INA149AIDR

INA149 www.ti.com SBOS579B – SEPTEMBER 2011 – REVISED JULY 2012 High Common-Mode Voltage Difference Amplifier FEATURES DESCRIPTION • • • The INA149 is a precision unity-gain difference amplifier with a very high input common-mode voltage range. It is a single, monolithic device that consists of a precision op amp and an integrated thinfilm resistor network. The INA149 can accurately measure small differential voltages in the presence of common-mode signals up to ±275 V. The INA149 inputs are protected from momentary common-mode or differential overloads of up to 500 V. 1 2 • • • Common-Mode Voltage Range: ±275 V Minimum CMRR: 90 dB from –40°C to +125°C DC Specifications: – Maximum Offset Voltage: 1100 μV – Maximum Offset Voltage Drift: 15 μV/°C – Maximum Gain Error: 0.02% – Maximum Gain Error Drift: 10 ppm/°C – Maximum Gain Nonlinearity: 0.001% FSR AC Performance: – Bandwidth: 500 kHz – Typical Slew Rate: 5 V/μs Wide Supply Range: ±2.0 V to ±18 V – Maximum Quiescent Current: 900 μA – Output Swing on ±15-V Supplies: ±13.5 V Input Protection: – Common-Mode: ±500 V – Differential: ±500 V In many applications, where galvanic isolation in not required, the INA149 can replace isolation amplifiers. This ability can eliminate costly isolated input side power supplies and the associated ripple, noise, and quiescent current. The excellent 0.0005% nonlinearity and 500-kHz bandwidth of the INA149 are superior to those of conventional isolation amplifiers. The INA149 is pin-compatible with the INA117 and INA148 type high common-mode voltage amplifiers and offers improved performance over both devices. The INA149 is available in the SOIC-8 package with operation specified over the extended industrial temperature range of –40°C to +125°C. APPLICATIONS High-Voltage Current Sensing Battery Cell Voltage Monitoring Power-Supply Current Monitoring Motor Controls Replacement for Isolation Circuits Common−Mode Rejection Ratio (dB) • • • • • 120 INA149 Competitor A 110 100 90 80 70 60 50 40 10 100 1k Frequency (Hz) 10k 100k 1 2 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. All trademarks are the property of their respective owners. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2011–2012, Texas Instruments Incorporated INA149 SBOS579B – SEPTEMBER 2011 – REVISED JULY 2012 www.ti.com 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. PACKAGE/ORDERING INFORMATION (1) (1) PRODUCT PACKAGE-LEAD PACKAGE DESIGNATOR PACKAGE MARKING INA149 SOIC-8 D INA149A For the most current package and ordering information, see the Package Option Addendum at the end of this document, or visit the device product folder at www.ti.com. ABSOLUTE MAXIMUM RATINGS (1) Over operating free-air temperature range, unless otherwise noted. INA149 UNIT Supply voltage (V+) – (V–) 40 V Input voltage range Continuous 300 V 500 V (V–) – 0.3 to (V+) + 0.3 V 10 mA Common-mode and differential, 10 s Maximum Voltage on REFA and REFB Input current on any input pin (2) Output short-circuit current duration Indefinite Operating temperature range –55 to +150 °C Storage temperature range –65 to +150 °C +150 °C Human body model (HBM) 1500 V Charged device model (CDM) 1000 V Machine model (MM) 100 V Junction temperature ESD rating (1) (2) 2 Stresses above these ratings may cause permanent damage. Exposure to absolute maximum conditions for extended periods may degrade device reliability. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those specified is not implied. REFA and REFB are diode clamped to the power-supply rails. Signals applied to these pins that can swing more than 0.3 V beyond the supply rails should be limited to 10 mA or less. Submit Documentation Feedback Copyright © 2011–2012, Texas Instruments Incorporated Product Folder Link(s): INA149 INA149 www.ti.com SBOS579B – SEPTEMBER 2011 – REVISED JULY 2012 ELECTRICAL CHARACTERISTICS: V+ = +15 V and V– = –15 V At TA = +25°C, RL = 2 kΩ connected to ground, and VCM = REFA = REFB = GND, unless otherwise noted. INA149 PARAMETER TEST CONDITIONS MIN TYP MAX UNIT ±0.02 %FSR GAIN Initial VOUT = ±10.0 V 1 Gain error VOUT = ±10.0 V ±0.005 Gain vs temperature, TA = –40°C to +125°C Nonlinearity V/V ±1.5 ±10 ppm/°C ±0.0005 ±0.001 %FSR 350 1100 3 15 OFFSET VOLTAGE Initial offset vs temperature, TA = –40°C to +125°C vs supply (PSRR), VS = ±2 V to ±18 V 90 µV µV/°C 120 dB Differential 800 kΩ Common-mode 200 INPUT Impedance Voltage range Common-mode rejection (CMRR) Differential –13.5 Common-mode –275 At dc, VCM = ±275 V 90 vs temperature, TA = –40°C to +125°C, at dc 90 At ac, 500 Hz, VCM = 500 VPP 90 At ac, 1 kHz, VCM = 500 VPP kΩ 13.5 V 275 V 100 dB dB dB 90 dB OUTPUT Voltage range –13.5 Short-circuit current Capacitive load drive No sustained oscillations 13.5 V ±25 mA 10 nF OUTPUT NOISE VOLTAGE 0.01 Hz to 10 Hz 10 kHz 20 µVPP 550 nV/√Hz DYNAMIC RESPONSE Small-signal bandwidth Slew rate VOUT = ±10-V step Full-power bandwidth VOUT = 20 VPP Settling time 0.01%, VOUT = 10-V step 1.7 500 kHz 5 V/µs 32 kHz 7 µs POWER SUPPLY Voltage range Quiescent current ±2 VS = ±18 V, VOUT = 0 V 810 vs temperature, TA = –40°C to +125°C ±18 V 900 µA 1.1 mA TEMPERATURE RANGE Specified –40 +125 °C Operating –55 +150 °C Storage –65 +150 °C Submit Documentation Feedback Copyright © 2011–2012, Texas Instruments Incorporated Product Folder Link(s): INA149 3 INA149 SBOS579B – SEPTEMBER 2011 – REVISED JULY 2012 www.ti.com ELECTRICAL CHARACTERISTICS: V+ = 5 V and V– = 0 V At TA = +25°C, RL = 2 kΩ connected to 2.5 V, and VCM= REFA = REFB = 2.5 V, unless otherwise noted. INA149 PARAMETER TEST CONDITIONS MIN TYP MAX UNIT GAIN Initial VOUT = 1.5 V to 3.5 V 1 Gain error VOUT = 1.5 V to 3.5 V ±0.005 %FSR Gain vs temperature, TA = –40°C to +125°C ±1.5 ppm/°C ±0.0005 %FSR Nonlinearity V/V OFFSET VOLTAGE 350 Initial offset vs temperature, TA = –40°C to +125°C µV 3 µV/°C vs supply (PSRR), VS = 4 V to 5 V 120 dB Differential 800 kΩ Common-mode 200 INPUT Impedance Voltage range Common-mode rejection Differential 1.5 Common-mode –20 kΩ 3.5 25 V V At dc, VCM = –20 V to 25 V 100 dB vs temperature, TA = –40°C to +125°C, at dc 100 dB At ac, 500 Hz, VCM = 49 VPP 100 dB 90 dB At ac, 1 kHz, VCM = 49 VPP OUTPUT Voltage range 1.5 Short-circuit current Capacitive load drive No sustained oscillations 3.5 V ±15 mA 10 nF OUTPUT NOISE VOLTAGE 0.01 Hz to 10 Hz 10 kHz 20 µVPP 550 nV/√Hz DYNAMIC RESPONSE Small-signal bandwidth Slew rate VOUT = 2 VPP step Full-power bandwidth VOUT = 2 VPP Settling time 0.01%, VOUT = 2 VPP step 500 kHz 5 V/µs 32 kHz 7 µs POWER SUPPLY Voltage range Quiescent current 4 VS = 5 V vs temperature, TA = –40°C to +125°C Submit Documentation Feedback 5 V 810 µA 1 mA Copyright © 2011–2012, Texas Instruments Incorporated Product Folder Link(s): INA149 INA149 www.ti.com SBOS579B – SEPTEMBER 2011 – REVISED JULY 2012 THERMAL INFORMATION INA149 THERMAL METRIC (1) D (SOIC) UNITS 8 PINS θJA Junction-to-ambient thermal resistance 110 θJCtop Junction-to-case (top) thermal resistance 57 θJB Junction-to-board thermal resistance 54 ψJT Junction-to-top characterization parameter 11 ψJB Junction-to-board characterization parameter 53 θJCbot Junction-to-case (bottom) thermal resistance N/A (1) °C/W For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953. PIN CONFIGURATION D PACKAGE SOIC-8 (TOP VIEW) 20 kΩ 380 kΩ REFB 1 8 NC 7 V+ 6 VOUT 5 REFA 380 kΩ −IN 2 380 kΩ + +IN 3 19 kΩ V− 4 PIN DESCRIPTIONS (1) NAME NO. –IN 2 Inverting input DESCRIPTION +IN 3 Noninverting input NC 8 No internal connection REFA 5 Reference input REFB 1 Reference input V– 4 Negative power supply V+ 7 Positive power supply (1) VOUT 6 Output In this document, (V+) – (V–) is referred to as VS. Submit Documentation Feedback Copyright © 2011–2012, Texas Instruments Incorporated Product Folder Link(s): INA149 5 INA149 SBOS579B – SEPTEMBER 2011 – REVISED JULY 2012 www.ti.com TYPICAL CHARACTERISTICS At TA = +25°C, RL = 2 kΩ connected to ground, and VS = ±15 V, unless otherwise noted. CMRR vs FREQUENCY COMMON-MODE REJECTION −40°C +25°C +125°C 80 60 40 20 2 0 −2 −4 10 100 1k 10k 100k Frequency (Hz) 1M 10M −6 −400 G001 −300 −200 −100 0 100 200 Common−Mode Input Voltage (V) 300 400 G066 Figure 1. Figure 2. COMMON-MODE OPERATING RANGE vs POWER-SUPPLY VOLTAGE TYPICAL GAIN ERROR FOR RL = 10 kΩ (Curves Offset for Clarity) 400 VS = ±18 V VS = ±15 V 350 300 250 200 150 100 VS = ±12 V VS = ±10 V 50 0 0 2 4 6 8 10 12 14 Power−Supply Voltage (±V) 16 18 −20 −16 −12 20 −8 G002 −4 0 4 8 Output Voltage (V) 12 Figure 4. TYPICAL GAIN ERROR FOR RL = 2 kΩ (Curves Offset for Clarity) TYPICAL GAIN ERROR FOR RL = 1 kΩ (Curves Offset for Clarity) 20 VS = ±12 V VS = ±10 V Output Error (2 mV/div) VS = ±18 V VS = ±15 V Output Error (2 mV/div) VS = ±12 V VS = ±10 V 16 G003 Figure 3. VS = ±18 V VS = ±15 V −20 −16 −12 −8 −4 0 4 8 Output Voltage (V) 12 16 20 −20 −16 −12 G004 Figure 5. 6 VS = ±18 V VS = ±15 V VS = ±10 V VS = ±5 V 4 Output Voltage (mV) 100 0 Common−Mode Operating Range (±V) 6 Output Error (2 mV/div) Common−Mode Rejection Ratio (dB) 120 −8 −4 0 4 8 Output Voltage (V) 12 16 20 G005 Figure 6. Submit Documentation Feedback Copyright © 2011–2012, Texas Instruments Incorporated Product Folder Link(s): INA149 INA149 www.ti.com SBOS579B – SEPTEMBER 2011 – REVISED JULY 2012 TYPICAL CHARACTERISTICS (continued) At TA = +25°C, RL = 2 kΩ connected to ground, and VS = ±15 V, unless otherwise noted. TYPICAL GAIN ERROR FOR LOW SUPPLY VOLTAGES (Curves Offset for Clarity) GAIN NONLINEARITY 10 VS = ±5 V VS = ±5 V VS = ±5 V VS = ±2.5 V 6 RL = 10 kΩ Output Error (2 mV/div) VS = ±15 V RL = 10 kΩ 8 Error (ppm) 4 RL = 2 kΩ RL = 1 kΩ 2 0 −2 −4 −6 −8 RL = 1 kΩ −5 −4 −3 −2 −1 0 1 2 Output Voltage (V) 3 4 −10 −12 −10 −8 5 −6 −4 −2 0 2 4 Output Voltage (V) G006 Figure 7. GAIN NONLINEARITY G014 8 6 6 4 4 Error (ppm) Error (ppm) 12 GAIN NONLINEARITY 2 0 −2 2 0 −2 −4 −4 −6 −6 −8 −8 −6 −4 −2 0 2 4 Output Voltage (V) 6 8 10 VS = ±15 V RL = 1 kΩ −10 −12 −10 −8 12 −6 −4 −2 0 2 4 Output Voltage (V) G015 Figure 9. 6 8 10 12 G016 Figure 10. GAIN NONLINEARITY OUTPUT VOLTAGE vs LOAD CURRENT 20 10 VS = ±12 V RL = 10 kΩ 8 −45°C +25°C +85°C +130°C 15 Output Voltage (V) 6 4 Error (ppm) 10 10 VS = ±15 V RL = 2 kΩ 8 2 0 −2 −4 −6 10 5 0 −5 −10 −15 −8 −10 −12 −10 −8 8 Figure 8. 10 −10 −12 −10 −8 6 −6 −4 −2 0 2 4 Output Voltage (V) 6 8 10 12 −20 0 G062 Figure 11. 5 10 15 20 25 Output Current (mA) 30 35 G017 Figure 12. Submit Documentation Feedback Copyright © 2011–2012, Texas Instruments Incorporated Product Folder Link(s): INA149 7 INA149 SBOS579B – SEPTEMBER 2011 – REVISED JULY 2012 www.ti.com TYPICAL CHARACTERISTICS (continued) At TA = +25°C, RL = 2 kΩ connected to ground, and VS = ±15 V, unless otherwise noted. GAIN vs FREQUENCY NOISE SPECTRAL DENSITY vs FREQUENCY 1000 Noise Spectral Density (nV/ Hz) 20 Gain (dB) 0 −20 −40 25 °C −40 °C 125 °C −60 −80 100 1k 10k 100k Frequency (Hz) 1M 900 800 700 600 500 400 10M 1 10 100 1k Frequency (Hz) G010 Figure 13. Noise (10 µV/div) Power−Supply Rejection Ratio (dB) POSITIVE PSRR vs FREQUENCY 10 0 Time (10 s/div) −40°C +25°C +125°C 10 100 Figure 15. 10k 100k G009 MAXIMUM POWER DISSIPATION vs TEMPERATURE 2 −40°C +25°C +125°C 10 100 1k Frequency (Hz) 10k Maximum Power Dissipation (W) Power−Supply Rejection Ratio (dB) 1k Frequency (Hz) Figure 16. NEGATIVE PSRR vs FREQUENCY 100k 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 −60 −40 −20 G064 Figure 17. 8 G008 120 110 100 90 80 70 60 50 40 30 20 G070 120 110 100 90 80 70 60 50 40 30 20 10 0 100k Figure 14. 0.01 Hz TO 10 Hz NOISE −50 −50 10k 0 20 40 60 80 100 120 140 160 Ambient Temperature (°C) G013 Figure 18. Submit Documentation Feedback Copyright © 2011–2012, Texas Instruments Incorporated Product Folder Link(s): INA149 INA149 www.ti.com SBOS579B – SEPTEMBER 2011 – REVISED JULY 2012 TYPICAL CHARACTERISTICS (continued) At TA = +25°C, RL = 2 kΩ connected to ground, and VS = ±15 V, unless otherwise noted. LARGE-SIGNAL STEP RESPONSE SMALL-SIGNAL STEP RESPONSE CL = 1000 pF RL = 2 kΩ Output Voltage (5 V/div) Output Voltage (25 mV/div) CL = 1000 pF RL = 2 kΩ Time (4 µs/div) Time (4 µs/div) G011 G012 Figure 19. Figure 20. −80 −100 0 nF 1 nF 3 nF 5 nF 10 nF 1.2 4 Error Voltage Output Voltage 2 1 0 0.8 −2 0.6 −4 0.4 −6 0.2 −8 0 −10 −0.2 0 20 40 60 80 Time (µs) 100 −12 120 Time (5 us/div) G018 G065 Figure 21. Figure 22. CMRR HISTOGRAM 20 0 10 18 8 −0.4 6 −0.6 4 −0.8 2 −1 0 Error Voltage −2 Output Voltage −4 −1.4 16 14 12 10 8 6 4 2 0 Time (5 us/div) G063 −30 −27 −24 −21 −18 −15 −12 −9 −6 −3 0 3 6 9 12 15 18 21 24 27 30 −0.2 Percent of Population (~5 kU) 12 Output Voltage (V) Error Voltage (mV) SETTLING TIME 0.2 −1.2 Output Voltage (V) SETTLING TIME 1.4 Error Voltage (mV) Voltage (mV) SMALL-SIGNAL RESPONSE vs CAPACITIVE LOAD 140 120 100 80 60 40 20 0 −20 −40 −60 CMRR (µV/V) Figure 23. G019 Figure 24. Submit Documentation Feedback Copyright © 2011–2012, Texas Instruments Incorporated Product Folder Link(s): INA149 9 INA149 SBOS579B – SEPTEMBER 2011 – REVISED JULY 2012 www.ti.com TYPICAL CHARACTERISTICS (continued) At TA = +25°C, RL = 2 kΩ connected to ground, and VS = ±15 V, unless otherwise noted. OFFSET VOLTAGE HISTOGRAM DIFFERENTIAL GAIN ERROR HISTOGRAM 12 20 Percent of Population (~5 kU) Percent of Population (~5 kU) 18 10 8 6 4 2 16 14 12 10 8 6 4 2 0 Offset Voltage (µV) −20 −18 −16 −14 −12 −10 −8 −6 −4 −2 0 2 4 6 8 10 12 14 16 18 20 −1000 −900 −800 −700 −600 −500 −400 −300 −200 −100 0 100 200 300 400 500 600 700 800 900 1000 0 Differential Gain Error (m%) G022 Figure 25. GAIN NONLINEARITY HISTOGRAM 35 35 30 30 Percent of Population (~5 kU) Percent of Population (~5 kU) PSRR HISTOGRAM 25 20 15 10 5 25 20 15 10 5 0.10 0.11 0.12 0.13 0.14 0.15 0.16 0.17 0.18 0.19 0.20 0.21 0.22 0.23 0.24 0.25 0.26 0.27 0.28 0.29 0.30 0 −1.50 −1.35 −1.20 −1.05 −0.90 −0.75 −0.60 −0.45 −0.30 −0.15 0.00 0.15 0.30 0.45 0.60 0.75 0.90 1.05 1.20 1.35 1.50 0 PSRR (µV/V) Nonlinearity Error (m%) G025 Figure 27. 50 1600 40 1200 30 800 20 CMRR (µV/V) Offset Voltage (µV) CMRR vs TEMPERATURE 2000 400 0 −400 10 0 −10 −800 −20 −1200 −30 −1600 −40 −2000 −75 −50 −25 0 G026 Figure 28. OFFSET VOLTAGE vs TEMPERATURE 25 50 75 100 125 150 175 Temperature (°C) G027 −50 −75 −50 −25 Figure 29. 10 G024 Figure 26. 0 25 50 75 100 125 150 175 Temperature (°C) G028 Figure 30. Submit Documentation Feedback Copyright © 2011–2012, Texas Instruments Incorporated Product Folder Link(s): INA149 INA149 www.ti.com SBOS579B – SEPTEMBER 2011 – REVISED JULY 2012 TYPICAL CHARACTERISTICS (continued) At TA = +25°C, RL = 2 kΩ connected to ground, and VS = ±15 V, unless otherwise noted. GAIN ERROR vs TEMPERATURE 50 1.6 40 1.2 30 0.8 20 Gain Error (m%) PSRR (µV/V) PSRR vs TEMPERATURE 2 0.4 0 −0.4 −0.8 10 0 −10 −20 −1.2 −30 −1.6 −40 −2 −75 −50 −25 0 −50 −75 −50 −25 25 50 75 100 125 150 175 Temperature (°C) G029 0 Figure 31. 25 50 75 100 125 150 175 Temperature (°C) G030 Figure 32. GAIN NONLINEARITY vs TEMPERATURE SLEW RATE vs TEMPERATURE 8 5 4 7 2 Slew Rate (V/µs) Linearity Error (m%) 3 1 0 −1 −2 −3 6 5 4 3 −4 −5 −75 −50 −25 0 2 −75 25 50 75 100 125 150 175 Temperature (°C) G031 −25 25 75 Temperature (°C) Figure 33. 175 G071 Figure 34. SLEW RATE vs POWER-SUPPLY VOLTAGE QUIESCENT CURRENT vs TEMPERAUTRE 5 1200 4 1000 Current (µA) Slew Rate (V/µs) 125 3 2 800 600 1 Negative Slew Rate Positive Slew Rate 0 0 5 10 15 20 25 Supply Voltage (V) 30 35 40 400 −75 −50 −25 G038 Figure 35. 0 25 50 75 100 125 150 175 Temperature (°C) G043 Figure 36. Submit Documentation Feedback Copyright © 2011–2012, Texas Instruments Incorporated Product Folder Link(s): INA149 11 INA149 SBOS579B – SEPTEMBER 2011 – REVISED JULY 2012 www.ti.com TYPICAL CHARACTERISTICS (continued) At TA = +25°C, RL = 2 kΩ connected to ground, and VS = ±15 V, unless otherwise noted. FREQUENCY RESPONSE vs CAPACITIVE LOAD QUIESCENT CURRENT vs SUPPLY VOLTAGE 1200 10 0 1000 Quiescent Current (µA) VOUT / VIN (dB) −10 −20 −30 −40 −50 0 nF 1 nF 3 nF 5 nF 10 nF −60 −70 −80 −90 100 800 600 400 −45°C +25°C +85°C +130°C 200 1k 10k 100k Frequency (Hz) 1M 0 10M 0 G044 Figure 37. MAXIMUM OUTPUT VOLTAGE vs FREQUENCY 6 8 10 12 14 Supply Voltage (±V) 16 18 20 G056 OVERLOAD RECOVERY 16 Input Output 25 12 20 Voltage (V) Maximum Output Voltage (±V) 4 Figure 38. 30 15 8 4 10 0 5 0 1k 10k 100k Frequency (Hz) −4 1M Time (1 µs/div) G057 Figure 39. G058 Figure 40. OVERLOAD RECOVERY QUIESCENT CURRENT HISTOGRAM 4 50 Input Output Percent of Population (~5 kU) 45 0 Voltage (V) 2 −4 −8 −12 40 35 30 25 20 15 10 5 −16 G067 0.70 0.71 0.72 0.73 0.74 0.75 0.76 0.77 0.78 0.79 0.80 0.81 0.82 0.83 0.84 0.85 0.86 0.87 0.88 0.89 0.90 0 Time (1 µs/div) Quiescent Current (mA) Figure 41. 12 G059 Figure 42. Submit Documentation Feedback Copyright © 2011–2012, Texas Instruments Incorporated Product Folder Link(s): INA149 INA149 www.ti.com SBOS579B – SEPTEMBER 2011 – REVISED JULY 2012 APPLICATION INFORMATION BASIC INFORMATION Figure 43 shows the basic connections required for dual-supply operation. Applications with noisy or highimpedance power-supply lines may require decoupling capacitors placed close to the device pins. The output voltage is equal to the differential input voltage between pins 2 and 3. The common-mode input voltage is rejected. Figure 44 shows the basic connections required for single-supply operation. −15 V 100 nF 1 F 15 V 4 1 −IN 2 +IN 3 20 kΩ 30 V 1 F 7 100 nF 4 380 kΩ 1 + 19 kΩ 6 VOUT = (+IN) − (−IN) −IN 2 +IN 3 5 GND 380 kΩ 380 kΩ 100 nF 380 kΩ GND 380 kΩ 380 kΩ 20 kΩ 1 F 7 + 19 kΩ 6 5 VOUT = (+IN) – (–IN) + VREF VREF Figure 43. Basic Power and Signal Connections for Figure 44. Basic Power and Signal Connections for Dual-Supply Operation Single-Supply Operation TRANSFER FUNCTION Most applications use the INA149 as a simple unity-gain difference amplifier. The transfer function is given in Equation 1: VOUT = (+IN) – (–IN) (1) Some applications, however, apply voltages to the reference terminals (REFA and REFB). The complete transfer function is given in Equation 2: VOUT = (+IN) – (–IN) + 20 × REFA – 19 × REFB (2) COMMON-MODE RANGE The high common-mode range of the INA149 is achieved by dividing down the input signal with a high precision resistor divider. This resistor divider brings both the positive input and the negative input within the input range of the internal operational amplifier. This input range depends on the supply voltage of the INA149. Both Figure 2 and Figure 3 can be used to determine the maximum common-mode range for a specific supply voltage. The maximum common-mode range can also be calculated by ensuring that both the positive and the negative input of the internal amplifier are within 1.5 V of the supply voltage. In case the voltage at the inputs of the internal amplifier exceeds the supply voltage, the internal ESD diodes start conducting current. This current must be limited to 10 mA to make sure not to exceed the absolute maximum ratings for the device. Submit Documentation Feedback Copyright © 2011–2012, Texas Instruments Incorporated Product Folder Link(s): INA149 13 INA149 SBOS579B – SEPTEMBER 2011 – REVISED JULY 2012 www.ti.com COMMON-MODE REJECTION Common-mode rejection (CMR) of the INA149 depends on the input resistor network, which is laser-trimmed for accurate ratio matching. To maintain high CMR, it is important to have low source impedance driving the two inputs. A 75-Ω resistance in series with pins 2 or 3 decreases the common-mode rejection ratio (CMRR) from 100 dB (typical) to 74 dB. Resistance in series with the reference pins also degrades CMR. A 4-Ω resistance in series with pins 1 or 5 decreases CMRR from 100 dB to 74 dB. Most applications do not require trimming. Figure 45 shows an optional circuit that may be used for trimming offset voltage and common-mode rejection. −15 V 15 V 4 15 V 1 100 µA ½ REF200 100 Ω + −IN 2 +IN 3 20 kΩ 7 380 kΩ 380 kΩ 380 kΩ + 6 19 kΩ (1) VOUT = (+IN) − (−IN) 5 10 kΩ 100 Ω 100 µA ½ REF200 −15 V (1) The OPA171 (a 36-V, low-power, RRO, general-purpose operational amplifier) can be used for this application. Figure 45. Offset Voltage Trim Circuit 14 Submit Documentation Feedback Copyright © 2011–2012, Texas Instruments Incorporated Product Folder Link(s): INA149 INA149 www.ti.com SBOS579B – SEPTEMBER 2011 – REVISED JULY 2012 MEASURING CURRENT The INA149 can be used to measure a current by sensing the voltage drop across a series resistor, RS. Figure 46 shows the INA149 used to measure the supply currents of a device under test. The sense resistor imbalances the input resistor matching of the INA149, thus degrading its CMR. Also, the input impedance of the INA149 loads RS, causing gain error in the voltage-to-current conversion. Both of these errors can be easily corrected. The CMR error can be corrected with the addition of a compensation resistor (RC), equal to the value of RS, as shown in Figure 46. If RS is less than 5 Ω, degradation in the CMR is negligible and RC can be omitted. If RS is larger than approximately 1 kΩ, trimming RC may be required to achive greater than 90-dB CMR. This error is caused by the INA149 input impedance mismatch. V− V+ (+275 V max) +VS 4 1 2 20 kΩ 380 kΩ RS 3 RC 7 380 kΩ 380 kΩ + 6 (1) 19 kΩ IDUT+ V− Device Under Test 1 5 V+ 4 20 kΩ VO = RS × IDUT+ 7 380 kΩ IDUT− 2 380 kΩ RS 3 RC 380 kΩ + 6 (1) 19 kΩ VO = RS × IDUT− 5 −VS (−275 V max) Figure 46. Measuring Supply Currents of a Device Under Test If RS is more than approximately 50 Ω, the gain error is greater than the 0.02% specification of the INA149. This gain error can be corrected by slightly increasing the value of RS. The corrected value (RS') can be calculated by RS' = RS × 380 kΩ/(380 kΩ – RS) (3) Example: For a 1-V/mA transfer function, the nominal, uncorrected value for RS would be 1 kΩ. A slightly larger value (RS' = 1002.6 Ω), compensates for the gain error as a result of loading. The 380-kΩ term in the equation for RS' has a tolerance of 25%, thus sense resistors above approximately 400 Ω may require trimming to achive gain accuracy better than 0.02%. Submit Documentation Feedback Copyright © 2011–2012, Texas Instruments Incorporated Product Folder Link(s): INA149 15 INA149 SBOS579B – SEPTEMBER 2011 – REVISED JULY 2012 www.ti.com NOISE PERFORMANCE The wideband noise performane of the INA149 is dominated by the internal resistor network. The thermal or Johnson noise of these resistors measures approximately 550 nV/√Hz. The internal op amp contributes virtually no excess noise at frequencies above 100 Hz. Many applications may be satisfied with less than the full 500-kHz bandwidth of the INA149. In these cases, the noise can be reduced with a low-pass filter on the output. The two-pole filter shown in Figure 47 limits bandwidth and reduces noise. Because the INA149 has a 1/f noise corner frequency of approximately 100 Hz, a cutoff frequency below 100 Hz does not further reduce noise. Component values for different filter frequencies are shown in Table 1. V− V+ 4 1 –IN 2 +IN 3 7 20 kΩ 380 kΩ 380 kΩ C2 + 380 kΩ 19 kΩ 6 R1 R2 + VOUT = (+IN) – (–IN) (1) 5 C1 (1) For most applications, the OPA171 can be used as an operational amplifier. For directly driving successive-approximation register (SAR) data converters, the OPA140 is a good choice. Figure 47. Output Filter for Noise Reduction Table 1. Components Values for Different Filter Bandwidths BUTTERWORTH LOW-PASS (f–3 dB) OUTPUT NOISE (mVPP) 200 kHz 1.8 100 kHz 1.1 11 kΩ 11.3 kΩ 10 kHz 0.35 11 kΩ 11.3 kΩ 1 nF 2 nF 1 kHz 0.11 11 kΩ 11.3 kΩ 10 nF 20 nF 100 Hz 0.05 11 kΩ 11.3 kΩ 0.1 µF 0.2 µF 16 R1 R2 C1 C2 100 pF 200 pF No filter Submit Documentation Feedback Copyright © 2011–2012, Texas Instruments Incorporated Product Folder Link(s): INA149 INA149 www.ti.com SBOS579B – SEPTEMBER 2011 – REVISED JULY 2012 ERROR BUDGET ANALYSIS The following error budget analysis demonstrates the importance of a high common-mode rejection ratio when measuring small differential signals in the presence of high common-mode voltages. Figure 48 shows a typical current measurement application. V− = −15 V V+ = +15 V 4 1 2 7 20 kΩ 380 kΩ 380 kΩ RS = 10 Ω 3 (1) RC = 10 Ω 380 kΩ + 6 19 kΩ VOUT 5 IMAX = 1 A VCM = 265 V (1) See the Measuring Current section for details about RC. Figure 48. Typical Current Measurement Application The maximum current through the shunt resistor (RS) is 1 A and generates a full-scale voltage drop of 10 V. All error sources in this calculation are shown in relation to this full-scale voltage. The common-mode voltage in this scenario is 265 V and the temperature range is from room temperature (+25°C) to +85°C. Table 2 shows the dominant error sources for the INA149 and a competitor device. Table 2. Error Budget Analysis ERROR SOURCE ERROR (ppm of FS) INA149 COMPETIOR A INA149 COMPETITOR A 0.02% FS 0.05% FS 200 500 1100 µV 1000 µV 110 100 265 V/90 dB = 8380 µV 265 V/77 dB = 37432 µV 838 3743 1148 4343 600 600 60 120 Accuracy, TA = +25°C Initial gain error Offset voltage Common mode Total acuracy error Temperature drift Gain Offset voltage 10 ppm/°C × 60°C 10 ppm/°C × 60°C 10 µV/°C × 60°C 20 µV/°C × 60°C Total drift error 660 720 Total error 1808 5063 If a smaller shunt resistor is used, the full-scale voltage drop is also smaller. A shunt resistor of 1 Ω causes a 1-V voltage drop with a current of 1 A flowing through it. The error of 1808 ppm for a full-scale voltage of 10 V becomes 18080 ppm (1.6%) for a full-scale voltage of only 1 V. This example demonstrates that the dominate source of error, even over temperature, comes from the CMRR specification of the devices. The common-mode error is 46% of the total error for the INA149 and 74% of the total error for the competitor device. Submit Documentation Feedback Copyright © 2011–2012, Texas Instruments Incorporated Product Folder Link(s): INA149 17 INA149 SBOS579B – SEPTEMBER 2011 – REVISED JULY 2012 www.ti.com BATTERY CELL VOLTAGE MONITOR The INA149 can be used to measure the voltages of single cells in a stacked battery pack. Figure 49 shows an examples for such an application. (+275 V max) +VS 2 3 INA149 + 2 3 INA149 + Repeat for each cell MSP430 16-Bit Ultra-LowPower Microcontroller ADS8638 12-bit, 8-Channel, Bipolar SAR ADC 2 3 INA149 + 2 3 INA149 + −VS (−275 V max) Figure 49. Battery Cell Voltage Monitor 18 Submit Documentation Feedback Copyright © 2011–2012, Texas Instruments Incorporated Product Folder Link(s): INA149 INA149 www.ti.com SBOS579B – SEPTEMBER 2011 – REVISED JULY 2012 REVISION HISTORY NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Changes from Revision A (November 2011) to Revision B • Page Changed package marking data in Package/Ordering Information table ............................................................................. 2 Submit Documentation Feedback Copyright © 2011–2012, Texas Instruments Incorporated Product Folder Link(s): INA149 19 PACKAGE OPTION ADDENDUM www.ti.com 6-Feb-2020 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) INA149AID ACTIVE SOIC D 8 75 Green (RoHS & no Sb/Br) NIPDAU Level-2-260C-1 YEAR -40 to 125 INA 149A INA149AIDR ACTIVE SOIC D 8 2500 Green (RoHS & no Sb/Br) NIPDAU Level-2-260C-1 YEAR -40 to 125 INA 149A (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