Texas Instruments XTR117AIDRBT

Overview

XTR117AIDRBT from Texas Instruments is a precision 4–20mA current-loop transmitter IC designed for industrial sensor signal conditioning and loop-powered field transmitters. It features 100× current gain (IO = 100 × IIN), ±0.05% span error, 130µA quiescent current, 5V on-chip regulator, and operates across –40°C to +125°C with 7.5V–36V loop supply range.

For engineers reviewing the XTR117AIDRBT datasheet, XTR117AIDRBT pinout, XTR117AIDRBT application, or XTR117AIDRBT equivalent, key selection criteria include its VSON-8 package thermal performance, IRET-referenced local ground architecture, external transistor–based high-current output stage, and compatibility with HART-compatible bypass capacitor configurations (2–3nF).

Technical Context

The XTR117AIDRBT implements a precision current-input amplifier with fixed 100× transconductance gain, where input current at IIN directly controls regulated 4–20mA output via an external NPN transistor (Q1) connected to B and E pins. Its internal 5V regulator powers external circuitry, with all return current routed through IRET to maintain accurate current-loop integrity.

It operates in a single functional mode within recommended conditions (V+ = 7.5–36V, TA = –40°C to +125°C), requiring no configuration or digital interface. Stability relies on external components: RIN sets input scaling, RLIM sets overcurrent limit, and a 2–10nF capacitor between V+ and IO ensures loop stability-critical for HART communication compliance.

Key Specifications

Pinout & Package

VSON-8 (DRB) package: 3mm × 3mm leadless QFN with exposed thermal pad on underside; requires soldering pad to IRET or floating per TI layout guidelines.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XTR117AIDRBT, XTR115IDGKR adds reference flexibility at the cost of higher power and reduced accuracy, while XTR116IDRBR matches power and package but trades 2.5V for 4.096V reference-making it optimal for high-resolution data acquisition where reference voltage directly impacts LSB size.

Availability

XTR117AIDRBT is available at Aetrix Electronics and suitable for pressure transmitter design, temperature sensor calibration, and PLC analog input validation requiring stable component supply across extended temperature and long-lifecycle industrial programs.

Supply support for XTR117AIDRBT 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 company specializing in analog, embedded processing, and high-reliability ICs for industrial, automotive, and communications markets.

The XTR117AIDRBT belongs to TI's precision current-loop transmitter product line, engineered specifically for robust, two-wire 4–20mA field instrumentation in harsh environments where accuracy, thermal stability, and loop power efficiency are critical.

FAQ

What is the function of the IRET pin on the XTR117AIDRBT?

The IRET pin on the XTR117AIDRBT serves as the local ground return for the internal 5V regulator and any external circuitry powered by VREG. All current drawn from VREG must return through IRET to ensure accurate 4–20mA output current, as the device measures and regulates loop current relative to this node. Connecting external sensor bias or reference circuits to IRET-not system ground-prevents ground-loop errors that would degrade span accuracy beyond ±0.05%.

Can the XTR117AIDRBT operate without an external transistor?

The XTR117AIDRBT can operate without an external transistor for low-current applications (<4mA), but it is not recommended above 4mA due to self-heating effects that degrade accuracy and reliability. The device is explicitly designed to offload high-current conduction (up to 20mA) to an external NPN transistor connected between B and E pins. Omitting Q1 risks exceeding the IC's thermal limits, causing drift in span error and nonlinearity-especially at elevated ambient temperatures or high loop voltages (>24V).

What is the maximum load resistance supported by the XTR117AIDRBT at 24V loop supply?

At 24V loop supply, the XTR117AIDRBT supports a maximum load resistance of 850Ω while maintaining full 4–20mA compliance. This is calculated from the minimum compliance voltage (7.5V) and maximum output current (20mA): (24V − 7.5V) ÷ 20mA = 825Ω, with 25Ω margin for PCB trace resistance and tolerance. For HART communication, keep RL ≤ 600Ω to ensure sufficient headroom for the 1mA AC signal superimposed on the DC loop current.

How does the XTR117AIDRBT handle reverse polarity on the loop supply?

The XTR117AIDRBT itself has no built-in reverse-polarity protection; however, its 7.5V minimum operating voltage allows integration of external protection such as a diode bridge (1.4V drop) or series diode (0.7V drop) without compromising functionality. TI recommends placing a diode bridge at the loop input terminals to enable operation with reversed wiring-ensuring the device receives correct polarity at V+ and IO pins while maintaining ≥9V compliance voltage, which remains sufficient for most industrial installations.

Is the XTR117AIDRBT compatible with HART communication protocols?

Yes, the XTR117AIDRBT supports HART communication when configured with a 2–3nF capacitor between V+ and IO pins, as specified in Section 8.1.6 of the datasheet. This value maintains >500kHz small-signal bandwidth while providing adequate decoupling for the 1mA peak-to-peak 1–2kHz HART frequency signal. Using the default 10nF capacitor (recommended for general stability) blocks HART frequencies; therefore, HART-capable designs must use the lower capacitance and verify loop impedance meets HART physical layer requirements (≥230Ω).