Texas Instruments TL431ACPKG3

Overview

TL431ACPKG3 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, 1 mA to 100 mA sink-current capability, and operation across −40°C to 125°C. It replaces Zener diodes in adjustable power supplies, isolated feedback loops, and industrial AC/DC converters.

For engineers reviewing the TL431ACPKG3 datasheet, TL431ACPKG3 pinout, TL431ACPKG3 application, or TL431ACPKG3 equivalent, key selection criteria include its A-grade (1%) accuracy, Q-temp rating (−40°C to 125°C), SOT-89 thermal performance (R_θJC = 9°C/W), and verified stability with ≥0.1 µF load capacitance in closed-loop regulation.

Technical Context

The TL431ACPKG3 implements an internal error amplifier and NPN pass transistor in a three-terminal shunt topology, where the REF pin senses voltage relative to ANODE and controls cathode current to maintain regulation. Its sharp turn-on characteristic and low 0.2 Ω dynamic impedance enable fast transient response in feedback paths.

It operates as a 2.5 V bandgap-referenced comparator driving an output stage, requiring external resistive divider between CATHODE and REF to set output voltage from 2.495 V to 36 V. Stability is maintained with load capacitance ≥0.1 µF and series resistance ≤150 Ω per TI's stability boundary curves for Q-temp devices.

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 TL431CDBZR, TL431ACPKG3 offers extended temperature operation and superior thermal dissipation; compared with TL431BQPK, it trades 0.5% accuracy for lower cost while retaining full Q-temp qualification and identical package compatibility.

Availability

TL431ACPKG3 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 sourcing.

Supply support for TL431ACPKG3 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 design.

The TL431 product line delivers cost-effective, high-stability shunt references for power supply feedback, voltage monitoring, and programmable threshold detection across automotive, industrial, and computing markets.

FAQ

What is the maximum cathode voltage rating for TL431ACPKG3?

The absolute maximum cathode-to-anode voltage (V_{K A}) for TL431ACPKG3 is 37 V. Operation up to 36 V is supported under recommended conditions. Exceeding 37 V risks permanent damage, and derating is advised for reliability in high-temperature environments. The TL431ACPKG3 datasheet specifies this limit in Section 6.1 Absolute Maximum Ratings.

Can TL431ACPKG3 replace a standard Zener diode in a linear regulator?

Yes, TL431ACPKG3 can directly replace Zener diodes in shunt regulator configurations. Its 2.495 V reference, low 0.2 Ω dynamic impedance, and sharp turn-on provide superior regulation accuracy and stability. Unlike Zeners, TL431ACPKG3 maintains consistent performance across temperature and current-verified in TI's SLVS543S datasheet Figures 6-1 and 6-3.

What is the minimum cathode current required for regulation in TL431ACPKG3?

The TL431ACPKG3 requires a minimum cathode current (I_min) of 0.4 mA to maintain regulation, with typical value 0.6 mA at 25°C. This ensures reliable startup and dropout behavior in low-power feedback circuits. Values are specified in Section 6.8 Electrical Characteristics of the TL431ACPKG3 datasheet under test condition V_KA = V_ref.

Does TL431ACPKG3 support capacitive loads, and what is the stability limit?

TL431ACPKG3 supports capacitive loads ≥0.1 µF when used with series resistance ≤150 Ω, per TI's stability boundary curves for Q-temp devices (Figure 6-18). Larger capacitances require careful phase-margin analysis; instability manifests as oscillation in the 10 kHz–100 kHz range. The TL431ACPKG3 datasheet recommends RC snubbers for >1 µF loads in noisy environments.

How does the REF pin input current affect resistor divider design for TL431ACPKG3?

The REF pin draws 2–4 µA typical input current, introducing gain error in high-value resistor dividers. For example, a 1 MΩ/1 MΩ divider adds ~2 mV offset. To limit error to <0.1%, use ≤200 kΩ total divider resistance. This behavior is documented in Section 6.8 (I_ref) and Figure 6-2 of the TL431ACPKG3 datasheet.