Texas Instruments INA322EA/250

Overview

INA322EA/250 from Texas Instruments is a micropower, single-supply, CMOS instrumentation amplifier in an 8-pin VSSOP (DGK) package, delivering rail-to-rail output swing, 500kHz bandwidth at G = 5V/V, ±10mV input offset voltage (max), and 40µA/channel quiescent current - optimized for low-power sensor signal conditioning in industrial and medical systems.

For engineers reviewing the INA322EA/250 datasheet, INA322EA/250 pinout, INA322EA/250 application, or INA322EA/250 equivalent, key selection criteria include its programmable gain architecture (G = 5 + 5(R₂/R₁)), –55°C to +125°C operating range, shutdown current <1µA, 10pA input bias current, and compatibility with bridge, RTD, and ECG front-ends requiring high CMRR up to 3kHz.

Technical Context

The INA322EA/250 implements a modified two-op-amp instrumentation topology with an integrated third gain stage, enabling precise differential amplification while maintaining micropower operation. Its internal 5V/V base gain is extended via external resistors R₁ and R₂, supporting total gains from 5 to 1000V/V with ≤0.4% gain error.

Input common-mode range extends from (V–) + 0.35V to (V+) – 1.2V (at VS = 2.7V), and the reference pin defines output zero level with direct +1 gain to VOUT - requiring low-impedance drive to preserve CMRR. Shutdown activation occurs when the SHUTDOWN pin falls below 0.8V (on 5V supply), reducing current to <1µA within nanoseconds.

Key Specifications

Pinout & Package

VSSOP-8 (DGK) package: 1.1mm max height, 3.0mm × 3.0mm body, 0.65mm lead pitch, exposed thermal pad (non-electrical), RoHS-compliant, MSL Level-2-260°C-1 year.

Key Features

Applications

Equivalent & Alternatives

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

Compared with INA322EA/250, INA333AIDR offers superior DC accuracy but sacrifices bandwidth and adds cost, while AD8420ARMZ delivers higher speed and CMRR at 10× higher quiescent current - making INA322EA/250 optimal for battery-powered, wide-temperature, programmable-gain sensor interfaces where 500kHz BW and <40µA IQ are essential.

Availability

INA322EA/250 is available at Aetrix Electronics and suitable for industrial sensor amplifiers, physiological signal conditioners, A/D converter front-ends, and differential line receivers requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for INA322EA/250 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 is a global semiconductor leader specializing in analog and embedded processing technologies, with decades of expertise in precision amplifiers and signal-chain solutions.

The INA322 family was designed specifically for low-power, wide-temperature, programmable-gain instrumentation in resource-constrained sensing systems - balancing micropower operation, rail-to-rail output, and robust CMRR for industrial and medical front-ends.

FAQ

What is the minimum supply voltage for reliable operation of the INA322EA/250?

The INA322EA/250 is fully specified from +2.7V to +5.5V, with functional operation down to +2.5V. At 2.7V, input common-mode range is 0.35V to 1.5V and output swing remains rail-to-rail for gains ≥10. Operating below 2.7V may reduce CMRR and increase offset error beyond datasheet limits, so +2.7V is the recommended minimum for guaranteed performance in the INA322EA/250.

How does the shutdown feature of the INA322EA/250 work, and what is its recovery time?

The INA322EA/250 enters shutdown when the SHUTDOWN pin voltage drops below 0.8V (on a 5V supply); quiescent current falls to <1µA per channel. Recovery to full operation occurs in microseconds - typically <2µs - with no external reset required. This makes the INA322EA/250 ideal for time-multiplexed sensor arrays where rapid on/off cycling conserves power without interrupting system timing.

Can the INA322EA/250 drive an ADC directly, and what load conditions are supported?

Yes, the INA322EA/250 is optimized to drive ADC inputs directly: it delivers rail-to-rail output swing (to within 20mV of V+ at G ≥ 10) into loads ≥25kΩ, with 0.1% settling in 8µs (G = 5, CL = 50pF). For heavier capacitive loads (>500pF) or low-impedance ADCs, an external buffer like OPA340 is recommended. The INA322EA/250's low output impedance at high frequencies ensures minimal distortion when driving sampling ADCs.

What is the role of the REF pin in the INA322EA/250, and how should it be connected?

The REF pin sets the output zero-reference level - the output voltage equals (V_IN+ – V_IN–) × G + V_REF. It must be driven by a low-impedance source (e.g., op-amp buffer or precision voltage divider) because series resistance degrades CMRR. REF also affects input common-mode range: V_REF must be ≥1.2V below V+ to avoid saturation. In single-supply ECG designs, REF is often set to mid-supply (e.g., +2.5V) to center the output swing - a key design consideration for the INA322EA/250.

Does the INA322EA/250 require external resistors for basic operation, and what gain options are available?

No - the INA322EA/250 operates at fixed G = 5V/V with R_G pin left open. External resistors R₁ and R₂ enable programmable gain using G = 5 + 5(R₂/R₁), supporting gains from 5 to 1000V/V. For G = 5, no external components are needed; for other gains, resistor matching and low-TC values are critical to minimize drift. Gain-setting errors from external resistors dominate total gain error in the INA322EA/250, so precision resistors are recommended for high-accuracy applications.