Texas Instruments ATL431LIBIDQNR

Overview

ATL431LIBIDQNR from Texas Instruments is a precision 2.5-V adjustable shunt voltage reference IC with 0.5% initial tolerance at 25°C, 0.3-Ω typical dynamic impedance, and operation across −40°C to +125°C. It functions as a three-terminal programmable shunt regulator in secondary-side feedback loops of isolated DC/DC converters, replacing Zener diodes with superior thermal stability and low quiescent current.

For engineers reviewing the ATL431LIBIDQNR datasheet, ATL431LIBIDQNR pinout, ATL431LIBIDQNR application, or ATL431LIBIDQNR equivalent, key selection criteria include cathode current range (0.08–15 mA), reference input current ≤0.4 µA, temperature drift ≤27 mV over Q-temp range, and compatibility with space-constrained designs using its 1.00 mm × 1.00 mm X2SON package.

Technical Context

The ATL431LIBIDQNR implements an internal bandgap reference and high-gain NPN-based error amplifier driving a Darlington output stage. Its closed-loop regulation relies on resistive feedback between cathode and reference pins to set output voltage from 2.5 V to 36 V.

In open-loop mode, it operates as a comparator with integrated 2.5-V reference, delivering fast response when supplied ≥0.08 mA cathode current and ≥10% overdrive voltage. Stability is internally compensated-no external capacitor required-but load capacitance must be selected per published boundary charts to avoid oscillation.

Key Specifications

Pinout & Package

ATL431LIBIDQNR is housed in a 4-pin X2SON (DQN) package with exposed thermal pad. The package measures 1.00 mm × 1.00 mm × 0.50 mm and is designed for solder reflow mounting with bottom-side thermal connection.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar shunt regulator applications.

Compared with TL431LIBIDBVR, ATL431LIBIDQNR saves >65% board area and improves thermal resistance by 53% (RθJA = 173.7°C/W vs. 371.7°C/W); compared with ATL431LIAIDQNR, it delivers twice the initial accuracy at minimal cost premium-critical for automotive ADAS power rails.

Availability

ATL431LIBIDQNR is available at Aetrix Electronics and suitable for automotive power management, industrial isolated DC/DC converters, and precision analog monitoring systems requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for ATL431LIBIDQNR 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 designing analog and embedded processing chips for industrial, automotive, and communications markets.

The ATL431LI family was developed specifically for high-accuracy, low-power shunt regulation in safety-critical automotive and industrial power supplies-emphasizing thermal stability, small size, and drop-in compatibility with legacy TL431 designs.

FAQ

What is the minimum cathode current required for regulation in ATL431LIBIDQNR?

The ATL431LIBIDQNR requires a minimum cathode current of 0.08 mA (80 µA) to maintain regulation. This value is the maximum specified Imin across temperature and ensures sufficient bias for the internal error amplifier and Darlington output stage to operate in linear mode. Operating below this level may result in loss of regulation accuracy or slow response in ATL431LIBIDQNR applications such as feedback loops or voltage monitors.

Does ATL431LIBIDQNR require an external output capacitor for stability?

No, ATL431LIBIDQNR is internally compensated and does not require an external capacitor between CATHODE and ANODE for basic stability. However, if a load capacitor is used-such as for noise filtering or transient response shaping-the designer must consult the stability boundary charts in the ATL431LIBIDQNR datasheet to select a value that avoids oscillation, especially under varying cathode current and voltage conditions.

How does the NC pin (Pin 2) in ATL431LIBIDQNR's X2SON package affect layout?

The NC pin (Pin 2) in ATL431LIBIDQNR has no internal connection and serves only as a mechanical placeholder in the X2SON-4 package. It must be left electrically floating or tied to ANODE (Pin 1); connecting it to any other net may cause unintended coupling or solder bridging. PCB layout should avoid routing signals or placing vias directly under this pin to prevent assembly defects.

Can ATL431LIBIDQNR replace TL431LI in existing designs?

Yes, ATL431LIBIDQNR is a pin-to-pin functional replacement for TL431LI in X2SON-4 layouts, offering identical electrical specifications plus lower minimum operating current and improved thermal performance. When migrating from TL431LI in SOT-23, board redesign is required due to different pin count and package dimensions-but the schematic topology remains unchanged.

What is the role of the thermal pad in ATL431LIBIDQNR's X2SON package?

The exposed thermal pad in ATL431LIBIDQNR's X2SON package provides a low-thermal-resistance path from the die to the PCB, reducing junction-to-board thermal resistance to 119.9°C/W. For optimal thermal performance and mechanical reliability, the pad must be soldered to a solid copper pour connected to system ground-ensuring efficient heat dissipation during continuous 15-mA cathode operation.