Texas Instruments TLV431ACLP

Overview

TLV431ACLP from Texas Instruments is a low-voltage adjustable precision shunt regulator in TO-92 (LP) package, featuring 1.24 V reference voltage with ±1% initial tolerance at 25°C, 0.25 Ω typical dynamic impedance, and operation down to 1.24 V cathode-anode voltage. It serves as a Zener diode replacement or integrated reference in isolated flyback secondary-side regulation for 3.3 V power supplies.

For engineers reviewing the TLV431ACLP datasheet, TLV431ACLP pinout, TLV431ACLP application, or TLV431ACLP equivalent, key selection criteria include reference accuracy over temperature (±12 mV from 0°C to 70°C), minimum cathode current (80 µA typical), ultra-low reference input current (0.5 µA max), and TO-92 thermal performance (140°C/W junction-to-ambient).

Technical Context

The TLV431ACLP implements a bandgap-referenced error amplifier with Darlington output stage, enabling precise shunt regulation via external resistor divider feedback between cathode and reference pins. Its open-loop configuration supports comparator operation with integrated 1.24 V reference, while closed-loop mode delivers stable voltage or current regulation without requiring output capacitance.

It operates across 0°C to 70°C (TLV431AC grade), supports cathode voltages from 1.24 V to 6 V, and maintains 0.25 Ω dynamic impedance up to 15 mA cathode current - critical for tight regulation in low-headroom SMPS feedback paths and voltage monitoring circuits.

Key Specifications

Pinout & Package

TLV431ACLP uses the TO-92 (LP) 3-pin through-hole package with lead pitch of 0.1 inch (2.54 mm). The package provides mechanical robustness and thermal dissipation suitable for board-level voltage referencing in industrial and consumer power supplies.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV431ACLP, TLV431AILP trades reference accuracy for broader temperature capability, while TLVH431CLP extends voltage and current range at the cost of reduced precision and different thermal characteristics - both require revalidation of feedback network and stability margins.

Availability

TLV431ACLP is available at Aetrix Electronics and suitable for industrial power supplies, embedded voltage monitoring systems, and optocoupler-based isolated DC-DC converters requiring stable component supply and long-term manufacturability.

Supply support for TLV431ACLP 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 shunt regulation and reference applications in space-constrained, energy-efficient power systems - targeting 3.3 V and lower isolated SMPS, battery-powered sensors, and programmable voltage monitors.

FAQ

What is the reference voltage tolerance of TLV431ACLP at 25°C?

The TLV431ACLP has a reference voltage tolerance of ±1% at 25°C, corresponding to a V_REF range of 1.228 V to 1.252 V. This specification is guaranteed per TI's SLVS139Z datasheet Section 5.6, and applies to the 'A' grade variant in TO-92 packaging. The TLV431ACLP maintains this accuracy across its commercial temperature range (0°C to 70°C), with total drift limited to ±12 mV.

Can TLV431ACLP replace a standard Zener diode in a 2.5 V regulation circuit?

Yes, TLV431ACLP can directly replace a 2.5 V Zener diode in most applications. Its 1.24 V reference allows output adjustment to 2.5 V using two external resistors, and it delivers superior performance: 0.25 Ω dynamic impedance vs. typical Zener impedance >10 Ω, ±1% initial tolerance vs. ±5% for general-purpose Zeners, and sharp turn-on behavior. The TLV431ACLP also draws only 0.5 µA reference current, reducing divider losses significantly.

What is the minimum cathode current required for regulation in TLV431ACLP?

The TLV431ACLP requires a minimum cathode current of 80 µA typical (55 µA min) to maintain regulation, as specified in Section 5.6 of the TI datasheet. This low I_K(min) enables use in ultra-low-power applications such as battery-backed voltage monitors or energy-harvesting systems. Operation below this threshold may result in degraded regulation accuracy or loss of control loop stability.

Does TLV431ACLP require an output capacitor for stability?

No, TLV431ACLP does not require an output capacitor for basic stability - it is internally compensated and remains stable without external capacitance between cathode and anode. However, if a capacitive load is present (e.g., optocoupler CTR variation or PCB trace capacitance), stability must be verified using TI's Figure 5-18–5-21 stability boundary charts. For marginal cases, a small ceramic capacitor (e.g., 100 pF–1 nF) may be added in parallel with the feedback resistor.

How does the TO-92 package of TLV431ACLP affect thermal performance?

The TO-92 (LP) package of TLV431ACLP has a junction-to-ambient thermal resistance (R_θJA) of 140°C/W, as documented in Section 5.4 of the TI datasheet. This allows safe continuous operation at up to ~150 mW power dissipation in still air. For higher-power applications, PCB copper area under the ANODE lead should be maximized, and ambient temperature must remain within 0°C to 70°C to maintain regulation accuracy and reliability. Derating is required above 70°C ambient.