Texas Instruments TLV431AID

Overview

TLV431AID from Texas Instruments is a low-voltage adjustable precision shunt regulator with 1.24 V reference voltage, 1% initial tolerance at 25°C, and operation from 1.24 V to 6 V output range. It functions as a programmable Zener replacement or error amplifier in isolated feedback loops, delivering 0.25 Ω typical dynamic impedance and 80 µA typical cathode current for regulation.

For engineers reviewing the TLV431AID datasheet, TLV431AID pinout, TLV431AID application, or TLV431AID equivalent, key selection criteria include reference accuracy over temperature (±6 mV from –40°C to 85°C), ultra-low cathode current requirement, SC-70 package footprint, and compatibility with optocoupler-based secondary-side regulation in 3.3 V flyback SMPS designs.

Technical Context

The TLV431AID implements a three-terminal shunt-regulator architecture with an internal bandgap reference and high-gain NPN-based error amplifier driving a Darlington sink output stage. Its closed-loop operation relies on resistive feedback between cathode and reference pins to set output voltage precisely across 1.24 V–6 V.

In open-loop mode, it operates as a comparator with integrated 1.24 V reference, requiring ≥55 µA cathode current for full gain and fast response. Thermal drift is specified at ±6 mV over –40°C to 85°C, and dynamic impedance remains stable ≤0.4 Ω up to 15 mA cathode current.

Key Specifications

Pinout & Package

TLV431AID is packaged in the ultra-small SC-70 (DCK) outline measuring 2.0 mm × 1.5 mm - 40% smaller than SOT-23-3 - with six terminals, including one no-connect (NC) and one substrate tie (pin 2).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV431AID, TLV431ACDBVR trades industrial temperature range for lower cost, while TLVH431ACDBVR extends voltage and current capability at the expense of pin compatibility and thermal performance - neither offers identical electrical or mechanical fit.

Availability

TLV431AID is available at Aetrix Electronics and suitable for industrial power supplies, isolated DC/DC converters, and embedded voltage monitoring systems requiring stable component supply and long-term manufacturability.

Supply support for TLV431AID 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-constrained and energy-efficient applications - targeting secondary-side control in isolated SMPS, portable device power rails, and precision analog subsystems.

FAQ

What is the maximum cathode-anode voltage rating for TLV431AID?

The absolute maximum cathode voltage (VKA) for TLV431AID is 7 V relative to the anode terminal. Exceeding this rating risks permanent damage. The recommended operating range is 1.24 V to 6 V, aligning with its design as a low-voltage adjustable shunt regulator. This limit is defined in Section 5.1 of the TI SLVS139Z datasheet and applies across all temperature grades of the TLV431AID device.

Does TLV431AID require an output capacitor for stability?

No, TLV431AID is internally compensated and does not require an output capacitor between cathode and anode for basic stability in shunt regulator configurations. However, when driving capacitive loads - such as optocoupler LEDs with parasitic capacitance or long PCB traces - phase margin can degrade. Figure 5-19 in the TLV431AID datasheet provides guidance on selecting stable capacitive loading based on VKA and temperature.

Can TLV431AID be used as a standalone comparator without external feedback?

Yes, TLV431AID functions as a comparator with integrated 1.24 V reference in open-loop mode. When configured with sufficient cathode current (≥55 µA), it delivers high open-loop gain and fast response. The REF pin serves as the input, and the CATHODE pin acts as the open-collector output. Output low is ~1 V; output high pulls toward the cathode supply rail, enabling direct interfacing with logic inputs when properly level-shifted.

What is the purpose of the substrate pin (Pin 2) on TLV431AID?

The substrate pin (Pin 2) on TLV431AID is a die attachment point that must be connected to the ANODE terminal or left electrically open - it has no internal circuit connection. This requirement ensures proper thermal dissipation and ESD protection. Leaving it unconnected or tying it to another potential violates the device's mechanical and electrical specifications and may compromise reliability or cause parametric shift during operation.

How does TLV431AID differ from TL431 in practical design?

TLV431AID differs from TL431 by offering a lower 1.24 V reference (vs 2.5 V), 10× lower minimum cathode current (80 µA vs 1 mA), and operation down to 1.24 V cathode-anode voltage. These differences enable TLV431AID to regulate sub-2.5 V rails, reduce standby power in feedback networks, and simplify designs for 3.3 V and lower systems - whereas TL431 remains suitable for higher-voltage, higher-current legacy applications.