Diodes Incorporated ZXRE250ASA-7

Overview

ZXRE250ASA-7 from Diodes Incorporated is a three-terminal adjustable precision shunt regulator with 1% initial reference voltage tolerance (2.495V ±1.0%), 40µA typical minimum cathode current for regulation, and operation from –40°C to +125°C. It replaces standard zener diodes in low-power voltage reference and feedback circuits, supporting adjustable output voltages from 2.5V to 36V using two external resistors - ideal for optocoupler linearisation and isolated power supply feedback loops.

For engineers reviewing the ZXRE250ASA-7 datasheet, ZXRE250ASA-7 pinout, ZXRE250ASA-7 application, or ZXRE250ASA-7 equivalent, key selection criteria include ultra-low cathode current requirement, tight reference voltage tolerance, SOT23 package thermal performance, and compatibility with existing TL431-based designs requiring improved efficiency at light loads.

Technical Context

The ZXRE250ASA-7 implements a bandgap-referenced shunt regulator architecture with internal temperature compensation, delivering stable 2.495V reference voltage across –40°C to +125°C with ≤16mV deviation over full range. Its dynamic output impedance is 0.2Ω typical, enabling high loop stability in closed-loop feedback configurations.

It operates as a two-node controlled current sink between cathode and anode, with reference input (REF) pin sensing the divider network. Regulation initiates when cathode-to-anode voltage exceeds VREF and cathode current exceeds 40µA - enabling precise threshold control in under-voltage/over-voltage protection circuits without external biasing.

Key Specifications

Pinout & Package

ZXRE250ASA-7 is housed in a RoHS-compliant SOT23 package (3-pin, 2.4mm × 2.9mm × 1.1mm), with thermal resistance θ_JA = 380°C/W. Pin 1 is ANODE, Pin 2 is CATHODE, Pin 3 is REF - confirmed per Diodes Incorporated DS35228 Rev. 7 Figure 1 (Top View).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP431SHA-TRG1, ZXRE250ASA-7 reduces minimum cathode current by 60%, enabling 2.5× longer battery life in always-on monitoring circuits; versus ZXRE250BSA-7, it trades 0.5% tolerance for lower cost while retaining identical thermal and noise performance.

Availability

ZXRE250ASA-7 is available at Aetrix Electronics and suitable for isolated power supply feedback, optocoupler linearisation, under-voltage lockout, and programmable voltage threshold detection requiring stable component supply across automotive, industrial, and consumer electronics programs.

Supply support for ZXRE250ASA-7 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 ICs, headquartered in Plano, Texas, with design and manufacturing operations across Asia and the Americas.

ZXRE250 belongs to Diodes' precision reference product line, engineered specifically for high-accuracy, low-power shunt regulation in space-constrained and thermally demanding applications such as automotive power management and industrial isolation interfaces.

FAQ

What is the maximum cathode voltage rating for ZXRE250ASA-7?

The absolute maximum cathode-to-anode voltage is 40V, with recommended operating range from V_REF (2.5V) to 36V. Exceeding 40V risks permanent device failure per DS35228 Rev. 7 Absolute Maximum Ratings table. Derating is advised above 125°C ambient due to junction temperature limits.

Can ZXRE250ASA-7 replace TL431 in existing designs?

Yes - ZXRE250ASA-7 uses identical SOT23 pinout and matches TL431's electrical function, but requires verification of cathode current margin: its 40µA minimum is significantly lower than TL431's ~100µA, so existing bias networks may need resistor value adjustment to ensure reliable startup under all conditions.

How does the 0.2Ω dynamic output impedance affect circuit stability?

This low impedance minimises voltage droop during fast load transients in feedback loops, reducing phase shift and improving phase margin in optocoupler-coupled SMPS designs. Stability testing per DS35228 Figure 12 confirms robust operation with 50pF–300nF capacitive loading, unlike higher-impedance alternatives that require careful compensation.

Is ZXRE250ASA-7 compliant with modern environmental standards?

Yes - it is fully RoHS 3 (2015/863/EU) compliant, lead-free, halogen-free (<900ppm Br/Cl, <1000ppm Sb), and classified as Diodes Incorporated's "Green" product per their quality documentation. No lead is purposely added, and packaging meets EU Directive 2002/95/EC requirements.