Texas Instruments TL431BCPKG3

Overview

TL431BCPKG3 from Texas Instruments is a precision programmable shunt voltage reference in SOT-89 package, delivering 2.495 V nominal reference voltage with ±0.5% initial tolerance at 25°C, 0.2 Ω typical dynamic impedance, and operation across −40°C to 125°C. It serves as a high-stability replacement for Zener diodes in feedback loops of isolated DC/DC converters, AC/DC power supplies, and servo drive control modules.

For engineers reviewing the TL431BCPKG3 datasheet, TL431BCPKG3 pinout, TL431BCPKG3 application, or TL431BCPKG3 equivalent, key selection criteria include its B-grade accuracy, Q-temp automotive qualification, low temperature drift (14 mV over −40°C to 125°C), and sink-current capability up to 100 mA - all critical for closed-loop regulation in industrial and automotive power systems.

Technical Context

The TL431BCPKG3 implements a three-terminal adjustable shunt regulator architecture with an internal error amplifier, reference, and output transistor. Its sharp turn-on characteristic and 0.2 Ω dynamic impedance enable stable regulation with minimal external components - typically just two resistors setting output from 2.5 V to 36 V.

It operates as a voltage-controlled current sink: when the REF pin voltage exceeds 2.495 V, the cathode-anode path conducts, sinking current proportional to the error signal. This behavior supports precise feedback in secondary-side regulation without optocoupler latency, especially in flyback and forward converters.

Key Specifications

Pinout & Package

SOT-89 package (3-pin, 4.5 mm × 2.5 mm × 1.5 mm body), thermally enhanced with exposed tab connected to ANODE for PCB heat sinking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431BQDBZR and TLVH431BQDBZR, TL431BCPKG3 offers superior thermal performance (52°C/W R_θJA) and mechanical robustness in SOT-89, making it optimal for high-power-density industrial and automotive power stages where sustained 100 mA sink current and thermal reliability are prioritized over miniaturization.

Availability

TL431BCPKG3 is available at Aetrix Electronics and suitable for rack server power, industrial AC/DC converters, and servo drive control modules requiring stable component supply with guaranteed long-term manufacturability.

Supply support for TL431BCPKG3 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 ICs, with decades of expertise in precision reference and power control solutions.

The TL431 product line delivers cost-effective, high-accuracy shunt references for feedback regulation in isolated power supplies, battery chargers, and industrial control systems - designed for reliability across commercial, industrial, and automotive environments.

FAQ

What is the reference voltage tolerance of TL431BCPKG3 at 25°C?

The TL431BCPKG3 has a reference voltage tolerance of ±0.5% at 25°C, corresponding to a 2.495 V nominal value with a min/max range of 2.483 V to 2.507 V. This B-grade accuracy is specified in Section 6.11 of the TI datasheet and applies strictly to the TL431BCPKG3 variant with Q-temp qualification. The tolerance remains valid only when operating within recommended conditions: cathode voltage between 2.5 V and 36 V, and cathode current between 1 mA and 100 mA.

Does TL431BCPKG3 support operation at −40°C to +125°C?

Yes, TL431BCPKG3 is rated for operation from −40°C to +125°C, as confirmed by its "Q" temperature suffix and characterization in Section 6.13 of the TI datasheet. This Q-temp rating meets automotive under-hood requirements and industrial extended-range needs. The device maintains its 2.495 V reference with ≤14 mV total deviation across this range, and its 0.2 Ω dynamic impedance remains stable per Figure 6-12. Thermal derating must follow R_θJA = 52°C/W and T_J(max) = 150°C limits.

What is the maximum cathode voltage rating for TL431BCPKG3?

The absolute maximum cathode-to-anode voltage (V_{K A}) for TL431BCPKG3 is 37 V, as stated in Section 6.1 Absolute Maximum Ratings. Operation beyond this risks permanent damage. For reliable regulation, the recommended operating range is V_ref to 36 V per Section 6.4. At 36 V cathode voltage, off-state cathode current remains ≤0.5 µA (Section 6.13), confirming safe blocking capability. Exceeding 36 V in normal operation violates recommended conditions and may degrade long-term stability.

How does TL431BCPKG3 differ from TL431BIDBZR?

TL431BCPKG3 uses SOT-89 packaging with Q-temp (−40°C to 125°C) rating and 0.5% initial accuracy, while TL431BIDBZR uses SOT-23-3 packaging with I-temp (−40°C to 85°C) rating and identical B-grade accuracy. Key differences include thermal resistance (52°C/W vs. 206°C/W), package size (4.5 × 2.5 mm vs. 2.9 × 1.3 mm), and maximum power dissipation (≈700 mW vs. ≈250 mW). TL431BCPKG3 is preferred for high-current, high-ambient applications; TL431BIDBZR suits compact, lower-power designs.

Can TL431BCPKG3 replace a Zener diode in feedback circuits?

Yes, TL431BCPKG3 is explicitly designed as a precision replacement for Zener diodes in feedback circuits, as stated in the Description section. Its advantages include 0.5% initial tolerance (vs. typical 5% for Zeners), 0.2 Ω dynamic impedance (vs. 10–100 Ω for Zeners), and adjustable output from 2.5 V to 36 V using two resistors. Unlike Zeners, it provides sharp turn-on and low temperature drift (14 mV over −40°C to 125°C), enabling stable regulation in switching power supplies, isolated DC/DC converters, and voltage monitors where Zener performance is insufficient.