Texas Instruments TLV431BQPK

Overview

TLV431BQPK from Texas Instruments is a low-voltage adjustable precision shunt regulator with 1.24 V reference voltage, 0.5% initial tolerance at 25°C, and operation from 1.24 V to 6 V output range. It delivers 0.25 Ω typical dynamic impedance, 80 µA typical cathode current, and supports secondary-side regulation in isolated flyback SMPSs.

For engineers reviewing the TLV431BQPK datasheet, TLV431BQPK pinout, TLV431BQPK application, or TLV431BQPK equivalent, key selection criteria include reference accuracy over temperature (±11 mV from –40°C to 125°C), ultra-low cathode current requirement, SOT-89-3 package thermal performance (R_θJA = 52°C/W), and compatibility with optocoupler-based feedback loops in 3.3 V systems.

Technical Context

The TLV431BQPK operates as a 3-terminal adjustable shunt reference using an internal bandgap reference and NPN-based error amplifier. Its open-loop mode functions as a comparator with integrated 1.24 V reference, while closed-loop configuration enables precise voltage regulation via external resistor divider feedback between cathode and reference pins.

It features internal compensation for stability without output capacitance, supports ≥100 µA minimum cathode current for regulation across –40°C to 125°C (Q-grade), and exhibits <0.5 µA reference terminal current - enabling high-impedance sensing and low-power monitoring applications.

Key Specifications

Pinout & Package

SOT-89-3 (PK) package: 4.5 mm × 4.095 mm footprint with exposed thermal pad; thermally enhanced for power dissipation up to 500 mW at T_A = 25°C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV431BQPK, TLV431BIDBZR trades thermal performance for footprint reduction, while TLVH431QPK extends voltage and current capability beyond TLV431B's specification - making TLV431BQPK optimal for cost-sensitive, thermally demanding 3.3 V–5 V isolated regulation.

Availability

TLV431BQPK is available at Aetrix Electronics and suitable for isolated flyback SMPSs, voltage monitoring systems, and precision current-sink circuits requiring stable component supply and automotive-grade temperature support (–40°C to 125°C).

Supply support for TLV431BQPK 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 specializing in analog and embedded processing technologies, with leadership in precision analog ICs and power management solutions.

The TLV431 family was designed specifically for low-voltage, high-accuracy shunt regulation in space- and power-constrained applications - targeting isolated power supplies, voltage supervision, and compact reference circuits.

FAQ

What is the maximum cathode voltage supported by TLV431BQPK?

The TLV431BQPK supports a maximum cathode-to-anode voltage (V_KA) of 7 V per absolute maximum ratings. Its recommended operating range is 1.24 V to 6 V, aligning with its design as a low-voltage shunt regulator. Exceeding 7 V risks permanent damage, and operation above 6 V voids guaranteed performance per datasheet specifications.

Does TLV431BQPK require an external capacitor for stability?

No, TLV431BQPK is internally compensated and remains stable without an external output capacitor between cathode and anode. This simplifies layout and reduces BOM count. However, if a capacitor is added for noise filtering, Figure 5-19 in the datasheet provides phase-margin guidance to avoid instability with capacitive loads up to 1 nF.

How does the TLV431BQPK differ from the standard TLV431 in terms of accuracy?

The TLV431BQPK belongs to the TLV431B grade, offering ±0.5% reference voltage tolerance at 25°C - tighter than TLV431A (±1%) and TLV431 (±1.5%). All grades share identical pinout, package, and functional behavior; only initial accuracy and temperature drift specifications differ across the B/A/blank variants.

Can TLV431BQPK be used as a comparator? If so, what are the key considerations?

Yes, TLV431BQPK operates in open-loop comparator mode when no feedback is applied to the REF pin. Key considerations include supplying ≥100 µA cathode current for full gain, ensuring ≥10% overdrive voltage above 1.24 V for fast response, and accounting for ~1 V output low-level voltage - which may require level-shifting for 1.8 V or 2.5 V logic interfaces.

What is the thermal performance of TLV431BQPK in the SOT-89 package?

TLV431BQPK in the PK (SOT-89-3) package has R_θJA = 52°C/W and R_θJC(top) = 9°C/W. At 25°C ambient, it supports up to 15 mA continuous cathode current with junction temperature below 125°C. The exposed thermal pad must be soldered to a copper pour for rated performance.