Diodes Incorporated AN431BN-ATRE1

Overview

AN431BN-ATRE1 from Diodes Incorporated is a three-terminal adjustable precision shunt regulator with 1.0% reference voltage tolerance, 2.5V nominal VREF, 36V max cathode voltage, and 100mA sink current capability in SOT-23 package. It replaces Zener diodes in feedback loops of switching power supplies, battery chargers, and precision voltage references where thermal stability and low dynamic impedance are critical.

For engineers reviewing the AN431BN-ATRE1 datasheet, AN431BN-ATRE1 pinout, AN431BN-ATRE1 application, or AN431BN-ATRE1 equivalent, key selection criteria include its 20ppm/°C typical temperature coefficient, 0.15Ω typical dynamic output resistance, 4.5mV typical reference deviation over –40°C to +125°C, and stable operation under capacitive loads up to 100µF.

Technical Context

The AN431BN-ATRE1 functions as a programmable two-input error amplifier with internal 2.5V bandgap reference, comparing REF pin voltage against VREF to control cathode current flow. Its high open-loop gain and low output impedance enable precise regulation across wide cathode voltage (2.5V–36V) and load current (1mA–100mA) ranges.

It operates as a shunt-based feedback element in isolated DC-DC converters, where cathode connects to secondary-side optocoupler input and REF pin ties to resistor divider output. Thermal stability is ensured by matched on-die transistor pairs and curvature-compensated bandgap design, supporting operation from –40°C to +125°C ambient.

Key Specifications

Pinout & Package

SOT-23 package: 3-pin surface-mount, 1.3mm height, RoHS-compliant lead-free construction with halogen- and antimony-free "Green" molding compound.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431BIDBZR and AS431ASTZTR-G1, AN431BN-ATRE1 delivers superior thermal stability (20ppm/°C vs. 30–50ppm/°C) and lower dynamic impedance (0.15Ω), making it optimal for high-reliability, wide-temperature applications where long-term reference drift must be minimized.

Availability

AN431BN-ATRE1 is available at Aetrix Electronics and suitable for switching power supply feedback, battery charger voltage regulation, and precision voltage reference applications requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for AN431BN-ATRE1 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 product line delivers precision shunt regulation for feedback-critical power systems, designed specifically to replace Zener diodes with enhanced thermal stability, noise immunity, and load transient response in compact SOT-23 packaging.

FAQ

What is the maximum cathode voltage rating for AN431BN-ATRE1?

The absolute maximum cathode voltage (VKA) is 40V, but the recommended operating maximum is 36V. Exceeding 36V risks exceeding power dissipation limits and degrading long-term reliability, especially above +85°C ambient. Operation at 36V requires limiting cathode current to ≤10mA to stay within 370mW PD rating.

Can AN431BN-ATRE1 drive an optocoupler directly in a flyback converter?

Yes - with cathode current up to 100mA, it can directly bias common optocouplers like PC817 or SFH615A. For a 1.2V LED forward voltage and 5mA target current, use R_K = (V_OUT − 1.2V)/5mA. Ensure REF pin voltage remains at exactly 2.5V via proper resistor divider scaling to maintain regulation accuracy.

How does the 1.0% VREF tolerance affect output voltage accuracy in a 12V application?

In a 12V design using V_OUT = V_REF × (1 + R1/R2), the 1.0% VREF tolerance contributes ±0.12V error before resistor tolerance. With 0.5% resistors, total output error is typically ±0.22V (±1.8%). This meets Class II adapter requirements and exceeds standard 5% SMPS tolerances.

Is AN431BN-ATRE1 compatible with existing TL431 PCB footprints?

Yes - it uses the same SOT-23 package with identical pinout (Anode=Pin1, Cathode=Pin2, REF=Pin3). No layout change is required. However, due to lower ZKA (0.15Ω vs. TL431's 0.22Ω), output capacitor ESR may require minor re-evaluation to avoid excessive phase margin loss in high-frequency converters.