Texas Instruments TL431BIPKG3

Overview

TL431BIPKG3 from Texas Instruments is a precision programmable shunt voltage reference in SOT-89 package, delivering 2.483–2.507 V reference voltage at 25°C with ±0.5% initial tolerance, 14–34 mV total temperature drift over −40°C to +125°C, and 0.2 Ω typical dynamic impedance. It operates as an adjustable feedback element in isolated DC-DC converters and industrial power supplies.

For engineers reviewing the TL431BIPKG3 datasheet, TL431BIPKG3 pinout, TL431BIPKG3 application, or TL431BIPKG3 equivalent, key selection criteria include its Q-grade automotive temperature range (−40°C to 125°C), B-grade accuracy, SOT-89 thermal performance (R_θJC = 9°C/W), and compatibility with optocoupler-based feedback loops in flyback and forward converters.

Technical Context

The TL431BIPKG3 implements a precision bandgap reference core with high-gain transconductance amplifier driving an NPN output stage, enabling sharp turn-on and stable regulation across 2.5 V to 36 V output ranges via two external resistors. Its internal architecture supports direct replacement of Zener diodes while offering superior thermal stability and lower output impedance.

It functions exclusively as a three-terminal shunt regulator: REF senses voltage relative to ANODE, ANODE serves as common return (typically grounded), and CATHODE sinks current to regulate the external voltage node. No internal voltage regulation or series pass element is present - operation depends entirely on external loop design and sink-current capability (1–100 mA).

Key Specifications

Pinout & Package

SOT-89 package (3-pin, 4.5 mm × 2.5 mm × 1.6 mm body) with exposed thermal pad connected internally to ANODE; optimized for high-power dissipation (R_θJA = 52°C/W, R_θJC = 9°C/W) in compact power supply layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431BIDBZR and TLVH431BQDBVR, TL431BIPKG3 provides superior thermal performance (9°C/W junction-to-case) and tighter 0.5% reference accuracy - making it optimal for high-reliability, medium-power isolated supplies where long-term stability and thermal margin are critical.

Availability

TL431BIPKG3 is available at Aetrix Electronics and suitable for rack server power, industrial AC/DC converters, and automotive body control modules requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for TL431BIPKG3 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 heritage in precision reference design.

The TL431 product line delivers cost-effective, high-stability shunt references for feedback, supervision, and voltage-setting functions in power conversion, industrial control, and automotive systems - prioritizing accuracy, thermal robustness, and layout simplicity.

FAQ

What is the reference voltage tolerance of TL431BIPKG3 at 25°C?

The TL431BIPKG3 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 TI's SLVS543S datasheet Section 6.13 and applies strictly under recommended operating conditions (I_KA = 10 mA, V_KA = V_ref). The TL431BIPKG3 maintains this tolerance across its full −40°C to +125°C operating range as part of its Q-grade qualification.

How does TL431BIPKG3 differ from standard TL431 variants in package and thermal performance?

The TL431BIPKG3 uses the SOT-89 package with an exposed thermal pad tied to ANODE, achieving R_θJC = 9°C/W - significantly lower than SOT-23-3 (76°C/W) or SOIC-8 (39°C/W) variants. This allows up to 1.5 W continuous power dissipation at T_A = 85°C, making TL431BIPKG3 ideal for higher-current feedback applications where thermal headroom is limited, unlike smaller-outline alternatives.

Can TL431BIPKG3 replace a Zener diode in linear regulator designs?

Yes, TL431BIPKG3 can directly replace Zener diodes in shunt-regulator configurations, offering superior performance: 0.2 Ω dynamic impedance vs. typical Zener impedance >10 Ω, ±0.5% initial accuracy vs. ±5% for standard Zeners, and guaranteed operation from −40°C to +125°C. However, TL431BIPKG3 requires ≥0.4 mA cathode current to regulate and cannot operate below ~2.5 V - unlike low-voltage Zeners.

What is the minimum cathode current required for TL431BIPKG3 to maintain regulation?

The TL431BIPKG3 requires a minimum cathode current (I_min) of 0.4–0.7 mA to maintain regulation, per Section 6.13 of the SLVS543S datasheet. This value varies slightly with temperature and cathode voltage but remains within this band across −40°C to +125°C. Designers must ensure the feedback resistor network or optocoupler LED path delivers ≥0.7 mA under worst-case conditions (e.g., minimum input voltage, maximum output voltage).

Is TL431BIPKG3 pin-compatible with other TL431 packages like SOIC-8 or PDIP-8?

No, TL431BIPKG3 is not pin-compatible with SOIC-8 or PDIP-8 variants. It uses a 3-pin SOT-89 configuration (REF–ANODE–CATHODE), whereas SOIC-8 and PDIP-8 packages follow an 8-pin layout with NC pins and different pin assignments (e.g., Pin 1 = CATHODE, Pin 2 = NC, Pin 3 = REF in SOIC). Direct PCB replacement requires layout revision; only SOT-89 footprint variants (e.g., TL431BIPK, TL431BIPKG4) share identical pinout and mechanical compatibility with TL431BIPKG3.