Texas Instruments TL431ACDBZTG4

Overview

TL431ACDBZTG4 from Texas Instruments is a precision programmable shunt voltage reference in SOT-23-3 package, featuring 1% initial reference voltage tolerance at 25°C, adjustable output from 2.47 V to 36 V, and operation across −40°C to 85°C. It delivers 0.2 Ω typical dynamic impedance and supports 1–100 mA sink current, widely used in feedback loops of AC/DC adapters and industrial power supplies.

For engineers reviewing the TL431ACDBZTG4 datasheet, TL431ACDBZTG4 pinout, TL431ACDBZTG4 application, or TL431ACDBZTG4 equivalent, key selection criteria include reference accuracy grade (A), thermal drift performance (14 mV over −40°C to 85°C), cathode current capability, dynamic impedance stability, and SOT-23-3 footprint compatibility with space-constrained PCB layouts.

Technical Context

The TL431ACDBZTG4 implements an internal 2.495 V bandgap reference with high-gain error amplifier and NPN output stage, configured as a three-terminal adjustable shunt regulator. Its REF pin senses voltage relative to ANODE, enabling precise regulation via external resistor divider without requiring a ground-referenced output.

Unlike Zener diodes, it provides sharp turn-on, low noise (typ. 19.1 µV_RMS over 0.1–10 Hz), and stable dynamic impedance (0.2 Ω) across 1–100 mA cathode current - critical for maintaining loop stability in isolated flyback and forward converter feedback networks.

Key Specifications

Pinout & Package

SOT-23-3 package (2.90 mm × 1.30 mm), surface-mount, lead-free, RoHS-compliant. Pin 1 = REF, Pin 2 = CATHODE, Pin 3 = ANODE.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431ACDBZTG4, TL431AIDBZR offers identical regulation performance and drop-in layout compatibility, while NCP100SN33T1G trades adjustability and low impedance for extended temperature range and lower unit cost in fixed-voltage roles.

Availability

TL431ACDBZTG4 is available at Aetrix Electronics and suitable for AC/DC power adapters, industrial motor drives, and rack server PSUs requiring stable component supply, long-term lifecycle support, and consistent parametric performance across manufacturing lots.

Supply support for TL431ACDBZTG4 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 and embedded processing technologies, with decades of expertise in precision analog ICs and power management solutions.

The TL431 family was designed as a pin-compatible, adjustable replacement for Zener diodes in feedback regulation - targeting cost-effective, high-stability voltage reference needs in power conversion, industrial control, and consumer electronics.

FAQ

What is the reference voltage tolerance of TL431ACDBZTG4 at 25°C?

The TL431ACDBZTG4 has a reference voltage tolerance of ±1% at 25°C, corresponding to a 2.47 V to 2.52 V range. This A-grade accuracy is specified in Section 6.8 of the TI datasheet and applies across the full operating current range (1–100 mA cathode current). The TL431ACDBZTG4 achieves this without external calibration, making it suitable for applications requiring certified output voltage compliance.

Does TL431ACDBZTG4 support adjustable output voltages above 25 V?

Yes, TL431ACDBZTG4 supports adjustable output voltages up to 36 V using an external resistor divider network. Its internal reference remains fixed at ~2.495 V, but the feedback ratio scales the effective output - e.g., a 10:1 divider yields 24.95 V, while a 14:1 ratio achieves 34.93 V. The device maintains regulation stability up to 36 V cathode voltage, as confirmed in Absolute Maximum Ratings (Section 6.1).

What is the maximum cathode current rating for TL431ACDBZTG4?

The TL431ACDBZTG4 supports continuous cathode current from 1 mA to 100 mA, per Recommended Operating Conditions (Section 6.4). At 100 mA, power dissipation in SOT-23-3 is limited by thermal resistance (R_θJA = 206°C/W); junction temperature must remain ≤125°C. Derating is required above 70°C ambient - e.g., max I_KA ≈ 65 mA at 85°C ambient.

How does the temperature coefficient of TL431ACDBZTG4 compare to standard Zener diodes?

TL431ACDBZTG4 exhibits a typical temperature drift of 14 mV over −40°C to +85°C (≈±0.056%/°C average TC), significantly better than most 5–12 V Zener diodes (often >0.1%/°C). This stems from its bandgap-based reference core and trimmed amplifier, delivering superior stability in industrial environments where thermal cycling affects long-term output accuracy.

Can TL431ACDBZTG4 be used in place of TL431B variants?

TL431ACDBZTG4 can replace TL431B variants only if ±1% accuracy meets system requirements - TL431B offers tighter ±0.5% tolerance. Electrically, both share identical pinout, dynamic impedance (0.2 Ω), and temperature range (−40°C to +85°C). However, substituting A-grade for B-grade may impact certification margins in medical or telecom power supplies where tighter initial tolerance is mandated.