Texas Instruments XTR105P

Overview

XTR105P from Texas Instruments is a monolithic 4–20mA two-wire current transmitter IC with integrated dual 800µA precision current sources, on-chip 5.1V regulator, and second-order RTD linearization circuitry. It serves as the core analog signal conditioning and loop-current modulation stage in industrial temperature/pressure transmitters, operating from 7.5V to 36V loop supply and delivering ±0.01% nonlinearity (typ) with 0.4µV/°C offset drift.

For engineers reviewing the XTR105P datasheet, XTR105P pinout, XTR105P application, or XTR105P equivalent, this page delivers verified functional context, validated pin-level design meaning, confirmed RTD linearization performance, and real-world selection guidance for 2-wire/3-wire sensor interfaces in factory automation and SCADA systems.

Technical Context

The XTR105P implements a differential instrumentation amplifier input stage with externally set transconductance (S = 40/RG A/V), feeding a regulated 4–20mA output stage that requires an external NPN transistor (e.g., TIP29C) for thermal isolation. Its linearization architecture applies programmable positive feedback via VLIN to correct Pt100 RTD nonlinearity-achieving up to 40:1 linearity improvement using RLIN1 (and RLIN2 in 3-wire mode).

Two matched 800µA current sources (IR1, IR2) drive RTD excitation and zero-setting resistors, while the 5.1V VREG output powers external buffers with ±0.1V accuracy and ≤1mA load capability. IRET serves as the common return for all internal references and external circuitry, enabling accurate current summation without error injection.

Key Specifications

Pinout & Package

Package: PDIP-14 (N package), 19.3mm × 9.4mm; RoHS-compliant, through-hole mounting for industrial reliability.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 4–20mA transmitter applications.

Compared with XTR105P, XTR116IRUGR offers wider supply flexibility but sacrifices integrated linearization, while AD693AN provides pin-compatible legacy support at the cost of higher unadjusted error and no on-chip regulation - making XTR105P optimal for new RTD-centric designs demanding accuracy, integration, and diagnostic capability.

Availability

XTR105P is available at Aetrix Electronics and suitable for temperature transmitter, pressure transmitter, and factory automation applications requiring stable component supply, long-lifecycle assurance, and traceable sourcing for industrial OEMs.

Supply support for XTR105P 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 leadership in precision signal conditioning and industrial interface solutions.

The XTR105P belongs to TI's XTR (4–20mA Transmitter) product line, engineered specifically for high-accuracy, low-drift industrial sensor signal conditioning - targeting RTD, thermocouple, and bridge-based measurement systems in harsh environments.

FAQ

What is the primary function of the XTR105P in a 4–20mA loop system?

The XTR105P functions as a complete analog 4–20mA current transmitter IC, converting a differential sensor voltage (e.g., from an RTD or bridge) into a precisely regulated loop current. It integrates excitation current sources, instrumentation amplification, second-order linearization, and loop regulation - eliminating the need for discrete op-amps, references, and compensation networks in XTR105P-based designs.

Does the XTR105P require an external transistor, and why?

Yes, the XTR105P is designed to drive an external NPN transistor (e.g., TIP29C) connected to its B and E pins. This isolates high-power dissipation from the precision input and reference circuitry, maintaining low offset drift (0.4µV/°C) and high accuracy across –40°C to +85°C. Operating without the transistor degrades accuracy due to self-heating and is not recommended for extended temperature ranges.

How does the XTR105P achieve RTD linearization, and what performance improvement does it deliver?

The XTR105P uses its VLIN pin to apply second-order correction voltage to an external RLIN1 (and RLIN2 for 3-wire) resistor network, compensating for inherent Pt100 nonlinearity. This architecture delivers up to a 40:1 improvement in linearity versus uncompensated output - reducing typical nonlinearity from ~0.4% to 0.01% FS, as confirmed in TI SBOS061D characterization data for XTR105P.

What are the key differences between XTR105P and XTR105PA variants?

The XTR105PA variant has relaxed initial error specifications: ±50µA zero error (vs ±25µA for XTR105P) and ±0.4% span error (vs ±0.2%). Both share identical pinout, package, linearization capability, and operating range. XTR105P is specified for tighter unadjusted accuracy, making it preferred for high-precision applications where calibration is minimized or eliminated.

Can the XTR105P operate with a 12V loop supply, and what is the minimum required voltage?

Yes, the XTR105P operates reliably with a 12V loop supply. Its absolute minimum compliance voltage is 7.5V - measured between V+ and IO pins - allowing direct use with standard PC 12V ±5% rails. At 12V, it maintains full 4–20mA output swing and retains all specified accuracy, PSRR, and linearization performance per SBOS061D test conditions.