Texas Instruments TL431ACDRE4

Overview

TL431ACDRE4 from Texas Instruments is a precision programmable shunt voltage reference IC with 1% initial tolerance at 25°C, adjustable output voltage from 2.47V to 36V, and operation across −40°C to 85°C. It delivers 0.2Ω typical dynamic impedance, 1mA–100mA sink-current capability, and low 6mV temperature drift (C-grade), widely used in feedback loops of isolated DC/DC converters and AC/DC power supplies.

For engineers reviewing the TL431ACDRE4 datasheet, TL431ACDRE4 pinout, TL431ACDRE4 application, or TL431ACDRE4 equivalent, key selection factors include its A-grade accuracy, SOIC-8 package thermal performance (R_θJA = 97°C/W), cathode current regulation range, and compatibility with optocoupler-based secondary-side feedback architectures.

Technical Context

The TL431ACDRE4 implements a three-terminal adjustable shunt regulator architecture with an internal 2.495V reference and high-gain error amplifier. Its sharp turn-on characteristic enables stable regulation without external compensation in most configurations, and active output circuitry ensures fast response to load transients.

It operates as a voltage-controlled current sink: when the REF pin voltage exceeds 2.495V, the cathode-anode path conducts to clamp VKA. The device requires ≥0.4mA minimum cathode current for regulation and maintains <0.5µA off-state leakage at 36V cathode voltage.

Key Specifications

Pinout & Package

TL431ACDRE4 is housed in an 8-pin SOIC (Small Outline Integrated Circuit) package with 4.90mm × 3.90mm body size and standard 1.27mm lead pitch. The package supports surface-mount reflow and offers R_θJA = 97°C/W for reliable thermal management in power supply PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431ACDRE4, TL431ACDR offers identical performance in different packaging, while TL431BIDR improves reference accuracy by 0.5% at the expense of higher unit cost-making TL431ACDRE4 optimal for cost-sensitive, thermally demanding industrial power designs requiring proven 1% stability.

Availability

TL431ACDRE4 is available at Aetrix Electronics and suitable for rack server power, industrial AC/DC, and servo drive control module applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for TL431ACDRE4 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management technologies, with decades of expertise in precision analog ICs.

The TL431 product line was designed specifically for high-stability, low-cost voltage reference applications in isolated switching power supplies, offering pin-compatible alternatives to Zener diodes with superior thermal drift and dynamic response.

FAQ

What is the reference voltage tolerance of TL431ACDRE4 at 25°C?

The TL431ACDRE4 has a reference voltage tolerance of ±1% at 25°C, corresponding to a 2.47V–2.52V range. This A-grade specification is confirmed in Section 6.8 of the TI datasheet (SLVS543S) under "Electrical Characteristics, TL431AC." The value is measured at 10mA cathode current and defines the initial accuracy before temperature and aging effects.

What package type does TL431ACDRE4 use, and what are its thermal characteristics?

TL431ACDRE4 uses an 8-pin SOIC package (body size 4.90mm × 3.90mm). Its junction-to-ambient thermal resistance (R_θJA) is 97°C/W, and junction-to-case (top) is 39°C/W. These values are specified in Section 6.3 of the datasheet and enable reliable operation at up to 100mA cathode current in standard 2-layer PCB layouts with moderate copper area.

Can TL431ACDRE4 replace a Zener diode in feedback circuits?

Yes, TL431ACDRE4 is explicitly designed as a superior replacement for Zener diodes in feedback circuits. Its active error amplifier provides sharper turn-on, lower dynamic impedance (0.2Ω vs typical Zener's 5–20Ω), and tighter temperature stability (≤25mV drift vs >50mV for 5% Zeners). TI's datasheet Section 3 confirms this use case for on-board regulation and switching power supplies.

What is the minimum cathode current required for TL431ACDRE4 to regulate properly?

The TL431ACDRE4 requires a minimum cathode current of 0.4mA to maintain regulation, as specified in Section 6.8 (I_min parameter). Below this threshold, the device exits regulation and cathode voltage rises uncontrollably. This value is validated across −40°C to +85°C and must be ensured in all operating conditions-including light-load and standby modes.

How does TL431ACDRE4 handle temperature variation across its operating range?

TL431ACDRE4 exhibits ≤25mV total reference voltage deviation (V_I(dev)) from −40°C to +85°C in SOIC-8 packages, per Section 6.8. This corresponds to ±0.1% drift on a 24V output rail. The device achieves this via curvature-compensated bandgap core and on-die trimming, making it significantly more stable than discrete Zener solutions over industrial temperature ranges.