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Texas Instruments INA111AU/1K
- Part No.:
- INA111AU/1K
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 16-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
INA111AU/1K.pdf
- Description:
- IC INST AMP 1 CIRCUIT 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,650
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Product details
Overview
INA111AU/1K from Texas Instruments (originally Burr-Brown) is a high-speed, FET-input instrumentation amplifier optimized for precision DC-coupled signal conditioning in data acquisition and medical instrumentation. It delivers 4 µs settling time to 0.01% at G = 100, 106 dB minimum CMRR at G = 100, and ±500 µV max input offset voltage over temperature - enabling accurate amplification of low-level sensor outputs such as bridge transducers and thermocouples.
For engineers reviewing the INA111AU/1K datasheet, INA111AU/1K pinout, INA111AU/1K application, or INA111AU/1K equivalent, this page provides verified technical context, package-specific pin mapping (SOIC-16), gain-setting resistor guidance, output sense feedback implementation, and validated alternative options for instrumentation-grade signal chains requiring low bias current (<20 pA), wide bandwidth (2 MHz at G = 1), and laser-trimmed DC accuracy.
Technical Context
The INA111AU/1K employs a current-feedback topology with three internal op amps (A1–A3), enabling extended bandwidth (2 MHz at G = 1) and fast settling (4 µs to 0.01% at G = 100) independent of traditional voltage-feedback limitations. Its gain is set by a single external resistor RG via G = 1 + 50 kΩ/RG, supporting gains from 1 to 10,000.
Unlike standard op amps, the SOIC-16 variant includes dedicated output sense (pin 12) and feedback (pin 11) terminals for remote load sensing and improved accuracy under trace impedance; these are internally shorted in the DIP version. Input common-mode range extends to ±12 V, but linear operation depends on output swing limits of A1/A2, as shown in the "Input Common-Mode Range vs Output Voltage" curve.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Gain Range | 1 to 10,000 - set by single external RG resistor; enables flexible scaling without complex resistor networks. |
| Settling Time (0.01%) | 4 µs at G = 100 - ensures rapid stabilization for multiplexed data acquisition systems sampling at ≥100 kSPS. |
| CMRR (min) | 106 dB at G = 100 - rejects interference from noisy industrial or medical environments when inputs are balanced. |
| Input Bias Current | ±20 pA max - minimizes voltage error across high-impedance sources (e.g., piezoelectric sensors, pH electrodes). |
| Input Offset Voltage | ±500 µV max - laser-trimmed for stable DC accuracy without external nulling in battery-powered portable instruments. |
| Bandwidth (–3 dB) | 2 MHz at G = 1, 450 kHz at G = 100 - supports wideband physiological signals (ECG, EEG) and dynamic strain measurements. |
| Supply Voltage Range | ±6 V to ±18 V - accommodates dual-rail industrial power supplies while maintaining rail-to-rail output swing capability. |
Pinout & Package
Sold in 16-pin SOIC (DW) package per TI's packaging addendum; MSL Level-3, 260°C peak reflow, tape-and-reel (1000 pcs/reel). Pin 1 orientation quadrant Q1 per JEDEC standard.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 13, 14, 15, 16 | No Connect (NC) | Unused die pads; must remain unconnected to avoid parasitic coupling or latch-up risk. |
| 5, 6 | Differential Input (VIN+, VIN–) | High-impedance FET inputs; require matched PCB traces and guard ring for optimal CMRR above 10 kHz. |
| 7 | Reference (Ref) | Output reference node; must be low-impedance (≤2 Ω) to preserve CMRR - connect directly to system ground or buffered reference. |
| 8 | Positive Supply (V+) | Connect to +VS rail with local 0.1 µF ceramic decoupling capacitor placed ≤5 mm from pin. |
| 9 | Negative Supply (V–) | Connect to –VS rail with identical decoupling; imbalance >100 mV between V+/V– grounds degrades PSRR. |
| 10 | Gain-Setting Resistor (RG) | Connect external RG between pins 10 and 11; values from 4.99 Ω (G = 10,000) to open (G = 1); wiring resistance affects high-gain accuracy. |
| 11 | Output (VO) | Main amplified output; drive capability up to ±25 mA short-circuit current; stable with ≤1000 pF capacitive load. |
| 12 | Output Sense (Feedback) | SOIC-only feature; connect directly to VO (pin 11) for standard use, or to remote load for improved accuracy - enables 4-wire sensing. |
Key Features
| Feature | Design Value |
|---|---|
| FET-input architecture | Input bias current <20 pA enables direct interfacing with high-Z sensors (e.g., glass pH electrodes, piezoresistive bridges) without signal degradation. |
| Current-feedback topology | Maintains 2 MHz bandwidth at G = 1 and 450 kHz at G = 100 - avoids gain-bandwidth trade-off typical of voltage-feedback amplifiers. |
| Laser-trimmed offset & drift | ±500 µV max offset and ±5 µV/°C max drift eliminate need for manual calibration in portable medical devices operating across –40°C to +85°C. |
| Dedicated output sense (SOIC only) | Pin 12 allows Kelvin connection to load - compensates for voltage drop across PCB traces or connectors in precision weigh-scale or industrial control applications. |
| Robust input protection | Withstands input voltages from (V– – 0.7 V) to (V+ + 15 V); clamp diodes unnecessary if source current limited to <1 mA - simplifies front-end design. |
Applications
| Bridge Transducer Amplifier | Medical ECG Signal Conditioning |
|---|---|
Use Scenario: Amplifying mV-level differential output from Wheatstone bridge pressure or load cells in industrial weighing systems. IC Role / Device Role / Timing Role: Precision instrumentation amplifier providing gain, common-mode rejection, and output referencing for ratiometric bridge excitation. Use Value: 106 dB CMRR suppresses supply noise and EMI; output sense (pin 12) corrects for trace resistance-induced gain error in long cable runs. |
Use Scenario: Front-end amplification of low-amplitude, high-impedance biopotential signals (e.g., ECG leads) in portable patient monitors. IC Role / Device Role / Timing Role: First-stage gain block with ultra-low input bias current to prevent electrode polarization and DC drift. Use Value: ±20 pA input bias current prevents charge accumulation on dry electrodes; 4 µs settling supports real-time ST-segment analysis at 500 Hz sampling. |
| Data Acquisition Channel | Thermocouple Interface |
Use Scenario: Multiplexed analog input channel in 12-bit ADC-based DAQ systems handling multiple sensor types (RTD, strain gauge, voltage). IC Role / Device Role / Timing Role: Programmable-gain instrumentation amplifier synchronized with channel switching to minimize settling latency. Use Value: Single RG resistor enables software-selectable gain (1–1000); 2 MHz bandwidth preserves transient fidelity during fast channel hopping. |
Use Scenario: Cold-junction compensated thermocouple amplifier in HVAC controllers and furnace monitoring. IC Role / Device Role / Timing Role: Differential amplifier rejecting millivolt-level thermal EMF while rejecting common-mode noise from heating elements. Use Value: ±500 µV offset ensures ≤0.5°C measurement error at 0°C; input common-mode range up to ±12 V accommodates wide ambient temperature swings. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar instrumentation amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD8421ARZ | Higher bandwidth (10 MHz at G = 1), lower noise (1.2 nV/√Hz), but higher input bias current (±1 nA) and no output sense pin. | Better for high-frequency sensor interfaces (e.g., ultrasonic NDT), unsuitable for ultra-high-Z sources like pH electrodes. | Select AD8421ARZ when bandwidth >5 MHz is required and source impedance <10 kΩ; avoid for thermocouple or piezo applications. |
| INA128UA | Lower cost, lower speed (125 kHz BW at G = 100), higher input bias current (±2 nA), same SOIC-16 footprint but no output sense pin. | Targeted at static or slow-varying measurements (e.g., load cell readouts, industrial process control) where settling time >10 µs is acceptable. | Choose INA128UA for cost-sensitive, low-speed applications where 4 µs settling and output sense are not required. |
Compared with AD8421ARZ and INA128UA, the INA111AU/1K uniquely balances sub-20 pA input bias, 4 µs settling, and SOIC-16 output sense capability - making it irreplaceable in portable medical devices and precision bridge DAQ systems demanding both DC accuracy and dynamic response.
Availability
INA111AU/1K is available at Aetrix Electronics and suitable for medical instrumentation, industrial data acquisition, and precision sensor interface applications requiring stable component supply, long-term lifecycle support, and consistent SOIC-16 tape-and-reel delivery.
Supply support for INA111AU/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 full production, qualification, and support for legacy precision analog products including the INA111 family.
The INA111 product line was designed specifically for high-fidelity, low-drift instrumentation signal chains in medical, test equipment, and industrial sensing - emphasizing FET input performance, laser-trimmed DC specs, and robust layout-insensitive operation.
FAQ
What is the correct way to connect the RG resistor for gain setting on the INA111AU/1K?
The RG resistor must be connected between pin 10 (RG terminal) and pin 11 (VO output) of the INA111AU/1K. For G = 1, leave pins 10 and 11 unconnected. For G = 100, use 511 Ω (1% tolerance); for G = 1000, use 49.9 Ω. Wiring resistance matters above G = 100 - keep traces short and avoid sockets. The INA111AU/1K gain equation is strictly G = 1 + 50 kΩ/RG, with internal 50 kΩ trimmed resistors defining accuracy.
Does the INA111AU/1K require external offset trimming in typical applications?
No - the INA111AU/1K is laser-trimmed for ±500 µV max input offset voltage and ±5 µV/°C max drift, eliminating need for external trim in most medical and industrial applications. Only high-precision systems demanding <50 µV offset (e.g., laboratory-grade DAQ) should consider optional Ref-pin trimming using an OPA177 buffer, as shown in Figure 2 of the INA111 datasheet. The INA111AU/1K's internal trimming covers full –40°C to +85°C range.
How does the output sense (pin 12) function in the INA111AU/1K, and when should it be used?
Pin 12 is the dedicated output sense (feedback) terminal unique to the SOIC-16 version of the INA111AU/1K. It must be connected to pin 11 (VO) for standard operation. For improved accuracy under load, connect pin 12 directly to the remote load point - enabling 4-wire sensing that cancels voltage drop across PCB traces or connectors. This feature is absent in DIP versions and critical for precision weigh-scale or motor current-sense applications where trace resistance exceeds 100 mΩ.
Can the INA111AU/1K operate with single-supply voltages?
No - the INA111AU/1K is specified only for dual-supply operation (±6 V to ±18 V) and lacks rail-to-rail input or output capability. Its input common-mode range is limited to ±12 V, and output swing is typically ±11 V into 2 kΩ. For single-supply designs, consider TI's INA333 or ADI's AD8226 - neither offers the INA111AU/1K's 4 µs settling or sub-20 pA bias current. Attempting single-supply use with level-shifting risks violating absolute maximum ratings and invalidating CMRR performance.
What layout practices maximize CMRR for the INA111AU/1K in high-noise environments?
To maximize CMRR, route VIN+ and VIN– traces as a tightly coupled, equal-length differential pair directly from the source to pins 5 and 6, with a solid ground plane beneath. Match trace capacitance using identical C1/C2 input filter caps (Figure 6), avoid vias near inputs, and keep Ref (pin 7) connection low-impedance (<2 Ω). Any series resistance in the Ref path degrades CMRR - e.g., 2 Ω reduces 90 dB CMRR to ~80 dB at G = 1. These practices ensure the INA111AU/1K achieves its rated 106 dB CMRR in real-world EMI-heavy settings.
INA111AU/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:
- 17V/µs
- Gain Bandwidth Product:
- -
- -3db Bandwidth:
- 2 MHz
- Current - Input Bias:
- 2 pA
- Voltage - Input Offset:
- 200 µV
- Current - Supply:
- 3.3mA
- Current - Output / Channel:
- 30 mA
- Voltage - Supply Span (Min):
- 12 V
- Voltage - Supply Span (Max):
- 36 V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
INA111AU/1K FAQ
1.How can I place an order for INA111AU/1K through Aetrix?
Please submit a Request for Quotation (RFQ) for INA111AU/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 INA111AU/1K reliable?
The price and inventory of INA111AU/1K are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for INA111AU/1K is usually 5 days.
3.What payment methods are accepted for INA111AU/1K?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for INA111AU/1K transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for INA111AU/1K?
INA111AU/1K orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your INA111AU/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 INA111AU/1K?
For technical support, including INA111AU/1K datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your INA111AU/1K requirements.
6.How does Aetrix verify that INA111AU/1K is sourced from the original manufacturer or authorized distributors?
All INA111AU/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 INA111AU/1K meets industry standards.
7.What is the process for return or replacement of INA111AU/1K?
All INA111AU/1K units undergo pre-shipment inspection (PSI). If there is an issue with INA111AU/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 INA111AU/1K part is unused and in its original packaging.
Return procedure for INA111AU/1K:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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