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Texas Instruments INA115BU
- Part No.:
- INA115BU
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 16-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
INA115BU.pdf
- Description:
- IC INST AMP 1 CIRCUIT 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:465
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Product details
Overview
INA115BU 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-noise environments. It delivers 115dB min CMRR at G=1000, ±40V input over-voltage protection, and 50µV max initial offset voltage - enabling use in bridge sensor interfaces, thermocouple amplification, and medical ECG front-ends.
For engineers reviewing the INA115BU datasheet, INA115BU pinout, INA115BU application, or INA115BU equivalent, key selection criteria include its SOL-16 (SOIC-16) package, gain-setting via single external resistor RG, laser-trimmed offset and drift performance, and operation across ±2.25V to ±18V supplies with –40°C to +85°C specification range.
Technical Context
The INA115BU implements a three-op-amp topology with accessible internal nodes (VO1, VO2, Gain Sense1/2), enabling switched-gain configurations and improved high-gain accuracy versus standard two-op-amp designs. Its input stage features on-chip 25kΩ feedback resistors and ±40V over-voltage protection diodes per input.
Gain is set by external RG using G = 1 + 50kΩ/RG, where the 50kΩ term derives from laser-trimmed on-die metal-film resistors. The Ref pin establishes output reference potential, requiring low-impedance connection to maintain CMRR; 5Ω series resistance degrades CMRR to ~80dB at G=1.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Gain Range | 1 to 10,000 V/V - set by single external resistor RG; enables flexible scaling without changing topology. |
| CMRR (G=1000) | 115 dB min - ensures accurate differential measurement in presence of large common-mode interference (e.g., 10V CM signal with 1mV differential). |
| Input Offset Voltage | ±50 µV max - supports sub-millivolt-level signal amplification without nulling circuitry in most applications. |
| Offset Drift | 0.25 µV/°C max - maintains calibration stability across industrial temperature range without recalibration. |
| Input Protection | ±40 V - allows direct connection to transducers exposed to transient surges (e.g., load cells, RTDs in harsh environments) without external clamping. |
| Supply Range | ±2.25 V to ±18 V - supports battery-powered (±3V) and high-voltage industrial (±15V) systems with same device. |
| Quiescent Current | 3 mA max - enables low-power data acquisition while retaining precision performance. |
Pinout & Package
SOL-16 surface-mount package (SOIC-16, package drawing DW), specified for –40°C to +85°C operating range. Pin 1 marked with dot; pin 1 quadrant Q1 per tape-and-reel standard.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | VO1 / Gain Sense1 | Output of first input op amp A1; used for feedback sensing or switched-gain control. |
| 2 | RG | External gain-setting resistor connection point (to pin 3); defines G = 1 + 50kΩ/RG. |
| 3 | V– | Negative power supply rail; must be decoupled locally for noise immunity. |
| 4 | VIN– | Inverting input terminal; requires bias current return path (e.g., matched resistor to Ref or V–). |
| 5 | VIN+ | Non-inverting input terminal; same bias current requirement as VIN–. |
| 6 | V+ | Positive power supply rail; local 0.1µF decoupling recommended. |
| 7 | NC | No connect - internally unused; must remain unconnected. |
| 8 | VO2 / Gain Sense2 | Output of second input op amp A2; paired with VO1 for advanced gain architectures. |
| 9 | NC | No connect - internally unused; must remain unconnected. |
| 10 | Ref | Output reference node; must be low-impedance (≤5Ω) to ground or system reference to preserve CMRR. |
| 11 | VO | Main output terminal; swing limited by supply rails and gain (e.g., ±13.5V at ±15V supplies, G=1). |
| 12 | Feedback | Output sense feedback node; must connect to VO (pin 11) unless remote-sensing at load is required. |
| 13 | NC | No connect - internally unused; must remain unconnected. |
| 14 | RG | Second terminal of external gain-setting resistor (to pin 2); completes gain equation path. |
| 15 | V+ | Redundant positive supply connection - electrically tied to pin 6; improves PSRR and thermal symmetry. |
| 16 | V– | Redundant negative supply connection - electrically tied to pin 3; improves PSRR and thermal symmetry. |
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 production systems. |
| Three-op-amp architecture with accessible nodes | VO1/VO2 and Gain Sense1/Sense2 pins enable true switched-gain amplifiers with <0.1% gain error across decades. |
| Integrated ±40V input protection | Withstands transients beyond supply rails without external components - reduces BOM count and PCB area in sensor interface designs. |
| Wide supply range (±2.25V to ±18V) | Operates from single 5V (±2.5V) up to ±15V industrial rails - one part supports portable and mains-powered equipment. |
| High CMRR at high gains | 115 dB minimum at G=1000 - rejects 300,000:1 common-mode interference, critical for microvolt-level thermocouple signals. |
Applications
| Bridge Amplifier | Thermocouple Amplifier |
|---|---|
Use Scenario: Amplifying mV-level differential output from strain-gauge Wheatstone bridges in load cells or pressure sensors under noisy industrial conditions. IC Role / Device Role / Timing Role: Precision instrumentation amplifier providing high CMRR, low offset, and stable gain to extract weak bridge signals amid 50/60Hz line noise and motor EMI. Use Value: Enables 16-bit+ resolution measurements without external filtering or chopper stabilization, reducing system latency and component count. | Use Scenario: Conditioning Type-K thermocouple outputs (≈41 µV/°C) in medical patient monitors or industrial process controllers with ambient temperature variations. IC Role / Device Role / Timing Role: Differential amplifier rejecting common-mode noise from long thermocouple leads while maintaining sub-0.5°C accuracy across –40°C to +85°C. Use Value: Laser-trimmed offset and 0.25 µV/°C drift ensure calibration holds over time and temperature - eliminating field recalibration cycles. |
| RTD Sensor Amplifier | Medical Instrumentation |
Use Scenario: Exciting and measuring 100Ω/1000Ω Pt RTDs in HVAC or laboratory temperature controllers where lead-wire resistance and self-heating must be minimized. IC Role / Device Role / Timing Role: Precision gain block with programmable RG setting, referenced to stable Ref node, enabling 4-wire Kelvin sensing and ratiometric excitation rejection. Use Value: ±40V input protection tolerates accidental probe contact with mains voltages during field service - improving product safety certification compliance. | Use Scenario: Front-end amplification in ECG machines where electrode half-cell potentials, motion artifacts, and 50/60Hz pickup must be rejected before ADC sampling. IC Role / Device Role / Timing Role: High-CMRR instrumentation amplifier with right-leg drive interface capability (via Ref and VO pins) to actively cancel common-mode interference. Use Value: 115dB CMRR at G=1000 suppresses >99.999% of 60Hz interference - enabling clean P/QRS waveforms without notch filters that distort ST segments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar instrumentation amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| INA128UA | Higher CMRR (130dB min at G=100), lower input bias current (500pA), but no VO1/VO2 pins; SO-8 package. | Better for ultra-low-bias applications (e.g., pH electrodes), but lacks switched-gain flexibility and requires different layout. | Select INA128UA when ultimate CMRR and femtoampere-level bias current outweigh need for gain-switching or SOIC-16 footprint. |
| AD620ARZ | Lower power (1.3mA), smaller SO-8 package, but only 100dB CMRR at G=1000 and no input over-voltage protection beyond ±Vs. | Suitable for space-constrained portable devices, but requires external protection for industrial transducer interfaces. | Choose AD620ARZ for battery-powered handheld instruments where size and quiescent current dominate over ruggedness and CMRR. |
Compared with INA128UA and AD620ARZ, the INA115BU uniquely combines SOIC-16 pin access to internal op-amp outputs (VO1/VO2), ±40V input protection, and laser-trimmed 115dB CMRR - making it the only option among the three capable of robust, reconfigurable switched-gain architectures in industrial sensor signal chains.
Availability
INA115BU is available at Aetrix Electronics and suitable for bridge amplifier designs, thermocouple signal conditioning, and medical ECG front-ends requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for INA115BU 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 full production and support for legacy precision analog products including the INA115 series.
The INA115BU belongs to TI's precision instrumentation amplifier product line, engineered for high-accuracy DC-coupled sensor signal conditioning in industrial automation, test equipment, and medical diagnostics where offset, drift, and CMRR directly impact measurement integrity.
FAQ
What is the maximum gain achievable with the INA115BU, and how is it set?
The INA115BU supports gains from 1 to 10,000 V/V, set by a single external resistor RG connected between pins 2 and 14. The gain equation is G = 1 + 50kΩ/RG. For G=10,000, RG = 5.001Ω (nearest 1% value: 4.99Ω). At high gains, routing RG with force-and-sense connections minimizes trace resistance errors. The INA115BU datasheet provides a table of standard RG values for common gains.
Does the INA115BU require external components for basic operation?
Yes - the INA115BU requires at minimum: (1) decoupling capacitors (0.1µF ceramic) on V+ (pins 6,15) and V– (pins 3,16), (2) an external RG resistor to set gain, and (3) a low-impedance connection (<5Ω) from Ref (pin 10) to system ground or reference. VO (pin 11) must connect to Feedback (pin 12) unless remote sensing is used. No external offset trim is needed due to laser trimming.
How does the INA115BU handle input over-voltage conditions?
The INA115BU includes integrated ±40V input over-voltage protection on both inputs, allowing survival of transients exceeding supply rails - e.g., –40V on VIN– and +40V on VIN+ simultaneously. Internal protection limits input current to ~1.5mA without damage, even with zero supply voltage. This eliminates need for external TVS diodes in many industrial sensor interfaces, unlike unprotected alternatives such as AD620ARZ.
Can the INA115BU operate from a single 5V supply?
Yes - the INA115BU operates from split supplies as low as ±2.25V (i.e., total 4.5V), enabling true single 5V rail operation with appropriate level-shifting. For single-supply use, Ref (pin 10) must be biased to mid-rail (e.g., 2.5V), and input common-mode range shifts accordingly (±1.25V around Ref). Output swing is reduced vs. dual supplies, but ±1.5V is achievable at ±2.25V supplies per the INA115BU specifications table.
What is the purpose of pins VO1 and VO2 on the INA115BU?
Pins VO1 (pin 1) and VO2 (pin 8) provide direct access to the outputs of the two input-stage operational amplifiers (A1 and A2). This enables advanced configurations like switched-gain amplifiers (using multiplexers on VO1/VO2), improved gain accuracy at high G, and custom feedback topologies. Unlike standard instrumentation amps, the INA115BU exposes these nodes - a key differentiator from alternatives like INA128UA or AD620ARZ which lack this feature.
INA115BU 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:
- 10 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
INA115BU FAQ
1.How can I place an order for INA115BU through Aetrix?
Please submit a Request for Quotation (RFQ) for INA115BU 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 INA115BU reliable?
The price and inventory of INA115BU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for INA115BU is usually 5 days.
3.What payment methods are accepted for INA115BU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for INA115BU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for INA115BU?
INA115BU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your INA115BU 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 INA115BU?
For technical support, including INA115BU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your INA115BU requirements.
6.How does Aetrix verify that INA115BU is sourced from the original manufacturer or authorized distributors?
All INA115BU 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 INA115BU meets industry standards.
7.What is the process for return or replacement of INA115BU?
All INA115BU units undergo pre-shipment inspection (PSI). If there is an issue with INA115BU, 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 INA115BU part is unused and in its original packaging.
Return procedure for INA115BU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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