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Texas Instruments INA115AU-1
- Part No.:
- INA115AU-1
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 16-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
INA115AU-1.pdf
- Description:
- IC INST AMP 1 CIRCUIT 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,217
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Product details
Overview
INA115AU-1 from Texas Instruments (originally Burr-Brown) is a precision instrumentation amplifier with three-op-amp architecture, designed for high-accuracy signal conditioning in low-noise, high-common-mode environments. It delivers 115dB min CMRR at G=1000, ±50µV max input offset voltage, and operates from ±2.25V to ±18V supplies - enabling use in battery-powered and industrial bridge sensor interfaces.
For engineers reviewing the INA115AU-1 datasheet, INA115AU-1 pinout, INA115AU-1 application, or INA115AU-1 equivalent, key selection considerations include gain-setting resistor dependency (G = 1 + 50kΩ/RG), ±40V input over-voltage protection, SOL-16 package thermal performance (θJA = 80°C/W), and verified operation across –40°C to +85°C.
Technical Context
The INA115AU-1 implements a classic three-op-amp topology with externally accessible A1/A2 outputs (pins 1 and 8) and dedicated feedback sense (pin 12), enabling switched-gain configurations and remote load sensing. Its laser-trimmed 25kΩ internal feedback resistors define the 50kΩ term in the gain equation and contribute directly to gain accuracy and drift specs.
Input over-voltage protection operates independently per input up to ±40V, with current limiting (~1.5mA) active even with zero supply voltage. The Ref pin (pin 9) sets output common-mode level and requires ≤5Ω impedance for full CMRR; improper routing degrades CMR to ~80dB at G=1.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Gain Range | 1 to 10,000 V/V via single external RG resistor - enables scalable signal amplification without topology change. |
| CMRR (G=1000) | 115 dB min - rejects >99.9997% of common-mode interference in noisy industrial environments. |
| Input Offset Voltage | ±50 µV max - reduces DC error in thermocouple or RTD measurements without calibration. |
| Input Bias Current | ±2 nA max - permits high-impedance sensor interfacing (e.g., piezoelectric transducers) with minimal loading. |
| Supply Voltage Range | ±2.25 V to ±18 V - supports single 5V systems (±2.5V) and high-voltage industrial rails. |
| Input Over-Voltage Rating | ±40 V - protects against transient surges in motor control or field wiring without external clamping. |
| Bandwidth (G=100) | 10 kHz - sufficient for ECG, strain gauge, and slow-scan data acquisition up to 1kSPS. |
Pinout & Package
SOL-16 surface-mount package (SOIC DW, 16-pin), specified for –40°C to +85°C operation, with θJA = 80°C/W and RoHS-compliant NIPDAU-DCC finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (VO1) | A1 output | Provides access to first input op-amp output for switched-gain or custom feedback paths. |
| 2 (Gain Sense1) | A1 feedback node | Connects to VO1 to enable internal 25kΩ feedback; required for standard operation. |
| 3 (RG) | Gain-setting terminal | Connects external resistor to set gain per G = 1 + 50kΩ/RG; open for G=1. |
| 4 (V–) | Negative supply rail | Must be decoupled locally; supports asymmetric supplies down to ±2.25V. |
| 5 (VIN–) | Inverting input | Differential input node with ±40V over-voltage protection and 10¹⁰Ω || 6pF impedance. |
| 6 (VIN+) | Non-inverting input | Differential input node mirrored to pin 5; same protection and impedance specs. |
| 7 (NC) | No connect | Internally unused; must remain unconnected per datasheet. |
| 8 (VO2) | A2 output | Provides access to second input op-amp output for parallel gain stages or diagnostics. |
| 9 (Ref) | Output reference | Sets output common-mode voltage; ≤5Ω impedance required to maintain 115dB CMRR. |
| 10 (V+) | Positive supply rail | Must be decoupled locally; same voltage range as V– (±2.25V to ±18V). |
| 11 (VO) | Main output | Final amplified output; drives 2kΩ loads with ±13.5V swing at ±15V supplies. |
| 12 (Feedback) | Output sense feedback | Must connect to VO (pin 11) for standard operation; enables remote load sensing for improved accuracy. |
| 13 (NC) | No connect | Internally unused; must remain unconnected. |
| 14 (Gain Sense2) | A2 feedback node | Connects to VO2 to enable internal 25kΩ feedback; required for standard operation. |
| 15 (RG) | Gain-setting terminal | Duplicate of pin 3; both RG pins must be tied together when using external resistor. |
| 16 (NC) | No connect | Internally unused; must remain unconnected. |
Key Features
| Feature | Design Value |
|---|---|
| Laser-trimmed offset & drift | ±50 µV max initial offset and ±0.25 µV/°C max drift - eliminates need for manual trimming in medical or test equipment. |
| Independent input over-voltage protection | Withstands ±40V on either input - prevents damage during sensor hot-plug or ESD events without external components. |
| Three-op-amp architecture with exposed A1/A2 outputs | Pins 1 and 8 provide direct access to input stage outputs - enables digital gain switching and diagnostic monitoring. |
| Single-resistor programmable gain | G = 1 + 50kΩ/RG - simplifies BOM and layout vs multi-resistor instrumentation amps; supports 1% resistor standard values. |
| Wide supply range with low quiescent current | Operates from ±2.25V with ≤3 mA total supply current - extends battery life in portable data loggers. |
Applications
| Bridge Amplifier | Thermocouple Amplifier |
|---|---|
Use Scenario: Amplifying mV-level differential signals from Wheatstone bridge strain gauges in load cells or pressure sensors. IC Role / Device Role / Timing Role: Precision instrumentation amplifier providing high CMRR and low noise to reject bridge excitation ripple and EMI. Use Value: Enables sub-0.01% full-scale measurement accuracy with no external trimming, leveraging ±50µV offset and 115dB CMRR at G=1000. | Use Scenario: Conditioning microvolt-level Seebeck voltages from K-type or J-type thermocouples in industrial ovens or HVAC systems. IC Role / Device Role / Timing Role: Low-drift, low-bias-current amplifier rejecting cold-junction compensation errors and line-frequency interference. Use Value: Delivers ±0.25µV/°C drift and ±2nA bias current - minimizes temperature-induced offset drift and input loading errors. |
| RTD Sensor Amplifier | Medical Instrumentation |
Use Scenario: Exciting and measuring resistance changes in Pt100 or Pt1000 RTDs for precision temperature monitoring in lab equipment. IC Role / Device Role / Timing Role: High-input-impedance amplifier with stable gain and low noise to resolve <1mΩ resistance shifts. Use Value: Supports 4-wire RTD configurations with gain accuracy of ±0.5% at G=1000 and 0.4µVp-p 0.1–10Hz noise - ensures <0.1°C resolution. | Use Scenario: Front-end amplification in ECG, EEG, or EMG systems where biopotential signals are buried in high-amplitude common-mode noise. IC Role / Device Role / Timing Role: Primary signal conditioner rejecting 50/60Hz mains interference while preserving µV-level physiological waveforms. Use Value: Achieves 115dB CMRR at G=1000 and ±40V input protection - meets IEC 60601-1 patient isolation requirements without additional circuitry. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar instrumentation amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| INA125P | Integrated precision current source (±0.05% accuracy) and excitation for 4-wire RTDs; higher quiescent current (4.5mA); SOIC-16 package. | Better suited for RTD sensor excitation and ratiometric measurement; lacks independent A1/A2 outputs for switched-gain. | Select INA125P when integrated current source simplifies 4-wire RTD design; choose INA115AU-1 when flexible gain switching or lowest offset drift is critical. |
| AD620ARZ | Lower input bias current (1nA typ), lower noise (9nV/√Hz), but no input over-voltage protection; SOIC-8 package; gain set by single resistor (G = 1 + 49.4kΩ/RG). | Preferred for ultra-low-noise applications with clean power; unsuitable for field-connected sensors requiring ±40V protection. | Select AD620ARZ for low-noise, low-power portable instruments; choose INA115AU-1 when robustness against industrial transients and wide supply range are mandatory. |
Compared with INA125P and AD620ARZ, the INA115AU-1 uniquely combines ±40V input protection, exposed A1/A2 outputs for gain switching, and laser-trimmed 0.25µV/°C drift - making it optimal for ruggedized, reconfigurable sensor front-ends where reliability and flexibility outweigh minimum noise or integrated excitation needs.
Availability
INA115AU-1 is available at Aetrix Electronics and suitable for bridge amplifier designs, thermocouple signal conditioning, and medical instrumentation requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for INA115AU-1 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Texas Instruments acquired Burr-Brown in 2000 and maintains its precision analog portfolio, emphasizing high-accuracy signal chain components for industrial, medical, and test equipment.
The INA115AU-1 belongs to TI's legacy instrumentation amplifier product line, engineered specifically for high-CMRR, low-drift sensor signal conditioning in harsh electrical environments with wide supply flexibility.
FAQ
What is the maximum gain achievable with the INA115AU-1, and how is it set?
The INA115AU-1 supports gains from 1 to 10,000 V/V, set by a single external resistor RG using the formula G = 1 + 50kΩ/RG. For G=10,000, RG = 5.001Ω (nearest 1% value: 4.99Ω). At high gains, wiring resistance becomes significant; the device's force-and-sense pin configuration (pins 1/2 and 8/14) helps mitigate this. The INA115AU-1 datasheet provides a table of standard 1% resistor values for common gains.
Does the INA115AU-1 require external components for basic operation?
Yes - the INA115AU-1 requires at minimum: (1) decoupling capacitors (0.1µF) on V+ and V– pins, (2) connection of pin 12 (Feedback) to pin 11 (VO), and (3) proper grounding of pin 9 (Ref) with ≤5Ω impedance to preserve CMRR. For G>1, an external RG resistor must connect between pins 3 and 15. The INA115AU-1 does not operate correctly without these connections, as confirmed in the "Basic Connections" application diagram.
How does the INA115AU-1 handle input over-voltage conditions, and what protection limits apply?
The INA115AU-1 provides per-input over-voltage protection rated to ±40V - meaning either input can withstand –40V or +40V relative to ground, even with no power applied. Internal circuitry limits input current to ~1.5mA during overload, preventing damage. This protection is active independently on each input, allowing safe operation in field-wired industrial sensors. The INA115AU-1 specification explicitly states "Input Safe Voltage: ±40V" under Absolute Maximum Ratings.
Can the INA115AU-1 be used with single-supply operation, and what are the constraints?
Yes - the INA115AU-1 operates with split supplies from ±2.25V to ±18V, enabling true single-supply use by setting V– = 0V and V+ = +5V (i.e., ±2.5V equivalent). However, the input common-mode range then becomes limited to ~1.25V below V+ and above V–, and output swing reduces to ±1V at ±2.25V supplies. Reference voltage (pin 9) must be biased within this range, typically at mid-supply. The INA115AU-1 datasheet confirms operation down to ±2.25V and specifies output swing under these conditions.
What is the purpose of pins 1 (VO1) and 8 (VO2) on the INA115AU-1, and are they required for standard use?
Pins 1 (VO1) and 8 (VO2) are the outputs of the two input-stage operational amplifiers (A1 and A2). They are not required for basic amplifier operation but enable advanced configurations: switched-gain circuits (by routing VO1/VO2 through multiplexers), remote load sensing (via pin 12 feedback), and diagnostic monitoring of input stage behavior. In standard use, they must be connected to their respective Gain Sense pins (2 and 14) to close the internal 25kΩ feedback paths. The INA115AU-1 functional diagram and Figure 2 confirm this dual-role design.
INA115AU-1 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 16-SOIC (0.295", 7.50mm Width)
- Packaging:
- Bulk
- Product Status:
- Active
- Amplifier Type:
- Instrumentation
- Number of Circuits:
- 1
- Output Type:
- -
- Slew Rate:
- 0.6V/µs
- Gain Bandwidth Product:
- -
- -3db Bandwidth:
- 1 MHz
- Current - Input Bias:
- 500 pA
- Voltage - Input Offset:
- 25 µV
- Current - Supply:
- 2.2mA
- Current - Output / Channel:
- 20 mA
- Voltage - Supply Span (Min):
- 4.5 V
- Voltage - Supply Span (Max):
- 36 V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
INA115AU-1 FAQ
1.How can I place an order for INA115AU-1 through Aetrix?
Please submit a Request for Quotation (RFQ) for INA115AU-1 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for INA115AU-1 reliable?
The price and inventory of INA115AU-1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for INA115AU-1 is usually 5 days.
3.What payment methods are accepted for INA115AU-1?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for INA115AU-1 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for INA115AU-1?
INA115AU-1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your INA115AU-1 order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for INA115AU-1?
For technical support, including INA115AU-1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your INA115AU-1 requirements.
6.How does Aetrix verify that INA115AU-1 is sourced from the original manufacturer or authorized distributors?
All INA115AU-1 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that INA115AU-1 meets industry standards.
7.What is the process for return or replacement of INA115AU-1?
All INA115AU-1 units undergo pre-shipment inspection (PSI). If there is an issue with INA115AU-1, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The INA115AU-1 part is unused and in its original packaging.
Return procedure for INA115AU-1:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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