Diodes Incorporated AP431SBN1TR-G1

Overview

AP431SBN1TR-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), low 50 µA typical minimum cathode current for regulation, and operation up to 36 V cathode voltage. It replaces Zener diodes in feedback loops of switching power supplies, USB chargers, and voltage adapters where low-power, high-stability regulation is required.

For engineers reviewing the AP431SBN1TR-G1 datasheet, AP431SBN1TR-G1 pinout, AP431SBN1TR-G1 application, or AP431SBN1TR-G1 equivalent, this device offers verified thermal stability (±11 mV over –40°C to +125°C), 0.1 Ω typical dynamic impedance, and SOT23-3 (N1) package compatibility for space-constrained PCB designs.

Technical Context

The AP431SBN1TR-G1 implements a bandgap-referenced error amplifier driving an NPN output stage, enabling precise voltage regulation via external resistor divider between cathode and reference pins. Its sharp turn-on characteristic and low temperature coefficient (–40°C to +125°C) ensure stable feedback across wide ambient conditions.

It operates as a two-quadrant shunt device: sinking 100 µA to 100 mA cathode current while maintaining regulation, with off-state cathode leakage below 1.0 µA at 36 V. The 0.1 Ω dynamic impedance supports fast transient response in closed-loop SMPS feedback paths.

Key Specifications

Pinout & Package

SOT23-3 (Package Code N1) surface-mount package with 1.3 mm height, JEDEC-compliant lead pitch (0.95 mm), and matte tin-plated terminals solderable per MIL-STD-202 Method 208.

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, the AP431SBN1TR-G1 delivers superior low-power performance (50 µA vs. 60–100 µA), tighter thermal drift (±11 mV vs. ±15–25 mV), and identical SOT23-3 footprint-making it optimal for space- and efficiency-critical SMPS feedback designs.

Availability

AP431SBN1TR-G1 is available at Aetrix Electronics and suitable for USB charger feedback, industrial 24 V SMPS regulation, and graphics card VRM monitoring requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AP431SBN1TR-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 ICs for power management, signal integrity, and connectivity applications.

The AP431S/AP431SH series was designed specifically for high-accuracy, low-power shunt regulation in isolated DC/DC converters-targeting replacements for Zener diodes where thermal stability and minimal bias current are critical.

FAQ

What is the maximum cathode voltage the AP431SBN1TR-G1 can regulate?

The AP431SBN1TR-G1 supports cathode voltages up to 36 V under recommended operating conditions. Absolute maximum rating is 40 V, but sustained operation above 36 V risks thermal overstress and reduced reliability. Designers must ensure power dissipation (VK × IKA) remains within the SOT23-3 package limit of 350 mW at +25°C ambient.

Does AP431SBN1TR-G1 require an external capacitor for stability?

No external capacitor is required for basic regulation stability. The device maintains phase margin >45° with capacitive loads up to 10 µF, as confirmed in the datasheet's stability boundary plot. For loads exceeding 10 µF or in high-noise environments, a 1 nF ceramic capacitor from REF to ANODE improves noise rejection without affecting regulation accuracy.

How does the 1.0% reference tolerance affect output voltage accuracy?

With 1.0% reference tolerance (±25 mV at 2.500 V), output voltage accuracy depends on resistor divider tolerance. Using 0.5% R1/R2 resistors yields total output error ≤±1.5% at 5 V and ≤±2.0% at 24 V. For tighter accuracy, combine with calibration or select the 0.5% variant (AP431SAN1TR-G1).

Can AP431SBN1TR-G1 replace TL431 in existing designs?

Yes-AP431SBN1TR-G1 is pin-compatible with TL431 in SOT23-3 footprint (N1) and shares identical electrical behavior: same reference voltage range, sink current capability, and functional block diagram. No schematic or layout changes are needed, though its lower 50 µA min cathode current may reduce no-load power by up to 30%.