Texas Instruments TL431CPKG3

Overview

TL431CPKG3 from Texas Instruments is a precision programmable shunt voltage reference IC with 2.495 V nominal reference voltage, ±0.5% initial tolerance at 25°C (B-grade), and operation across −40°C to 125°C. It delivers 1 mA to 100 mA sink current, features 0.2 Ω typical dynamic impedance, and enables adjustable output from 2.495 V to 36 V using two external resistors-commonly deployed in feedback loops of isolated DC/DC converters and AC/DC power supplies.

For engineers reviewing the TL431CPKG3 datasheet, TL431CPKG3 pinout, TL431CPKG3 application, or TL431CPKG3 equivalent, key selection criteria include reference accuracy over temperature, cathode current capability, dynamic impedance stability, and compatibility with SOT-89 thermal and layout constraints in high-reliability power regulation designs.

Technical Context

The TL431CPKG3 implements an internal bandgap reference, error amplifier, and NPN output transistor in a three-terminal shunt topology. Its REF pin senses voltage relative to ANODE, triggering cathode current conduction when the sensed voltage exceeds Vref; this closed-loop behavior replaces discrete Zener diodes in precision regulation circuits.

It operates as a 2.495 V threshold comparator with sharp turn-on characteristics and low output noise (<10 µV_RMS over 0.1–10 Hz). The device's thermal drift is specified at ≤14 mV over −40°C to 125°C (Q-temp grade), and its dynamic impedance remains stable below 0.5 Ω up to 100 kHz.

Key Specifications

Pinout & Package

SOT-89 package (PK) with 3 pins, 4.5 mm × 2.5 mm footprint, and exposed thermal pad for enhanced power dissipation (R_θJC(top) = 9°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431CDBZR, TL431CPKG3 offers 67% lower thermal resistance and 67% higher power handling-critical for sustained 100 mA sink operation. Versus TLVH431BIDBVR, it provides tighter 0.5% accuracy and higher 2.495 V reference, better suited for legacy 5 V/12 V/24 V power architectures requiring minimal redesign.

Availability

TL431CPKG3 is available at Aetrix Electronics and suitable for rack server power, industrial AC/DC, and servo drive control module applications requiring stable component supply, long-lifecycle support, and guaranteed traceable sourcing.

Supply support for TL431CPKG3 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 design.

The TL431 product line was engineered for high-accuracy, wide-temperature shunt regulation in power supply feedback, voltage monitoring, and programmable threshold detection-targeting industrial, automotive, and telecom infrastructure.

FAQ

What is the reference voltage tolerance of TL431CPKG3 at 25°C?

The TL431CPKG3 has a reference voltage tolerance of ±0.5% at 25°C, corresponding to a 2.495 V nominal value with a range of 2.483 V to 2.507 V. This B-grade accuracy is confirmed in Section 6.11 of the TI SLVS543S datasheet and applies specifically to the TL431BQ variant in SOT-89 packaging. TL431CPKG3 is the Q-temp qualified version of the B-grade device.

Can TL431CPKG3 replace a Zener diode in a linear regulator design?

Yes, TL431CPKG3 can directly replace Zener diodes in linear regulator feedback or shunt regulation roles due to its sharp turn-on characteristic, 0.2 Ω dynamic impedance, and adjustable 2.495 V–36 V output. Unlike Zeners, TL431CPKG3 maintains stable regulation across temperature and current, eliminating the need for series resistors to limit Zener current drift.

What is the maximum cathode voltage rating for TL431CPKG3?

The absolute maximum cathode voltage (V_KA) for TL431CPKG3 is 37 V, referenced to the ANODE pin. The recommended operating range is V_ref to 36 V. Exceeding 37 V risks permanent damage, per Section 6.1 of the TI SLVS543S datasheet. This rating is identical across all TL431 variants, including TL431CPKG3.

Does TL431CPKG3 require external compensation for stability?

TL431CPKG3 does not require external compensation in most standard configurations. Its internal architecture stabilizes with ≥100 nF output capacitance and typical feedback resistor values (e.g., 10 kΩ/100 kΩ). Figure 6-18 in the datasheet confirms stability boundaries up to 100 mA cathode current and 10 µF load capacitance without added components.

How does the thermal performance of TL431CPKG3 compare to SOT-23 versions?

TL431CPKG3 in SOT-89 achieves R_θJA = 52°C/W and R_θJC(top) = 9°C/W, significantly outperforming SOT-23-3 versions (R_θJA = 206°C/W). This allows TL431CPKG3 to dissipate up to 0.5 W continuously at 25°C ambient-nearly 3× more than TL431CDBZR-making it suitable for high-current feedback paths in industrial power supplies.