INA1 (R) 28 INA128 INA129 INA1 29 INA1 28 INA1 29 Precision, Low Power INSTRUMENTATION AMPLIFIERS FEATURES DESCRIPTION LOW OFFSET VOLTAGE: 50V max The INA128 and INA129 are low power, general purpose instrumentation amplifiers offering excellent accuracy. Their versatile 3-op amp design and small size make them ideal for a wide range of applications. Current-feedback input circuitry provides wide bandwidth even at high gain (200kHz at G = 100). LOW DRIFT: 0.5V/C max LOW INPUT BIAS CURRENT: 5nA max HIGH CMR: 120dB min INPUTS PROTECTED TO 40V WIDE SUPPLY RANGE: 2.25 to 18V A single external resistor sets any gain from 1 to 10,000. INA128 provides an industry standard gain equation; INA129's gain equation is compatible with the AD620. LOW QUIESCENT CURRENT: 700A 8-PIN PLASTIC DIP, SO-8 The INA128/INA129 is laser trimmed for very low offset voltage (50V), drift (0.5V/C) and high common-mode rejection (120dB at G 100). It operates with power supplies as low as 2.25V, and quiescent current is only 700A--ideal for battery operated systems. Internal input protection can withstand up to 40V without damage. APPLICATIONS BRIDGE AMPLIFIER THERMOCOUPLE AMPLIFIER RTD SENSOR AMPLIFIER MEDICAL INSTRUMENTATION DATA ACQUISITION The INA128/INA129 is available in 8-pin plastic DIP, and SO-8 surface-mount packages, specified for the -40C to +85C temperature range. The INA128 is also available in dual configuration, the INA2128. V+ 7 - 2 VIN INA128: INA128, INA129 Over-Voltage Protection G=1+ A1 40k 1 INA129: 40k G=1+ 25k(1) A3 RG 8 + VIN 3 50k RG 6 49.4k RG VO 25k(1) Over-Voltage Protection 5 A2 40k NOTE: (1) INA129: 24.7k Ref 40k 4 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 (c)1995 Burr-Brown Corporation PDS-1296C Printed in U.S.A. October, 1996 SPECIFICATIONS At TA = +25C, VS = 15V, RL = 10k, unless otherwise noted. INA128P, U INA129P, U PARAMETER CONDITIONS INPUT Offset Voltage, RTI Initial TA = +25C vs Temperature TA = TMIN to TMAX vs Power Supply VS = 2.25V to 18V Long-Term Stability Impedance, Differential Common-Mode VO = 0V Common-Mode Voltage Range(1) Safe Input Voltage Common-Mode Rejection VCM = 13V, RS = 1k G=1 G=10 G=100 G=1000 MIN TYP MAX 50 500/G 0.5 20/G 1 100/G (V+) - 2 (V-) + 2 10 100/G 0.2 2/G 0.2 20/G 0.1 3/G 1010 || 2 1011 || 9 (V+) - 1.4 (V-) + 1.7 80 100 120 120 86 106 125 130 2 30 1 30 BIAS CURRENT vs Temperature Offset Current vs Temperature NOISE VOLTAGE, RTI f = 10Hz f = 100Hz f = 1kHz fB = 0.1Hz to 10Hz Noise Current f=10Hz f=1kHz fB = 0.1Hz to 10Hz GAIN Gain Equation, INA128 INA129 Range of Gain Gain Error Gain vs Temperature(2) 50k (or 49.4k) Resistance(2, 3) Nonlinearity OUTPUT Voltage: Positive Negative Load Capacitance Stability Short-Circuit Current INA128PA, UA INA129PA, UA MIN 40 73 93 110 110 5 1 VO = 13.6V, G=1 G=10 G=100 G=1000 RL = 10k RL = 10k (V+) - 1.4 (V-) + 1.4 MAX 25 100/G 125 1000/G 0.2 5/G 1 20/G 2 200/G 5 G = 1000, RS = 0 G=1 G=10 G=100 G=1000 G=1 TYP UNITS V V/C V/V V/mo || pF || pF V V V dB dB dB dB 10 10 nA pA/C nA pA/C 10 8 8 0.2 nV/Hz nV/Hz nV/Hz Vp-p 0.9 0.3 30 pA/Hz pA/Hz pAp-p 1 + (50k/RG) 1 + (49.4k/RG) V/V V/V V/V % % % % ppm/C ppm/C % of FSR % of FSR % of FSR % of FSR 0.01 0.02 0.05 0.5 1 25 0.0001 0.0003 0.0005 0.001 10000 0.024 0.4 0.5 1 10 100 0.001 0.002 0.002 (Note 4) (V+) - 0.9 (V-) + 0.8 1000 +6/-15 0.1 0.5 0.7 2 0.002 0.004 0.004 V V pF mA MHz kHz kHz kHz V/s s s s s s FREQUENCY RESPONSE Bandwidth, -3dB Overload Recovery G=1 G=10 G=100 G=1000 VO = 10V, G=10 G=1 G=10 G=100 G=1000 50% Overdrive POWER SUPPLY Voltage Range Current, Total VIN = 0V Slew Rate Settling Time, 0.01% TEMPERATURE RANGE Specification Operating JA 8-Pin Dip SO-8 SOIC 1.3 700 200 20 4 7 7 9 80 4 2.25 15 700 -40 -40 80 150 18 750 85 125 V A C C C/W C/W Specification same as INA128P, U or INA129P, U. NOTE: (1) Input common-mode range varies with output voltage--see typical curves. (2) Guaranteed by wafer test. (3) Temperature coefficient of the 50k (or 49.4k) term in the gain equation. (4) Nonlinearity measurements in G = 1000 are dominated by noise. Typical nonlinearity is 0.001%. ELECTROSTATIC DISCHARGE SENSITIVITY PIN CONFIGURATION 8-Pin DIP and SO-8 Top View RG 1 8 RG V-IN 2 7 V+ V+IN 3 6 VO V- 4 5 Ref 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. ABSOLUTE MAXIMUM RATINGS Supply Voltage .................................................................................. 18V Analog Input Voltage Range ............................................................. 40V Output Short-Circuit (to ground) .............................................. Continuous Operating Temperature ................................................. -40C to +125C Storage Temperature ..................................................... -40C to +125C Junction Temperature .................................................................... +150C Lead Temperature (soldering, 10s) ............................................... +300C ORDERING INFORMATION PRODUCT PACKAGE PACKAGE DRAWING NUMBER(1) INA128PA INA128P INA128UA INA128U 8-Pin Plastic DIP 8-Pin Plastic DIP SO-8 Surface-Mount SO-8 Surface-Mount 006 006 182 182 -40C to +85C -40C to +85C -40C to +85C -40C to +85C INA129PA INA129P INA129UA INA129U 8-Pin Plastic DIP 8-Pin Plastic DIP SO-8 Surface-Mount SO-8 Surface-Mount 006 006 182 182 -40C to +85C -40C to +85C -40C to +85C -40C to +85C TEMPERATURE RANGE NOTE: (1) For detailed drawing and dimension table, please see end of data sheet, or Appendix C of Burr-Brown IC Data Book. 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. TYPICAL PERFORMANCE CURVES At TA = +25C, VS = 15V, unless otherwise noted. COMMON-MODE REJECTION vs FREQUENCY GAIN vs FREQUENCY 60 140 G = 1000V/V G = 100V/V G = 1000V/V Common-Mode Rejection (dB) 50 40 Gain (dB) G = 100V/V 30 20 G = 10V/V 10 0 G = 1V/V -10 -20 120 G = 10V/V 100 G = 1V/V 80 60 40 20 0 1k 10k 100k 1M 10M 10 100 1k 100k 10k Frequency (Hz) Frequency (Hz) POSITIVE POWER SUPPLY REJECTION vs FREQUENCY NEGATIVE POWER SUPPLY REJECTION vs FREQUENCY 140 140 120 120 1M Power Supply Rejection (dB) Power Supply Rejection (dB) G = 1000V/V G = 1000V/V 100 G = 100V/V 80 60 G = 10V/V 40 G = 1V/V 80 60 G = 10V/V 40 G = 1V/V 20 20 0 0 10 15 100 1k 10k 100k 100 100k INPUT COMMON-MODE RANGE vs OUTPUT VOLTAGE, VS = 15V INPUT COMMON-MODE RANGE vs OUTPUT VOLTAGE, VS = 5, 2.5V G=1 VD/2 + VCM +15V - VO + - Ref + -15V -10 3 2 G=1 0 5 Output Voltage (V) 10 15 G=1 G 10 1 0 G=1 -1 -2 -3 VS = 5V VS = 2.5V -4 -5 G 10 G 10 4 G=1 VD/2 0 1M 5 G 10 5 -10 10k Frequency (Hz) 10 -15 -15 1k Frequency (Hz) G 10 -5 10 1M Common-Mode Voltage (V) Common-Mode Voltage (V) G = 100V/V 100 -5 -5 -4 -3 -2 -1 0 1 Output Voltage (V) 2 3 4 5 TYPICAL PERFORMANCE CURVES (CONT) At TA = +25C, VS = 15V, unless otherwise noted. SETTLING TIME vs GAIN 100 10 G = 10V/V 1 10 G = 100, 1000V/V Current Noise 0.01% Settling Time (s) G = 1V/V 100 100 Input Bias Current Noise (pA/ Hz) Input-Referred Voltage Noise (nV/ Hz) INPUT- REFERRED NOISE vs FREQUENCY 1k 0.1 1 1 10 100 1k 0.1% 10 1 10k 1 10 100 Frequency (Hz) 1000 Gain (V/V) QUIESCENT CURRENT and SLEW RATE vs TEMPERATURE INPUT OVER-VOLTAGE V/I CHARACTERISTICS 0.85 5 6 3 5 0.75 4 Slew Rate 0.7 3 IQ 0.65 Input Current (mA) 0.8 Slew Rate (V/s) Quiescent Current (A) 4 Flat region represents normal linear operation. 2 G = 1V/V 0 -1 -50 -25 0 25 50 75 100 VIN G = 1000V/V -4 -75 +15V G = 1V/V -2 -3 2 0.6 G = 1000V/V 1 IIN -15V -5 1 125 -50 -40 -30 -20 -10 0 10 20 30 40 50 Input Voltage (V) Temperature (C) INPUT BIAS CURRENT vs TEMPERATURE INPUT OFFSET VOLTAGE WARM-UP 2 10 6 Input Bias Current (nA) Offset Voltage Change (V) 8 4 2 0 -2 -4 1 IOS 0 IB -1 -6 Typical IB and IOS Range 2nA at 25C -8 -2 -10 0 100 200 300 Time (s) 400 500 -75 -50 -25 0 25 50 Temperature (C) 75 100 125 TYPICAL PERFORMANCE CURVES (CONT) At TA = +25C, VS = 15V, unless otherwise noted. OUTPUT VOLTAGE SWING vs POWER SUPPLY VOLTAGE V+ (V+)-0.4 (V+)-0.4 Output Voltage Swing (V) (V+) (V+)-0.8 (V+)-1.2 (V+)+1.2 (V-)+0.8 +25C +85C (V+)-0.8 -40C (V+)-1.2 RL = 10k (V-)+1.2 +25C -40C (V-)+0.8 +85C -40C (V-)+0.4 (V-)+0.4 V- +85C V- 0 1 2 3 4 0 5 Output Current (mA) 10 15 20 Power Supply Voltage (V) SHORT-CIRCUIT OUTPUT CURRENT vs TEMPERATURE MAXIMUM OUTPUT VOLTAGE vs FREQUENCY 30 16 Peak-to-Peak Output Voltage (Vpp) 18 -ISC 14 12 10 8 6 +ISC 4 2 G = 10, 100 25 G=1 G = 1000 20 15 10 5 0 0 -75 -50 -25 0 25 50 75 100 1k 125 10k TOTAL HARMONIC DISTORTION + NOISE vs FREQUENCY 1 VO = 1Vrms 500kHz Measurement Bandwidth 0.1 100k Frequency (Hz) Temperature (C) THD + N (%) Short Circuit Current (mA) Output Voltage (V) OUTPUT VOLTAGE SWING vs OUTPUT CURRENT G=1 RL = 10k G = 100, RL = 100k 0.01 G = 1, RL = 100k Dashed Portion is noise limited. 0.001 100 1k 10k Frequency (Hz) G = 10V/V RL = 100k 100k 1M TYPICAL PERFORMANCE CURVES (CONT) At TA = +25C, VS = 15V, unless otherwise noted. SMALL-SIGNAL (G = 100, 1000) SMALL-SIGNAL (G = 1, 10) G=1 G = 100 20mV/div 20mV/div G = 10 G = 1000 5s/div 20s/div LARGE-SIGNAL (G = 1, 10) LARGE-SIGNAL (G = 100, 1000) G=1 G = 100 5V/div 5V/div G = 10 G = 1000 5s/div VOLTAGE NOISE 0.1 to 10Hz INPUT-REFERRED, G 100 0.1V/div 1s/div 20s/div APPLICATION INFORMATION accurate absolute values. The accuracy and temperature coefficient of these internal resistors are included in the gain accuracy and drift specifications of the INA128/INA129. Figure 1 shows the basic connections required for operation of the INA128/INA129. Applications with noisy or high impedance power supplies may require decoupling capacitors close to the device pins as shown. SETTING THE GAIN 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 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 (possibly an unstable gain error) in gains of approximately 100 or greater. Gain is set by connecting a single external resistor, RG, connected between pins 1 and 8: DYNAMIC PERFORMANCE The output is referred to the output reference (Ref) terminal which is normally grounded. This must be a low-impedance connection to assure good common-mode rejection. A resistance of 8 in series with the Ref pin will cause a typical device to degrade to approximately 80dB CMR (G = 1). INA128: INA129: G = 1+ The typical performance curve "Gain vs Frequency" shows that, despite its low quiescent current, the INA128/INA129 achieves wide bandwidth, even at high gain. This is due to the current-feedback topology of the input stage circuitry. Settling time also remains excellent at high gain. (1) 50k G = 1+ RG (2) 49. 4k RG NOISE PERFORMANCE The INA128/INA129 provides very low noise in most applications. Low frequency noise is approximately 0.2Vp-p measured from 0.1 to 10Hz (G 100). This provides dramatically improved noise when compared to state-of-theart chopper-stabilized amplifiers. Commonly used gains and resistor values are shown in Figure 1. The 50k term in Equation 1 (49.4k in Equation 2) comes from the sum of the two internal feedback resistors of A1 and A2. These on-chip metal film resistors are laser trimmed to V+ 0.1F INA128: G=1+ INA129: 50k G=1+ RG INA128 7 49.4k RG INA128, INA129 - VIN 2 INA129 DESIRED GAIN (V/V) RG () NEAREST 1% RG () RG () NEAREST 1% RG () 1 2 5 10 20 50 100 200 500 1000 2000 5000 10000 NC 50.00k 12.50k 5.556k 2.632k 1.02k 505.1 251.3 100.2 50.05 25.01 10.00 5.001 NC 49.9k 12.4k 5.62k 2.61k 1.02k 511 249 100 49.9 24.9 10 4.99 NC 49.4k 12.35k 5489 2600 1008 499 248 99 49.5 24.7 9.88 4.94 NC 49.9k 12.4k 5.49k 2.61k 1k 499 249 100 49.9 24.9 9.76 4.87 Over-Voltage Protection A1 40k 1 + - ) VO = G * (VIN - VIN A3 RG 6 + 8 25k(1) Load VO - + VIN 3 5 A2 Over-Voltage Protection 40k 4 NOTE: (1) INA129: 24.7k V- NC: No Connection. Also drawn in simplified form: - VIN RG + VIN FIGURE 1. Basic Connections. 40k 25k(1) INA128 Ref VO 0.1F 40k Ref OFFSET TRIMMING The INA128/INA129 is 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 Ref terminal is summed with the output. The op amp buffer provides low impedance at the Ref terminal to preserve good common-mode rejection. - VIN V+ INA128 VO INA128 47k 47k Thermocouple V+ RG Microphone, Hydrophone etc. INA128 100A 1/2 REF200 Ref 10k IN OPA177 10mV Adjustment Range 10k 100 100 100A 1/2 REF200 INA128 Center-tap provides bias current return. V- FIGURE 2. Optional Trimming of Output Offset Voltage. FIGURE 3. Providing an Input Common-Mode Current Path. INPUT BIAS CURRENT RETURN PATH The input impedance of the INA128/INA129 is extremely high--approximately 1010. However, a path must be provided for the input bias current of both inputs. This input bias current is approximately 2nA. High input impedance means that this input bias current changes very little with varying input voltage. linear common-mode input range is related to the output voltage of the complete amplifier. This behavior also depends on supply voltage--see performance curves "Input Common-Mode Range vs Output Voltage". 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. 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 possible advantages of lower input offset voltage due to bias current and better high-frequency common-mode rejection. INPUT COMMON-MODE RANGE The linear input voltage range of the input circuitry of the INA128/INA129 is from approximately 1.4V below the positive supply voltage to 1.7V above the negative supply. As a differential input voltage causes the output voltage increase, however, the linear input range will be limited by the output voltage swing of amplifiers A1 and A2. So the Input-overload can produce an output voltage that appears normal. For example, if an input overload condition drives both input amplifiers to their positive output swing limit, the difference voltage measured by the output amplifier will be near zero. The output of A3 will be near 0V even though both inputs are overloaded. LOW VOLTAGE OPERATION The INA128/INA129 can be operated on power supplies as low as 2.25V. Performance remains excellent with power supplies ranging from 2.25V 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 assure that the input voltages remain within their linear range. Voltage swing requirements of internal nodes limit the input commonmode range with low power supply voltage. Typical performance curves, "Input Common-Mode Range vs Output Voltage" show the range of linear operation for 15V, 5V, and 2.5V supplies. RG = 5.6k 2.8k G = 10 LA RA RG/2 VO INA128 Ref 2.8k 390k VG 1/2 OPA2131 RL VG 1/2 OPA2131 NOTE: Due to the INA128's current-feedback topology, VG is approximately 0.7V less than the common-mode input voltage. This DC offset in this guard potential is satisfactory for many guarding applications. 10k 390k FIGURE 4. ECG Amplifier With Right-Leg Drive. V+ +5V 10.0V 6 REF102 2.5V - V R1 RG 300 VO INA128 2 R2 4 Ref 2.5V + V Pt100 Cu K Cu - RG VO INA128 Ref ISA TYPE C1 0.1F OPA130 R1 1M f-3dB = Ref SEEBECK COEFFICIENT (V/C) R1, R2 E + Chromel - Constantan 58.5 66.5k J + Iron - Constantan 50.2 76.8k K + Chromel - Alumel 39.4 97.6k T + Copper - Constantan 38.0 102k 1 2R1C1 = 1.59Hz MATERIAL VO INA128 R3 100 = Pt100 at 0C FIGURE 5. Bridge Amplifier. VIN + RG FIGURE 7. Thermocouple Amplifier With RTD ColdJunction Compensation. FIGURE 6. AC-Coupled Instrumentation Amplifier. - VIN R1 RG IO = INA128 VIN *G R1 + Ref IB A1 A1 IB Error OPA177 OPA131 OPA602 OPA128 1.5nA 50pA 1pA 75fA IO Load FIGURE 8. Differential Voltage to Current Converter.