Texas Instruments TL431BQPKG3

Overview

TL431BQPKG3 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, 14–34 mV total temperature drift over −40°C to +125°C, and 0.2 Ω typical dynamic impedance - used for feedback regulation in isolated DC/DC converters and industrial power supplies.

For engineers reviewing the TL431BQPKG3 datasheet, TL431BQPKG3 pinout, TL431BQPKG3 application, or TL431BQPKG3 equivalent, key selection criteria include automotive-grade temperature range (−40°C to 125°C), low output noise, sharp turn-on characteristic for Zener replacement, and sink-current capability up to 100 mA in compact SOT-89 thermal package.

Technical Context

The TL431BQPKG3 implements an adjustable shunt regulator architecture with internal error amplifier, reference, and NPN pass transistor - enabling precise voltage setting from 2.495 V to 36 V via two external resistors. Its Q-temp grade guarantees operation across −40°C to +125°C ambient, meeting automotive and harsh industrial requirements.

It features active output circuitry for fast turn-on, low 2–4 µA reference input current, and stable regulation down to 0.4 mA cathode current. Dynamic impedance remains ≤0.5 Ω below 1 kHz, supporting high-loop-gain feedback in switching power supply control circuits without external compensation in many cases.

Key Specifications

Pinout & Package

SOT-89 package (3-pin, 4.5 mm × 2.5 mm × 1.5 mm body) with exposed thermal pad; designed for surface-mount assembly and efficient heat transfer to PCB copper.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431BQDBZR and TLVH431BQDBVR, TL431BQPKG3 provides superior thermal management in high-current applications, maintains direct compatibility with legacy SOT-89 layouts, and delivers optimal accuracy/stability trade-off for industrial power systems requiring long-term reliability.

Availability

TL431BQPKG3 is available at Aetrix Electronics and suitable for industrial AC/DC power supplies, rack server power modules, and servo drive control requiring stable component supply with guaranteed long-term availability and traceable sourcing.

Supply support for TL431BQPKG3 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 leadership in precision reference design.

The TL431 product line was engineered for high-accuracy, low-drift voltage regulation in safety-critical power conversion systems - targeting automotive, industrial, and computing infrastructure applications demanding long-term stability and wide temperature operation.

FAQ

What is the reference voltage tolerance of TL431BQPKG3 at 25°C?

The TL431BQPKG3 has a reference voltage tolerance of ±0.5% at 25°C, corresponding to a nominal 2.495 V output with minimum 2.483 V and maximum 2.507 V. This tight tolerance is specified in Section 6.13 of the TI SLVS543S datasheet and enables high-accuracy feedback without post-production calibration. The TL431BQPKG3 maintains this grade across its full −40°C to +125°C operating range.

Does TL431BQPKG3 support operation beyond 100 mA cathode current?

No - TL431BQPKG3 is rated for continuous cathode current from 0.4 mA to 100 mA per absolute maximum ratings (Section 6.1). Exceeding 100 mA risks thermal overstress or parametric shift; the device's 0.2 Ω dynamic impedance and SOT-89 thermal resistance (R_θJC = 9°C/W) are optimized for this range. For higher currents, parallel devices or external pass transistors are required - TL431BQPKG3 itself must remain within its 100 mA limit.

How does the TL431BQPKG3 pinout differ from TL431BQDBZR?

TL431BQPKG3 uses SOT-89 pinout: Pin 1 = REF, Pin 2 = ANODE, Pin 3 = CATHODE. TL431BQDBZR uses SOT-23-3: Pin 1 = CATHODE, Pin 2 = ANODE, Pin 3 = REF. They are electrically identical but mechanically incompatible - direct substitution requires PCB layout change. The ANODE pin on TL431BQPKG3 is internally bonded to the substrate and must be connected to ground or left open per datasheet guidance.

Can TL431BQPKG3 replace a Zener diode in linear regulator designs?

Yes - TL431BQPKG3 is explicitly designed as a precision Zener diode replacement. Its sharp turn-on, low dynamic impedance (0.2 Ω), and 0.5% tolerance outperform most discrete Zeners. In linear regulator applications, it provides stable reference for series pass transistors with far better temperature stability (14–34 mV drift vs. typical Zener's >50 mV) and lower noise - confirmed in TI's Application Report SLVA493.

What is the maximum cathode voltage rating for TL431BQPKG3?

The absolute maximum cathode-to-anode voltage (V_KA) for TL431BQPKG3 is 37 V, with recommended operating range from V_ref (≈2.495 V) to 36 V. This rating is defined in Section 6.1 of the SLVS543S datasheet and applies across the full −40°C to +125°C temperature range. Operating above 36 V risks permanent damage even for brief transients unless clamped externally.