Diodes Incorporated ZHT431C02STOB

Overview

ZHT431C02STOB from Diodes Incorporated is a three-terminal adjustable precision shunt regulator with 2% initial tolerance, programmable output voltage from 2.5 V to 20 V via external resistors, ±30 mV reference voltage deviation over −55°C to +125°C, and 100 mA cathode current sink capability. It replaces discrete Zener diodes in voltage monitoring and over/under-voltage protection circuits requiring stable regulation across extended temperature ranges.

For engineers reviewing the ZHT431C02STOB datasheet, ZHT431C02STOB pinout, ZHT431C02STOB application, or ZHT431C02STOB equivalent, key selection criteria include its TO-92 package footprint, 67 ppm/°C max temperature coefficient, low dynamic output impedance (0.75 Ω), and compatibility with series/shunt regulator topologies in industrial power supplies.

Technical Context

The ZHT431C02STOB operates as a two-input, one-output shunt reference: the reference input (VREF) senses a fraction of cathode voltage (VZ) through an external resistor divider, while the cathode (VZ) sinks current to maintain regulation. Its internal bandgap-derived reference ensures temperature-compensated operation without external components.

It functions only when cathode current exceeds 50 mA minimum for regulation and supports open-loop gain stability up to 100 kHz with ≤100 pF load capacitance. The device exhibits −1.85 to −2.7 mV/V cathode voltage sensitivity and maintains <0.2 mA reference current drift over full temperature range.

Key Specifications

Pinout & Package

Package: TO-92 - axial-leaded through-hole plastic package with 12.5-inch reel packaging (1500 units/reel), suitable for manual assembly and wave soldering in legacy industrial designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431ACDBVR and KA431AZTA, ZHT431C02STOB offers balanced precision (2%), TO-92 compatibility, halogen-free construction, and superior temperature stability (67 ppm/°C vs. 100 ppm/°C), making it optimal for industrial through-hole designs requiring regulatory compliance and thermal robustness.

Availability

ZHT431C02STOB is available at Aetrix Electronics and suitable for industrial power supplies, embedded voltage monitors, and over/under-voltage protection circuits requiring stable component supply with long-term obsolescence management.

Supply support for ZHT431C02STOB 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 and signal integrity solutions for industrial, computing, and consumer markets.

The ZHT431 product line delivers precision shunt regulation for applications demanding wide temperature operation, low drift, and programmable voltage setpoints-targeting legacy and new-design power supervision in harsh environments.

FAQ

What is the minimum cathode current required for ZHT431C02STOB to regulate?

The ZHT431C02STOB requires a minimum cathode current of 50 mA to enter and maintain regulation mode, as specified in the Recommended Operating Conditions table. Below this threshold, the device cannot sustain stable reference voltage at the VREF pin, resulting in loss of output control. This value is measured at VZ = VREF and Tamb = 25°C, and remains valid across the full −55°C to +125°C operating range.

Can ZHT431C02STOB replace a standard 5.1 V Zener diode directly?

No direct replacement is possible without external resistors. Unlike a fixed Zener, ZHT431C02STOB requires two external resistors to program its output voltage. To replicate 5.1 V regulation, use R1 = 10.2 kΩ and R2 = 10 kΩ in the standard divider configuration. The device offers superior temperature stability (67 ppm/°C vs. >500 ppm/°C for typical Zeners) and tighter tolerance (2% vs. 5–10%).

Is ZHT431C02STOB RoHS compliant and halogen-free?

Yes. ZHT431C02STOB uses Diodes Incorporated's "Green" molding compound, explicitly defined as containing no bromine (Br) or antimony (Sb), satisfying both RoHS Directive 2011/65/EU and JEDEC JS709B halogen-free requirements. The "-7" suffix denotes this material variant, and the TO-92 package carries full compliance documentation traceable to manufacturing lot data.

What is the maximum power dissipation for ZHT431C02STOB in TO-92 package?

In the TO-92 package, ZHT431C02STOB has a maximum power dissipation of 330 mW at ambient temperature (Tamb = 25°C), derived from its 150 mA absolute maximum cathode current rating and 20 V maximum cathode voltage. Thermal derating applies above 25°C at 3.3 mW/°C, limiting usable power at +125°C ambient to approximately 40 mW without heatsinking or airflow.