Texas Instruments ATL431LIBQDQNR

Overview

ATL431LIBQDQNR from Texas Instruments is a precision programmable shunt voltage reference IC with 0.5% initial tolerance at 25°C, 2.5 V nominal reference voltage, adjustable output up to 36 V, 0.3 Ω typical dynamic impedance, and operation across −40°C to +125°C for automotive-grade applications. It functions as a three-terminal adjustable shunt regulator in secondary-side feedback loops of isolated DC-DC converters.

For engineers reviewing the ATL431LIBQDQNR datasheet, ATL431LIBQDQNR pinout, ATL431LIBQDQNR application, or ATL431LIBQDQNR 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 X2SON-4 (DQN) package compatibility with space-constrained PCB layouts.

Technical Context

The ATL431LIBQDQNR implements an internal bandgap reference and high-gain transconductance amplifier driving a Darlington sink output stage. Its closed-loop regulation relies on external resistor feedback between cathode and reference pins to set output voltage from 2.5 V to 36 V.

It operates in two primary functional modes: open-loop comparator mode (with integrated 2.5 V reference for undervoltage/overvoltage detection) and closed-loop shunt regulator mode (for precision voltage or current regulation). Stability is internally compensated but requires load capacitance selection per published boundary charts to avoid oscillation.

Key Specifications

Pinout & Package

ATL431LIBQDQNR is packaged in a 1.00 mm × 1.00 mm, 4-pin X2SON (DQN) package with exposed thermal pad. The package supports high-density routing and enhanced thermal performance in compact power supplies.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431LIBQDBVR, ATL431LIBQDQNR offers 54% lower junction-to-ambient thermal resistance and 60% smaller footprint-critical for thermally constrained, high-power-density designs. Versus ATL431LIAQDQNR, it delivers twice the initial accuracy at identical package size and temperature rating, justifying premium for precision regulation.

Availability

ATL431LIBQDQNR is available at Aetrix Electronics and suitable for automotive power conversion, industrial voltage monitoring, and precision current sinking requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for ATL431LIBQDQNR 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 ICs, embedded processors, and digital signal solutions for automotive, industrial, and communications markets.

The ATL43xLI family was developed specifically for high-accuracy, low-quiescent-current shunt regulation in automotive-grade isolated power supplies and safety-critical monitoring systems.

FAQ

What is the maximum cathode voltage rating for ATL431LIBQDQNR?

The ATL431LIBQDQNR has an absolute maximum cathode voltage (VKA) rating of 37 V, with recommended operating range from VREF (2.5 V) to 36 V. Exceeding 37 V risks permanent damage. This rating enables use in 24 V and 36 V automotive systems with margin for transients. Always reference the Absolute Maximum Ratings table in the SLVSDU6D datasheet for derating guidance at elevated temperatures.

Does ATL431LIBQDQNR require an external capacitor for stability?

No, ATL431LIBQDQNR is internally compensated and stable without an output capacitor between cathode and anode. However, when used with capacitive loads (e.g., optocoupler CTR compensation or EMI filtering), stability depends on load capacitance and cathode current. TI's stability boundary charts (Figures 13–16 in SLVSDU6D) define safe CL–IKA operating regions-capacitors outside those zones may cause oscillation. Always validate with bench testing under worst-case conditions.

How does the NC pin (Pin 2) in the DQN package affect layout?

The NC pin (Pin 2) in the ATL431LIBQDQNR X2SON-4 package has no internal connection and must remain unconnected. TI recommends either leaving it floating or connecting it to ground for mechanical stability-never tie it to voltage rails or signals. Grounding Pin 2 improves solder joint reliability and thermal conduction to the PCB, but does not alter electrical performance. Follow TI's DQN layout guidelines (Section 13.3, SLVSDU6D) for thermal pad exposure and solder mask clearance.

Can ATL431LIBQDQNR replace TL431LI in existing designs?

ATL431LIBQDQNR is a pin-to-pin functional replacement for TL431LI in X2SON-4 (DQN) packages, with identical pinout, electrical specs, and Q-temp qualification. However, its lower minimum cathode current (80 µA vs. 100 µA for TL431LI) improves light-load efficiency. Verify thermal performance: ATL431LIBQDQNR's lower RθJA (173.7°C/W) may require updated thermal modeling. No PCB changes are needed if migrating from TL431LIQDQNR or compatible variants.

What is the role of the thermal pad in the ATL431LIBQDQNR DQN package?

The exposed thermal pad in the ATL431LIBQDQNR X2SON-4 package serves as a primary heat dissipation path from the die to the PCB. TI specifies it should be connected to a large copper pour or ground plane to achieve the rated RθJB of 119.9°C/W. Omitting thermal pad connection increases junction temperature by >40°C at 10 mA IKA, risking thermal shutdown or accelerated aging. Use solder paste stencil design per TI's DQN packaging recommendations to ensure void-free attachment.