Texas Instruments TLV431ACLPRE3

Overview

TLV431ACLPRE3 from Texas Instruments is a low-voltage adjustable precision shunt regulator with 1.24 V reference voltage, ±1% initial tolerance at 25°C, 0.25 Ω typical dynamic impedance, 80 µA typical minimum cathode current, and operation from 1.24 V to 6 V output range. It serves as a Zener replacement or error amplifier in isolated flyback secondary-side regulation for 3.3 V SMPS designs.

For engineers reviewing the TLV431ACLPRE3 datasheet, TLV431ACLPRE3 pinout, TLV431ACLPRE3 application, or TLV431ACLPRE3 equivalent, key selection considerations include reference accuracy over temperature (±4 mV from 0°C to 70°C), ultra-low cathode current requirement, SC-70 package footprint compatibility, and open-loop comparator functionality with integrated reference.

Technical Context

The TLV431ACLPRE3 implements a bandgap-referenced transconductance amplifier driving a Darlington sink output stage, enabling precise shunt regulation without external compensation. Its internal architecture supports both closed-loop regulation (via resistive feedback from cathode to reference) and open-loop comparator operation with built-in 1.24 V threshold.

It operates across 0°C to 70°C (TLV431AC grade), requires ≥55 µA cathode current for regulation, and maintains stable performance with no output capacitor needed-unlike many linear regulators-due to internal frequency compensation optimized for cathode-anode load conditions.

Key Specifications

Pinout & Package

TLV431ACLPRE3 uses the LP (TO-92, 3-pin) package: molded plastic case with axial leads, 5.2 mm length × 3.68 mm diameter, lead pitch 1.27 mm, rated for 140°C/W junction-to-ambient thermal resistance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV431BCLPRE3, TLV431ACLPRE3 trades 0.5% accuracy for lower cost and broader availability; compared with TLVH431CLPRE3, it offers TO-92 compatibility and lower quiescent current but limits max output to 6 V and cathode current to 15 mA-making it optimal for cost-sensitive, low-power, 3.3 V–5 V systems.

Availability

TLV431ACLPRE3 is available at Aetrix Electronics and suitable for industrial power supplies, embedded sensor nodes, and consumer adapter designs requiring stable component supply, long-term manufacturability, and RoHS-compliant through-hole packaging.

Supply support for TLV431ACLPRE3 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 leader delivering analog and embedded processing solutions, with over 50 years of innovation in precision analog ICs and power management.

The TLV431 family was designed specifically for low-voltage, low-power shunt regulation and integrated reference applications-targeting cost-sensitive, space-constrained systems where TL431's 2.5 V reference and 1 mA minimum current are limiting.

FAQ

What is the reference voltage tolerance of TLV431ACLPRE3 at 25°C?

The TLV431ACLPRE3 has a reference voltage tolerance of ±1% at 25°C, corresponding to 1.24 V ±12.4 mV. This is confirmed in Section 5.6 of the TI datasheet SLVS139Z, which specifies min/max values of 1.228 V and 1.252 V under test conditions of VKA = VREF and IK = 10 mA. The "A" suffix denotes the 1% grade, distinct from TLV431B (0.5%) and base TLV431 (1.5%). TLV431ACLPRE3 maintains this specification across its commercial temperature range (0°C to 70°C).

Can TLV431ACLPRE3 replace a standard Zener diode in a 3.3 V regulator?

Yes, TLV431ACLPRE3 is explicitly designed as a Zener diode replacement. With its 1.24 V reference, adjustable output up to 6 V, 0.25 Ω dynamic impedance, and sharp turn-on characteristic, it delivers significantly better regulation accuracy and temperature stability than discrete Zeners. In a 3.3 V application, two resistors set the output precisely, and the device sinks cathode current only as needed-unlike Zeners that dissipate power continuously. TLV431ACLPRE3 also supports open-loop comparator use, adding functionality beyond passive Zener behavior.

What is the minimum cathode current required for regulation in TLV431ACLPRE3?

The TLV431ACLPRE3 requires a minimum cathode current (IK(min)) of 55 µA to 80 µA for proper regulation, depending on temperature and operating conditions. Per Section 5.6 of the datasheet, this is specified as 55–80 µA for TLV431AC (0°C to 70°C). This ultra-low requirement-orders of magnitude less than TL431's 1 mA-enables use in battery-backed or ultra-low-power systems. Below this threshold, gain drops and regulation degrades; design must ensure continuous IK ≥55 µA under all operating conditions.

Does TLV431ACLPRE3 require an output capacitor for stability?

No, TLV431ACLPRE3 does not require an output capacitor for stability. Its internal compensation is optimized for direct cathode-to-anode loading, eliminating the need for external capacitance in standard shunt regulator configurations. This is confirmed in Section 7.3 ("Feature Description") of the datasheet, which states: "Unlike many linear regulators, TLV431 is internally compensated to be stable without an output capacitor." However, if a capacitor is added for filtering, Figure 5-19 provides phase margin vs. capacitive load guidance to avoid oscillation-especially important in high-noise environments or when driving long traces.

What package type does TLV431ACLPRE3 use, and how does it differ from other TLV431 variants?

TLV431ACLPRE3 uses the LP (TO-92, 3-pin) package: a through-hole, axial-leaded plastic case measuring 5.2 mm × 3.68 mm. This differs from surface-mount variants like DBZ (SOT-23-3), DCK (SC-70), or PK (SOT-89). The LP package provides mechanical robustness, ease of prototyping, and compatibility with legacy designs. Unlike SOT-23 or SC-70, LP has no exposed pad and higher thermal resistance (140°C/W), making it suitable for moderate-power applications (<15 mA cathode current) where solder reflow or space constraints are not primary concerns. All TLV431x LP variants share identical pinout: Pin 1 = CATHODE, Pin 2 = ANODE, Pin 3 = REF.