Texas Instruments TLV431AQPKG3

Overview

TLV431AQPKG3 from Texas Instruments is a low-voltage adjustable precision shunt regulator with 1.24 V reference voltage, ±1.5% initial tolerance at 25°C, and operation over –40°C to 125°C. It delivers 0.25 Ω typical dynamic impedance, 80 µA typical minimum cathode current, and supports output voltage adjustment from 1.24 V to 6 V using two external resistors. It serves as a Zener diode replacement in isolated flyback secondary-side regulation for 3.3 V SMPS designs.

For engineers reviewing the TLV431AQPKG3 datasheet, TLV431AQPKG3 pinout, TLV431AQPKG3 application, or TLV431AQPKG3 equivalent, key selection considerations include its Q-grade automotive temperature range (–40°C to 125°C), SC-70 (DCK) package footprint, cathode-to-anode voltage headroom requirement, and compatibility with optocoupler-based feedback loops in compact power supplies.

Technical Context

The TLV431AQPKG3 implements a bandgap-referenced error amplifier driving a Darlington sink output stage. Its internal reference is trimmed to 1.24 V with ±1.5% accuracy at 25°C and exhibits 11 mV max VREF deviation across –40°C to 125°C. The device operates in open-loop comparator mode or closed-loop shunt regulation depending on external feedback configuration.

It requires ≥55 µA cathode current to maintain regulation and draws only 0.15–0.5 µA reference terminal current. Unlike standard linear regulators, it is internally compensated and stable without an output capacitor, though capacitive load stability depends on VKA and must be verified per Figure 5-19 of the datasheet.

Key Specifications

Pinout & Package

The TLV431AQPKG3 is housed in an ultra-small SC-70 (DCK) package measuring 2.0 mm × 1.5 mm, offering 40% smaller footprint than SOT-23-3. This thermally efficient 6-pin surface-mount package supports high-density PCB layouts in space-constrained power modules.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV431BQPKG3, TLV431AQPKG3 trades reference accuracy for lower unit cost while retaining identical thermal and packaging specs; compared with TLVH431QDBVR, it offers smaller footprint and lower power consumption but sacrifices voltage range and current capability.

Availability

TLV431AQPKG3 is available at Aetrix Electronics and suitable for automotive power management, industrial SMPS feedback, and battery-powered voltage monitoring requiring stable component supply across extended temperature ranges.

Supply support for TLV431AQPKG3 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 for low-voltage, high-accuracy shunt regulation in space- and power-constrained applications including isolated power supplies, voltage supervisors, and programmable current sources.

FAQ

What is the reference voltage tolerance of TLV431AQPKG3 at 25°C?

The TLV431AQPKG3 has a reference voltage tolerance of ±1.5% at 25°C, meaning its VREF falls between 1.221 V and 1.259 V under nominal conditions. This tolerance is specified in Section 5.6 of the TI datasheet SLVS139Z and applies specifically to the 'AQ' variant. The wider tolerance reflects cost-optimized performance for applications where moderate precision suffices, such as general-purpose voltage monitoring or non-critical feedback loops.

Can TLV431AQPKG3 operate with a cathode-to-anode voltage below 1.24 V?

No, TLV431AQPKG3 cannot regulate with VKA below 1.24 V - its minimum operating cathode voltage equals its internal reference voltage. Per Section 5.3 of the datasheet, recommended VKA is VREF to 6 V. Attempting operation below 1.24 V results in unregulated, high-impedance behavior. For sub-1.24 V references, consider dedicated low-VREF ICs like REF3012 or LM4040A12, as TLV431AQPKG3's architecture requires ≥1.24 V headroom to bias its internal amplifier and Darlington stage.

What is the maximum cathode current rating for TLV431AQPKG3?

The absolute maximum cathode current for TLV431AQPKG3 is ±20 mA, as stated in Section 5.1 (Absolute Maximum Ratings). However, the recommended operating condition limits continuous cathode current to 15 mA (Section 5.3). Exceeding 15 mA risks thermal overload in the SC-70 package due to its 87°C/W junction-to-ambient thermal resistance - sustained operation above this level requires careful PCB copper pour design or derating per Figure 5-4 and thermal metrics in Section 5.4.

How does the SC-70 package of TLV431AQPKG3 affect thermal performance?

The SC-70 (DCK) package of TLV431AQPKG3 has a junction-to-ambient thermal resistance (RθJA) of 87°C/W, per Section 5.4. This is higher than larger packages like SOT-89 (52°C/W) but optimized for minimal footprint. In practice, this means a 10 mA cathode current at 5 V VKA (50 mW dissipation) raises junction temperature by ~4.35°C above ambient - acceptable for most applications. To maintain reliability at full rated current, use ≥1 cm² of 2-oz copper connected to ANODE and substrate pins as a thermal pad, per TI's layout guidance in Section 8.4.

Is TLV431AQPKG3 pin-compatible with TLV431A or TLV431B in SC-70?

Yes, TLV431AQPKG3 shares identical SC-70 (DCK) pinout and mechanical dimensions with all TLV431x variants in the same package, including TLV431A and TLV431B. Pin functions - CATHODE (1), REF (3), ANODE (6), NC (4,5), Substrate (2) - are consistent across the family per Table 4-1 and Figures 4-5. This allows drop-in replacement for accuracy or temperature grade upgrades without PCB revision, provided the application tolerates the respective VREF tolerance (±1.5% for AQ, ±1.0% for AA, ±0.5% for AB).