Diodes Incorporated AS431IAZTR-G1

Overview

AS431IAZTR-G1 from Diodes Incorporated is a three-terminal adjustable precision shunt regulator with 0.5% initial reference voltage tolerance (2.500 V), 10 µA typical minimum cathode current for regulation, and guaranteed thermal stability from –40°C to +125°C. It replaces Zener diodes in switching power supplies, battery chargers, and precision voltage references where low output impedance (0.15 Ω typical) and sharp turn-on are required.

For engineers reviewing the AS431IAZTR-G1 datasheet, AS431IAZTR-G1 pinout, AS431IAZTR-G1 application, or AS431IAZTR-G1 equivalent, key selection criteria include cathode voltage range (2.5–36 V), dynamic impedance (<0.5 Ω), reference current (0.035 µA typical), and SOT-89 package compatibility with high-current shunt regulator topologies.

Technical Context

The AS431IAZTR-G1 operates as a programmable shunt reference using an internal bandgap reference and transconductance amplifier. Its functional block diagram shows a differential input stage comparing REF-to-ANODE voltage against VREF (2.5 V), driving a cathode sink transistor with low output impedance and high open-loop gain.

It achieves stable regulation under capacitive loads up to 100 µF without oscillation across cathode voltages from 5 V to 10 V, and maintains <4.5 mV reference deviation over –40°C to +125°C - enabled by matched on-die resistor networks and curvature-compensated bandgap design.

Key Specifications

Pinout & Package

AS431IAZTR-G1 is packaged in SOT-89 (Option 1), with gull-wing leads and exposed thermal pad. The package measures 4.40 × 2.60 × 1.60 mm and is RoHS-compliant and halogen-free.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431ACDR and AP431SAG-13, AS431IAZTR-G1 uniquely balances 0.5% tolerance, SOT-89 thermal performance (770 mW), and 10 µA regulation threshold - making it optimal for medium-power industrial adapters where layout reuse and thermal margin are critical.

Availability

AS431IAZTR-G1 is available at Aetrix Electronics and suitable for USB-C PD adapters, laptop charger feedback loops, and industrial PLC I/O modules requiring stable component supply with full industrial temperature range support.

Supply support for AS431IAZTR-G1 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 AS431I series belongs to Diodes' precision shunt regulator product line, designed specifically for replacing Zener diodes in high-stability, wide-temperature switching power supplies and battery charging systems.

FAQ

What is the maximum cathode voltage the AS431IAZTR-G1 can regulate?

The AS431IAZTR-G1 supports cathode voltages up to 36 V under recommended operating conditions. Its absolute maximum cathode voltage is 40 V, but sustained operation above 36 V risks exceeding thermal limits or degrading long-term stability. Designers must ensure power dissipation (VKA × IKA) stays within the SOT-89 package's 770 mW limit at ambient temperatures up to +125°C.

Can AS431IAZTR-G1 replace a standard Zener diode directly?

Yes - AS431IAZTR-G1 functions as a 3-pin drop-in replacement for Zener diodes in shunt regulator configurations. Unlike passive Zeners, it requires a resistor divider between cathode and reference pins to set output voltage. Its active architecture delivers superior temperature coefficient (4.5 mV max drift), lower dynamic impedance (0.15 Ω), and sharper knee characteristics than discrete Zeners.

Does AS431IAZTR-G1 require external compensation for stability?

No external compensation is required for stability with capacitive loads up to 100 µF, as confirmed in the datasheet's stability boundary plots. The device remains stable across cathode voltages from 5 V to 10 V with no oscillation. For VKA > 10 V or loads exceeding 100 µF, a small series resistor (≤10 Ω) at the cathode may be added to damp high-frequency peaking.

How does the 0.5% VREF tolerance impact output accuracy in a typical application?

In a standard resistor-divider configuration (VOUT = VREF × (1 + R1/R2)), the 0.5% VREF tolerance contributes directly to initial output error. With 1% resistors, total initial error remains ≤2.5%. Over temperature, the combined effect of VREF drift (±4.5 mV) and resistor TCR adds <±0.3% additional error from –40°C to +125°C - enabling ±1% overall output accuracy in well-designed systems.