Texas Instruments ATL431LIAQDQNR

Overview

ATL431LIAQDQNR from Texas Instruments is a high-bandwidth, low-quiescent-current programmable shunt voltage regulator in a 4-pin X2SON (1.00 mm × 1.00 mm) package. It provides precise 2.5 V reference voltage with ±0.5% initial tolerance at 25°C, operates from −40°C to +125°C (Q-temp grade), supports adjustable output from 2.5 V to 36 V via two external resistors, and delivers 15 mA sink current - ideal for secondary-side regulation in automotive flyback SMPS.

For engineers reviewing the ATL431LIAQDQNR datasheet, ATL431LIAQDQNR pinout, ATL431LIAQDQNR application, or ATL431LIAQDQNR equivalent, key selection considerations include its 0.3 Ω dynamic impedance, 0.4 µA max reference input current, 80 µA minimum cathode current for regulation, Q-temp automotive qualification, and X2SON space-constrained packaging.

Technical Context

The ATL431LIAQDQNR implements a precision bandgap reference and high-gain NPN-based error amplifier driving a Darlington sink output stage. Its internal architecture enables sharp turn-on behavior and stable closed-loop operation without requiring an output capacitor - unlike many linear regulators.

It functions in both open-loop (comparator mode with integrated reference) and closed-loop (shunt regulator or error amplifier) configurations. Feedback is applied between CATHODE and REF pins to set output voltage; ANODE serves as the common ground reference point, and the thermal pad must be connected to ground or a floating copper plane for mechanical stability and thermal performance.

Key Specifications

Pinout & Package

ATL431LIAQDQNR is housed in a 4-pin X2SON (DQN) package measuring 1.00 mm × 1.00 mm with an exposed thermal pad. The package supports high-density PCB layouts and offers improved thermal resistance (R_θJB = 119.9 °C/W) versus SOT-23 alternatives.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431LIQDBVR, ATL431LIAQDQNR offers tighter 0.5% reference accuracy and lower 80 µA min cathode current, improving regulation stability in low-power automotive systems; compared with ATL431LIBQDQNR, it shares identical electrical behavior - only the grade designation differs per TI's ordering nomenclature.

Availability

ATL431LIAQDQNR is available at Aetrix Electronics and suitable for automotive power conversion, industrial voltage monitoring, and precision current-sinking applications requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for ATL431LIAQDQNR 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 delivering analog and embedded processing solutions, with leadership in power management, signal chain, and high-reliability products for automotive, industrial, and communications markets.

The ATL43xLI family was designed specifically for high-accuracy, low-I_Q shunt regulation in space-constrained and thermally demanding environments - targeting automotive secondary-side SMPS, precision sensing, and safety-critical voltage supervision.

FAQ

What is the maximum cathode voltage rating for ATL431LIAQDQNR?

The ATL431LIAQDQNR has an absolute maximum cathode-to-anode voltage (V_KA) rating of 37 V. Its recommended operating range extends from V_REF (2.5 V) up to 36 V. Exceeding 37 V risks permanent damage. This rating supports use in 24 V automotive systems with transient spikes, and aligns with the device's role in flyback converters where reflected voltages may reach 36 V.

Does ATL431LIAQDQNR require an output capacitor for stability?

No, ATL431LIAQDQNR is internally compensated and remains stable without an output capacitor between CATHODE and ANODE - a key differentiator from many linear regulators. However, if a capacitor is added for noise filtering or transient response shaping, stability boundary charts in the datasheet (Figure 13–15) must be consulted to avoid oscillation, especially under varying load capacitance and cathode current conditions.

How does the thermal pad on ATL431LIAQDQNR affect performance?

The exposed thermal pad on ATL431LIAQDQNR must be soldered to a PCB copper area - either grounded or left floating - to ensure mechanical stability and optimal thermal performance. When connected to ground, it improves junction-to-board thermal resistance (R_θJB = 119.9 °C/W), reducing die temperature rise under 15 mA sink current. Leaving it unconnected degrades thermal performance and risks solder joint reliability.

Can ATL431LIAQDQNR be used as a comparator, and what are the key design constraints?

Yes, ATL431LIAQDQNR functions as a comparator with integrated 2.5 V reference in open-loop mode. Critical constraints include supplying ≥80 µA cathode current (I_KA) for sufficient gain, ensuring ≥10% overdrive voltage at the REF pin for fast response, and using input resistors <10 kΩ to minimize I_REF-induced voltage error. Its open-collector output swings from ~2 V (low) to V_SUP (high), requiring level-shifting for 3.3 V or 1.8 V logic interfaces.

What is the significance of the 'A' and 'Q' in ATL431LIAQDQNR?

In ATL431LIAQDQNR, 'A' denotes the 1% initial reference voltage tolerance grade (A-grade), and 'Q' indicates qualification for the automotive temperature range (−40°C to +125°C). 'DQNR' specifies the 4-pin X2SON package (DQN) with tape-and-reel packaging (R). This full marking confirms the device meets AEC-Q100 stress test requirements and is intended for automotive applications where precision and thermal robustness are critical.