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Texas Instruments INA125UA
- Part No.:
- INA125UA
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
INA125UA.pdf
- Description:
- IC INST AMP 1 CIRCUIT 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:644
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Product details
Overview
INA125UA from Texas Instruments (originally Burr-Brown) is a precision instrumentation amplifier with integrated voltage reference, designed for bridge sensor signal conditioning in industrial and battery-powered systems. It delivers 100 dB min CMR at G=100, 250 µV max input offset voltage, and selectable 2.5 V / 5 V / 10 V reference outputs - enabling direct excitation of strain gauge and RTD bridges.
For engineers reviewing the INA125UA datasheet, INA125UA pinout, INA125UA application, or INA125UA equivalent, this page provides verified specifications, SO-16 package layout, sleep-mode power management details, and validated alternative options for transducer interface design.
Technical Context
The INA125UA integrates two high-precision op amps (A1 and A2) in a three-op-amp instrumentation topology with laser-trimmed internal 60 kΩ gain-setting resistors. Its reference section uses ratio-trimmed bandgap circuitry to deliver ±0.5% accurate 2.5 V / 5 V / 10 V outputs with ±35 ppm/°C drift.
Sleep mode is controlled by a dedicated logic-level input (pin 2), reducing quiescent current to ±1 µA while raising output impedance to ~80 kΩ. Gain is set externally via RG between pins 8–9 per G = 4 + 60 kΩ/RG, supporting 4–10,000× linear range without trimming.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Gain Range | 4 to 10,000 V/V - set by single external resistor RG; enables scalable amplification without recalibration. |
| Input Offset Voltage | ±250 µV max - ensures sub-0.01% error in 10 mV full-scale bridge outputs at G=100. |
| CMR @ G=100 | 100 dB min - rejects common-mode noise from long cable runs or noisy industrial grounds. |
| Reference Accuracy | ±0.5% max - supports ratiometric ADC conversion with <0.1% system gain error contribution. |
| Quiescent Current | 460 µA typical - enables multi-year operation on coin-cell batteries in portable data loggers. |
| Sleep Current | ±1 µA max - allows duty-cycled acquisition with >99% power reduction during idle periods. |
| Supply Range | ±1.35 V to ±18 V dual or +2.7 V to +36 V single - supports legacy ±15 V rails and modern low-voltage IoT nodes. |
| Input Protection | ±40 V absolute max - survives ESD events and wiring faults without external clamping diodes. |
Pinout & Package
INA125UA is housed in a 16-pin SOIC (SO-16) surface-mount package with 1.27 mm pitch, JEDEC MS-012AC compliant, and moisture sensitivity level 3 (260°C reflow).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (V+) | Positive supply input | Accepts +2.7 V to +36 V; powers all internal amplifiers and reference circuitry. |
| 2 (SLEEP) | Shutdown control input | Logic-low ≤100 mV activates sleep mode; logic-high ≥2.7 V enables normal operation. |
| 3 (V−) | Negative supply input | Accepts −1.35 V to −18 V in dual supply; tied to ground in single-supply configurations. |
| 4 (VREFOUT) | Reference output node | Delivers selected reference voltage (2.5/5/10 V) to bridge excitation or ADC reference inputs. |
| 5 (IAREF) | Instrumentation amp reference | Output common point; must be low-impedance grounded to maintain >80 dB CMR. |
| 6 (VIN−) | Inverting input | Differential input terminal; requires bias current return path (e.g., matched resistors to IAREF). |
| 7 (VIN+) | Non-inverting input | Differential input terminal; shares same high-Z, ±40 V protected input structure as pin 6. |
| 8, 9 (RG) | External gain resistor terminals | Connects RG to set gain per G = 4 + 60 kΩ/RG; values from 6 Ω (G=10k) to open (G=4). |
| 10 (VO) | Amplifier output | Single-ended output referenced to IAREF; swings to within 0.9 V of V+ and 0.4 V of V−. |
| 11 (Sense) | Reference current sense | Monitors reference load current; used internally to regulate VREF accuracy under varying loads. |
| 12 (VREF10) | 10 V reference selection | Connecting VREFOUT (pin 4) here configures 10 V output; laser-trimmed for ±0.5% initial accuracy. |
| 13 (VREFBG) | Bandgap reference (1.24 V) | Provides 1.24 V ±0.5% output; usable when supply headroom is limited (e.g., +2.7 V operation). |
| 14 (VREF5) | 5 V reference selection | Enables 5 V bridge excitation; matches standard ADC reference voltages for ratiometric measurement. |
| 15 (VREF2.5) | 2.5 V reference selection | Supports low-power sensors and 3.3 V microcontroller interfaces with minimal headroom. |
| 16 (VREFCOM) | Reference common | Return path for reference current (~180 µA); connect to sensor ground to avoid ground loops. |
Key Features
| Feature | Design Value |
|---|---|
| Laser-trimmed gain resistors | 60 kΩ internal resistors trimmed for ±0.075% gain error at G=10, eliminating external calibration. |
| Pin-selectable reference outputs | Hardware-configured 2.5 V / 5 V / 10 V / 1.24 V outputs - no software or external DAC required. |
| Integrated input protection | ±40 V fault tolerance on VIN+/VIN− - removes need for discrete TVS diodes in harsh environments. |
| Low-drift offset voltage | 2 µV/°C max drift - maintains <1 µV error over −40°C to +85°C industrial temperature range. |
| Single-resistor gain programming | G = 4 + 60 kΩ/RG equation - simplifies BOM and layout vs. multi-resistor instrumentation amps. |
| Sleep-mode wake-up time | 150 µs typical - enables rapid sampling bursts without sacrificing power savings in intermittent use. |
Applications
| Pressure Bridge Amplifier | Temperature RTD Interface |
|---|---|
|
Use Scenario: Strain gauge bridge in hydraulic pressure transducer operating at 125°C ambient. IC Role / Device Role / Timing Role: Provides 10 V bridge excitation and 100× differential amplification with ratiometric rejection of supply variation. Use Value: Delivers 0.1% total system accuracy despite ±40 V EMI transients and 85°C temperature swing. |
Use Scenario: 3-wire Pt100 RTD measurement in factory automation PLC analog input module. IC Role / Device Role / Timing Role: Supplies precise 2.5 V excitation and amplifies low-level ΔV across RTD with 100 dB CMR against motor drive noise. Use Value: Enables 0.05°C resolution without 4–20 mA loop conversion or external precision references. |
| Battery-Powered Data Logger | Multi-Channel Industrial DAQ |
|
Use Scenario: Portable vibration monitor logging accelerometer data every 10 seconds using CR2032 cell. IC Role / Device Role / Timing Role: Sleeps between samples (1 µA), wakes to acquire and amplify sensor signal, then returns to ultra-low-power state. Use Value: Extends battery life to >3 years while maintaining 250 µV offset stability across operating temperature. |
Use Scenario: 16-channel programmable gain amplifier board for test equipment with shared reference bus. IC Role / Device Role / Timing Role: Each INA125UA provides independent gain and reference selection; VREFCOM pins daisy-chained to common sensor ground. Use Value: Eliminates channel-to-channel crosstalk from reference coupling and reduces PCB area by 40% vs. discrete solutions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar instrumentation amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD8226ARMZ | No integrated reference; requires external 2.5 V reference; lower quiescent current (350 µA); 35 nV/√Hz noise. | Best for space-constrained designs where reference is already available; not suitable for standalone bridge excitation. | Select when system already includes precision reference and lowest possible noise is critical. |
| INA333AIDR | Includes internal RG; no selectable reference outputs; 10 µV max offset; 36 V supply max; SO-8 package. | Optimized for low-cost, low-power portable medical sensors; lacks multi-voltage reference flexibility. | Select for consumer-grade wearable devices requiring smallest footprint and lowest offset, not industrial bridge excitation. |
Compared with AD8226ARMZ and INA333AIDR, the INA125UA uniquely combines pin-selectable reference outputs, ±40 V input protection, and SO-16 layout compatibility - making it the only option that replaces discrete bridge driver + amplifier + reference subsystems without redesign.
Availability
INA125UA is available at Aetrix Electronics and suitable for pressure transducers, RTD interfaces, and battery-powered data loggers requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for INA125UA 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 conditioning for industrial, medical, and test equipment markets.
The INA125 series was designed specifically for integrated bridge sensor signal chains - combining instrumentation amplification, excitation, and reference in one SO-16 IC to reduce system cost and improve measurement integrity.
FAQ
What is the maximum supply voltage for INA125UA?
The INA125UA supports a dual supply range of ±1.35 V to ±18 V or a single supply from +2.7 V to +36 V. Absolute maximum ratings specify 36 V between V+ and V−, and ±40 V on VIN+/VIN− inputs regardless of supply state - ensuring robustness during power sequencing or fault conditions. Operation beyond these limits risks permanent damage.
How do I configure the INA125UA for 5 V bridge excitation?
To configure 5 V bridge excitation, connect pin 4 (VREFOUT) to pin 14 (VREF5). This selects the laser-trimmed 5 V reference output, accurate to ±0.5% with ±35 ppm/°C drift. Ensure V+ is at least 6.25 V (5 V + 1.25 V dropout) and tie VREFCOM (pin 16) to system ground or sensor common to maintain reference stability and avoid ground loops.
Can the INA125UA operate from a +3.3 V supply?
Yes, the INA125UA operates from +3.3 V single supply, but only the 1.24 V bandgap reference (VREFBG, pin 13) is usable due to minimum headroom requirements. Connect VREFOUT (pin 4) to VREFBG (pin 13), tie V− and VREFCOM (pin 16) to ground, and ensure VIN+/VIN− remain ≥1 V above ground for linear operation. Output swing will be limited to ~0.15 V above ground under load.
What is the purpose of the Sense pin (pin 11) on the INA125UA?
Pin 11 (Sense) monitors reference load current to dynamically adjust VREF regulation. It enables the internal reference amplifier to compensate for voltage drop across internal resistance under varying load conditions (0–5 mA), maintaining ±0.5% accuracy. External connection is not required - Sense is an internal diagnostic node routed to the die for process calibration and cannot be accessed by the user.
Does the INA125UA require external capacitors for stability?
The INA125UA is unity-gain stable and does not require external compensation capacitors. However, 0.1 µF ceramic decoupling capacitors are recommended between V+ and V− near the device pins to suppress high-frequency supply noise. For VREFOUT, a 100 pF capacitor to VREFCOM improves transient response and reduces 0.1 Hz–10 Hz noise - especially critical when using the 10 V reference output.
INA125UA Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Amplifier Type:
- Instrumentation
- Number of Circuits:
- 1
- Output Type:
- -
- Slew Rate:
- 0.2V/µs
- Gain Bandwidth Product:
- -
- -3db Bandwidth:
- 150 kHz
- Current - Input Bias:
- 10 nA
- Voltage - Input Offset:
- 50 µV
- Current - Supply:
- 460µA
- Current - Output / Channel:
- 12 mA
- Voltage - Supply Span (Min):
- 2.7 V
- Voltage - Supply Span (Max):
- 36 V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
INA125UA FAQ
1.How can I place an order for INA125UA through Aetrix?
Please submit a Request for Quotation (RFQ) for INA125UA 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 INA125UA reliable?
The price and inventory of INA125UA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for INA125UA is usually 5 days.
3.What payment methods are accepted for INA125UA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for INA125UA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for INA125UA?
INA125UA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your INA125UA 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 INA125UA?
For technical support, including INA125UA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your INA125UA requirements.
6.How does Aetrix verify that INA125UA is sourced from the original manufacturer or authorized distributors?
All INA125UA 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 INA125UA meets industry standards.
7.What is the process for return or replacement of INA125UA?
All INA125UA units undergo pre-shipment inspection (PSI). If there is an issue with INA125UA, 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 INA125UA part is unused and in its original packaging.
Return procedure for INA125UA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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