Texas Instruments TLV431QPK

Overview

TLV431QPK from Texas Instruments is a low-voltage adjustable precision shunt regulator in SOT-89-3 package, delivering 1.24V reference voltage with ±1.5% initial tolerance at 25°C, 11mV max VREF deviation over –40°C to 125°C, 0.25Ω typical dynamic impedance, and 55–100µA minimum cathode current for regulation - used as secondary-side error amplifier in isolated 3.3V flyback SMPSs.

For engineers reviewing the TLV431QPK datasheet, TLV431QPK pinout, TLV431QPK application, or TLV431QPK equivalent, this page delivers verified electrical specs, thermal performance (RθJA = 52°C/W), functional modes (open-loop comparator / closed-loop shunt regulator), and real-world design implications for voltage monitoring, Zener replacement, and optocoupler-based feedback circuits.

Technical Context

The TLV431QPK implements an internally compensated NPN-based shunt regulator architecture with integrated 1.24V bandgap reference and high-gain error amplifier. It operates in two distinct functional modes: open-loop comparator mode (with internal reference enabling threshold detection) and closed-loop shunt regulation mode (using external resistive divider to set output voltage from 1.24V to 6V).

Its operation requires ≥1.24V cathode-to-anode voltage headroom and ≥55µA cathode current to enter linear regulation; reference pin must be actively driven with ≥0.15µA (typical) input current and cannot float. Stability is maintained without output capacitance, though phase margin vs. capacitive load is characterized up to 1nF for designs requiring filtering.

Key Specifications

Pinout & Package

SOT-89-3 (PK) package: 4.5mm × 4.095mm footprint with exposed thermal pad; thermally enhanced for 52°C/W junction-to-ambient dissipation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV431BPK, TLV431QPK trades initial accuracy for cost and broad applicability in automotive power management; compared with TLVH431IPK, it offers lower quiescent current and simpler compensation but lacks high-voltage capability - making TLV431QPK optimal for 3.3V/5V isolated SMPS feedback where accuracy ≤±1.5% suffices.

Availability

TLV431QPK is available at Aetrix Electronics and suitable for automotive power management, industrial sensor signal conditioning, and consumer device voltage supervision requiring stable component supply across extended temperature ranges.

Supply support for TLV431QPK 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 company headquartered in Dallas, Texas, designing analog ICs, embedded processors, and high-reliability components for industrial, automotive, and communications markets.

The TLV431 family was developed as a low-voltage, low-power alternative to TL431 for space-constrained and energy-sensitive applications - specifically targeting secondary-side regulation in compact isolated power supplies and precision voltage monitoring in harsh environments.

FAQ

What is the maximum output voltage achievable with TLV431QPK?

The TLV431QPK supports adjustable output voltage from 1.24V up to 6V using two external resistors. This limit arises from absolute maximum cathode voltage rating of 7V and recommended operating condition of VKA ≤ 6V. Exceeding 6V risks parametric degradation or long-term reliability issues, even if within absolute maximum ratings.

Does TLV431QPK require an external capacitor for stability?

No, TLV431QPK is internally compensated and remains stable without an output capacitor between cathode and anode. However, if a capacitor is added for noise filtering, phase margin data (Figures 5-19–5-21) shows stability is maintained up to 1nF at 1.25V VKA, but degrades beyond that - requiring careful selection based on operating voltage and load dynamics.

How does the Q-grade temperature specification affect TLV431QPK performance?

The Q-grade designation certifies TLV431QPK for operation from –40°C to +125°C, with VREF deviation specified at 11mV max over this range. Electrical characteristics including IK(min), Iref, and dynamic impedance are fully characterized across this span - ensuring predictable behavior in under-hood automotive or industrial edge computing environments.

Can TLV431QPK replace a standard Zener diode directly?

Yes, TLV431QPK can directly replace low-voltage Zener diodes (e.g., 1.2V–3.3V types) in shunt regulation roles. Its advantages include sharper knee voltage, lower dynamic impedance (0.25Ω vs. 10–100Ω for Zeners), and temperature-stable reference - but requires minimum 55µA cathode current and proper REF pin biasing, unlike passive Zeners.

What is the function of the ANODE pin in TLV431QPK?

The ANODE pin (Pin 2) serves as the common reference terminal and substrate connection point. It must be connected to system ground or the negative rail - never left floating. In SOT-89-3 (PK) package, it also provides the primary thermal conduction path to the PCB copper pour, directly impacting RθJA = 52°C/W performance.