Texas Instruments INA105KU

Overview

INA105KU from Texas Instruments is a monolithic precision unity-gain differential amplifier comprising a high-accuracy op amp and laser-trimmed 25kΩ on-chip metal film resistor network. It delivers 72dB minimum CMRR, ±0.025% max gain error, and 1MHz bandwidth for accurate signal conditioning in high-noise industrial measurement systems.

For engineers reviewing the INA105KU datasheet, INA105KU pinout, INA105KU application, or INA105KU equivalent, key selection criteria include guaranteed CMRR over temperature, input common-mode range extending beyond rails (±20V at ±15V supplies), low 20μV/°C offset drift, and SOIC-8 packaging compatibility with automated assembly.

Technical Context

The INA105KU implements a fixed G = 1 difference amplifier topology using four precisely matched internal resistors to eliminate external resistor matching errors. Its bipolar or CMOS input stage (depending on chip site origin) enables rail-to-rail common-mode input operation up to ±20V with ±15V supplies.

Functionally, it operates as a single-mode precision analog front-end building block: the Sense and Ref pins allow offset nulling and output referencing, while the matched 25kΩ resistive network ensures stable gain accuracy and CMRR tracking across –40°C to +85°C.

Key Specifications

Pinout & Package

INA105KU is packaged in an 8-pin SOIC (D package), 4.90mm × 6.00mm body size, surface-mount compatible with standard reflow profiles.

Key Features

Applications

Equivalent & Alternatives

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

Compared with INA105KU, INA106KP improves DC precision at equal package and layout compatibility, while AD629ARZ trades low-voltage flexibility and trim capability for ultra-high common-mode tolerance-making INA105KU optimal for industrial sensor signal chains below 20V common-mode.

Availability

INA105KU is available at Aetrix Electronics and suitable for battery formation systems, industrial data loggers, servo drive feedback circuits, and analog level transmitters requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for INA105KU 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 signal chain components.

The INA105KU belongs to TI's precision differential amplifier product line, engineered specifically for high-accuracy industrial measurement systems where resistor matching, thermal stability, and rail-extended input range are critical design constraints.

FAQ

What is the maximum common-mode input voltage supported by the INA105KU?

The INA105KU supports a common-mode input voltage range of ±20V when operated with ±15V supplies. This rail-extended range is achieved through internal 25kΩ resistor division and enables direct interfacing with industrial sensors without external attenuation. Operation outside this range risks input stage damage or degraded CMRR, and the device's absolute maximum ratings specify signal input pins must remain within 0V to VS.

Can the INA105KU operate from a single supply?

Yes, the INA105KU can operate from a single supply between 10V and 36V, per its Recommended Operating Conditions. However, the input common-mode and output swing ranges become asymmetric relative to ground. For example, with +30V/0V supply, the usable common-mode range shifts toward mid-supply, and the Ref pin must be biased accordingly to maintain linear operation-TI recommends using dual supplies for full-spec performance.

What is the function of the Sense pin (Pin 5) on the INA105KU?

The Sense pin (Pin 5) connects to an internal 25kΩ resistor and is used in advanced configurations such as instrumentation amplifier guard drive generation or precision summing networks. In basic unity-gain differential amplifier mode, it remains unused but must be terminated-TI advises connecting it to V– or leaving it open only if layout parasitics are negligible. Misuse (e.g., interchanging with Ref) degrades CMRR due to resistor ratio mismatch.

How does the INA105KU achieve its specified CMRR over temperature?

The INA105KU achieves 72dB minimum CMRR over –40°C to +85°C through laser trimming of four on-chip 25kΩ metal film resistors with tightly matched temperature coefficients (TCR). This on-die matching ensures resistor ratios remain stable across temperature, preserving gain accuracy and common-mode rejection-unlike discrete implementations where external resistor TCR mismatches dominate drift.

Is the INA105KU pin-compatible with other members of the INA105 family?

Yes, all INA105 variants-including INA105KP, INA105AM, and INA105BM-share identical SOIC-8 (KU), PDIP-8 (KP), and TO-99 (AM/BM) packages and pinouts. The INA105KU specifically uses the SOIC-8 package with K-grade performance (–40°C to +85°C), and its pin functions (e.g., +In, –In, Ref, Sense) are electrically and physically identical across variants-enabling drop-in replacement where temperature and precision requirements align.