Texas Instruments TL431BCDBZT

Overview

TL431BCDBZT from Texas Instruments is a precision programmable shunt voltage reference in SOT-23-3 package, featuring 0.5% initial reference voltage tolerance at 25°C (B grade), 2.483–2.507 V reference voltage, and operation across −40°C to 125°C (Q temperature grade). It delivers 0.2 Ω typical dynamic impedance and supports 1–100 mA sink current, widely used in feedback loops of isolated DC/DC converters and AC/DC power supplies.

For engineers reviewing the TL431BCDBZT datasheet, TL431BCDBZT pinout, TL431BCDBZT application, or TL431BCDBZT equivalent, this page provides verified electrical specifications, thermal performance data, stability boundary conditions for capacitor-loaded configurations, and validated alternative options for industrial power regulation design.

Technical Context

The TL431BCDBZT implements an internal error amplifier with high-gain transconductance stage driving a NPN output transistor, enabling sharp turn-on and precise regulation via external resistor divider between cathode and reference pins. Its three-terminal shunt topology replaces Zener diodes in closed-loop feedback paths where low output impedance and tight voltage accuracy are required.

As a Q-grade device, TL431BCDBZT is characterized for −40°C to 125°C operation and exhibits ≤34 mV total reference voltage deviation over that range. Its 0.2 Ω dynamic impedance and low 1.2 µA max reference input current drift ensure stable regulation under varying load and temperature conditions in high-reliability power systems.

Key Specifications

Pinout & Package

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

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431BCDBZT, TL431BIDBZR trades extended temperature capability for lower cost in non-automotive applications, while TLVH431BQDBZR offers lower reference voltage and higher sink current for modern low-voltage power architectures - both require layout verification due to differing thermal and stability profiles.

Availability

TL431BCDBZT is available at Aetrix Electronics and suitable for rack server power, industrial AC/DC, and servo drive control module applications requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for TL431BCDBZT 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 reference design and power management ICs.

The TL431 product line was engineered for high-accuracy, low-drift shunt regulation in isolated power supplies and industrial control systems - delivering Zener replacement performance with programmable flexibility and robust thermal behavior.

FAQ

What is the reference voltage tolerance of TL431BCDBZT at 25°C?

The TL431BCDBZT has a reference voltage tolerance of ±0.5% at 25°C, corresponding to a 2.483–2.507 V range. This B-grade accuracy is specified in Section 6.11 of the TI SLVS543S datasheet and applies strictly to the TL431BCDBZT variant with SOT-23-3 packaging and Q-temperature qualification. The tolerance remains valid under 10 mA cathode current and nominal cathode-to-anode voltage conditions.

Does TL431BCDBZT support operation at 125°C?

Yes, TL431BCDBZT is a Q-grade device characterized for continuous operation from −40°C to +125°C. Its electrical parameters-including reference voltage deviation (≤34 mV), dynamic impedance (0.2–0.5 Ω), and sink current capability (1–100 mA)-are guaranteed across this full range per Section 6.13 of the official TI datasheet. Thermal derating is not required up to T_J = 150°C.

What is the maximum cathode current for TL431BCDBZT?

The TL431BCDBZT supports a continuous cathode current range of 1 mA to 100 mA, as defined in Section 6.4 (Recommended Operating Conditions) and verified in Sections 6.11–6.13 of the TI datasheet. Absolute maximum cathode current is ±150 mA (Section 6.1), but sustained operation above 100 mA requires thermal validation due to SOT-23-3 package limitations (R_θJA = 206°C/W).

Can TL431BCDBZT replace a standard Zener diode?

Yes, TL431BCDBZT functions as a precision programmable Zener replacement with superior performance: it offers adjustable output (2.5 V to 36 V), 0.5% initial tolerance vs. typical ±5% Zener tolerance, 0.2 Ω dynamic impedance vs. 10–100 Ω for Zeners, and guaranteed operation across −40°C to +125°C. Its active circuitry provides sharper knee characteristics and lower noise than passive Zener devices.

What is the dynamic impedance of TL431BCDBZT and why does it matter?

The TL431BCDBZT has a typical dynamic impedance of 0.2 Ω (max 0.5 Ω) at frequencies ≤1 kHz and cathode currents from 1 mA to 100 mA. This low value ensures minimal output voltage variation during rapid load transients-critical for maintaining regulation stability in switching power supplies and preventing feedback loop oscillation when paired with optocouplers and capacitive loads.