Diodes Incorporated ZR431LF02TA

Overview

ZR431LF02TA from Diodes Incorporated is a 2.5% tolerance, adjustable precision shunt regulator in SOT23 package, featuring 1.24 V reference voltage, 50 ppm/°C max temperature coefficient, and 100 μA–25 mA cathode current capability. It serves as a programmable voltage reference in feedback loops of switch-mode power supplies, enabling stable 3.3 V or 3 V output generation via external resistor dividers.

For engineers reviewing the ZR431LF02TA datasheet, ZR431LF02TA pinout, ZR431LF02TA application, or ZR431LF02TA equivalent, key selection criteria include reference voltage accuracy over temperature, dynamic output impedance (≤2 Ω), minimum regulation current (30–100 μA), cathode voltage range (1.24–10 V), and SOT23 thermal resistance (380 °C/W).

Technical Context

The ZR431LF02TA implements a bandgap-based, temperature-compensated reference core with internal error amplifier and NPN pass transistor. Its three-terminal architecture allows direct integration into shunt or series regulator topologies without external biasing components.

It operates as a two-input comparator: the reference input (VREF) compares against a divided cathode voltage, driving the cathode terminal to maintain regulation. Output voltage is set by R1/R2 ratio per VOUT = VREF × (1 + R1/R2), with VREF fixed at 1.24 V (±2.5%).

Key Specifications

Pinout & Package

SOT23-3 surface-mount package (JEDEC TO-236AB), 2.9 mm × 1.3 mm footprint, 1.1 mm height, with 0.95 mm lead pitch. Thermal resistance θJA = 380 °C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431ACDBVR and KIA431AP, ZR431LF02TA offers balanced performance: lower reference current than TL431 for energy-constrained designs, and superior temperature stability versus KIA431AP-making it optimal for industrial SMPS feedback where accuracy, efficiency, and thermal robustness are jointly prioritized.

Availability

ZR431LF02TA is available at Aetrix Electronics and suitable for switch-mode power supplies, voltage supervision circuits, overvoltage protection systems, and precision series regulator references requiring stable component supply and long-term manufacturability.

Supply support for ZR431LF02TA 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, headquartered in Plano, Texas, serving industrial, computing, consumer, and communications markets with high-reliability components.

The ZR431L product line delivers precision shunt regulation for power management feedback and voltage monitoring, designed specifically to replace zener diodes with improved accuracy, temperature stability, and current-handling capability.

FAQ

What is the minimum cathode current required for regulation in ZR431LF02TA?

The ZR431LF02TA requires a minimum cathode current (IZ(MIN)) of 30 µA to 100 µA to maintain regulation, depending on operating temperature and cathode voltage. This value is specified in the Electrical Characteristics table under Recommended Operating Conditions and must be met to ensure stable reference voltage output across the full –40°C to +85°C range.

Can ZR431LF02TA replace a standard zener diode directly in existing circuits?

Yes, ZR431LF02TA can directly replace zener diodes in most shunt regulator applications, provided the circuit provides ≥30 µA cathode current and uses a two-resistor divider to set the desired output voltage. Unlike zeners, it requires connection of all three pins (cathode, anode, reference), and its lower dynamic impedance improves regulation under varying loads.

How does the reference input current (IREF) affect resistor selection in the voltage divider?

With IREF ranging from 0.02 µA to 0.4 µA, the ZR431LF02TA draws negligible current from the divider node, allowing use of high-value resistors (e.g., 100 kΩ–1 MΩ) without significant loading error. This reduces power dissipation in the divider and enables battery-operated designs with multi-year standby life.

Is ZR431LF02TA qualified for automotive applications?

No-ZR431LF02TA is specified for industrial temperature range (–40°C to +85°C) and is not AEC-Q200 qualified. While it operates within common automotive ambient temperatures, Diodes Incorporated does not certify this variant for automotive use; designers requiring automotive qualification should consult the ZR431LQ series or equivalent AEC-Q200-compliant shunt regulators.