Texas Instruments ATL431AIDBZR

Overview

ATL431AIDBZR from Texas Instruments is a 2.5V adjustable precision shunt regulator in SOT-23 package, delivering 0.5% reference voltage tolerance at 25°C, 35µA minimum cathode current, 0.3Ω maximum dynamic impedance, and stable operation from –40°C to +85°C. It serves as a low-power Zener replacement in secondary-side regulation of isolated flyback converters.

For engineers reviewing the ATL431AIDBZR datasheet, ATL431AIDBZR pinout, ATL431AIDBZR application, or ATL431AIDBZR equivalent, this page provides verified electrical specifications, thermal performance data, stability boundaries for capacitive loads, functional mode distinctions (open-loop comparator vs closed-loop shunt regulator), and design guidance for voltage monitoring and error amplification in power management systems.

Technical Context

The ATL431AIDBZR implements an internally compensated three-terminal shunt architecture with a Darlington output stage, enabling stable regulation without external capacitance. Its reference input current remains ≤150nA across temperature, and its cathode current range spans 35µA to 100mA - exceeding TL431 by >20×.

It operates in two distinct functional modes: open-loop comparator mode (with integrated 2.5V reference) for voltage threshold detection, and closed-loop shunt regulator mode (using resistive feedback between CATHODE and REF) for precise output voltage programming from 2.5V to 36V.

Key Specifications

Pinout & Package

SOT-23 (DBZ) package, 2.90mm × 1.60mm body size, surface-mountable with standard reflow profile.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431ACDBVR, ATL431AIDBZR reduces no-load cathode current by 65% and improves reference tolerance by 2×, making it optimal for energy-sensitive isolated supplies; versus ATL431LIYPR, it trades Q-grade temperature range for lower cost in commercial/industrial use cases.

Availability

ATL431AIDBZR is available at Aetrix Electronics and suitable for secondary-side regulation in flyback SMPSs, voltage monitoring circuits, and adjustable current referencing applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for ATL431AIDBZR 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 ATL43x product line was developed to replace TL431 in low-power, high-accuracy shunt regulation applications - specifically targeting reduced no-load current, tighter reference tolerance, and improved thermal stability in isolated power supplies.

FAQ

What is the minimum cathode current required for regulation in ATL431AIDBZR?

The ATL431AIDBZR requires a minimum cathode current of 35µA (maximum specification) to maintain regulation. This value is confirmed in Section 5.5 of the datasheet under "Imin" test condition (VKA = Vref). Operating below this threshold may result in insufficient gain and unstable regulation. The ATL431AIDBZR achieves >20× improvement over TL431's 100µA minimum, directly enabling ultra-low-power standby modes in ATL431AIDBZR-based designs.

Can ATL431AIDBZR operate without an output capacitor?

Yes, ATL431AIDBZR is internally compensated and stable with no capacitive load - a key feature confirmed in the "Features" section and Figure 5-14 through 5-21 stability boundary plots. This eliminates the need for output capacitance in most shunt regulator configurations. However, if an output capacitor is used, its value and ESR must stay within stability regions shown in those figures (e.g., ESR < 20mΩ for CKA < 2000pF at VKA = 15V), especially at low cathode currents.

What is the reference voltage tolerance of ATL431AIDBZR at 25°C?

The ATL431AIDBZR has a reference voltage tolerance of ±0.5% at 25°C, as specified in Section 5.6 ("Electrical Characteristics, ATL431Bx") and labeled "B Grade" in the Features table. This corresponds to a VREF range of 2487 mV to 2512 mV under test conditions (VKA = Vref, IKA = 1mA). This tolerance is tighter than the A-grade (±1%) variant and is explicitly assigned to part numbers ending in "B", including ATL431AIDBZR.

How does ATL431AIDBZR differ from TL431 in terms of thermal drift?

ATL431AIDBZR exhibits 5mV maximum reference voltage deviation over –40°C to +85°C, versus up to 12mV for standard TL431 variants. This improvement is documented in Section 5.5 (VI(dev)) and the "Typical Characteristics" plot (Figure 5-1). The tighter drift stems from enhanced bandgap design and process optimization, making ATL431AIDBZR more suitable for applications demanding consistent regulation across industrial temperature ranges without additional calibration.

What package type is used for ATL431AIDBZR?

ATL431AIDBZR uses the SOT-23 (DBZ) package, with nominal body dimensions of 2.90mm × 1.60mm, as stated in the "Device Information" table and Figure 4-1. Pin 1 is CATHODE, Pin 2 is REF, and Pin 3 is ANODE - matching the ATL431 pinout (distinct from ATL432's swapped CATHODE/REF). This 3-pin surface-mount package supports automated assembly and meets JEDEC MO-178 standards.