Diodes Incorporated AN431AN-ATRG1

Overview

AN431AN-ATRG1 from Diodes Incorporated is a three-terminal adjustable precision shunt regulator with 0.5% reference voltage tolerance, 2.5V to 36V programmable output range, and low dynamic impedance (0.15Ω typical). It operates from –40°C to +125°C and replaces Zener diodes in switching power supplies, battery chargers, and precision voltage references.

For engineers reviewing the AN431AN-ATRG1 datasheet, AN431AN-ATRG1 pinout, AN431AN-ATRG1 application, or AN431AN-ATRG1 equivalent, key selection criteria include reference voltage accuracy, thermal stability over full temperature range, cathode current capability (1–100 mA), capacitive load stability, and SOT-23 package compatibility with space-constrained PCB layouts.

Technical Context

The AN431AN-ATRG1 functions as a two-input error amplifier with internal 2.5V bandgap reference, comparing external feedback voltage at the REF pin against VREF to control cathode current. Its sharp turn-on and low output impedance enable stable regulation even under varying load and input conditions.

It supports both standard shunt regulation and high-current configurations via external pass transistors, and integrates low-noise design with <4.5mV typical reference deviation across –40°C to +125°C - critical for precision feedback loops in DC/DC converters and voltage adapters.

Key Specifications

Pinout & Package

AN431AN-ATRG1 is housed in a standard SOT-23 package with gull-wing leads, optimized for automated assembly and thermal performance (θJC = 135°C/W). Pin assignments are verified per Diodes Inc. DS37414 Rev. 3-2.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431ACDBVR and AS431ASTZTR-G1, AN431AN-ATRG1 delivers superior thermal stability (20 ppm/°C vs. 25 ppm/°C), lower dynamic impedance (0.15Ω vs. 0.2Ω), and full industrial temperature qualification - making it optimal for high-reliability power management in automotive and industrial environments.

Availability

AN431AN-ATRG1 is available at Aetrix Electronics and suitable for switching power supplies, battery chargers, and precision voltage adapters requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AN431AN-ATRG1 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability power management, signal integrity, and protection solutions for industrial, computing, and consumer markets.

The AN431 series belongs to Diodes' precision reference product line, engineered specifically for high-accuracy, thermally stable shunt regulation in cost-sensitive yet performance-critical power conversion systems.

FAQ

What is the minimum cathode current required for regulation in AN431AN-ATRG1?

The minimum cathode current (IKA min) required for regulation is 0.4 mA typical and 1.0 mA maximum at 25°C, per DS37414 Rev. 3-2 Electrical Characteristics table. This ensures reliable turn-on and stable reference operation even under light-load conditions in low-power adapter or standby circuits.

Can AN431AN-ATRG1 drive a 100 µF capacitor directly without oscillation?

Yes - the AN431AN-ATRG1 remains stable with up to 100 µF capacitive load across all operating voltages (VKA = VREF to 15V), as confirmed by the "Stability Boundary Conditions vs. Load Capacitance" plot on page 8 of DS37414. No external compensation is needed for typical bulk capacitance filtering.

How does the reference current (IREF) affect external resistor selection?

IREF is typically 0.7 µA and max 4 µA at 25°C. Since IREF flows into the REF pin, it introduces a small error in the feedback divider ratio - for 1% accuracy, R1 and R2 should be chosen so that divider current (VREF/R2) exceeds IREF by ≥10×, e.g., R2 ≤ 25 kΩ when VREF = 2.5V.

Is AN431AN-ATRG1 pin-compatible with TL431 in SOT-23 packages?

Yes - AN431AN-ATRG1 uses identical SOT-23 pinout (Anode–Cathode–Ref) and shares functional equivalence with TL431-family devices. However, its lower tempco and impedance provide measurable performance improvement in thermally demanding applications without layout changes.