Texas Instruments XTR101AP

Overview

XTR101AP from Texas Instruments is a precision 4–20mA two-wire transmitter IC integrating an instrumentation amplifier, voltage-controlled current source, and dual matched 1mA current references. It delivers ≤30µV max offset voltage, ≤0.75µV/°C drift, and 0.01% nonlinearity over −40°C to +85°C, enabling high-accuracy signal conditioning for millivolt-level transducer outputs in industrial process control.

For engineers reviewing the XTR101AP datasheet, XTR101AP pinout, XTR101AP application, or XTR101AP equivalent, this page provides verified technical context, DIP-14 package mapping, confirmed pin functions (e.g., pins 3/4 = differential inputs, pin 7 = output/E, pins 10/11 = IREF1/IREF2), and real-world design implications of its true two-wire operation, current-mode transmission, and optional external transistor support.

Technical Context

The XTR101AP implements a single-supply, two-wire architecture where power and 4–20mA signal share one wire pair via modulated supply current. Its core comprises a laser-trimmed instrumentation amplifier with 90–100dB DC CMRR and ≥10GΩ input impedance, feeding a voltage-controlled current source that maintains linear regulation across 11.6V–40V supply range.

Two precision 1mA current sources (pins 10/11) provide excitation for RTDs, thermocouples, and bridge sensors while enabling zero-span elevation/suppression circuits. Bandwidth control (pins 12/13) allows configurable low-pass filtering, and optional external NPN transistor (e.g., TIP29B) reduces thermal feedback to improve long-term offset stability under full-scale load conditions.

Key Specifications

Pinout & Package

DIP-14 plastic package (N designation), 19.1mm × 6.6mm body, 2.54mm pitch, through-hole mounting. Pin 1 marked with dot; pin 12/13 support bandwidth control via external capacitor.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD693ARZ and XTR115UA, the XTR101AP uniquely combines laser-trimmed precision (30µV offset), dual matched current sources, and analog flexibility-making it irreplaceable for high-stability, self-contained analog transmitter designs without microcontrollers.

Availability

XTR101AP is available at Aetrix Electronics and suitable for industrial process control, factory automation, and power plant monitoring requiring stable component supply and long-term lifecycle continuity.

Supply support for XTR101AP 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 XTR series was designed specifically for ruggedized 4–20mA industrial transmitters-emphasizing two-wire efficiency, noise immunity, and sensor-agnostic signal conditioning for pressure, temperature, and strain measurement.

FAQ

What is the maximum allowable input signal voltage for XTR101AP?

The XTR101AP supports a maximum differential input voltage (e2 − e1) of 1V when RS = ∞, scaling down proportionally as RS decreases. For example, with RS = 278Ω (typical for 100mV FS), the full-scale input is limited to ~100mV. Input common-mode voltage must remain between +4V and +6V relative to pin 7 to ensure linear operation-exceeding this range risks clipping or increased nonlinearity. The XTR101AP datasheet specifies these limits under Absolute Maximum Ratings and Electrical Characteristics sections.

Does XTR101AP require an external transistor for standard industrial use?

The XTR101AP operates reliably with its internal transistor for most applications, including 4–20mA output into 250Ω–600Ω loads at 24V supply. An external NPN transistor (e.g., TIP29B) is optional and recommended only for high-accuracy installations where thermal drift must be minimized-such as RTD transmitters with <±0.05°C requirements or long-duration unattended monitoring. The XTR101AP's internal design already delivers ≤30µV offset and ≤0.75µV/°C drift without external components.

How does XTR101AP handle thermocouple burn-out detection?

The XTR101AP provides inherent downscale burn-out detection: when a thermocouple opens, bias current flowing into the high-impedance +In pin (pin 4) forces the output current to drop to ~3.8mA-the lower limit of its derated operating range. This behavior is confirmed in the Application Information section and demonstrated in Figures 16–17 of the XTR101AP datasheet. No additional circuitry is needed; the feature relies on the IC's internal current source topology and is active in all standard configurations.

Can XTR101AP be used with both RTDs and thermocouples in the same design?

Yes-the XTR101AP supports both RTD and thermocouple interfaces through reconfigurable external circuitry. For RTDs, use pins 10/11 to supply matched 1mA excitation across a 3- or 4-wire element and sense differential voltage at pins 3/4. For thermocouples, configure one current source for cold-junction compensation (e.g., diode bias) and the other for reference voltage generation, as shown in Figure 10 of the XTR101AP datasheet. The XTR101AP's flexible input stage and dual references enable either topology without hardware change.

What is the purpose of pins 12 and 13 on XTR101AP?

Pins 12 and 13 on the XTR101AP are bandwidth control terminals that accept an external capacitor to set the dominant pole frequency of the instrumentation amplifier. Adding capacitance between these pins and ground reduces system bandwidth-e.g., 100pF yields ~10Hz cutoff, suppressing 50/60Hz line noise in electrically noisy plants. This function is documented in the Typical Characteristics section and Figure 12 of the XTR101AP datasheet; it does not affect DC accuracy but improves noise rejection in slow-process applications.