INA 126 ® INA INA 212 INA 126 INA126 INA2126 6 212 6 INA 2126 MicroPOWER INSTRUMENTATION AMPLIFIER Single and Dual Versions FEATURES DESCRIPTION ● LOW QUIESCENT CURRENT: 175µA/chan. The INA126 and INA2126 are precision instrumentation amplifiers for accurate, low noise differential signal acquisition. Their two-op-amp design provides excellent performance with very low quiescent current (175µA/chan.). This, combined with wide operating voltage range of ±1.35V to ±18V, makes them ideal for portable instrumentation and data acquisition systems. ● WIDE SUPPLY RANGE: ±1.35V to ±18V ● LOW OFFSET VOLTAGE: 250µV max ● LOW OFFSET DRIFT: 3µV/°C max ● LOW NOISE: 35nV/√ Hz ● LOW INPUT BIAS CURRENT: 25nA max Gain can be set from 5V/V to 10000V/V with a single external resistor. Laser trimmed input circuitry provides low offset voltage (250µV max), low offset voltage drift (3µV/°C max) and excellent common-mode rejection. Single version package options include 8-pin plastic DIP, SO-8 surface mount, and fine-pitch MSOP-8 surface-mount. Dual version is available in the space-saving SSOP-16 finepitch surface mount, SO-16, and 16-pin DIP. All are specified for the –40°C to +85°C industrial temperature range. ● 8-PIN DIP, SO-8, MSOP-8 SURFACE- MOUNT DUAL: 16-Pin DIP, SO-16, SSOP-16 APPLICATIONS ● INDUSTRIAL SENSOR AMPLIFIER: Bridge, RTD, Thermocouple ● PHYSIOLOGICAL AMPLIFIER: ECG, EEG, EMG ● MULTI-CHANNEL DATA ACQUISITION ● PORTABLE, BATTERY OPERATED SYSTEMS V+ INA2126 2 + VIN 9 6 + –) G VO = (VIN – VIN 7 G=5+ 4 40kΩ V+ 10kΩ 7 80k RG RG INA126 + VIN 3 3 6 8 + – V–) G VO = (VIN IN G = 5 + 80k RG 40kΩ + VIN 10kΩ 1 – VIN RG 10kΩ 40kΩ 15 11 13 10kΩ 40kΩ 10kΩ 1 – VIN 5 + – V –) G VO = (VIN IN G=5+ 10 80k RG RG 2 40kΩ 14 10kΩ 5 – VIN 4 16 8 40kΩ 12 V– V– International Airport Industrial Park • Mailing Address: PO Box 11400, Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd., Tucson, AZ 85706 • Tel: (520) 746-1111 • Twx: 910-952-1111 Internet: http://www.burr-brown.com/ • FAXLine: (800) 548-6133 (US/Canada Only) • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132 ©1996 Burr-Brown Corporation PDS-1365C Printed in U.S.A. September, 1997 SPECIFICATIONS At TA = +25°C, VS = ±15V, RL = 25kΩ, unless otherwise noted. INA126P, U, E INA2126P, U, E PARAMETER CONDITIONS INPUT Offset Voltage, RTI vs Temperature vs Power Supply (PSRR) Input Impedance Safe Input Voltage Common-Mode Voltage Range Channel Separation (dual) Common-Mode Rejection INA2126U (dual SO-16) MIN VS = ±1.35V to ±18V RS = 0 RS = 1kΩ VO = 0V G = 5, dc RS = 0, VCM = ±11.25V (V–)–0.5 (V–)–10 ±11.25 83 80 INPUT BIAS CURRENT vs Temperature Offset Current vs Temperature GAIN Gain Equation Gain Error vs Temperature Gain Error vs Temperature Nonlinearity Slew Rate Settling Time, 0.01% Overload Recovery MAX ±100 ±0.5 5 109 || 4 ±250 ±3 15 (V+)+0.5 (V+)+10 ±11.5 130 94 94 MIN G=5 G = 100 G = 500 VO = ±10V, G = 5 10V Step, G = 5 10V Step, G = 100 10V Step, G = 500 50% Input Overload POWER SUPPLY Voltage Range Current (per channel) TEMPERATURE RANGE Specification Range Operation Range Storage Range Thermal Resistance, θJA 8-Pin DIP SO-8 Surface-Mount MSOP-8 Surface-Mount 16-Pin DIP (dual) SO-16 (dual) SSOP-16 (dual) ±1.35 ±15 ±175 –40 –55 –55 100 150 200 80 100 100 ±150 ✻ ✻ ✻ ±500 ±5 50 µV µV/°C µV/V Ω || pF V V V dB dB dB 90 ✻ ✻ ✻ ✻ ✻ ✻ ±2 ✻ ✻ ✻ ✻ ✻ ✻ ✻ ✻ ✻ 200 9 1.8 0.4 30 160 1500 4 IO = 0 UNITS 74 –25 (V+)–0.9 (V+)–0.75 (V–)+0.95 (V–)+0.8 +10/–5 1000 MAX ✻ 35 35 45 0.7 60 2 RL = 25kΩ RL = 25kΩ Short-Circuit to Ground TYP ✻ ✻ ✻ G = 5 to 10k G = 5 + 80kΩ/RG ±0.02 ±0.1 ±2 ±10 ±0.2 ±0.5 ±25 ±100 ±0.002 ±0.012 NOISE Voltage Noise, f = 1kHz f = 100Hz f = 10Hz fB = 0.1Hz to 10Hz Current Noise, f = 1kHz fB = 0.1Hz to 10Hz FREQUENCY RESPONSE Bandwidth, –3dB TYP –10 ±30 ±0.5 ±10 VO = ±14V, G = 5 G=5 VO = ±12V, G = 100 G = 100 G = 100, VO = ±14V OUTPUT Voltage, Positive Negative Short-Circuit Current Capacitive Load Drive INA126PA, UA, EA INA2126PA, UA, EA ±18 ±200 ✻ +85 +125 +125 ✻ ✻ ✻ –50 ±5 ±0.18 ✻ ±1 ✻ ✻ nA pA/°C nA pA/°C V/V V/V % ppm/°C % ppm/°C % ✻ ✻ ✻ ✻ ✻ ✻ nV/√Hz nV/√Hz nV/√Hz µVp-p fA/√Hz pAp-p ✻ ✻ ✻ ✻ V V mA pF ✻ ✻ ✻ ✻ ✻ ✻ ✻ ✻ kHz kHz kHz V/µs µs µs µs µs ✻ ✻ ✻ ✻ ✻ ✻ ✻ ✻ ✻ ✻ V µA ✻ ✻ ✻ °C °C °C °C/W °C/W °C/W °C/W °C/W °C/W ✻ Specification same as INA126P, INA126U, INA126E; INA2126P, INA2126U, INA2126E. The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN assumes no responsibility for the use of this information, and all use of such information shall be entirely at the user’s own risk. Prices and specifications are subject to change without notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. BURR-BROWN does not authorize or warrant any BURR-BROWN product for use in life support devices and/or systems. ® INA126, INA2126 2 ABSOLUTE MAXIMUM RATINGS(1) PIN CONFIGURATION (Single) Top View 8-Pin DIP, SO-8, MSOP-8 RG 1 8 RG V–IN 2 7 V+ V+IN 3 6 VO V– 4 5 Ref Power Supply Voltage, V+ to V– ........................................................ 36V Input Signal Voltage(2) ........................................... (V–)–0.7 to (V+)+0.7V Input Signal Current(2) ...................................................................... 10mA Output Short Circuit ................................................................. Continuous Operating Temperature ................................................. –55°C to +125°C Storage Temperature ..................................................... –55°C to +125°C Lead Temperature (soldering, 10s) ............................................... +300°C NOTES: (1) Stresses above these ratings may cause permanent damage. (2) Input signal voltage is limited by internal diodes connected to power supplies. See text. ELECTROSTATIC DISCHARGE SENSITIVITY PIN CONFIGURATION (Dual) Top View 16-Pin DIP, SO-16, SSOP-16 – VINA 1 – 16 VINB + VINA 2 + 15 VINB RGA 3 14 RGB RGA 4 13 RGB RefA 5 12 RefB VOA 6 11 VOB SenseA 7 10 SenseB V– 8 9 This integrated circuit can be damaged by ESD. Burr-Brown 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. V+ PACKAGE INFORMATION PACKAGE PACKAGE DRAWING NUMBER(1) PACKAGE MARKING ORDERING NUMBER TRANSPORT MEDIA INA126PA INA126P 8-Pin DIP 8-Pin DIP 006 006 INA126PA INA126P INA126PA INA126P Rails Rails INA126UA INA126U SO-8 SO-8 182 182 INA126UA INA126U INA126UA INA126U Rails or Reel Rails or Reel MSOP-8 " MSOP-8 " 337 " 337 " A26(3) " A26(3) " INA126EA-250 INA126EA-2500 INA126E-250 INA126E-2500 Reel Only " Reel Only " INA2126PA INA2126P 16-Pin DIP 16-Pin DIP 180 180 INA2126PA INA2126P INA2126PA INA2126P Rails Rails INA2126UA INA2126U SO-16 SO-16 265 265 INA2126UA INA2126U INA2126UA INA2126U Rails Rails SSOP-16 " SSOP-16 " 322 " 322 " INA2126EA " INA2126E " INA2126EA-250 INA2126EA-2500 INA2126E-250 INA2126E-2500 Reel Only " Reel Only " PRODUCT Single INA126EA(2) " INA126E(2) " Dual INA2126EA(2) " INA2126E(2) " NOTES: (1) For detailed drawing and dimension table, see end of data sheet, or Appendix C of Burr-Brown IC Data Book. (2) MSOP-8 and SSOP-16 packages are available only on 250 or 2500 piece reels. (3) Grade designation is marked on reel. ® 3 INA126, INA2126 TYPICAL PERFORMANCE CURVES At TA = +25°C and VS = ±15V, unless otherwise noted. GAIN vs FREQUENCY COMMON-MODE REJECTION vs FREQUENCY 70 110 G = 1000 100 Common-Mode Rejection (dB) 60 Gain (dB) 50 G = 100 40 30 G = 20 20 G=5 10 0 90 80 70 G = 1000 60 50 G = 100 40 30 G=5 20 10 –10 0 100 1k 10k 100k 1M 10 100 1k 10k 100k Frequency (Hz) Frequency (Hz) POSITIVE POWER SUPPLY REJECTION vs FREQUENCY NEGATIVE POWER SUPPLY REJECTION vs FREQUENCY 120 1M 120 100 Power Supply Rejection (dB) Power Supply Rejection (dB) G = 1000 G = 100 80 60 40 G=5 20 100 0 60 G = 100 40 G=5 20 0 100 1k 10k 100k 1M 10 100k INPUT COMMON-MODE VOLTAGE RANGE vs OUTPUT VOLTAGE, VS = ±5V tput swing—see 5 0 +15V + VD/2 – + VD/2 VO Ref – + VCM –15V –10 text tput swing—see Limited by A2 ou –5 0 5 10 tput swing—see 4 Limited by A2 ou 3 VS = ±5V 2 text VS = +5V/0V 1 VREF = 2.5V 0 –1 –2 –3 tput swing—see Limited by A2 ou –4 text –5 15 –5 Output Voltage (V) –4 –3 –2 –1 0 1 Output Voltage (V) ® INA126, INA2126 1M 5 text 10 –10 10k INPUT COMMON-MODE RANGE vs OUTPUT VOLTAGE, VS = ±15V Limited by A2 ou –15 –15 1k Frequency (Hz) 15 –5 100 Frequency (Hz) Input Common-Mode Voltage (V) 10 Common-Mode Voltage (V) G = 1000 80 4 2 3 4 5 TYPICAL PERFORMANCE CURVES (CONT) At TA = +25°C and VS = ±15V, unless otherwise noted. SETTLING TIME vs GAIN INPUT-REFERRED NOISE vs FREQUENCY 1000 1k 10 100 Current Noise 1 Settling Time (µs) Voltage Noise 0.01% Input Current Noise (fA/√Hz) Input Voltage Noise (nV/√Hz) 100 10 10 1 10 100 1k 0.1% 100 1 10k 10 100 1k Frequency (Hz) Gain (V/V) INPUT-REFERRED OFFSET VOLTAGE WARM-UP QUIESCENT CURRENT AND SLEW RATE vs TEMPERATURE 10 300 0.6 –SR 4 2 (Noise) 0 –2 –4 –6 0.5 +SR 200 0.4 150 VS = ±1.35V VS = ±5V IQ 100 50 0.3 0.2 0.1 –8 –10 0 0 1 2 3 4 5 6 7 8 9 10 –75 –50 –25 25 50 75 Time After Turn-On (ms) Temperature (°C) TOTAL HARMONIC DISTORTION+NOISE vs FREQUENCY OUTPUT VOLTAGE SWING vs OUTPUT CURRENT 1 100 0 125 V+ Output Voltage (V) (V+)–1 THD+N (%) 0 0.1 RL = 10kΩ 0.01 Sourcing Current (V+)–2 (V–)+2 (V–)+1 RL = 100kΩ Sinking Current G=5 0.001 V– 10 100 1k 10k 0 1 2 3 4 5 Output Current (mA) Frequency (Hz) ® 5 INA126, INA2126 Slew Rate (V/µs) 250 6 Quiescent Current (µA) Offset Voltage Change (µV) 8 TYPICAL PERFORMANCE CURVES (CONT) At TA = +25°C and VS = ±15V, unless otherwise noted. SMALL-SIGNAL RESPONSE, G = 100 20mV/div 20mV/div SMALL-SIGNAL RESPONSE, G = 5 50µs/div LARGE-SIGNAL RESPONSE, G = 5 VOLTAGE NOISE, 0.1Hz to 10Hz 5V/div 0.2µV/div 50µs/div 50µs/div 500ms/div CHANNEL SEPARATION vs FREQUENCY, RTI (Dual Version) 160 150 G = 1000 Separation (dB) 140 130 G = 100 120 110 G=5 100 RL = 25kΩ 90 Measurement limited by amplifier or measurement noise. 80 70 60 100 1k 10k Frequency (Hz) ® INA126, INA2126 6 100k 1M APPLICATION INFORMATION equation (1). Low resistor values required for high gain can make wiring resistance important. Sockets add to the wiring resistance, which will contribute additional gain error in gains of approximately 100 or greater. Figure 1 shows the basic connections required for operation of the INA126. Applications with noisy or high impedance power supplies may require decoupling capacitors close to the device pins as shown. The output is referred to the output reference (Ref) terminal which is normally grounded. This must be a low-impedance connection to ensure good common-mode rejection. A resistance of 8Ω in series with the Ref pin will cause a typical device to degrade to approximately 80dB CMR. OFFSET TRIMMING The INA126 and INA2126 are laser trimmed for low offset voltage and offset voltage drift. Most applications require no external offset adjustment. Figure 2 shows an optional circuit for trimming the output offset voltage. The voltage applied to the Ref terminal is added to the output signal. An op amp buffer is used to provide low impedance at the Ref terminal to preserve good common-mode rejection. Dual versions (INA2126) have feedback sense connections, SenseA and SenseB. These must be connected to their respective output terminals for proper operation. The sense connection can be used to sense the output voltage directly at the load for best accuracy. – VIN SETTING THE GAIN RG Gain is set by connecting an external resistor, RG, as shown: G = 5+ 80kΩ RG INA126 + VIN ✻ VO V+ Ref 100µA 1/2 REF200 (1) 100Ω 10kΩ OPA237 ±10mV Adjustment Range Commonly used gains and RG resistor values are shown in Figure 1. 100Ω The 80kΩ term in equation 1 comes from the internal metal film resistors which are laser trimmed to accurate absolute values. The accuracy and temperature coefficient of these resistors are included in the gain accuracy and drift specifications. 100µA 1/2 REF200 ✻ Dual version has external sense connection. The stability and temperature drift of the external gain setting resistor, RG, also affects gain. RG’s contribution to gain accuracy and drift can be directly inferred from the gain V– FIGURE 2. Optional Trimming of Output Offset Voltage. V+ 0.1µF Pin numbers are for single version DESIRED GAIN (V/V) RG (Ω) NEAREST 1% RG VALUE 5 10 20 50 100 200 500 1000 2000 5000 10000 NC 16k 5333 1779 842 410 162 80.4 40.1 16.0 8.0 NC 15.8k 5360 1780 845 412 162 80.6 40.2 15.8 7.87 7 INA126 3 + VIN 8 6 A1 G = 5 + 80k RG 40kΩ + – V–) G VO = (VIN IN ✻ 10kΩ + RG 10kΩ Load VO – NC: No Connection. 1 – VIN A2 2 40kΩ Also drawn in simplified form: 5 Ref + VIN 4 0.1µF RG – VIN INA126 ✻ VO V– Ref ✻ Dual version has external sense connection. FIGURE 1. Basic Connections. ® 7 INA126, INA2126 INPUT BIAS CURRENT RETURN The internal op amp A2 is identical to A1 and its output swing is limited to typically 0.7V from the supply rails. When the input common-mode range is exceeded (A2’s output is saturated), A1 can still be in linear operation and respond to changes in the non-inverting input voltage. The output voltage, however, will be invalid. The input impedance of the INA126/2126 is extremely high—approximately 109Ω. However, a path must be provided for the input bias current of both inputs. This input bias current is typically –10nA (current flows out of the input terminals). High input impedance means that this input bias current changes very little with varying input voltage. LOW VOLTAGE OPERATION Input circuitry must provide a path for this input bias current for proper operation. Figure 3 shows various provisions for an input bias current path. Without a bias current path, the inputs will float to a potential which exceeds the commonmode range and the input amplifiers will saturate. The INA126/2126 can be operated on power supplies as low as ±1.35V. Performance remains excellent with power supplies ranging from ±1.35V to ±18V. Most parameters vary only slightly throughout this supply voltage range—see typical performance curves. Operation at very low supply voltage requires careful attention to ensure that the commonmode voltage remains within its linear range. See “Input Common-Mode Voltage Range.” If the differential source resistance is low, the bias current return path can be connected to one input (see the thermocouple example in Figure 3). With higher source impedance, using two equal resistors provides a balanced input with advantages of lower input offset voltage due to bias current and better high-frequency common-mode rejection. Microphone, Hydrophone etc. The INA126/2126 can be operated from a single power supply with careful attention to input common-mode range, output voltage swing of both op amps and the voltage applied to the Ref terminal. Figure 4 shows a bridge amplifier circuit operated from a single +5V power supply. The bridge provides an input common-mode voltage near 2.5V, with a relatively small differential voltage. INA126 INPUT PROTECTION 47kΩ 47kΩ Thermocouple The inputs are protected with internal diodes connected to the power supply rails. These diodes will clamp the applied signal to prevent it from exceeding the power supplies by more than approximately 0.7V. If the signal source voltage can exceed the power supplies, the source current should be limited to less than 10mA. This can generally be done with a series resistor. Some signal sources are inherently currentlimited and do not require limiting resistors. INA126 10kΩ CHANNEL CROSSTALK—DUAL VERSION The two channels of the INA2126 are completely independent, including all bias circuitry. At DC and low frequency there is virtually no signal coupling between channels. Crosstalk increases with frequency and is dependent on circuit gain, source impedance and signal characteristics. As source impedance increases, careful circuit layout will help achieve lowest channel crosstalk. Most crosstalk is produced by capacitive coupling of signals from one channel to the input section of the other channel. To minimize coupling, separate the input traces as far as practical from any signals associated with the opposite channel. A grounded guard trace surrounding the inputs helps reduce stray coupling between channels. Carefully balance the stray capacitance of each input to ground, and run the differential inputs of each channel parallel to each other, or directly adjacent on top and bottom side of a circuit board. Stray coupling then tends to produce a common-mode signal that is rejected by the IA’s input. INA126 Center-tap provides bias current return. FIGURE 3. Providing an Input Common-Mode Current Path. INPUT COMMON-MODE RANGE The input common-mode range of the INA126/2126 is shown in typical performance curves. The common-mode range is limited on the negative side by the output voltage swing of A2, an internal circuit node that cannot be measured on an external pin. The output voltage of A2 can be expressed as: – + – – (VIN – VIN ) (10kΩ/RG) VO2 = 1.25 VIN (2) (Voltages referred to Ref terminal, pin 5) ® INA126, INA2126 8 The ADS7817’s VREF input current is proportional to conversion rate. A conversion rate 10kS/s or slower assures enough current to turn on the reference diode. Converter input range is ±1.2V. Output swing limitation of INA126 limits the A/D converter to somewhat greater than 11 bits of range. +5V 7 R1, C1, R2: 340Hz LP INA126 2.5V + ∆V INA126 and ADS7817 are available in fine-pitch MSOP-8 package 3 6 A1 8 40kΩ 8 R1 1kΩ ✻ 2 +IN 10kΩ Bridge Sensor RG C1 0.47µF 10kΩ 3 1 R2 1kΩ A2 2.5V – ∆V –IN 1 2 40kΩ 5 1.2V ADS7817 12-Bit A/D CS Ck VREF 6 Serial Data 5 Chip Select 7 Clock 33µA 4 6 8 4 D REF1004C-1.2 4 A similar instrumentation amplifier, INA125, provides an internal reference voltage for sensor excitation and/or A/D converter reference. ✻ Dual version has external sense connection. Pin numbers shown are for single version. FIGURE 4. Bridge Signal Acquisition—Single 5V Supply. – R1 VIN RG INA126 + ✻ Ref IB IO = A1 A1 IB Error OPA177 OPA130 OPA602 OPA129 ±1.5nA ±20pA ±1pA ±100fA VIN •G R1 IO Load ✻ Dual version has external sense connection. FIGURE 5. Differential Voltage-to-Current Converter. ® 9 INA126, INA2126