Diodes Incorporated AS431IARTR-G1

Overview

AS431IARTR-G1 from Diodes Incorporated is a three-terminal adjustable precision shunt regulator with 0.5% initial reference voltage tolerance, 2.5V to 36V programmable output range, 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 cathode current (10µA typ.) and low dynamic impedance (0.15Ω typ.) are critical.

For engineers reviewing the AS431IARTR-G1 datasheet, AS431IARTR-G1 pinout, AS431IARTR-G1 application, or AS431IARTR-G1 equivalent, key selection criteria include minimum cathode current for regulation, reference voltage drift over temperature, dynamic impedance under load, and SOT-89 package thermal resistance (29°C/W).

Technical Context

The AS431IARTR-G1 implements a bandgap-referenced error amplifier driving an NPN output stage, enabling precise feedback control in isolated DC-DC converters and adjustable linear regulators. Its sharp turn-on characteristic and low 4.5mV typical reference deviation across −40°C to +125°C support stable regulation in thermally varying environments.

It operates as a two-quadrant shunt device: sinking 50µA–100mA cathode current while maintaining <0.5Ω dynamic impedance up to 100kHz. The 0.5% VREF tolerance at +25°C and −1.0 to −2.7 mV/V cathode voltage sensitivity ensure predictable setpoint accuracy in resistor-divider-based feedback networks.

Key Specifications

Pinout & Package

AS431IARTR-G1 is packaged in RoHS-compliant, halogen-free SOT-89 (Option 1) with exposed thermal pad. Pin 1 = REF, Pin 2 = ANODE, Pin 3 = CATHODE (top view). The SOT-89 footprint provides superior thermal performance versus SOT-23 and TO-92 variants.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431ACDR and AP431SARTG-13, AS431IARTR-G1 delivers superior thermal stability (4.5mV drift), lower dynamic impedance (0.15Ω), and optimized SOT-89 thermal performance (29°C/W) - making it preferred for high-accuracy, high-power shunt regulation in industrial and automotive power supplies.

Availability

AS431IARTR-G1 is available at Aetrix Electronics and suitable for switching power supplies, battery chargers, and precision voltage references requiring stable component supply, long-term lifecycle support, and RoHS 3 compliance.

Supply support for AS431IARTR-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 semiconductor company specializing in discrete, analog, and mixed-signal devices for power management, signal integrity, and connectivity applications.

The AS431I product line delivers high-precision, thermally stable shunt regulators targeting industrial power conversion, consumer charging, and embedded system voltage monitoring - with emphasis on low bias current and wide temperature operation.

FAQ

What is the maximum cathode voltage rating for AS431IARTR-G1?

The absolute maximum cathode-to-anode voltage (VKA) is 40V, but the recommended operating maximum is 36V. Exceeding 36V risks exceeding the specified electrical characteristics and may degrade long-term reliability. Operation at 40V is only permissible under short-duration transient conditions defined in the Absolute Maximum Ratings table.

Can AS431IARTR-G1 be used with ceramic output capacitors without oscillation?

Yes - the AS431IARTR-G1 is designed for high stability under capacitive loads. The datasheet confirms stable operation with ≥100µF ceramic capacitors across its full operating range, provided the cathode current remains within 50µA–100mA and the load capacitor is placed directly at the cathode pin with minimal trace inductance.

How does the 0.5% VREF tolerance impact output voltage accuracy in a 12V application?

In a 12V design using R1/R2 = 3.8, the 0.5% VREF tolerance contributes ±0.0125V error at the reference node. Combined with resistor tolerance (e.g., 1% metal film), total output error remains within ±1.2%, meeting most industrial power supply specifications without trimming.

Is the SOT-89 package of AS431IARTR-G1 compatible with standard reflow profiles?

Yes - the SOT-89 package is rated for standard lead-free reflow (J-STD-020, peak 260°C). Its exposed thermal pad requires appropriate stencil design (≥70% paste coverage) and thermal relief vias to achieve reliable solder joint formation and meet the 29°C/W θJC specification.