditioning Schematic Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 27 ADVANCE INFORMATION OPAx189 is employed here due to the excellent input offset voltage (0.4-µV) and input offset voltage drift (0.0035-µV/°C), the low broadband noise (5.8-nV/√Hz) and zero-flicker noise, and excellent linearity and high input impedance. The two-amp IA configuration removes the dc bias and amplifies the differential signal of interest and drives the 24-bit, delta-sigma ADS1225 analog-to-digital converter (ADC) for acquisition and conversion. The ADS1225 features a 100-SPS data rate, single-cycle settling, and simple conversion control with the dedicated START pin. OPA189, OPA2189, OPA4189 SBOS830 – JUNE 2017 www.ti.com 11 Power Supply Recommendations The OPAx189 is specified for operation from 4.5 V to 36 V (±2.25 V to ±18 V); many specifications apply from –40°C to +125°C. The Typical Characteristics presents parameters that can exhibit significant variance with regard to operating voltage or temperature. CAUTION Supply voltages larger than 40 V can permanently damage the device (see the Absolute Maximum Ratings). Place 0.1-μF bypass capacitors close to the power-supply pins to reduce errors coupling in from noisy or high-impedance power supplies. For more detailed information on bypass capacitor placement, see the Layout section. ADVANCE INFORMATION 28 Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 OPA189, OPA2189, OPA4189 www.ti.com SBOS830 – JUNE 2017 12 Layout For best operational performance of the device, use good PCB layout practices, including: • Noise can propagate into analog circuitry through the power pins of the circuit as a whole and the op amp itself. 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 as possible to the device. A single bypass capacitor from V+ to ground is applicable for singlesupply applications. • Separate grounding for analog and digital portions of circuitry is one of the simplest and most effective methods of noise suppression. One or more layers on multilayer PCBs are usually devoted to ground planes. A ground plane helps distribute heat and reduces EMI noise pickup. Make sure to physically separate digital and analog grounds paying attention to the flow of the ground current. For more detailed information, see The PCB is a component of op amp design'. • To reduce parasitic coupling, run the input traces as far away as possible from the supply or output traces. If these traces cannot be kept separate, crossing the sensitive trace perpendicular is much better as opposed to in parallel with the noisy trace. • Place the external components as close as possible to the device. As illustrated in Figure 20, keeping RF and RG close to the inverting input minimizes parasitic capacitance. • Keep the length of input traces as short as possible. Always remember that the input traces are the most sensitive part of the circuit. • Consider a driven, low-impedance guard ring around the critical traces. A guard ring can significantly reduce leakage currents from nearby traces that are at different potentials. • For best performance, TI recommends cleaning the PCB following board assembly. • Any precision integrated circuit may experience performance shifts due to moisture ingress into the plastic package. Following any aqueous PCB cleaning process, TI recommends baking the PCB assembly to remove moisture introduced into the device packaging during the cleaning process. A low temperature, post cleaning bake at 85°C for 30 minutes is sufficient for most circumstances. 12.2 Layout Example GND +V R3 Use ground pours for shielding the input signal pairs Place bypass capacitors as close to device as possible (avoid use of vias) C3 C4 C3 R3 IN± 1 NC NC C4 8 IN± IN+ 1 NC NC 8 2 ±IN V+ 7 3 +IN OUT 6 4 V± NC 5 +V R1 R1 2 ±IN ± V+ 7 3 +IN + OUT 6 R2 4 V± NC 5 OUT OUT R2 -V C1 IN+ R4 GND R4 C2 Place components close to device and to each other to reduce parasitic errors C1 -V Use a lowESR,ceramic bypass capacitor C2 Copyright © 2017, Texas Instruments Incorporated Figure 20. Operational Amplifier Board Layout for Difference Amplifier Configuration Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 29 ADVANCE INFORMATION 12.1 Layout Guidelines OPA189, OPA2189, OPA4189 SBOS830 – JUNE 2017 www.ti.com 13 Device and Documentation Support 13.1 Device Support 13.1.1 Development Support 13.1.1.1 TINA-TI™ (Free Software Download) TINA-TI™ is a simple, powerful, and easy-to-use circuit simulation program based on a SPICE engine. TINATI™ is a free, fully-functional version of the TINA™ software, preloaded with a library of macromodels in addition to a range of both passive and active models. TINA-TI™ provides all the conventional dc, transient, and frequency domain analysis of SPICE, as well as additional design capabilities. Available as a free download from the Analog eLab Design Center, TINA-TI™ offers extensive post-processing capability that allows users to format results in a variety of ways. Virtual instruments offer the ability to select input waveforms and probe circuit nodes, voltages, and waveforms, creating a dynamic quick-start tool. NOTE These files require that either the TINA software (from DesignSoft™) or TINA-TI™ software be installed. Download the free TINA-TI™ software from the TINA-TI™ folder. ADVANCE INFORMATION 13.1.1.2 TI Precision Designs TI Precision Designs are available online at http://www.ti.com/ww/en/analog/precision-designs/. TI Precision Designs are analog solutions created by TI’s precision analog applications experts and offer the theory of operation, component selection, simulation, complete PCB schematic and layout, bill of materials, and measured performance of many useful circuits. 13.2 Documentation Support 13.2.1 Related Documentation For related documentation see the following: • Zero-drift Amplifiers: Features and Benefits (SBOA182) • The PCB is a component of op amp design (SLYT166) • Operational amplifier gain stability, Part 3: AC gain-error analysis (SLTY383) • Operational amplifier gain stability, Part 2: DC gain-error analysis (SLYT374) • Using infinite-gain, MFB filter topology in fully differential active filters (SLYT343) • Op Amp Performance Analysis (SBOA054) • Single-Supply Operation of Operational Amplifiers (SBOA059) • Tuning in Amplifiers (SBOA067) • Shelf-Life Evaluation of Lead-Free Component Finishes (SZZA046) • Feedback Plots Define Op Amp AC Performance (SBOA015) • EMI Rejection Ratio of Operational Amplifiers (SBOA128) 13.3 Related Links The table below lists quick access links. Categories include technical documents, support and community resources, tools and software, and quick access to sample or buy. Table 3. Related Links 30 PARTS PRODUCT FOLDER ORDER NOW TECHNICAL DOCUMENTS TOOLS & SOFTWARE SUPPORT & COMMUNITY OPA189 Click here Click here Click here Click here Click here OPA2189 Click here Click here Click here Click here Click here OPA4189 Click here Click here Click here Click here Click here Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 OPA189, OPA2189, OPA4189 www.ti.com SBOS830 – JUNE 2017 13.4 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. 13.5 Community Resources The following links connect to TI community resources. Linked contents are 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. TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help solve problems with fellow engineers. Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and contact information for technical support. TINA-TI, E2E are trademarks of Texas Instruments. WEBENCH is a registered trademark of Texas Instruments. Bluetooth is a registered trademark of Bluetooth SIG, Inc. DesignSoft, TINA are trademarks of DesignSoft, Inc. All other trademarks are the property of their respective owners. 13.7 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. 13.8 Glossary SLYZ022 — TI Glossary. This glossary lists and explains terms, acronyms, and definitions. 14 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. 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Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: OPA189 OPA2189 OPA4189 31 ADVANCE INFORMATION 13.6 Trademarks PACKAGE OPTION ADDENDUM www.ti.com 11-Aug-2017 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) Op Temp (°C) Device Marking (4/5) OPA189ID PREVIEW SOIC D 8 75 TBD Call TI Call TI -40 to 125 OPA189IDR PREVIEW SOIC D 8 2500 TBD Call TI Call TI -40 to 125 OPA2189ID PREVIEW SOIC D 8 75 TBD Call TI Call TI -40 to 125 OPA2189IDGKR PREVIEW VSSOP DGK 8 2500 TBD Call TI Call TI -40 to 125 OPA2189IDGKT PREVIEW VSSOP DGK 8 250 TBD Call TI Call TI -40 to 125 OPA2189IDR PREVIEW SOIC D 8 2500 TBD Call TI Call TI -40 to 125 POPA189ID ACTIVE SOIC D 8 75 TBD Call TI Call TI -40 to 125 (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 <=1000ppm threshold. Antimony trioxide based flame retardants must also meet the <=1000ppm threshold requirement. (3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Device Marking for that device. (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish value exceeds the maximum column width. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and Addendum-Page 1 Samples PACKAGE OPTION ADDENDUM www.ti.com 11-Aug-2017 continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. 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