Texas Instruments INA122UA/2K5G4

Overview

INA122UA/2K5G4 from Texas Instruments is a single-supply, micropower instrumentation amplifier designed for precision differential signal acquisition in battery-powered systems. It delivers 60μA quiescent current, rail-to-rail output swing, and 250μV max offset voltage, enabling accurate sensor interfacing in portable medical and industrial transmitters.

For engineers reviewing the INA122UA/2K5G4 datasheet, INA122UA/2K5G4 pinout, INA122UA/2K5G4 application, or INA122UA/2K5G4 equivalent, key selection criteria include gain-setting resistor configuration (RG), input bias current path design, common-mode input range at low supply voltages, and thermal derating for SOIC-8 packaging in continuous operation.

Technical Context

The INA122UA/2K5G4 implements a two-op-amp architecture with laser-trimmed internal resistors to achieve 3μV/°C max offset drift and 96dB typical CMRR. Its input stage uses precision level-shifting buffers to extend common-mode range to ground on single supplies as low as +2.2V.

Gain is set externally via RG between pins 1 and 8 using G = 5 + 200kΩ/RG, supporting 5V/V to 10,000V/V. The device operates across −40°C to +85°C and maintains rail-to-rail output swing into 20kΩ loads with ≤0.1V headroom at ±15V supplies.

Key Specifications

Pinout & Package

INA122UA/2K5G4 is supplied in an 8-pin SOIC package (4.9mm × 6mm) rated for −40°C to +85°C operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD623ARZ and INA333AIDR, the INA122UA/2K5G4 uniquely balances micropower operation (60μA), rail-to-rail output, and wide supply range (2.2V–36V) in a single SOIC-8 package-making it optimal for field-deployable, battery-backed sensor nodes where supply flexibility and output dynamic range are critical.

Availability

INA122UA/2K5G4 is available at Aetrix Electronics and suitable for portable medical devices, industrial field transmitters, infusion pumps, pressure sensing modules, and electrocardiogram systems requiring stable component supply across extended production lifecycles.

Supply support for INA122UA/2K5G4 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 heritage in precision signal conditioning ICs.

The INA122 belongs to TI's precision instrumentation amplifier product line, engineered specifically for low-power, high-accuracy sensor signal acquisition in portable and field-deployable measurement systems.

FAQ

What is the recommended gain-setting resistor value for 100× gain with INA122UA/2K5G4?

For 100× gain, the INA122UA/2K5G4 requires RG = 2.1kΩ, calculated using G = 5 + 200kΩ/RG. TI recommends using a 1% metal-film resistor (e.g., 2.10kΩ) placed directly between pins 1 and 8 with minimal trace length to preserve CMRR. The INA122UA/2K5G4 datasheet Table 6-1 confirms this value yields ±0.5% gain error at 25°C.

Can INA122UA/2K5G4 operate from a single 3.3V supply while maintaining rail-to-rail output?

Yes, the INA122UA/2K5G4 supports single-supply operation down to +2.2V and delivers rail-to-rail output swing. At +3.3V supply, its output typically swings within 100mV of each rail into a 20kΩ load, enabling full-scale use of 12-bit ADCs without level-shifting. This behavior is verified in the INA122UA/2K5G4 Typical Characteristics curves (Figure 5-10).

How does the REF pin affect common-mode rejection in INA122UA/2K5G4?

The REF pin of the INA122UA/2K5G4 must be driven by a low-impedance source (<10Ω) to maintain specified CMRR. A 10Ω series resistance degrades typical CMRR from 96dB to ~80dB. In most applications, REF is grounded directly; for offset trimming, an op-amp buffer (e.g., OPA391) is recommended. This requirement is explicitly documented in the INA122UA/2K5G4 datasheet Section 7.1.1.

What is the maximum allowable input voltage beyond the supply rails for INA122UA/2K5G4?

The INA122UA/2K5G4 input pins include internal clamp diodes to ±VS rails. Absolute maximum rating allows input voltage from (V–)–0.3V to (V+)+0.3V. Exceeding this by more than 0.3V risks exceeding the 5mA absolute maximum input current, potentially damaging clamps. For overvoltage protection, TI recommends limiting source current with series resistors when inputs may exceed rails.

Does INA122UA/2K5G4 require input bias current return paths, and how should they be implemented?

Yes-the INA122UA/2K5G4 has ~−10nA input bias current flowing out of both inputs. A return path is mandatory to prevent saturation. For low-impedance bridges, connect one input to ground through a resistor; for high-impedance sources like thermocouples, use matched resistors to both inputs. This design requirement is detailed in INA122UA/2K5G4 datasheet Section 7.1.2 and Figure 7-2.