Diodes Incorporated AP431IBNTR-G1

Overview

AP431IBNTR-G1 from Diodes Incorporated is a 3-terminal adjustable precision shunt regulator with 1.0% initial reference voltage tolerance (2.500 V at +25°C), 50 µA typical minimum cathode current for regulation, 0.1 Ω typical dynamic impedance, and operation from -40°C to +125°C. It replaces Zener diodes in feedback loops of switching power supplies, battery chargers, and voltage adapters where low-power regulation and thermal stability are critical.

For engineers reviewing the AP431IBNTR-G1 datasheet, AP431IBNTR-G1 pinout, AP431IBNTR-G1 application, or AP431IBNTR-G1 equivalent, this device serves as a programmable 2.5–36 V shunt reference with sharp turn-on, low temperature coefficient (11 mV deviation over -40°C to +125°C), and compatibility with capacitive loads - key selection criteria for isolated flyback and QR-PSR converter designs.

Technical Context

The AP431IBNTR-G1 implements a bandgap-referenced error amplifier with high-gain transconductance architecture, enabling precise regulation via external resistor dividers. Its internal reference is trimmed to ±1.0% at +25°C and exhibits only ±11 mV drift across -40°C to +125°C.

It operates as a 3-terminal sink device: REF senses the divided output, ANODE connects to system ground, and CATHODE sinks current into the primary-side controller's feedback pin. The 50 µA typical I_K(A,min) allows stable regulation even under ultra-low standby currents - critical for Energy Star-compliant AC/DC adapters.

Key Specifications

Pinout & Package

SOT-23 package (code N), 3-pin, lead-free and RoHS-compliant. Pin 1 = REF, Pin 2 = ANODE, Pin 3 = CATHODE. Anode must be connected to system ground; cathode connects to optocoupler LED anode or controller feedback pin; reference input monitors output voltage divider.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431ACDBVR and AS431ATBZTR-G1, AP431IBNTR-G1 delivers superior low-current regulation (50 µA vs. 60–100 µA) in a space-constrained SOT-23 package, making it optimal for high-density, ultra-low-standby AC/DC converters where thermal margin and footprint are limiting factors.

Availability

AP431IBNTR-G1 is available at Aetrix Electronics and suitable for USB-C PD adapters, laptop AC/DC chargers, and industrial 24 V power supplies requiring stable component supply, long-term lifecycle support, and RoHS/Green compliance.

Supply support for AP431IBNTR-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-efficiency power management, signal integrity, and protection solutions for consumer, industrial, and automotive markets.

The AP431i series was designed specifically for high-accuracy, low-quiescent-current shunt regulation in isolated switch-mode power supplies - addressing the need for stable feedback under ultra-light loads and wide temperature extremes.

FAQ

What is the maximum cathode voltage the AP431IBNTR-G1 can regulate?

The AP431IBNTR-G1 supports cathode voltages up to 36 V under recommended operating conditions. Its absolute maximum cathode voltage rating is 40 V, but sustained operation above 36 V risks exceeding thermal limits or degrading long-term stability. For 48 V systems, external clamping or series resistors are required to limit VKA.

Can AP431IBNTR-G1 replace TL431 in existing designs without layout changes?

Yes - AP431IBNTR-G1 uses the same SOT-23 (N) package and identical pinout (REF-ANODE-CATHODE) as TL431 variants. No PCB modification is needed. However, its lower 50 µA minimum cathode current may require reducing the upper feedback resistor value to maintain sufficient bias current in high-impedance divider networks.

Does AP431IBNTR-G1 require external compensation for stability?

No external compensation is required for typical optocoupler-based feedback configurations. The device is internally compensated and remains stable with ≥100 nF capacitive load on the cathode, as verified in Diodes' application circuits. Instability may occur only with >1 µF bulk capacitance directly at the cathode node without series resistance.

What does the "G1" suffix indicate in AP431IBNTR-G1?

The "G1" suffix denotes Diodes Incorporated's Green compliance level: fully lead-free, halogen-free (<900 ppm Br/Cl, <1000 ppm Sb), and compliant with EU RoHS Directive 2011/65/EU. It confirms the part meets IPC-1752A material declaration requirements and carries no intentionally added lead or hazardous substances.