Texas Instruments TL431AQPKG3

Overview

TL431AQPKG3 from Texas Instruments is a precision programmable shunt voltage reference in SOT-89 package, delivering 2.47–2.52 V reference voltage (±1% initial tolerance at 25°C), −40°C to +125°C operating range, and 0.2 Ω typical dynamic impedance. It regulates output by sinking 1–100 mA cathode current and serves as a Zener diode replacement in feedback loops of isolated DC/DC converters and industrial power supplies.

For engineers reviewing the TL431AQPKG3 datasheet, TL431AQPKG3 pinout, TL431AQPKG3 application, or TL431AQPKG3 equivalent, key selection criteria include its Q-grade automotive temperature rating, low 14–34 mV reference voltage drift over full temperature range, adjustable 2.5 V to 36 V output via two external resistors, and compatibility with stability-critical closed-loop regulation designs.

Technical Context

The TL431AQPKG3 implements an internal error amplifier comparing REF pin voltage against a trimmed 2.495 V bandgap reference; when REF exceeds Vref, the cathode sinks current to maintain regulation. Its sharp turn-on characteristic and low output impedance enable fast transient response in switching power supply feedback paths.

Designed for high-reliability applications, it features ±2000 V HBM ESD rating, operates up to 150°C junction temperature, and maintains stable performance across wide cathode voltage (2.5 V to 36 V) and cathode current (1 mA to 100 mA) ranges without external compensation in most configurations.

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 TL431AQPKG3, TL431ACPK trades extended temperature capability for lower cost and wider reference tolerance, while TL431BQPK delivers tighter 0.5% initial accuracy at same Q-grade thermal rating-enabling higher-output-accuracy designs without changing layout or thermal design.

Availability

TL431AQPKG3 is available at Aetrix Electronics and suitable for rack server power, industrial AC/DC converters, and servo drive control modules requiring stable component supply across extended temperature and long product lifecycles.

Supply support for TL431AQPKG3 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 reference and power control ICs.

The TL431 family was designed as a pin-compatible, adjustable shunt reference to replace discrete Zener diodes in feedback networks-targeting high-reliability power conversion, industrial control, and automotive systems.

FAQ

What is the reference voltage tolerance of TL431AQPKG3 at 25°C?

The TL431AQPKG3 has a reference voltage tolerance of ±1% at 25°C, corresponding to a 2.47–2.52 V range. This A-grade specification is confirmed in Section 6.10 of the TI datasheet SLVS543S, and applies specifically to the Q-temp variant in PK package. The TL431AQPKG3 maintains this tolerance across its full −40°C to +125°C operating range with defined drift limits.

How does TL431AQPKG3 differ from standard TL431 variants?

The TL431AQPKG3 combines three distinguishing attributes: the "A" grade (±1% initial tolerance), "Q" temperature rating (−40°C to +125°C), and "PK" SOT-89 package. Unlike C- or I-grade versions, TL431AQPKG3 is qualified for automotive under-hood and industrial high-ambient applications. Its SOT-89 form factor provides superior thermal dissipation versus SOT-23, supporting higher continuous cathode current in compact layouts.

Can TL431AQPKG3 replace a Zener diode in feedback circuits?

Yes, TL431AQPKG3 is explicitly designed as a superior Zener diode replacement in voltage regulation feedback paths. Its 0.2 Ω dynamic impedance, sharp turn-on, and adjustable 2.5–36 V output via external resistors provide significantly better regulation accuracy, temperature stability, and transient response than discrete Zeners. TI's datasheet confirms its use in on-board regulation, switching power supplies, and adjustable power supplies.

What is the maximum cathode voltage rating for TL431AQPKG3?

The absolute maximum cathode voltage (VKA) for TL431AQPKG3 is 37 V, as specified in Section 6.1 of the TI datasheet SLVS543S. The recommended operating range is Vref to 36 V. Exceeding 37 V risks permanent damage. This rating applies across the full −40°C to +125°C temperature range and is independent of cathode current level within rated limits.

Does TL431AQPKG3 require external compensation for stability?

TL431AQPKG3 typically operates stably without external compensation when driving standard optocoupler-based feedback networks. However, stability depends on load capacitance and cathode current-Figure 6-18 in the datasheet defines safe operating boundaries. For CL > 10 nF or IKA < 1 mA, a small series resistor (e.g., 10–100 Ω) at the cathode may be needed to prevent oscillation. Always verify loop stability per application conditions.