Texas Instruments TLVH431ACLPE3

Overview

TLVH431ACLPE3 from Texas Instruments is a low-voltage adjustable precision shunt regulator with 1.24 V reference voltage, ±0.5% initial tolerance at 25°C (B-grade), and operation down to 1.24 V cathode-anode voltage. It delivers 100 μA to 70 mA cathode current, 0.25 Ω typical dynamic impedance, and full-spec performance from –40°C to +125°C. It serves as an ultra-low-leakage Zener replacement and voltage reference in isolated flyback SMPS feedback loops.

For engineers reviewing the TLVH431ACLPE3 datasheet, TLVH431ACLPE3 pinout, TLVH431ACLPE3 application, or TLVH431ACLPE3 equivalent, key selection criteria include reference accuracy grade (B), TO-92 package thermal resistance (140°C/W), minimum regulation current (100 μA), dynamic impedance (0.25 Ω), and compatibility with optocoupler-based secondary-side regulation in 3.3 V systems.

Technical Context

The TLVH431ACLPE3 implements a bandgap-referenced error amplifier with Darlington output stage, enabling sharp turn-on and stable closed-loop regulation when configured with external resistive dividers. Its internal 1.24 V reference is trimmed at wafer test for B-grade (±0.5%) accuracy, and its open-loop gain supports comparator-mode operation with integrated threshold.

Unlike the TL431, it operates with ≥1.24 V headroom and draws only 100 μA minimum cathode current for regulation-enabling use in ultra-low-power 3.3 V and battery-backed systems. The TO-92 package (LP suffix) provides 4.3 mm × 4.3 mm body size and 140°C/W junction-to-ambient thermal resistance, suitable for moderate-power shunt applications without heatsinking.

Key Specifications

Pinout & Package

TLVH431ACLPE3 uses the TO-92 (LP) package: 4.30 mm × 4.30 mm body, axial lead configuration, through-hole mounting. Pin 1 = CATHODE, Pin 2 = ANODE, Pin 3 = REF.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLVH431ACLPE3, TLVH431ACLP trades 0.5% accuracy for lower unit cost in identical TO-92 form factor, while TLVH431BCLPR retains B-grade precision but shifts to SMT assembly and demands careful thermal management due to 47% higher R_θJA.

Availability

TLVH431ACLPE3 is available at Aetrix Electronics and suitable for industrial power supplies, battery-powered instrumentation, and automotive body electronics requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for TLVH431ACLPE3 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 specializing in analog, embedded processing, and power management technologies, with decades of expertise in precision reference and power control ICs.

The TLVH431 family was designed specifically for low-voltage, high-accuracy shunt regulation in isolated DC/DC converters, data converter references, and intelligent power monitoring-addressing limitations of legacy TL431 in modern 3.3 V and battery-operated systems.

FAQ

What is the reference voltage tolerance of TLVH431ACLPE3 at 25°C?

The TLVH431ACLPE3 has a reference voltage tolerance of ±0.5% at 25°C, corresponding to the 'B' grade designation in its part number. This means its V_REF falls between 1.234 V and 1.246 V under nominal conditions, as confirmed in Section 5.7 of the TI SLVS555N datasheet. This tight tolerance makes TLVH431ACLPE3 suitable for high-accuracy applications such as precision ADC references and calibrated voltage monitors.

Can TLVH431ACLPE3 operate with a cathode voltage below 2.5 V?

Yes, TLVH431ACLPE3 is explicitly designed for low-voltage operation and regulates stably with cathode-to-anode voltage as low as 1.24 V-the value of its internal reference. Unlike the TL431 (2.5 V reference), TLVH431ACLPE3 supports direct use in 1.8 V, 2.5 V, and 3.3 V systems. Its minimum cathode current requirement remains 100 μA even at this low headroom, enabling reliable regulation in ultra-low-power configurations.

What package type does TLVH431ACLPE3 use, and what are its thermal characteristics?

TLVH431ACLPE3 uses the TO-92 (LP) package: a 3-pin through-hole plastic case measuring 4.30 mm × 4.30 mm. Its junction-to-ambient thermal resistance (R_θJA) is 140°C/W, allowing up to ~150 mW power dissipation at 25°C ambient before reaching the 150°C absolute maximum junction temperature. This makes TLVH431ACLPE3 appropriate for moderate-shunt-current applications without additional heatsinking.

How does TLVH431ACLPE3 function in comparator mode?

In comparator mode, TLVH431ACLPE3 operates open-loop: the REF pin receives a scaled version of the monitored voltage, while the cathode drives a load (e.g., optocoupler LED or pull-up resistor). When the REF voltage exceeds 1.24 V, the cathode sinks current sharply-acting as a precision threshold detector. No external reference is needed, and its 100 μA minimum cathode current ensures sufficient gain for clean switching behavior across –40°C to +125°C.

Is TLVH431ACLPE3 compatible with optocoupler-based feedback in isolated power supplies?

Yes, TLVH431ACLPE3 is widely used-and recommended by TI-for secondary-side regulation in isolated flyback and forward converters with optocouplers like PC817. Its 1.24 V reference enables regulation of outputs as low as ~2.7 V (1.24 V + optocoupler LED V_F), and its 100 μA minimum cathode current ensures stable operation even at light loads. TI's Application Report SLUA671 confirms TLVH431ACLPE3's suitability for UCC28600-based designs.