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Texas Instruments INA115AU/1K
- Part No.:
- INA115AU/1K
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 16-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
INA115AU/1K.pdf
- Description:
- IC INST AMP 1 CIRCUIT 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,473
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Product details
Overview
INA115AU/1K from Texas Instruments (formerly Burr-Brown) is a precision instrumentation amplifier with three-op-amp architecture, designed for low-noise, high-accuracy signal conditioning in sensor interfaces. It delivers 50 µV max input offset voltage, 115 dB min CMRR at G=1000, ±40 V input over-voltage protection, and operates from ±2.25 V to ±18 V supplies - ideal for thermocouple, RTD, and bridge-based industrial measurement systems.
For engineers reviewing the INA115AU/1K datasheet, INA115AU/1K pinout, INA115AU/1K application, or INA115AU/1K equivalent, this page provides verified technical context, gain-setting resistor guidance, input bias current return path requirements, common-mode range limitations, and validated alternatives for switched-gain, medical ECG, and data acquisition designs.
Technical Context
The INA115AU/1K implements a classic three-op-amp topology with externally accessible A1/A2 outputs (pins 1 and 8) and dedicated feedback sense (pin 12), enabling precise load-referred output regulation and switched-gain configurations. Its laser-trimmed 50 kΩ internal feedback resistor pair sets gain via single external RG per G = 1 + 50 kΩ/RG.
Input over-voltage protection operates independently per input up to ±40 V without damage or latch-up, even with zero supply. The Ref pin (pin 10) defines output reference potential and requires ≤5 Ω impedance for >100 dB CMRR; pin 12 must be connected to pin 11 (VO) unless remote sensing is used.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Gain Range | 1 to 10,000 V/V - set by single external RG; G=1 requires no resistor but specific pin shorts. |
| Input Offset Voltage | ±50 µV max (RTI) - enables sub-100 µV system-level DC accuracy without trimming. |
| CMRR | 115 dB min at G=1000 - ensures rejection of 10 V common-mode interference down to ~32 µV error. |
| Input Protection | ±40 V absolute max - survives transient overloads without damage, even with unpowered supplies. |
| Supply Range | ±2.25 V to ±18 V - supports battery-powered (±3 V) and industrial (±15 V) rails with 3 mA max quiescent current. |
| Bandwidth | 1 MHz at G=1, 1 kHz at G=1000 - trade-off between gain and small-signal speed is explicit and predictable. |
| Operating Temp | –40°C to +85°C - specified performance across full industrial temperature range. |
Pinout & Package
SOL-16 surface-mount package (SOIC-16, TI package code DW), 10.3 mm × 7.5 mm body, 1.27 mm pitch, RoHS-compliant NiPdAu lead finish, MSL Level-3.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (VO1) | A1 output | Provides access to first-stage output; used in switched-gain and remote-sense configurations. |
| 2 (Gain Sense1) | A1 output sense | Connects to VO1 for internal feedback; required for proper A1 operation when VO1 is loaded. |
| 3 (RG) | Gain-setting resistor terminal | One end of external RG; other end connects to pin 14. Sets gain per G = 1 + 50 kΩ/RG. |
| 4 (V–) | Negative supply | Must be decoupled locally; supports operation down to ±2.25 V. |
| 5 (IN–) | Inverting input | Differential input node; requires bias current return path (e.g., matched resistors to V– or Ref). |
| 6 (IN+) | Non-inverting input | Differential input node; same bias current requirement as IN–. |
| 7 (NC) | No connect | Internally unused; leave floating or grounded per layout best practice. |
| 8 (VO2) | A2 output | Provides access to second-stage output; symmetric to VO1 for dual-output topologies. |
| 9 (NC) | No connect | Internally unused; leave floating or grounded. |
| 10 (Ref) | Output reference | Defines output common-mode level; must be low-impedance (≤5 Ω) for full CMRR spec. |
| 11 (VO) | Main output | Final amplified output; drives 2 kΩ load to ±13.5 V with ±15 V supplies. |
| 12 (Feedback) | Output sense feedback | Must connect to VO (pin 11) unless using remote sensing; critical for stability and accuracy. |
| 13 (V+) | Positive supply | Must be decoupled locally; same voltage magnitude as V– for symmetrical operation. |
| 14 (RG) | Gain-setting resistor terminal | Second end of external RG; completes gain-setting network with pin 3. |
| 15 (Gain Sense2) | A2 output sense | Connects to VO2 for internal feedback; required when VO2 is loaded. |
| 16 (NC) | No connect | Internally unused; leave floating or grounded. |
Key Features
| Feature | Design Value |
|---|---|
| Laser-trimmed 50 kΩ feedback resistors | Enables accurate, low-drift gain setting without external precision resistors; contributes to ±0.5% gain error at G=1000. |
| Independent ±40 V input protection | Prevents damage during sensor disconnect, ESD events, or power sequencing faults - no external clamps needed. |
| Accessible A1/A2 outputs (pins 1 & 8) | Supports true switched-gain architectures with multiplexed RG networks and eliminates gain peaking at G=1. |
| Low 0.25 µV/°C offset drift | Maintains calibration integrity over industrial temperature range without active compensation circuits. |
| Dedicated Ref and Feedback pins | Enables ground-referenced or level-shifted outputs and remote-sense accuracy for long-cable or high-current loads. |
Applications
| Bridge Amplifier | Thermocouple Amplifier |
|---|---|
|
Use Scenario: Wheatstone bridge output from strain gauge or pressure sensor, typically <10 mV full-scale, with high common-mode noise in factory environments. IC Role / Device Role / Timing Role: Precision differential-to-single-ended conversion with gain programmability and rail-to-rail common-mode rejection. Use Value: Delivers 115 dB CMRR at G=1000 to suppress 10 V line-frequency interference, enabling 16-bit resolution from low-level bridge signals. |
Use Scenario: Type-K thermocouple measuring 0°C to 1000°C in furnace control, requiring cold-junction compensation and sub-1°C accuracy. IC Role / Device Role / Timing Role: High-input-impedance, low-drift front-end amplifier with stable gain and minimal self-heating error. Use Value: 50 µV max offset and 0.25 µV/°C drift ensure <0.5°C measurement error over full temperature range without recalibration. |
| RTD Sensor Amplifier | Medical Instrumentation |
|
Use Scenario: 3-wire Pt100 RTD in HVAC or process control, excited by constant current source, requiring linearization and noise immunity. IC Role / Device Role / Timing Role: Low-bias-current (2 nA max), high-CMRR instrumentation amplifier for ratiometric measurement against excitation reference. Use Value: Input bias current <2 nA minimizes voltage drop across 100 Ω RTD, preserving linearity; ±40 V protection guards against field wiring faults. |
Use Scenario: ECG front-end amplifying microvolt-level cardiac signals in presence of 50/60 Hz mains interference and electrode motion artifacts. IC Role / Device Role / Timing Role: Primary gain stage with right-leg drive interface support (via Ref and VO2 pins) and overload-safe inputs. Use Value: 115 dB CMRR rejects common-mode mains noise; ±40 V input tolerance prevents damage during defibrillation events or lead disconnection. |
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 (±0.1% max) and reference; fixed G=5, no external RG; SO-8 package. | Better suited for 4–20 mA loop-powered transmitters; lacks programmable gain and A1/A2 access. | Select INA125P only when integrated excitation and fixed gain simplify design; not a drop-in replacement. |
| AD8421ARZ | 10 nV/√Hz noise (vs 11 nV/√Hz @1kHz), 130 dB CMRR, 20 MHz bandwidth at G=1; SOIC-8, no A1/A2 outputs. | Superior high-frequency CMR and noise for wideband sensor signals; no switched-gain capability. | Choose AD8421ARZ for >100 kHz applications or where board space limits SOIC-16 use; requires different layout and gain network. |
Compared with INA115AU/1K, INA125P trades programmable gain and topology flexibility for integrated excitation, while AD8421ARZ offers higher bandwidth and CMRR but abandons the three-op-amp architecture needed for true switched-gain and remote sensing.
Availability
INA115AU/1K is available at Aetrix Electronics and suitable for industrial sensor interfaces, medical device signal chains, and test equipment requiring stable component supply with guaranteed long-term manufacturability and traceable sourcing.
Supply support for INA115AU/1K 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, low-drift, and robust industrial-grade signal conditioning ICs.
The INA115 belongs to TI's legacy instrumentation amplifier family designed specifically for DC-coupled, low-frequency sensor signal conditioning - prioritizing offset, drift, CMRR, and input protection over speed or power efficiency.
FAQ
What is the correct way to configure INA115AU/1K for G=1 operation?
For G=1, leave RG unconnected but short pins 2–3 and pins 14–15 to engage internal 25 kΩ feedback resistors. To reduce gain peaking, additionally short pins 1–2–3 and pins 8–14–15. Do not connect RG - doing so forces G > 1. The INA115AU/1K datasheet confirms this configuration avoids instability while maintaining full CMRR and bandwidth.
Does INA115AU/1K require external input protection diodes?
No. The INA115AU/1K includes monolithic input protection that withstands ±40 V continuously on either input, even with zero supply voltage. External diodes add noise and leakage, degrading the 2 nA max input bias current spec. This protection is intrinsic to the INA115AU/1K silicon design and verified in Absolute Maximum Ratings.
How does the Ref pin affect common-mode rejection in INA115AU/1K?
The Ref pin (pin 10) sets the output common-mode voltage. A series impedance >5 Ω here degrades CMRR to ~80 dB (G=1), per the INA115AU/1K datasheet. For full 115 dB CMRR, Ref must connect directly to a low-impedance ground or reference - never through a resistor or filter. This requirement is fundamental to INA115AU/1K's three-op-amp architecture.
Can INA115AU/1K drive a 600 Ω audio line?
No. The INA115AU/1K is rated for 2 kΩ minimum load (±13.5 V swing @ ±15 V supplies). Driving 600 Ω risks output clipping, thermal stress, and degraded THD. Use a buffer op amp (e.g., OPA1632) after the INA115AU/1K if low-impedance driving is required - the INA115AU/1K itself is not intended for audio line-driving duty.
What is the maximum safe RG value for stable operation of INA115AU/1K?
The INA115AU/1K remains stable with RG up to 50 kΩ (G=2), confirmed by the Gain vs Frequency curve showing no peaking. For G=1, RG is omitted entirely. Values >50 kΩ (e.g., G=1.5) are not characterized; TI recommends staying within the 1–10,000 gain range documented in the INA115AU/1K datasheet to guarantee phase margin and settling behavior.
INA115AU/1K Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 16-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- 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/1K FAQ
1.How can I place an order for INA115AU/1K through Aetrix?
Please submit a Request for Quotation (RFQ) for INA115AU/1K 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/1K reliable?
The price and inventory of INA115AU/1K are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for INA115AU/1K is usually 5 days.
3.What payment methods are accepted for INA115AU/1K?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for INA115AU/1K transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for INA115AU/1K?
INA115AU/1K orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your INA115AU/1K 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/1K?
For technical support, including INA115AU/1K datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your INA115AU/1K requirements.
6.How does Aetrix verify that INA115AU/1K is sourced from the original manufacturer or authorized distributors?
All INA115AU/1K 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/1K meets industry standards.
7.What is the process for return or replacement of INA115AU/1K?
All INA115AU/1K units undergo pre-shipment inspection (PSI). If there is an issue with INA115AU/1K, 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/1K part is unused and in its original packaging.
Return procedure for INA115AU/1K:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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