® INA141 INA 141 INA 141 Precision, Low Power, G = 10, 100 INSTRUMENTATION AMPLIFIER FEATURES DESCRIPTION ● LOW OFFSET VOLTAGE: 50µV max ● LOW DRIFT: 0.5µV/°C max The INA141 is a low power, general purpose instrumentation amplifier offering excellent accuracy. Its versatile 3-op amp design and small size make it ideal for a wide range of applications. Current-feedback input circuitry provides wide bandwidth even at high gain (200kHz at G = 100). ● ACCURATE GAIN: ±0.05% at G = 10 ● LOW INPUT BIAS CURRENT: 5nA max ● HIGH CMR: 117dB min ● INPUTS PROTECTED TO ±40V ● WIDE SUPPLY RANGE: ±2.25 to ±18V Simple pin connections set an accurate gain of 10 or 100V/V without external resistors. Internal input protection can withstand up to ±40V without damage. ● LOW QUIESCENT CURRENT: 750µA ● 8-PIN PLASTIC DIP, SO-8 ● BRIDGE AMPLIFIER The INA141 is laser trimmed for very low offset voltage (50µV), drift (0.5µV/°C) and high commonmode rejection (117dB at G = 100). It operates with power supplies as low as ±2.25V, and quiescent current is only 750µA—ideal for battery operated systems. ● THERMOCOUPLE AMPLIFIER ● RTD SENSOR AMPLIFIER ● MEDICAL INSTRUMENTATION The INA141 is available in 8-pin plastic DIP, and SO-8 surface-mount packages, specified for the –40°C to +85°C temperature range. APPLICATIONS ● DATA ACQUISITION V+ 7 – VIN 2 1 Over-Voltage Protection INA141 A1 40kΩ 252Ω 40kΩ 25kΩ G = 10 or G =100 A3 5050Ω 8 + VIN 3 6 VO 252Ω 25kΩ Over-Voltage Protection 5 A2 40kΩ Ref 40kΩ 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 ® PDS-1297B 1 INA141 SPECIFICATIONS At TA = +25°C, VS = ±15V, and RL = 10kΩ, unless otherwise noted. INA141P, U PARAMETER CONDITIONS INPUT Offset Voltage, RTI vs Temperature vs Power Supply Long-Term Stability TYP MAX ±50 ±100 ±0.5 ±2 ±1 ±10 (V+) – 2 (V–) + 2 ±20 ±50 ±0.2 ±0.5 ±0.4 ±2 0.2 0.5 1010 || 2 1010 || 9 (V+) – 1.4 (V–) + 1.7 117 100 125 106 G = 100 G = 10 G = 100 G = 10(2) VS = ±2.25 to ±18V, G = 100 G = 10 G = 100 G = 10 Impedance, Differential Common-Mode Common-Mode Voltage Range(1) Safe Input Voltage Common-Mode Rejection VO = 0V VCM = ±13V, ∆RS = 1kΩ G = 100 G = 10 ±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 f = 10Hz f = 100Hz f = 1kHz fB = 0.1Hz to 10Hz Noise Current f = 10Hz f = 1kHz fB = 0.1Hz to 10Hz GAIN Gain Error Gain vs Temperature(2) Nonlinearity G = 100, RS = 0Ω G = 10, RS = 0Ω VO = ±13.6V, G = 100 G = 10 G = 10, 100 G = 100 G = 10 OUTPUT Voltage: Positive Negative Load Capacitance Stability Short-Circuit Current FREQUENCY RESPONSE Bandwidth, –3dB RL = 10kΩ RL = 10kΩ Overload Recovery G = 100 G = 10 VO = ±10V, G = 10 VO = ±5V, G = 100 G = 10 50% Overdrive POWER SUPPLY Voltage Range Current, Total VIN = 0V Slew Rate Settling Time, 0.01% (V+) – 1.4 (V–) + 1.4 MIN TYP MAX UNITS ±125 ±250 ±1.5 ±2.5 ±3 ±20 ✻ ✻ ✻ ✻ ✻ ✻ ✻ ✻ ✻ ✻ ✻ ✻ ✻ ✻ µV µV µV/°C µV/°C µV/V µV/V µV/mo µV/mo Ω || pF Ω || pF V V V 110 93 120 100 ±40 ✻ ±5 ✻ ✻ ✻ ✻ ±5 dB dB ±10 ±10 nA pA/°C nA pA/°C 10 8 8 0.2 22 13 12 0.6 ✻ ✻ ✻ ✻ ✻ ✻ ✻ ✻ nV/√Hz nV/√Hz nV/√Hz µVp-p nV/√Hz nV/√Hz nV/√Hz µVp-p 0.9 0.3 30 ✻ ✻ ✻ pA/√Hz pA/√Hz pAp-p ±0.03 ±0.01 ±2 ±0.0005 ±0.0003 ±0.075 ±0.05 ±10 ±0.002 ±0.001 ✻ ✻ ✻ ✻ ✻ ✻ ✻ (V+) – 0.9 (V–) + 0.9 1000 +6/–15 200 1 4 9 7 4 ±2.25 TEMPERATURE RANGE Specification Operating θJA 8-Pin DIP SO-8 SOIC INA141PA, UA MIN ±15 ±750 –40 –40 ±18 ±800 ✻ 85 125 ✻ ✻ 80 150 ±0.15 ±0.15 ✻ ±0.004 ±0.002 % % ppm/°C % of FSR % of FSR ✻ ✻ ✻ ✻ V V pF mA ✻ ✻ ✻ ✻ ✻ ✻ kHz MHz V/µs µs µs µs ✻ ✻ ✻ ✻ ✻ ✻ V µA ✻ ✻ °C °C °C/W °C/W ✻ Specification same as INA141P, U. NOTE: (1) Input common-mode range varies with output voltage—see typical curves. (2) Guaranteed by wafer test. 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. ® INA141 2 ELECTROSTATIC DISCHARGE SENSITIVITY PIN CONFIGURATION 8-Pin DIP and SO-8 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. Top View J 1 8 J – IN 2 7 V+ V+IN 3 6 VO V– 4 5 Ref V 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 ORDERING INFORMATION Supply Voltage .................................................................................. ±18V Analog Input Voltage Range ............................................................. ±40V Output Short-Circuit (to ground) .............................................. Continuous Operating Temperature ................................................. –40°C to +125°C Storage Temperature ..................................................... –40°C to +125°C Junction Temperature .................................................................... +150°C Lead Temperature (soldering, 10s) ............................................... +300°C PRODUCT PACKAGE PACKAGE DRAWING NUMBER(1) INA141PA INA141P INA141UA INA141U 8-Pin Plastic DIP 8-Pin Plastic DIP SO-8 Surface-Mount SO-8 Surface-Mount 006 006 182 182 TEMPERATURE RANGE –40°C to +85°C –40°C to +85°C –40°C to +85°C –40°C to +85°C NOTE: (1) For detailed drawing and dimension table, please see end of data sheet, or Appendix C of Burr-Brown IC Data Book. ® 3 INA141 TYPICAL PERFORMANCE CURVES At TA = +25°C and VS = ±15V, unless otherwise noted. COMMON-MODE REJECTION vs FREQUENCY GAIN vs FREQUENCY 140 60 G = 100V/V Common-Mode Rejection (dB) 50 40 Gain (dB) G = 100V/V 30 20 G = 10V/V 10 0 –10 G = 10V/V 100 80 60 40 20 0 –20 1k 10k 100k 1M 10 10M 100 1k 100k 10k Frequency (Hz) Frequency (Hz) POSITIVE POWER SUPPLY REJECTION vs FREQUENCY NEGATIVE POWER SUPPLY REJECTION vs FREQUENCY 140 140 120 120 100 Power Supply Rejection (dB) Power Supply Rejection (dB) 120 G = 100V/V 80 60 G = 10V/V 40 1M G = 100V/V 100 80 60 G = 10V/V 40 20 20 0 0 10 100 1k 10k 100k 10 1M 100 1k 10k 100k Frequency (Hz) Frequency (Hz) INPUT COMMON-MODE RANGE vs OUTPUT VOLTAGE, VS = ±15V INPUT COMMON-MODE RANGE vs OUTPUT VOLTAGE, VS = ±5, ±2.5V 15 1M 5 Common-Mode Voltage (V) Common-Mode Voltage (V) 4 10 5 VD/2 0 VD/2 + –5 VCM +15V – VO + – Ref + –15V –10 3 2 1 0 –1 –2 –3 VS = ±5V VS = ±2.5V –4 –15 –15 –10 –5 0 5 10 –5 –5 15 Output Voltage (V) –3 –2 –1 0 1 Output Voltage (V) ® INA141 –4 4 2 3 4 5 TYPICAL PERFORMANCE CURVES (CONT) At TA = +25°C and VS = ±15V, unless otherwise noted. G = 10V/V 1 10 G = 100V/V Current Noise Quiescent Current (µA) 10 100 Input Bias Current Noise (pA/√ Hz) Input-Referred Voltage Noise (nV/√ Hz) 100 1k 0.1 1 1 10 100 1k 0.9 6 0.85 5 0.8 4 Slew Rate 0.75 3 IQ 0.7 2 0.65 10k –75 –50 –25 Frequency (Hz) INPUT OVER-VOLTAGE V/I CHARACTERISTICS 8 Input Current (mA) Flat region represents normal linear operation. Input Offset Voltage Change (µV) 4 G = 100V/V 1 G = 10V/V 0 –1 +15V G = 10V/V –2 INA141 –3 G = 100V/V VIN –4 25 50 75 IIN –15V –5 –20 –10 0 1 125 6 4 2 0 –2 –4 –6 –8 –10 –50 –40 –30 100 INPUT OFFSET VOLTAGE WARM-UP 10 2 0 Temperature (°C) 5 3 Slew Rate (V/µs) QUIESCENT CURRENT and SLEW RATE vs TEMPERATURE INPUT- REFERRED NOISE vs FREQUENCY 10 20 30 40 0 50 400 300 200 100 Input Voltage (V) Time (µs) INPUT BIAS CURRENT vs TEMPERATURE OUTPUT VOLTAGE SWING vs OUTPUT CURRENT 2 500 (V+) Output Voltage (V) Input Bias Current (nA) (V+)–0.4 1 IOS 0 IB –1 Typical IB Range ±2nA at 25°C (V+)–0.8 (V+)–1.2 (V+)+1.2 (V–)+0.8 (V–)+0.4 –2 V– –75 –50 –25 0 25 50 75 100 125 0 Temperature (°C) 1 2 3 4 Output Current (mA) ® 5 INA141 TYPICAL PERFORMANCE CURVES (CONT) At TA = +25°C and VS = ±15V, unless otherwise noted. SHORT-CIRCUIT OUTPUT CURRENT vs TEMPERATURE OUTPUT VOLTAGE SWING vs POWER SUPPLY VOLTAGE 18 V+ 16 Short-Circuit Current (mA) +25°C +85°C (V+)–0.8 –40°C (V+)–1.2 RL = 10kΩ (V–)+1.2 +25°C –40°C (V–)+0.8 (V–)+0.4 +85°C –40°C +85°C –ISC 14 12 10 8 6 +ISC 4 2 0 V– 0 5 10 15 –75 20 –50 –25 0 25 50 75 100 Power Supply Voltage (V) Temperature (°C) MAXIMUM OUTPUT VOLTAGE vs FREQUENCY TOTAL HARMONIC DISTORTION + NOISE vs FREQUENCY 30 125 1 G = 10, 100 VO = 1Vrms 500kHz Measurement Bandwidth 25 20 THD+N (%) Peak-to-Peak Output Voltage (Vpp) Output Voltage Swing (V) (V+)–0.4 15 0.1 RL = 10kΩ G = 100, RL = 100kΩ 0.01 10 G = 10V/V RL = 100kΩ 5 Dashed Portion is noise limited. 0.001 0 1k 10k 100k 100 1M Frequency (Hz) 10k Frequency (Hz) ® INA141 1k 6 100k TYPICAL PERFORMANCE CURVES (CONT) At TA = +25°C and VS = ±15V, unless otherwise noted. LARGE-SIGNAL STEP RESPONSE SMALL-SIGNAL STEP RESPONSE G = 10 G = 10 20mV/div 5V/div G = 100 G = 100 5µs/div 5µs/div VOLTAGE NOISE 0.1 to 10Hz INPUT-REFERRED, G = 100 0.1µV/div 1s/div ® 7 INA141 APPLICATION INFORMATION Gains between 10 and 100 can be achieved by connecting an external resistor to the jumper pins. This is not recommended, however, because the ±25% variation of internal resistor values makes the required external resistor value uncertain. A companion model, INA128, features accurately trimmed internal resistors so that gains from 1 to 10,000 can be set with an external resistor. Figure 1 shows the basic connections required for operation of the INA141. 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 assure 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 (G = 1). DYNAMIC PERFORMANCE The typical performance curve “Gain vs Frequency” shows that, despite its low quiescent current, the INA141 achieves wide bandwidth, even at G = 100. This is due to the currentfeedback topology of the INA141. Settling time also remains excellent at G = 100. SETTING THE GAIN Gain is selected with a jumper connection as shown in Figure 1. G = 10V/V with no jumper installed. With a jumper installed, G = 100V/V. To preserve good gain accuracy, this jumper must have low series resistance. A resistance of 0.5Ω in series with the jumper will decrease the gain by 0.1%. NOISE PERFORMANCE The INA141 provides very low noise in most applications. Low frequency noise is approximately 0.2µVp-p measured from 0.1 to 10Hz (G = 100). This provides dramatically improved noise when compared to state-of-the-art chopperstabilized amplifiers. Internal resistor ratios are laser trimmed to assure excellent gain accuracy. Actual resistor values can vary by approximately ±25% from the nominal values shown. V+ 0.1µF 7 – VIN 2 1 G = 10 (no connection) or G = 100 (connect jumper) INA141 Over-Voltage Protection A1 40kΩ 252Ω 40kΩ 25kΩ A3 5050Ω 8 6 + – ) VO = G • (VIN – VIN + 252Ω 25kΩ Load VO – + VIN 3 5 A2 Over-Voltage Protection 40kΩ 4 V– Also drawn in simplified form: – VIN INA141 + VIN VO Ref FIGURE 1. Basic Connections. ® INA141 8 0.1µF 40kΩ Ref OFFSET TRIMMING The INA141 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. INA141 47kΩ 47kΩ Thermocouple – VIN INA141 V+ INA141 V+ Microphone, Hydrophone etc. VO 100µA 1/2 REF200 Ref 10kΩ IN OPA177 ±10mV Adjustment Range 10kΩ 100Ω INA141 100Ω 100µA 1/2 REF200 Center-tap provides bias current return. V– FIGURE 3. Providing an Input Common-Mode Current Path. FIGURE 2. Optional Trimming of Output Offset Voltage. 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 the INA141 will be near 0V even though both inputs are overloaded. INPUT BIAS CURRENT RETURN PATH The input impedance of the INA141 is extremely high— approximately 1010Ω. 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. LOW VOLTAGE OPERATION The INA141 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 through 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 common-mode range with low power supply voltage. Typical performance curves, “Input Common-Mode Range vs Output Voltage” show the range of linear operation for ±15V, ±5, and ±2.5V supplies. 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 of the INA141 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 PROTECTION The inputs of the INA141 are individually protected for voltages up to ±40V. For example, a condition of –40V on one input and +40V on the other input will not cause damage. Internal circuitry on each input provides low series impedance under normal signal conditions. To provide equivalent protection, series input resistors would contribute excessive noise. If the input is overloaded, the protection circuitry limits the input current to a safe value of approximately 1.5 to 5mA. The typical performance curve “Input Bias Current vs Common-Mode Input Voltage” shows this input current limit behavior. The inputs are protected even if the power supplies are disconnected or turned off. INPUT COMMON-MODE RANGE The linear input voltage range of the input circuitry of the INA141 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 to increase, however, the linear input range will be limited by the output voltage swing of amplifiers A1 and A2. So the 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”. ® 9 INA141 1/4 OPA4131 VO INA141 1/4 OPA4131 LA RA Ref G = 10 20kΩ 390kΩ VG 1/4 OPA4131 RL 20kΩ 1/4 OPA4131 10kΩ 390kΩ FIGURE 4. ECG Amplifier With Right-Leg Drive. +5V V+ +15V 10.0V 2.5V – ∆V REF102 R1 VO INA141 300Ω 6 2 R2 4 Ref 2.5V + ∆V Pt100 –15V Cu K Cu Ref R3 100Ω = Pt100 at 0°C – VIN + VO INA141 Ref VO INA141 FIGURE 5. Bridge Amplifier. C1 0.1µF OPA602 ISA TYPE R1 1MΩ 1 f–3dB = 2πR1C1 = 1.59Hz FIGURE 6. AC-Coupled Instrumentation Amplifier. MATERIAL SEEBECK COEFFICIENT (µV/°C) R1, R2 E + Chromel – Constantan 58.5 66.5kΩ J + Iron – Constantan 50.2 76.8kΩ K + Chromel – Alumel 39.4 97.6kΩ T + Copper – Constantan 38.0 102kΩ FIGURE 7. Thermocouple Amplifier With RTD ColdJunction Compensation. – R1 VIN IO = INA141 VIN •G R1 + Ref IB IO A1 A1 IB Error OPA177 OPA131 OPA602 OPA128 ±1.5nA 50pA ±1pA ±75fA Load FIGURE 8. Differential Voltage to Current Converter. ® INA141 10