Texas Instruments INA125PA

Overview

INA125PA from Burr-Brown (now Texas Instruments) is a precision instrumentation amplifier with integrated 1.24V/2.5V/5V/10V voltage reference, designed for bridge sensor signal conditioning in industrial and battery-powered systems. It delivers 250µV max input offset, 100dB min CMR at G=100, and operates from ±1.35V to ±18V dual supply or +2.7V to +36V single supply.

For engineers reviewing the INA125PA datasheet, INA125PA pinout, INA125PA application, or INA125PA equivalent, key selection criteria include its laser-trimmed gain-setting architecture (G = 4 + 60kΩ/R_G), sleep-mode quiescent current of ±1µA, ±40V input protection, and 16-pin DIP package compatibility with legacy industrial PCB layouts.

Technical Context

The INA125PA integrates two high-precision op amps (A1 and A2) in a three-op-amp instrumentation topology with laser-trimmed internal 30kΩ/10kΩ resistor networks. Its gain is set externally via a single resistor (RG) between pins 8 and 9, enabling programmable gains from 4 to 10,000 while maintaining 0.075% max gain error at G=10.

The on-chip voltage reference uses bandgap-derived architecture with pin-selectable outputs (VREFBG, VREF2.5, VREF5, VREF10) and ±0.5% initial accuracy. Reference output stability is maintained by routing IAREF to low-impedance ground and limiting series resistance to ≤12Ω to preserve >80dB CMR.

Key Specifications

Pinout & Package

INA125PA is packaged in a 16-pin plastic DIP (dual in-line package) with 0.3-inch body width and through-hole mounting. Thermal resistance θ_JA is 80°C/W, supporting operation from –40°C to +85°C ambient.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar instrumentation amplifier applications.

Compared with INA125PA, INA126PA trades lower sleep current for rail-to-rail output capability, while AD620ARZ reduces footprint but requires external reference circuitry-making INA125PA optimal for cost-sensitive, reference-integrated industrial sensor nodes.

Availability

INA125PA is available at Aetrix Electronics and suitable for pressure transducer interfaces, multi-channel data acquisition systems, and battery-powered portable meters requiring stable component supply and long-term industrial temperature support.

Supply support for INA125PA 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

Burr-Brown Corporation, acquired by Texas Instruments in 2000, specialized in high-precision analog ICs for industrial and instrumentation markets before integration into TI's precision analog portfolio.

The INA125 product line was engineered specifically for bridge-based sensor signal conditioning, combining excitation and amplification functions to simplify front-end design in factory automation and process control systems.

FAQ

What is the maximum gain achievable with INA125PA and how is it set?

The INA125PA achieves a maximum gain of 10,000 V/V by connecting a 6Ω resistor between pins 8 and 9 (RG). Gain follows the equation G = 4 + 60kΩ/R_G, where RG values are selected from the manufacturer's table - for example, 60.4Ω yields G=1000. The INA125PA's laser-trimmed internal resistors ensure gain accuracy remains within ±0.1% at G=500, critical for high-resolution strain gauge measurements.

Does INA125PA support single-supply operation and what are the constraints?

Yes, INA125PA operates from +2.7V to +36V single supply. Key constraints include connecting IAREF, VREFCOM, and V− to ground; ensuring VIN+ and VIN− remain ≥1V above ground for linear operation; and selecting VREFOUT ≤ (V+ − 1.25V). For example, with +5V supply, only VREFBG (1.24V) or VREF2.5 are valid - using VREF10 would violate dropout requirements. Output swing is limited to ~150mV above ground under load.

How does the sleep mode function on INA125PA and what is its wake-up behavior?

INA125PA enters sleep mode when the SLEEP pin voltage is ≤100mV (referenced to VREFCOM), reducing quiescent current to ±1µA. Wake-up occurs when SLEEP rises ≥2.7V, with typical turn-on settling time of <150µs for output offset stabilization. During wake-up, input-referred offset voltage changes by <100µV - verified in production testing - ensuring minimal measurement disturbance in duty-cycled data loggers using the INA125PA.

Can INA125PA drive ADCs directly and what reference voltage options are available?

Yes, INA125PA can directly drive SAR and delta-sigma ADCs via its VREFOUT pin, which provides pin-selectable 1.24V (bandgap), 2.5V, 5V, or 10V references with ±0.5% initial accuracy. When VREFOUT is tied to VREF5, the INA125PA supplies both bridge excitation and ADC reference - enabling true ratiometric conversion that cancels supply-voltage drift. This eliminates external reference ICs in systems like PLC analog input cards using the INA125PA.

What is the input protection architecture of INA125PA and how does it handle overvoltage events?

INA125PA incorporates internal input protection circuitry that limits input current to 120–190µA during ±40V overvoltage events - sufficient to prevent damage without external components. Each input features low-impedance clamping under normal conditions, avoiding the noise penalty of series resistors. Protection remains active even with power supplies disconnected, making the INA125PA robust against wiring errors in field-installed pressure transmitters where accidental 24V shorts occur.